Cementitious material are required to be in the final shape as we required. Say, Cubes, I, cylinder, etc. Cement can be sued with water + some sort of chemicals Or cement + fine aggregates, say mortar OR cement + Fine aggregates + Coarse aggregate.. say concrete.
When cement is mixed with some other material, it may behave not exactly how the cement has to be behaved. So this is must and should that we have to make proper study on this and then only we can use at site level to fulfill the end requirement.
Concrete can be defined as coarse aggregate suspended in the mortar, and the mortar is that in which fine aggregates were suspended in the cement paste and the cement paste is the mixture of cement + water.
Basic rule:
Cement and water are only the react in the hydration process and becomes the binder.
High strength is required = less should be the porosity.
If the porosity is low = Durability will be high.
Hence, the process of hydration and the 3 parameters i.e., Strength, porosity and the durability is inter-dependent.
3 phase system of concrete:
> Aggregate
> Mortar
> ITZ - Interface transition zone - surface of aggregate and the mortar.
ITZ is the resultant of bleeding / segregation process around the aggregates - this effects the micro cracking - strength, material transportation and the durability.
> Mortar
> ITZ - Interface transition zone - surface of aggregate and the mortar.
ITZ is the resultant of bleeding / segregation process around the aggregates - this effects the micro cracking - strength, material transportation and the durability.
Basic properties of concrete:
1. Fresh concrete properties
2. Hardened concrete properties
1. Fresh concrete properties:
a. Workablity: ease of work of concrete at different parts of form work. Testing can be done by:
a.1 Slump cone test - The best testing method - Concrete can be stiff concrete - normal concrete - highly workable concrete.
a.2 Compaction factor test
a.3 Vee-bee test
a.4 Flow table test: https://annayyachandrashekar.blogspot.com/2018/02/flow-test.html
b. Air content: air in concrete in 2 ways, i.e. entrapped and the entrained air (AE).
> More air content - good workability.
> More air content - decreases the strength.
> More air content - good resistance freeze and thawing.
Tested using pressure meter as per ASTM C 232 - https://annayyachandrashekar.blogspot.com/2018/07/method-for-density-unit-weight-yield.html
Non AE - 1 - 2%
AE - 4-6%
c. Temperature: In the process of hydration heat generates and the temperature increases. Tested using normal thermometer.
Concrete casted at temp of 29 Deg C and with 17.5 Hrs temp rises to 63 Deg C and cool down it took 4 days (96 Hrs)
d. Setting time of concrete: Not equal to cement. This parameters helps in desinging the cold joints, form work, concreting rate, etc.
Tested by using penetrometer apparatus. As per IS 8142, initial setting time is determined @ PR = 3.43Mpa and the final setting time = 26.97 Mpa.
e. Bleeding : Movement of water present in the concrete to the top surface after placing.
2. Hardened concrete properties
a. Strength
a.1 - Compression strength
a.2 - Tensile strength
a.3 - Flexural strength
b. Durability
b.1 - Chloride penetration - results in the reinforcement corrosion so chloride permeability test shall be tested using rapid chloride permeabality test as per ASTM C 1202.
b.2 - Alkali aggregate resitivity: Aggregates shall be non-recitative but some are reactive, hence we need to test them.
b.3 -
1. Consider the following sets of statements.
A. Slump is a measure of the workability of concrete.
B. Workability of the concrete is also an indirect measure of its strength.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. Consider the following sets of statements.
A. Increase in the air content in concrete decreases its workability.
B. Air entrainment is recommended for concrete to be used in an environment where
cyclic freezing and thawing of pore water is expected.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. Consider the following set of statements.
A. Strength of concrete increases if the water-cement ratio is increased.
B. Porosity in concrete increases if the water-cement ratio is decreased.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Consider the following sets of statements.
A. Flyash is mixed with other raw materials during blending before heating during the
manufacture of cement.
B. Gypsum is added during the manufacture of cement principally to regulate the setting time of aluminates in the cement.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. Consider the following sets of statements.
A. Concrete used in rigid pavement construction is high workability concrete.
B. Concrete used in a foundation having a heavy reinforcement should be stiff.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. Consider the following sets of statements.
A. Classification of concrete based on the Rapid Chloride Permeability Test is based on ‘Amperes’.
B. The Durability Factor for concrete is estimated for concretes likely to be exposed to alkali aggregate reactions.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. Consider the following sets of statements.
A. The sources of ‘alkalis’ in concrete in the context of AAR is cement.
B. Expansion on account of AAR is attributed to absorption of water by the reaction products of alkalis and reactive silica.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
8. Consider the following sets of statements.
A. Formation of the ITZ around coarse aggregate in concrete is a manifestation of bleeding in concrete.
B.Paste in the ITZ is characterized by a slightly lower water-cement ratio than the paste elsewhere.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
9. With regard to chemical composition of portland cement,
A. The quantity of C3S and C2S is the highest and lowest than that of other compounds respectively.
B. The oxides SiO2 (silica) and Al2O3 (alumina) are present in minor amounts.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
10. With regard to the IS specifications for 33, 43 and 53 grade cements used in India,
A. The initial setting time for the three grades of cement should be lower than 30 minutes.
B. The designation of grades are based on compressive strength achieved at 28 days
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
11. In portland cement
A. Gypsum is added to control the quick reactivity of C3A.
B. The normal dosage of gypsum is in the range of 4%-6%.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
12. The pair of statements are as follows.
A. Unsoundness of portland cement is said to exist if free CaO content is < 0.8%.
B. Unsoundness of portland cement does not exist if MgO content is > 6%.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
13. With regard to the cooling of clinker after burning,
A. Slow cooling of clinker is recommended to increase its reactivity.
B. The temperature range in the cooling zone is 1450 - 25 Deg C.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
14. With regard to the mixing process of raw materials in the production of portland cement,
A. Wet process is preferred over dry process due to lower energy requirement and production cost.
B. Aluminate and Belite are the last compounds formed in the kiln.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
15. With regard to heating or burning process that happens in the kiln,
A. Limestone gets converted to CaO in the ‘Calcination’ zone.
B. Alite gets converted to Belite in the ‘Clinkering’ zone of the kiln.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
16. With regard to the physical properties of portland cement.
A. Grey colour of cement is due to iron content in the raw materials.
B. Blain’s apparatus is used to determine the fineness of cement.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
17. With regard to heating or burning process that happens in the kiln,
A. Significant amounts of carbon-dioxide is evolved in the ‘Clinkering’ zone.
B. C3S is the last compound that is formed in the ‘Calcination’ zone.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
18. With regard to the temperature in the kiln,
A. The temperature range in the ‘Clinkering’ zone is 900 - 1350 Deg C.
B. The temperature range in the ‘Dehydration’ zone is lower than 600 Deg C
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Test No 2
1. With regard to the abrasion test on aggregates,
A. In Los-Angeles abrasion test, the limited value of the percentage weight of aggregates sieved through 1.7 mm sieve is 30% for aggregates to be used for concrete applications other than wearing surfaces.
B. Aggregate samples are subjected to little or no impact loads in Deval’s abrasion test
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. With regard to the chemical properties of aggregates,
A. In soundness test, the loss of weight of aggregates due to soaking in sodium sulfate solution for fine aggregate shall be greater than 10%.
B. One factor that triggers expansion is alkali-silica reaction is availability of moisture.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. With regard to the condition of aggregates exposed to atmosphere:
A. The difference between the weights of aggregates in the saturated wet and saturated surface-dried condition is called ‘water absorption’.
B. If ‘air-dried’ aggregates are used, no additional water is required to be added to the mix or free water while making concrete
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. With regard to the size distribution of aggregates,
A. Cumulative percentage retained values are used to determine the fineness modulus
while cumulative percentage passing values are used to establish grading curve.
B. A fineness modulus value of 8 for an aggregate sample indicates that it is fine
aggregate.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. With regard to the effect of shape of aggregates on concrete property,
A. Rounded aggregates are preferred from the standpoint of workability.
B. Flat and elongated aggregates are preferred from the standpoint of strength.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. With regard to the aggregate production operations,
A. Cone and roller crushers are typical examples of primary and secondary crushers,
respectively.
B. Ball mill grinders are used to reduce large-sized aggregates such as boulders to
small-sized coarse aggregate.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. Two strategies to improve the workability of concrete without changing its proportions
much,
A. Decrease the fine to coarse aggregate proportion keeping all other proportions fixed.
B. Increase the aggregate size.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
8. With regard to the use of air-entraining agents,
A. Crystal pressures are developed when concrete does not have sufficient air-voids of specific size range.
B. Air-entraining agents has polar chains with hydrophilic ends, which helps in
producing air-voids of specific size range.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
9. With regard to the use of chemical admixtures,
A. Accelerators are used to improve workability.
B. The dosage of chemical admixtures is usually greater than 2% by weight of cement
used.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Text 3:
1. With regard to the morphology of compounds present in portland cement
A. The structure of both aluminates and alumino-ferrites can be ‘cubic’ or close to ‘cubic
B. The specific gravity of alumino-ferrites is higher than that of aluminates
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. With regard to ‘burnability’ of clinker,
A. Information about the liquid portion of the clinker can be understood from lime
saturation factor.
B. The ratio of oxides of alumina and iron is not an important factor to determine lime
saturation factor
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. With regard to the basic understanding of shrinkage of PCBPS,
A. For the same w/c, concrete shrinks more than mortars due to the presence of coarse
aggregates
B. For the same w/co, mortar shrinks more than paste due to the presence of fine
aggregates
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Consider the following set of statements
A. The formation of hydrogarnet results in ‘Quick’ set
B. ‘Normal’ set is formed due to the formation of ‘Aft’ or ‘Afm’ or ‘Aft and Afm’
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. With regard to the morphology of hydrated compounds,
A. Ettringite crystals are ‘hexagonal’ shaped
B. The formation of ettringite results in huge consumption of water
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. Consider the following statements:
A. Through-solution mode governs the later age strength development of PCBPSs
B. Silicate ions in cement are very fast in reacting with water to form compounds compared to
other ions
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. Consider the following statements:
A. During the ‘dormant’ and ‘steady’ stage of hydration, the rate of heat evolved is constantly
high
B. Water is not freely available for hydration as soon as the tobermorite gel is formed on the
outer surface of cement grain
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
8. Consider the following statements
A. Capillary pores are larger in size compared to gel pores
B. Small meso pores and interlayer are part of capillary pores
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
9. Consider the following statements
A. Calcium ions in pore solution are consumed during the formation of hydrated
compounds
B. Pore solution primarily contains sulphates after 28 days of curing period
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
10. Consider the following statements
A. Pore size distribution of PCBPS is smaller with curing period or time
B. In MIP, the threshold diameter is actually the size referring to the point of entry of
mercury into the paste
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Test No 4:
1. Consider the following statements
A.Tobermorite gel is formed only after the first six hours of cement hydration
B.The increase in the growth of tobermorite gel results in a decrease in the porosity of
PCBPSs
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. Consider the following statements
A. As the period of curing increases, the degree of cement hydration usually increases
B. Porosity is a direct function of amount of capillary pores in the system
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. Consider the following statements
A. Whether or not capillary and gel pores contain water does not depend on degree of hydration.
B. With an increase in the degree of hydration, the amount of gel pores decreases
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Consider the following statements
A. Evaporable water is the summation of water in the capillary and gel pores together
B. Non-evaporable water content is approximately equal to the chemically combined
water and equal to 0.18a
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. Consider the following statements
A. Porosity, gel-to-space ratio and degree of hydration of PCBPSs are macro-level
parameters, which help in correlating with their strength
B. The gel-to-space ratio is indirectly proportional to the strength of the PCBPSs
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. In PCBPSs,
A. The co-efficient of permeability is higher at early curing periods compared to later
curing periods
B. The co-efficient of permeability increases with increase in the w/c
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. Consider the following statements
A. The distribution and nature of pores controls the strength and permeability of
PCBPSs
B. Capillary pores are interconnected at early curing periods compared to later curing
periods
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
8. Consider the following statements
A. A pour measuring more than 1000m will qualify as 'mass concrete' as per the
definition of mass concrete given by the American Concrete Institute.
B. All concretes placed in concrete dams should be considered as mass concrete.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
9. Consider the following statements
A. Thermal stresses are generated in concrete if the rate of dissipation of heat is lower than the rate of evolution of heat.
B. The temperature in the core of large concrete block may be higher than the
temperature at the surface.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
10. Consider the following statements
A. The amount of heat generated and the heat dissipated are directly related to the
volume and the surface area, respectively, of the concrete pour.
B. In 'normal' concrete construction, thermal stresses are not usually a problem
because the volume of pours is small.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Test No 5:
1. Consider the following statements
A. The relationship between “economic” and “societal” factors is termed as “bearability.”
B. The opportunities for trade comes under “economic factors” whereas that of
productivity comes under “societal factors of sustainability
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. Consider the following statements
A. Sustainable design provides more focus for “economic” and “social” factors
compared to “environmental” factors
B. Mineral admixtures can be used as sustainable design strategy in PCBPSs
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. Consider the following statements
A. Under usual situations, every tonne of portland cement produced in the plant
liberates approximately twice the amount of carbon-dioxide
B. The approximate amount of carbon-dioxide that is present in atmosphere after the
2000 AD is approximately above 350 ppmv
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Consider the following statements
A. Sustainability of portland cement can be improved by using non-renewable
resources in the production process
B. One strategy to incorporate sustainability in the production of portland cement is to
increase the quantity of limestone in the raw materials before burning process
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. Consider the following statements
A. Fly ash particles are more or less spherical in shape
B. The shape of fly ash increases the water requirement for a given slump
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. Consider the following statements
A. The fineness of fly ash is approximately in the range of 160-500 Smtr / kg
B. The specific gravity of fly ash is expressed as a function of its chemical composition and physical characteristics
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. Consider the following statements
A.Fly ash obtained from bituminous coal has higher CaO content than those obtained
from lignitic sources
B.Fly ash obtained from bituminous coal is pale yellow in colour
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Test No 6:
1. Consider the following statements
A. Fly ash can be used in higher amounts for soil stabilization than when it is used in
building blocks and other concrete products
B. In the case of soil stabilization, the conventional wisdom of strength increasing with
a decrease in the water-to-cement (w/c) or water-to-cementitious material (w/cm) ratio, does not apply.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. Consider the following statements
A. The source of coal from which fly ash is obtained plays an important role in deciding
its composition
B. Fly ash obtained from bituminuous variety of coal has higher CaO content than fly
ash obtained from lignitic variety of coal
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. Consider the following statements
A. If the S+A+F content of fly ash from a certain source is 60%, then it can be classified as ‘Class C fly ash.’
B. In addition to the S+A+F content of fly ash, Indian Standard provides limits for the
amount of silica and reactive silica present in fly ash
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Consider the following statements
A. During pozzolanic reaction of fly ash particles, the C/S ratio of the secondary C-S-H gel formed is < 1.5.
B. Recommended dosage of fly ash for cement based application as per IS specification is 15%-60%.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. Consider the following statements
A. The heat of hydration of PCBPS increases and its setting time decreases with the
addition of fly ash at recommended dosage levels
B. Fly ash mixtures provide higher early-age strength and lower later-age strength
compared to mixtures that do not contain fly ash
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. Consider the following statements
A. Silica fume is obtained as a by-product from the production of iron or copper
B. Quartz can be one raw material in the production of silica fume
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. Consider the following statements
A. The very fine size of silica fume particle increase the water demand of PCBPSs
B. The bulk density of silica fume in agglomerated form is higher than in undensified form
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
8. As per IS specifications,
A. The minimum quantity of silica present in silica fume is 95%
B. The minimum 7-day compressive strength of mixtures containing silica fume is 95% that of control mixture
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
9. Consider the following statements
A. The recommended range of dosage level for slag as a pozzolanic material in PCBPS is ~25%-40%
B. Segregation and bleeding potential increases with the addition of silica fume
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Test No 7
1. In context of low heat of hydration cement as defined by Indian standards
A. The maximum heat of hydration is given only at 7 days
B. The maximum initial setting time is given as 60 minutes
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. In the rapid chloride penetration test
A. Current is passed for 3 hrs
B. A voltage of 60V is impressed across the two faces of the concrete disc
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. In the salt ponding test
A. The test is carried out for 75 days
B. the minimum thickness of the concrete specimens is 90 mm
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Hydration of cement leads to
A. Reduction in total pore volume
B. Refinement of pore structure
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. As per the classification of ASTM for early strength cement
A. The minimum fineness required is 365 Smtr /kg as compared to 550 Smtr/kg for general cement
B. Tri calcium silicate content required is about half that in general cement
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. Consider the following set of statements
A. Entrapped air voids can sometimes be seen on surface on a core of concrete
B. In a suspension of cement particles in water, the former tend to form flocs
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. In mercury intrusion porosimetry
A. As the applied pressure is increased, larger pores get filled
B. The total intrusion volume data can be used to obtain differential intrusion volume
data
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Test No 8
1. Consider the following statements
A. Strength of concrete, S, can be modelled as S = S0 [exp(-kp)], where S0 and p are the strength of the coarse aggregate, and, the porosity of the hardened cement paste, respectively with k being an empirical constant.
B. The strength of the concrete determined using cubical specimens is higher than that determined using cylindrical specimens.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. Consider the following statements
A. The stress strain curve for concrete in tension may be taken to be same as that in
compression.
B. The stress strain curve of concrete shows a clear yield point.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. Consider the following statements
A. Concrete is cured to prevent bleeding.
B. Steam curing is used in cases where higher early strength is required.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Consider the following statements
A. For the same total volume of pores, the shrinkage in a cement paste with a higher volume of large pores will be lower than a paste with a higher volume of smaller sized pores.
B. For the same total volume of pores, the strength of a cement paste with a higher volume of large pores will be lower than a paste with a higher volume of smaller sized pores.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. Consider the following statements
A. IS 456-2000 divides the environmental conditions of exposure for concrete into five classes.
B. As per IS 456-2000 The minimum grade of concrete that can be used in reinforced concrete is M20.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. Consider the following statements
A. As the age at loading increases, the concrete shows less creep strain for the same elastic strain so long as the elastic strains are not very high.
B. Creep is the change in stress levels for a constant level of strain or deformation.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. When determining the compressive strength of concrete as per Indian Standards
A. The cubes taken during concrete construction should be sprayed with curing compounds immediately after being taken out of the moulds.
B. The cubes should be removed from the curing pond and completely dried before testing.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
8. A concrete mix design uses 1200 kg of coarse aggregate and 350 kg cement per Cmtr
of concrete. A small mixer is being used and there is only 50 kg of cement per batch. Volume batching is used to measure the raw materials. The length and width of the box is known to be 40 cm and 30 cm respectively. It is known that 3 boxes of aggregate were used for a batch of concrete. Assuming 40% voids in a coarse aggregate filled box and specific gravity of coarse aggregate to be 2.75, the height of the box is........:
43.3 cm
33.3 cm
25.5 cm
28.9 cm
Explanation:
Aggregate corresponding to 50 kg of cement = 1200 / 350 X 50 = 171.42kg
Volume of aggregate = 171.42 Kg / 2.75 = 62.3 Ltr
Volume of aggregate in one box = 62.3/ 3 = 20.78 liter
Let h be the height of box, then 40 𝑥 30 𝑥 ℎ 𝑥 0.6 / 1000 = 20.78 Thus h = 28.9 cm
9. In a mix design, per 1 Cmtr of concrete, 170 kg water, 400kg cement 666 kg sand, 460kg 10 mm aggregate and 694 kg 20 mm aggregate were used. Specific gravity of cement and aggregates are 3.14 and 2.59 respectively. The percentage paste content and mortar content in concrete by volume is _____ and _______ respectively.
29.7 and 55.4
55.4 and 29.7
47.4 and 55.4
29.7 and 47.4
Explanation:
Volume of water Vw = 170 liter
Volume of cement Vc = 400 / 3.14 =127.38 liter
Volume of sand Vs = 666 / 2.59 = 257.14 liter
Volume of coarse aggregates Vca = (460+694) / 2.59 = 445.55
Total volume = 1000 lites
Volume of paste Vp = Vc + Vw = 170+ 127.38 = 297.38 liter
% volume of paste = 29.7
Volume of mortar = Vp + Vs = 297.38+257.14 = 554.52 liter
% volume mortar = 55.4
Unit Test No 1:
1. Addition of pozzolana to Ordinary Portland Cement (OPC), causes
Decrease in the early strength
Increase in later age strength with curing
Reduction in bleeding
All of the above
2. Which of the following statements is True
If excess lime is present in cement, it causes the cement paste to expand and disintegrate
If excess silica is present in cement, it causes the cement paste to set slowly
If excess alumina is present in cement, it reduces the strength of the cement
All the above
3. The type of cement most suitable to construct a concrete dam, is
Ordinary Portland cement
Rapid hardening cement
Low heat cement
Sulfate resistant cement
4. Concrete attains its full strength after ____ of curing under water.
7 days
14 days
28 days
None of these
5. Which of the following factors affect the workability of concrete
Water content and its temperature
Shape and size of the aggregates
Grading and surface textures of the aggregates
All the above
6. The top diameter, bottom diameter and the height of a slump mouldare
10 cm, 20 cm, 30 cm
10 cm, 30 cm, 20 cm
20 cm, 10 cm, 30 cm
20 cm, 30 cm, 10 cm
7. Vicat apparatus is used for determining ___ of the cement
Fineness
Consistency
Compressive strength
Soundness
8. For a concrete with a water-cement ratio of 0.6, and unit water content of 180 kgs/Cmtr, the absolute volume of cement in the mix is ____ liter. (Take the specific gravity of cement as 3.15 if required)
300
108
95.2
34.2
9. The increased cohesiveness of concrete, makes it
Less liable to segregation
More flowable
More liable to bleeding
More pumpable
10. Which of the following is the ‘odd’ test of the following
Slump test of concrete
Air content in concrete
Bleeding of concrete
Compressive strength of concrete
Unit Test No 2:
1. Consider the following set of statements:
A. Workability of concrete increases if either (a) Unit water content, or, (b) the entrained air
content, in the mix is increased.
B. Use of concretes with a high water-cement ratio is recommended in environment where cyclic freezing and thawing is expected.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
2. Consider the following set of statements:
A. Rate of rise of temperature during the hydration is constant regardless of the temperature of the atmosphere.
B. Time taken to reach maximum temperature during hydration of concrete is longer than the time taken to reach the atmospheric temperature after maximum (peak) temperature has been reached.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
3. Consider the following set of statements:
A. Strength of concrete increases as its workability decreases.
B. If the maximum size of the aggregate is reduced, the workability of concrete increases.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
4. Consider the following set of statements in the context of ITZ formation in concrete:
A. It essentially becomes a weak link and promotes ingress of deleterious substances within concrete.
B. It is a manifestation of local bleeding within concrete.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
5. Consider the following sets of statements in the context of damage in concrete in beams
in framed reinforced concrete structure due to alkali-aggregate reactions:
A. Beams in a interior of the structure, not exposed to rainwater, show lower levels of deterioration compared to beams on the outside (exposed) of the frame.
B. Higher chloride penetration may be expected in a marine structure cast with reactive
aggregates than a similar structure cast with non-reactive aggregates.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
6. Consider the following sets of statements.
A. During manufacture of cement C3S is formed as the last compound.
B. Rapid cooling of clinkers produces large crystals of each phase than slow cooling.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
7. Consider the following set of statements:
A. Consumption of chemical admixture increases as fineness of cement is increased.
B. For a given w/c, finer cement gives more strength during the initial hydration than coarser cement.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
8. Which of the following option represents the correct match
1 Alite A C2S
2 Belite B MgO
3 Brucite C C3S
4 Periclase D Mg(OH)2
1-A, 2-B, 3-C, 4-D
1-C, 2-A, 3-D, 4-B
1-A, 2-C, 3-B, 4-D
1-A, 2-C, 3-D, 4-B
9. Consider the following set of statements:
A. Carbon dioxide is released in calcination zone of the kiln during cement production.
B. In clinkering zone Alite converts to Belite.
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Unit Test No 3:
A. Log-Angeles and Deval’s test is primarily used for understanding the mechanical
properties of coarse aggregates
B. The sieve size that is used to screen the processed fractions in Los-Angeles abrasion
test for qualifying aggregates for concrete application is 4.75 mm
1 point1)
a. Both statements are True
b. Both statements are False
c. Statement A is False and B is True
d. Statement A is True and B is False
2. Consider the following statements:
A. In soundness test for coarse aggregates, the limited value for the loss of weight of aggregates
due to soaking in magnesium sulfate solution is 18%
B. The pores in rocks are usually discontinuous and their porosity values rarely
exceeds 10%
a. Both statements are True
b. Both statements are False
c. Statement A is False and B is True
d. Statement A is True and B is False
3) Consider the following statements:
A. The difference between the weights of aggregates in the saturated wet and saturated surface dried condition expressed as a percentage is called ‘water absorption’
B. The crusher in which non-spherical rigid metal thick blades are carefully positioned to break aggregates through tange ntial hit mechanism is ‘roller’ crusher
a. Both statements are True
b. Both statements are False
c. Statement A is False and B is True d. Statement A is True and B is False
4) Consider the following statements:
A. Flat and elongated aggregates are not preferred for concrete due to heterogeneity and other
segregation problems
B. Soundness tests for cement and aggregates are meant to understand chemical
properties of ingredients
a. Both statements are True
b. Both statements are False
c. Statement A is False and B is True
d. Statement A is True and B is False
5) Consider the following statements:
A.Primary crushers are used to reduce aggregates to lower than 4.75 microns size
B.Rounded aggregates are preferred from the standpoint of workability
a. Both statements are True
b. Both statements are False
c. Statement A is False and B is True
d. Statement A is True and B is False
6) Consider the following statements:
A. By decreasing the fine to coarse aggregate proportion keeping all other proportions fixed, the
workability of concrete can be increased
B. Fine aggregates can have fineness modulus value of 3.5 as per IS standards
a. Both statements are True
b. Both statements are False
c. Statement A is False and B is True
d. Statement A is True and B is False
7) Consider the following statements:
A. Entraining air of specified size range in concrete can help in relieving crystal pressures in
freeze-thaw environments
B. Air-entraining admixtures and retarders are typical examples of set-control
admixtures
a. Both statements are True
b. Both statements are False
c. Statement A is False and B is True
d. Statement A is True and B is False
Unit Test No w3-a3:
Consider the following statements:
A. The alkali content in cement can change the crystal structure of C3A.
B. The ionic form of aluminate in C3A is AlO2
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
A. Certain amount of CaO constituted from gypsum should be subtracted from the LSF of portland cement in order to arrive at the LSF of portland clinker
B. LSF > 1 indicates that alite to belite ratio is high
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
A.ITZ is a weak zone that contains higher amounts of water, portlandite and tobermorite
B.Aggregates are inert in nature and their presence or properties are not vital in deciding the
properties of concrete
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
A. Afm’ refers to ‘Monosulphoaluminates’
B. ‘Tobermorite’ refers to ‘C-S-H’ gel
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
A. The calcium and silicate ions dissociate faster than aluminate and sulphate ions during the early stages of cement hydration process to form C-S-H gel
B. The total heat evolved during the ‘acceleration’ stage of cement hydration is higher than the total heat evolved during the ‘deceleration’ stage
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
A. Shrinkage effects in PCBPS are related to the changes in its porosity
B. Heat of hydration of PCBPS is a measure of the enthalpy of the reaction
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
A. Pore size distribution of cement paste is measured using mercury intrusion porosimetry (MIP) technique
B. In MIP, the threshold diameter is actually the size referring to the point of entry of
mercury into the paste
Both statements are True
Both statements are False
Statement A is False and B is True
Statement A is True and B is False
Unit Test No w4-a4:
Some of the Common question:
1. In the context of chemical complexes in ordinary portland cement, identify the FALSE statement.
a. One of the hydration products of C3S is referred to as tobermorite gel
b. C3S, C2S, C3A and C4AF are generally referred to as ‘Bogues compounds’
c. C2S is responsible for the later-age strength gain during the hydration of cement
d. C3A and C4AF react during the first 2 to 4 hours after water is added to portland cement
2. In the context of addition of gypsum during the manufacture of portland cement, identify the TRUE statement.
a. The addition of gypsum affects the setting time behavior of cement
b. Gypsum affects the strength development of cement
c. Gypsum affects both the setting time and strength development behavior of cement
d. Gypsum neither affects the setting time nor strength development behavior of cement
3. In the context of fineness of cement, identify the FALSE statement.
a. Fineness of cement is determined using the Blaine’s apparatus
b. The rate of heat of hydration is independent of the fineness of cement
c. The shrinkage of cement paste increases with the increase in the fineness of cement
d. The fineness of 53-grade cement is higher than the fineness of 33-grade cement
4. In the context of coarse aggregate used in concrete, identify the TRUE statement.
a. Flaky aggregates increase the strength of concrete due to interlocking between aggregates
b. Rounded aggregates increase the workability of concrete due to higher paste requirement
c. Gradation of aggregates (particle size distribution) is not an important criterion in the selection of aggregates
d. According to the provisions of IS 456:2000, the nominal maximum size of aggregate should be less than ¼ of the minimum thickness of member
5. In the context of concrete, identify the FALSE statement.
a. For the same w/c ratio, the strength of concrete is higher than that of cement paste and mortar
b. According to the provisions of IS 10262, the target mean strength of concrete mix should be equal to the characteristic strength plus 1.65 times the standard deviation
c. Stress strain curve of concrete may be taken to be linear upto about 30-40% of the ultimate load (strength)
d. Concrete shows strain softening behavior after the ultimate load in a strain-controlled test
1. Identify the TRUE statement with regard to the chemical composition of portland cement
a. Both SiO2 and Al2O3 are present in almost equal amounts
b. Both Na2O and K2O are present in small quantities and contribute to the alkali content of the cement
c. SiO2 is the highest among all other oxides
d. CaO is a minor compound
2. Identify the TRUE statement with regard to the workability tests for concrete
a. Flow table test is more suitable for highly workable concretes
b. Both slump cone and compaction factor tests are recommended for very low workable concretes
c. Both Vee-Bee and compaction factor tests are recommended for highly workable concretes
d. Both flow table and compaction factor tests are recommended for stiffer concretes
3. Identify the FALSE statement with regard to the production of portland cement
a. Only C3A is produced at temperature above 1000 °C
b. C3A is produced in the clinkering zone of the kiln
c. C3S is produced in the clinkering zone of the kiln at temperature above 1000 °C
d. Both C2S and C4AF are produced in the calcination zone of the kiln
4. Identify the FALSE statement with regard to the IS specifications for grades of portland cement
a. The initial setting time for the three grades of cement should be higher than 30 minutes
b. The final setting time for the three grades of cement should be lower than 10 hours
c. The maximum specified fineness for all grades of cement is 225 m2/kg
d. The designation of grades is based on compressive strength of mortar cubes achieved at 28 days
5. Identify the TRUE statement with regard to the Interfacial Transition Zone (ITZ) of concrete
a. Ingress of deleterious substances in concrete is not possible through ITZ
b. w/c is lower in ITZ than in the main body of mortar
c. Segregation encourage the formation of ITZ
d. The strength of concrete is not affected by ITZ
6. Identify the TRUE statement with regard to the Alkali Aggregate Reaction (AAR) of concrete
a. AAR is caused due to the presence of alkali and reactive aggregate
b. Increase in the ingress of deleterious substances may be expected with reactive aggregates
c. In AAR, cracking initiates on the cement paste
d. Total alkali content of concrete (not cement) is usually calculated in terms of Na2O or K2O equivalent
7. Identify the TRUE statement with regard to the cooling zone in the production of portland cement
a. Rapid cooling of clinker is preferred as it allows MgO to be contained in the crystal phases of compounds as impurities, which can otherwise cause unsoundness
b. Slow cooling of clinker is preferred due to better thermal stability attained during the cooling phase
c. Reactivity of unhydrated compounds are independent of the rate of cooling
d. Slow cooling of clinker produces larger crystals which helps in reducing the energy required to grind the clinker
8. Identify the FALSE statement with regard to the fineness of cement
a. Wagner’s turbidimeter is one of the methods used to measure fineness
b. Higher specific surface area of cement grains indicates reduced particle size
c. Higher cement fineness increases the rate of hydration reaction
d. The properties of concrete is independent of the cement fineness
9. Identify the FALSE statement with regard to the production process of portland cement
a. Significant amounts of carbon-dioxide are evolved in the calcination zone
b. C3S is the first compound that is formed in the ‘Calcination’ zone
c. Limestone gets converted to CaO in the ‘Calcination’ zone
d. Belite gets converted to Alite in the ‘Clinkering’ zone
10 Figure (1) and Figure (2) given below illustrate two models that can be used to study the response of concrete to applied compressive load. Identify the FALSE statement.
a. The strain in the mortar and coarse aggregate phases for configuration shown in Figure 1 is the same
b. The stress in the mortar and coarse aggregate phases for configuration shown in Figure 2 is the same
c. The load carried by the mortar and coarse aggregate phases for configuration shown in Figure 1 is the same
d. The load carried by the mortar and coarse aggregate phases for the configuration shown in Figure 2 is the same
a. In impact crusher, the aggregates get broken through rolling mechanism of two rollers
b. Both roller crusher and jaw crusher are types of secondary crusher
c. Primary crusher is used to reduce large-sized aggregates such as boulders to small-sized coarse aggregatesd. Secondary crusher is used to reduce aggregates to sizes lower than 4.75 microns
2. Identify the TRUE statement with regard to the shape of coarse aggregate used in concrete
a. Rounded aggregates have higher surface to volume ratio and require higher amount of paste to fully coat the aggregate surfaces as compared to crushed aggregates
b. Flat and elongated aggregates are preferred from the standpoint of strength
c. Angular aggregates are crushed rocks having more or less defined edges
d. Flaky aggregates have higher thickness as compared to their other two dimensions
3. Identify the TRUE statement with regard to the size and gradation of aggregates used in concrete
a. According to IS 456:2000, the nominal maximum size of aggregates is usually taken as 5 mm less than the maximum size of aggregates in a given aggregate sample
b. IS specifications do not allow combined gradation of coarse and fine aggregates to be used in concrete
c. Using larger maximum size of aggregates results in increased volume of voids in the system
d. Using large-sized aggregates affect the workability of concrete
4. Identify the FALSE statement with regard to the gradation of aggregates used in concrete
a. According to IS 383, fine aggregates conforming to Zone IV should not be used in reinforced concrete
b. According to IS 383, Zone II sand has higher fineness modulus than Zone III sand
c. Two aggregates samples with different grading curves can have same values of fineness modulus
d. According to IS 2386, 5% tolerance in the variability of gradation is acceptable on all the IS designated sieves
5. Identify the FALSE statement with regard to the properties of natural aggregates
a. The coefficient of permeability typically varies from 10-8 to 10-12 cm/s
b. As per IS, the loss of weight of fine aggregates due to soaking in sodium sulfate solution in a soundness test should not exceed 18% for the aggregate to be used in reinforced concretec. Petrographic examination is one of the methods to determine the potential alkali aggregate reactivity of an aggregate sample
d. The percentage of volume of pores or porosity is usually very low
6. Identify the FALSE statement with regard to the mechanical properties of coarse aggregates
a. The mechanism of abrasion action in Devel’s abrasion and Los Angeles abrasion drum are not differentb. In the Impact test for aggregates, higher weight of sample passing through 2.36 mm sieve at the end of the test indicates weaker aggregates
c. In Los Angeles abrasion test, aggregate gradation plays an important role in deciding the number of steel ball to be used as external charge
d. Aggregates can be used in concrete if their crushing value is higher than 30% and lower than 45%
7. Consider the data for sieve analysis of a coarse aggregate sample given in the following table.
Which of the following values correctly indicate the fineness modulus of the aggregate sample?
a. 6.0
b. 6.5
c. 7.0
d. 7.5
8. Identify the TRUE statement with regard to the use of accelerators in concrete construction
a. Accelerators are used during colder environments to increase the setting time of concrete
b. The IS 9103 has the provision that 28 days compressive strength of the sample containing accelerators should not be less than 90% of the control sample c. The dosage of accelerators should not exceed 4% by weight of cement used
d. The IS 9103 have the provision that after 28 days of water curing, the flexural strength of the sample containing accelerators should not be less than 90% of the control sample
9. Identify the FALSE statement with regard to use of air entrainment agents in concrete
a. Air entraining agent create unfrozen pore to relieve hydraulic pressure
b. Their effectiveness can be evaluated by measuring the air content of fresh concrete using pressure method, volumetric method and gravimetric method.
c. The air content of air-entrained concrete mixture is in the range of 3.5-7% by volume
d. They have non-polar molecular chain with hydrophilic end
10. Identify the FALSE statement with regard to the use of water reducing admixtures (WRAs) in concrete
a. WRAs are added directly to the mix water during the mixing of ingredients in the production of concrete to avoid dispersion problems
b. WRAs can be used to reduce the cement content in a concrete mix and thereby help in the development of high strength concrete
c. WRAs contain salts of lignosulfonic acids or hydroxylated carboxylic acids
d. According to provisions in IS 9103, the , the 28 days compressive strength of concrete containing WRAs should be at least 25% more than the control concrete
1. Identify the FALSE statement with regards to the morphology of compounds present in ordinary portland cement
a. The structure of silicates in alite and belite can be explained as more or less ‘hexagonal’ or ‘prismatic’
b. The silicate ions in alite and belite exist as ‘orthosilicates’
c. The structure of both aluminates and alumino-ferrites is ‘cubic’ or close to ‘cubic’
d. The specific gravity of C4AF is higher than that of C3A
2. The following table lists the quantity of various oxides present in a sample of cement. The C3S and C3A content in the cement sample is _____ and_____ respectively.
[Hint: Use the appropriate set of Bogue’s equations, given below for your reference, based on A/F ratio]
Bogue’s equation set 1
C3S = 4.071C – 7.600S – 6.718A – 1.430F – 2.852S̅
C2S = 2.867S – 0.7544C3S
C3A = 2.650A – 1.692F
C4AF = 3.043F
Bogue’s equation set 2
C3S = 4.071C – 7.600S – 4.479A – 2.859F – 2.852S̅
C2S = 2.867S – 0.7544C3S
C3A = 0
C4AF = 2.100A + 1.702F
a. 65.0, zero
b. 55.3, 11.5
c. 11.17, zero
d. 18.5, 11.5
3. Identify the TRUE statement with regards to the reactivity of clinker compound
a. Slow cooling increases the reactivity of compounds
b. C2S and C3S both are slow reactive compounds in cement clinker
c. C4AF compound rapidly react with the water because of the presence of the aluminates
d. Burnability and cooling of clinker are extremely important from the standpoint of reactivity of clinker compounds
4. Identify the FALSE statement with regards to the hydration of C3A
a. Monosulphates are formed due to the reaction between ettringite and C3A because of lack of sulphates
b. Normal set is a condition that results in the formation of ettringite
c. Quick set is a condition that arises when very less sulfates are present
d. False set is a condition that results in the formation of hydrogarnet
5. Identify the TRUE statement with regards to the hydration mechanism of ordinary portland cement
a. Water is not freely available for hydration in the topo-chemical mode of hydration reaction
b. The total quantity of tobermorite gel is higher during the through-solution period than the topochemical period of cement hydration
c. Through-solution hydration mechanism is perceived to be dominant during the period when water is added to cement to the time when the initial setting time has reached
d. The total heat evolved during the ‘acceleration’ stage of cement hydration is higher than the total heat evolved during the ‘deceleration’ stage
6. Identify the TRUE statement with regards to the heat of hydration liberated during the hydration of Ordinary Portland Cement
a. On account of liberation of heat of hydration in a concrete pour, lower temperatures may be expected to exist at the surface of concrete than at its core
b. The total heat liberated per gram of ordinary portland cement is independent of the composition of cement
c. The rate of heat liberation is independent of the fineness of the cement
d. The heat of hydration of cement liberated in a concrete is dissipated only through the surfaces of the concrete in contact with the atmosphere
7. Identify the TRUE statement with regards to the hydration of ordinary portland cement
a. In the dormant period, the kinetics of reaction of cement is chemical control and helps in determining the initial set
b. The acceleration period determines the rate of hardening and initiates the formation of hydration product
c. In the deacceleration period, the kinetics of reaction is nucleation control and helps in determining the rate of early strength gain
d. The steady state period determines the later age strength gain as it occurs after the topochemical hydration of cement stops
8. Identify the FALSE statement with regards to hydration products formed as a result of the reaction between OPC and water
a. Tobormorite gel has a high surface area and occupies higher solid volume than calcium hydroxide (CH)
b. CH helps in maintaining the pH of the pore solution in the range of 12-13
c. Aft have a prismatic long needle like structure whereas the structure of Afm can be described as non-porous hexagonal prisms
d. Aft contributes to stiffening of mixtures and strength development at early ages
9. Identify the FALSE statement with regards to the porosity in hydrated cement paste (hcp)
a. The quantity of alkali ions in the pore solution is the highest after 28 days of curing period compared to all other ions
b. In mercury intrusion porosimetry (MIP), the threshold diameter is actually the size referring to the point of entry of mercury into the paste
c. Shrinkage and creep are the properties of concrete affected by the presence of the micropores in the hcp
d. Bug holes are formed in concrete due to the entrapment of air and have adverse effect of increasing the porosity and permeability of the concrete
10. Identify the FALSE statement with regards to the porosity in hydrated cement paste (hcp)
a. At early curing periods, the porosity is low since the capillary pores are not inter-connected
b. Micro-level parameters such as porosity and pore size distribution govern the strength and permeability of hcp
c. Chemically combined water and water in the mesopores are important components of gel pore water
d. While comparing different hcps having pore connectivity, their permeability increases with increase in the w/c used
1. Identify the FALSE statement with regard to the Power’s model for hydration of portland cement based paste system (PCBPS)
a. Cement gels are basically considered as colloids
b. The model establishes the relationship between volume of gel and strength of PCBPS
c. The model establishes the relationship between porosity and strength of PCBPS
d. The model is applicable for all curing conditions
2. Identify the FALSE statement with regard to portland cement based paste systems (PCBPSs)
a. C-S-H gel does not exert crystal pressure during its growth due to limited space within the system
b. Aft exerts crystal pressure during its growth due to limited space within the system
c. Degree of hydration increases with increase in the time of curing
d. Degree of hydration of cement system is unaffected by the presence of impurities in C3S and C2S
3. Identify the TRUE statement with regard to degree of hydration of ordinary portland cement
a. Degree of cement hydration is independent of w/c ratio
b. Both degree of cement hydration and porosity increases as the period of curing increases
c. Evaporable water content is a measure of the chemically combined water directly present in hydrated compounds
d. The hydration of C3A is rapid without gypsum
4. Identify the TRUE statement with regard to portland cement based paste systems (PCBPSs)
a. Evaporable water considers only the water present in capillary pores
b. The amount of water in the pores (both gel and capillary pores) is independent of the w/c ratio
c. The amount of gel pores at 28 day curing period in PCBPSs having different w/c ratio may be taken to be equal
d. The minimum w/c ratio for complete hydration of PCBPS with gel pores fully saturated is 0.42
5. Identify the TRUE statement with regard to portland cement based paste systems (PCBPSs)
a. For a fully saturated system, the amount of non-evaporable water is higher than evaporable water
b. For a fully saturated system, the sum of evaporable and non-evaporable water is about 36%
c. The strength of PCBPSs increases as the gel-to-space ratio in the system increases
d. Compared to C3S, the rate of hydration for both C3A and C2S is lower
6. Identify the FALSE statement with regard to portland cement based paste systems (PCBPSs)
a. Washburn’s equation is used to calculate the porosity of PCBPSs
b. At early curing periods, the porosity of the system is low since the capillary pores are disconnected
c. Irrespective of the w/c ratio, the permeability of PCBPS typically in the range of about 10-5 to 10-13 m/s
d. The size of connected capillary pores in system is measured in terms of effective or critical pore access diameter
7. Identify the FALSE statement with regard to heat of hydration of portland cement based paste systems (PCBPSs)
a. The total heat evolved at any instant of time within the system is related to the heat of hydration of the individual Bogue’s compounds and their quantities present in cement
b. For casting concrete in low temperature environments, the heat of hydration values are beneficial as its provides information about the activation energy for hydration
c. The total heat evolution trend helps to understand precisely the chemical reactions occurring during the cement hydration process
d. Specific heat of concrete is one parameter that determines the dissipation of heat within concrete
8. Identify the FALSE statement with regard to heat of hydration of portland cement based paste systems
a. Thermal stresses are generated inside concrete if the rate of dissipation of heat is lower than the rate of evolution of heat
b. The time taken to reach the maximum temperature in a concrete mixture increases with the increase in the thickness of the member
c. The rate of heat evolution during hydration of C3A decreases with increase in the amount of the gypsum present in cement
d. Coefficient of thermal expansion of coarse aggregates is one parameter that determine the heat of hydration in concrete
9. Identify the TRUE statement with regard to mass concrete
a. Cement used should have lower C2S and C3A from the standpoint of temperature rise in concrete
b. Reducing the cement content by using higher coarse aggregate content helps in reducing the temperature rise
c. Cement having lower fineness is preferred as it allows the dissipation of heat at a faster rate
d. The heat dissipation is easier in members having larger volume-to-surface area ratio
10. Identify the TRUE statement with regard to Thermal Cracking Index (TCI)
a. Thermal Cracking Index (TCI) as defined as the ratio of the instantaneous thermal stress to the instantaneous tensile strength of the concrete
b. Thermal Cracking Index (TCI) is an intrinsic property of a given concrete
c. An equation of the type E=5000√fck can be used in the computation of the TCI
d. As the TCI increases, the likelihood of occurrence of thermal cracking in the concrete also increases
W5-A5
1. Identify the TRUE statement with regard to the sustainability
1.Identify the TRUE statement with regards to the portland cement based paste systems (PCBPS)
a. As per IS 12600, both initial and final setting time of low heat cement are higher than the ordinary portland cement
b. Low heat cement has higher C2S content than any other types of portland cement
c. Sulfate resistance cement has higher C3A content than the ordinary portland cement
d. High early strength cement has larger average particle size than the ordinary portland cement
2. Identify the TRUE statement with regards to the mercury intrusion porosimetry and its use in porosity related studies of cement paste and concrete
a. As the age of concrete increases, the threshold diameter of pores decreases
b. The total intrusion volume data cannot be used to obtain the differential intrusion volume data
c. Mercury is preferred for use because it wets the surface of the pore walls
d. The ‘critical diameter’ indicates the average size of pores at which the onset of permeation of mercury into the sample occurs
3. Identify the TRUE statement with regards to the porosity studies of cementitious materials
a. If two different cement paste samples have same porosity (in terms of grams per cc), it implies that the pore size distribution of the two samples should also be identical
b. Porosity is directly related to the amount of capillary pores in the system
c. A higher range of pore size in portland cement based paste systems (PCBPSs) can be observed with the increase in the curing period
d. Porosity and permeability can be related to each other when the pore connectivity in the pore system is low
4. Identify the FALSE statement with regards to the porosity studies of cementitious materials
a. The addition of fly ash results in the refinement of porosity and pore size distribution of portland cement based paste systems (PCBPSs)
b. When comparing cement pastes of same porosity, the paste with lower volume of larger pores will have higher strength
c. At early curing periods, the porosity is low because the capillary pores have lesser connectivity
d. The refinement of pore structure of PCBPS is the result of the continued hydration
5. Identify the FALSE statement with regard to the permeability of concrete
a. The strength of concrete increases as its permeability decreases
b. The macropores and large mesopores both affect the permeability of concrete
c. Inter connected pores allow more transport of deleterious materials in concrete during the service life of the structure
d. At early curing periods, the permeability is low because the capillary pores have lower connectivity
6. Identify the TRUE statement with regard to the rapid chloride permeability test used for concrete
a. Classification of concrete based on the rapid chloride permeability test is based on charge passed expressed in ‘Coulombs’
d. Reservoirs used in the test are filled with 0.3M NaCl and 0.3M NaOH solutions
c. The method for carrying out the test is given in ASTM C1201
d. In the test, a potential difference of 60V is applied across the two faces of concrete disc for a 3-hour period
7. Identify the FALSE statement with regard to the salt ponding test used for concrete
a. The ponding in the test is carried out for a period of 90 days
b. A 3% NaCl solution is used for ponding the surface
c. Specimens are moist cured for 14 days and then stored in drying room at 100% relative humidity for 50 days before testing
d. The method for carrying out the test is given in AASHTO T259
8. Identify the FALSE statement with regard to the determination of water permeability of concrete
a. The method is mostly suited for concrete with high permeability
b. In modified water permeability test method, the test is carried out on concrete disc
c. In modified water permeability test, the depth of penetration is taken as a measure of permeability
d. The test is carried out by applying pressure on water to accelerate and facilitate penetration of water into the concrete
9. Consider the information given in the following table regarding the different types of cement as per ASTM standards, and properties or use of the cement.
Which of the following correctly matches the types and the properties of the cement?
1-A, 2-C, 3-B, 4-E, 5-D
1-E, 2-A, 3-D, 4-C, 5-B
1-B, 2-D, 3-A, 4-C, 5-E
1-D, 2-E, 3-B, 4-A, 5-C
10. Consider the following table giving the constituents of concrete in one column and approximate range of volume occupied by different constituents.
Which of the following correctly matches the different constituents and their volume fractions in normal concrete?
1-D, 2-C, 3-A, 4-E, 5-B
1-E, 2-D, 3-A, 4-B, 5-C
1-E, 2-D, 3-A, 4-B, 5-C
1-C, 2-D, 3-E, 4-A, 5-B
You may submit any number of times before the due date. The final submission will be considered for grading.
8W-8A
b. 55.3, 11.5
c. 11.17, zero
d. 18.5, 11.5
3. Identify the TRUE statement with regards to the reactivity of clinker compound
a. Slow cooling increases the reactivity of compounds
b. C2S and C3S both are slow reactive compounds in cement clinker
c. C4AF compound rapidly react with the water because of the presence of the aluminates
d. Burnability and cooling of clinker are extremely important from the standpoint of reactivity of clinker compounds
4. Identify the FALSE statement with regards to the hydration of C3A
a. Monosulphates are formed due to the reaction between ettringite and C3A because of lack of sulphates
b. Normal set is a condition that results in the formation of ettringite
c. Quick set is a condition that arises when very less sulfates are present
d. False set is a condition that results in the formation of hydrogarnet
5. Identify the TRUE statement with regards to the hydration mechanism of ordinary portland cement
a. Water is not freely available for hydration in the topo-chemical mode of hydration reaction
b. The total quantity of tobermorite gel is higher during the through-solution period than the topochemical period of cement hydration
c. Through-solution hydration mechanism is perceived to be dominant during the period when water is added to cement to the time when the initial setting time has reached
d. The total heat evolved during the ‘acceleration’ stage of cement hydration is higher than the total heat evolved during the ‘deceleration’ stage
6. Identify the TRUE statement with regards to the heat of hydration liberated during the hydration of Ordinary Portland Cement
a. On account of liberation of heat of hydration in a concrete pour, lower temperatures may be expected to exist at the surface of concrete than at its core
b. The total heat liberated per gram of ordinary portland cement is independent of the composition of cement
c. The rate of heat liberation is independent of the fineness of the cement
d. The heat of hydration of cement liberated in a concrete is dissipated only through the surfaces of the concrete in contact with the atmosphere
7. Identify the TRUE statement with regards to the hydration of ordinary portland cement
a. In the dormant period, the kinetics of reaction of cement is chemical control and helps in determining the initial set
b. The acceleration period determines the rate of hardening and initiates the formation of hydration product
c. In the deacceleration period, the kinetics of reaction is nucleation control and helps in determining the rate of early strength gain
d. The steady state period determines the later age strength gain as it occurs after the topochemical hydration of cement stops
8. Identify the FALSE statement with regards to hydration products formed as a result of the reaction between OPC and water
a. Tobormorite gel has a high surface area and occupies higher solid volume than calcium hydroxide (CH)
b. CH helps in maintaining the pH of the pore solution in the range of 12-13
c. Aft have a prismatic long needle like structure whereas the structure of Afm can be described as non-porous hexagonal prisms
d. Aft contributes to stiffening of mixtures and strength development at early ages
9. Identify the FALSE statement with regards to the porosity in hydrated cement paste (hcp)
a. The quantity of alkali ions in the pore solution is the highest after 28 days of curing period compared to all other ions
b. In mercury intrusion porosimetry (MIP), the threshold diameter is actually the size referring to the point of entry of mercury into the paste
c. Shrinkage and creep are the properties of concrete affected by the presence of the micropores in the hcp
d. Bug holes are formed in concrete due to the entrapment of air and have adverse effect of increasing the porosity and permeability of the concrete
10. Identify the FALSE statement with regards to the porosity in hydrated cement paste (hcp)
a. At early curing periods, the porosity is low since the capillary pores are not inter-connected
b. Micro-level parameters such as porosity and pore size distribution govern the strength and permeability of hcp
c. Chemically combined water and water in the mesopores are important components of gel pore water
d. While comparing different hcps having pore connectivity, their permeability increases with increase in the w/c used
1. Identify the FALSE statement with regard to the Power’s model for hydration of portland cement based paste system (PCBPS)
a. Cement gels are basically considered as colloids
b. The model establishes the relationship between volume of gel and strength of PCBPS
c. The model establishes the relationship between porosity and strength of PCBPS
d. The model is applicable for all curing conditions
2. Identify the FALSE statement with regard to portland cement based paste systems (PCBPSs)
a. C-S-H gel does not exert crystal pressure during its growth due to limited space within the system
b. Aft exerts crystal pressure during its growth due to limited space within the system
c. Degree of hydration increases with increase in the time of curing
d. Degree of hydration of cement system is unaffected by the presence of impurities in C3S and C2S
3. Identify the TRUE statement with regard to degree of hydration of ordinary portland cement
a. Degree of cement hydration is independent of w/c ratio
b. Both degree of cement hydration and porosity increases as the period of curing increases
c. Evaporable water content is a measure of the chemically combined water directly present in hydrated compounds
d. The hydration of C3A is rapid without gypsum
4. Identify the TRUE statement with regard to portland cement based paste systems (PCBPSs)
a. Evaporable water considers only the water present in capillary pores
b. The amount of water in the pores (both gel and capillary pores) is independent of the w/c ratio
c. The amount of gel pores at 28 day curing period in PCBPSs having different w/c ratio may be taken to be equal
d. The minimum w/c ratio for complete hydration of PCBPS with gel pores fully saturated is 0.42
5. Identify the TRUE statement with regard to portland cement based paste systems (PCBPSs)
a. For a fully saturated system, the amount of non-evaporable water is higher than evaporable water
b. For a fully saturated system, the sum of evaporable and non-evaporable water is about 36%
c. The strength of PCBPSs increases as the gel-to-space ratio in the system increases
d. Compared to C3S, the rate of hydration for both C3A and C2S is lower
6. Identify the FALSE statement with regard to portland cement based paste systems (PCBPSs)
a. Washburn’s equation is used to calculate the porosity of PCBPSs
b. At early curing periods, the porosity of the system is low since the capillary pores are disconnected
c. Irrespective of the w/c ratio, the permeability of PCBPS typically in the range of about 10-5 to 10-13 m/s
d. The size of connected capillary pores in system is measured in terms of effective or critical pore access diameter
7. Identify the FALSE statement with regard to heat of hydration of portland cement based paste systems (PCBPSs)
a. The total heat evolved at any instant of time within the system is related to the heat of hydration of the individual Bogue’s compounds and their quantities present in cement
b. For casting concrete in low temperature environments, the heat of hydration values are beneficial as its provides information about the activation energy for hydration
c. The total heat evolution trend helps to understand precisely the chemical reactions occurring during the cement hydration process
d. Specific heat of concrete is one parameter that determines the dissipation of heat within concrete
8. Identify the FALSE statement with regard to heat of hydration of portland cement based paste systems
a. Thermal stresses are generated inside concrete if the rate of dissipation of heat is lower than the rate of evolution of heat
b. The time taken to reach the maximum temperature in a concrete mixture increases with the increase in the thickness of the member
c. The rate of heat evolution during hydration of C3A decreases with increase in the amount of the gypsum present in cement
d. Coefficient of thermal expansion of coarse aggregates is one parameter that determine the heat of hydration in concrete
9. Identify the TRUE statement with regard to mass concrete
a. Cement used should have lower C2S and C3A from the standpoint of temperature rise in concrete
b. Reducing the cement content by using higher coarse aggregate content helps in reducing the temperature rise
c. Cement having lower fineness is preferred as it allows the dissipation of heat at a faster rate
d. The heat dissipation is easier in members having larger volume-to-surface area ratio
10. Identify the TRUE statement with regard to Thermal Cracking Index (TCI)
a. Thermal Cracking Index (TCI) as defined as the ratio of the instantaneous thermal stress to the instantaneous tensile strength of the concrete
b. Thermal Cracking Index (TCI) is an intrinsic property of a given concrete
c. An equation of the type E=5000√fck can be used in the computation of the TCI
d. As the TCI increases, the likelihood of occurrence of thermal cracking in the concrete also increases
W5-A5
1. Identify the TRUE statement with regard to the sustainability
a. The one factor that combines economic, social and environmental factors together is called “Ecology.”
b. Development against air pollution and preservation of natural resources are grouped under the “environmental facet” of sustainability
c. From the stand point of sustainability, one should consider primarily the current requirements and not the future requirement
d. Sustainable design focuses more on consciousness of the society
2. Identify the FALSE statement with regard to the sustainability
a. The three environmental issues connected with the cement production are carbon dioxide emission, depletion of natural resource and waste disposal
b. During the calcination stage of cement production, approximately 50% of the carbon dioxide is produced
c. The production energy for portland cement concrete is considerably lower than the production energy of portland cement
d. The energy required for producing reinforced concrete is higher than that of plain cement concrete
3. Identify the FALSE statement with regard to the sustainability
a. The sustainable benefits of portland cement based paste systems are increased by using mineral admixtures as a substitute for cement
b. Performance based specifications provide more flexibility for the industry to produce their own proprietary materials or product that can enhance sustainability
c. Industrial by-product materials which are heated at controlled temperatures during the production of other raw materials can be grouped as artificial pozzolans
d. The physical and chemical requirements for portland cement are given significant consideration in “performance based specification”
4. Identify the FALSE statement with regard to pozzolans
a. Supplementary cementitious material also referred as pozzolans
b. The naturally occurring pozzolans such as diatomized earth and volcanic glasses or tuffs are obtained from the same sources
c. By definition, pozzolans largely contain either calcium compound or calcium alumino material or a combination of these compounds
d. Fly ash and silica fume by itself are non- hydraulic binders
5. Identify the FALSE statement with regard to pozzolans
a. Diatomaceous earth is produced by controlled heating of pozzolanic materials in a kiln
b. Silica fume and slag are industry based pozzolanic materials
c. Reactive phase present in calcined clay or metakaolin is amorphous alumino-silicates
d. The principle component present in fly ash is ‘carbon’
6. Identify the TRUE statement with regard to fly ash
a. Secondary C-S-H gel produced during the pozzolanic reaction is of the same nature as that of C-S-H gel produced during the hydration of silicates
b. Fly ash is the principal component present in coal
c. The class or type of fly ash changes with changes in the properties of coal
d. Bottom ash is heavier than fly ash but have same particle size, shape and mineralogy
7. Identify the TRUE statement with regard to the morphology of fly ash
a. Cement and fly ash particles are spherical in shape
b. Fly ash improve the flow property of mixture because of ball bearing effect of spherical particle
c. Cenosphere ash particles are hollow particles having smaller particles inside
d. The shape of fly ash particle is independent of the coal combustion and condensation condition
8. Identify the TRUE statement with regard to the particle size of fly ash
a. The particle size of fly ash is in the range of 1 nm to 100 nm
b. Samples having same specific surface area always have same particle size
c. According to ASTM C618, the fineness limit for fly ash is less than 43% should be retained on 325 sieve or 45 microns sieve
d. Fly ash with lower average particle size have faster rate of reaction and contribute to early age strength
9. Identify the FALSE statement with regard to the density of fly ash
a. Amount of iron oxide present in fly ash affect the specific gravity of fly ash
b. Fly ash with low bulk density have lower amount of pleurosphere
c. Density of fly ash is independent of the calcium content present in fly ash
d. Bulk density of fly-ash is increased by packing the material tightly
10. Identify the FALSE statement with regard to the color and oxide composition fly ash
a. Fly ash obtained from sub-bituminous has lower amounts of CaO than SiO2
b. Fly ash obtained from bituminous source contains lower amount of SiO2 as compared to sub bituminous source
c. Class F fly-ash is more greyish compared to Class C fly ash
d. Fly ash obtain from bituminous source have yellowish brown color
6W-6A
1. Consider the following statements is FALSE in the context of the use of fly ash as partial replacement for portland cement
a. The normal dosage of fly ash addition is in the range of 15% - 35% (replacement of portland cement)
b. Fly ash can be used with other materials to produce building blocks for construcing masonry walls
c. In alkali activated fly ash concretes, cement is completely replaced by fly ash
d. In the manufacture of portland pozzolona cement with fly ash addition, the fly ash is added during the grinding of clinker
2. Identify the TRUE statement with regard to the classification of fly ash
a. Fly ash of lignitic variety usually contains higher amounts of (S + A + F) as compared to other fly ashes
b. As per Indian Standards, the (S+A+F) content should be less than 70% for siliceous fuel ash
c. As per Indian Standards, calcareous fuel ash should contain at least 25% SiO2
d. Class F fly ashes have higher iron content and lower calcium content than Class C fly ashes
3. Identify the FALSE statement with regard to the use of fly ash as partial replacement for portland cement in concrete
a. Fly ash particles of size greater than 45 micron in diameter do not usually take part in the strength development process and only act as filler in concrete
b. With the addition of fly ash, the porosity of portland cement based paste systems (PCBPSs) and the pore size distribution are refined
c. Flow and compressive strength tests are the only characterization tests for fly ash, which are mentioned in Indian Standardsd. One factor that affects the air content of PCBPS due to fly ash addition is its carbon content
4. Identify the FALSE statement with regard to fly ash
a. Moisture content in fly ash causes significant problems during handling and transportation
b. Sulfate resistance of portland cement based paste systems (PCBPSs) is reduced with fly ash addition due to reduction in their porosity and permeability
c. Addition of fly ash to concrete decreases the heat of hydration and increases the setting time
d. The use of fly ash in PCBPSs is usually preferred for cold weather concreting
5. Identify the TRUE statement with regard to the physical requirements of fly ash
a. As per IS, the minimum fineness specified for fly ash is lower than the minimum fineness specified for ordinary portland cement
b. Minimum expansion by Le Chatelier specified in Indian Standard is 0.80%
c. As per IS, the reduction in compressive strength of concrete mixtures containing fly ash upto 20% as compared to the control or reference mixture is acceptabled. As per IS, at least 34% (by weight) of the particles should be retained on the 45 micron sieve after wet sieving the fly ash
6. Identify the TRUE statement with regard to the physical and chemical requirements given in relevant Indian Standards for the use of silica fume as a pozzolonic material
a. The maximum SiO2 content of silica fume should be 85%
b. The mean particle diameter is approximately 1/100 times of the average particle diameter of ordinary portland cementc. The minimum compressive strength at 28 days of silica fume mixture as a percentage of control mixture should be 85%
d. Minimum specific surface area of silica fume should be 15 cm2/g
7. Identify the TRUE statement with regard to the use of silica fume as a pozzolonic material
a. Silica fume is not recommended as an admixture in grouts because it reduces the cohesiveness and plasticity of the mixture
b. Silica fume can be white in colour if its oxide compositions are appropriately modified
c. The C/S ratio of secondary C-S-H gel produced during the pozzolanic reaction of silica fume is equal to 2.0
d. The spherical shape of silica fume particles helps in decreasing water demand or requirement in concrete of a given or required workability
8. Identify the TRUE statement with regard to the use of ground granulated blast furnace slag (GGBFS) as a pozzolonic material
a. If the average 28-day strength of control or reference mixture is upto 20% lower than that of a similar concrete mixture containing GGBFS, the slag is classified as “Grade 80” slag
b. Slag particles are angular in shape like ordinary portland cement
c. Addition of GGBFS to an ordinary portland cement system increases its water demand for a given workability
d. GGBFS is preferred for the situation that requires the quick removal of formwork
9. Identify the TRUE statement with regard to the use of ground granulated blast furnace slag (GGBFS) as a pozzolonic material
a. The addition of GGBFS reduces the compressive strength of concrete at 0 to 56 day curing period
b. At higher replacement level of GGBFS, the setting time of portland cement based paste systems reduces
c. The addition to GGBFS to ordinary portland cement system is independent of the system’s ability to entrain air
d. GGBFS contains higher amounts of magnesia and free lime than silica fume
10. Identify the FALSE statement with regard to pozzolans
a. Silica fume reduces the bleeding in a concrete mixture due to high specific surface area
b. Ground granulated blast furnace slag usually contains higher amounts of calcium oxide than fly ash
c. The specific gravity and fineness of ground granulated blast furnace slag is higher and lower than that of silica fume, respectively
d. Silica fume is used in mass construction as it significantly reduces heat of hydration
1. Consider the following statements is FALSE in the context of the use of fly ash as partial replacement for portland cement
a. The normal dosage of fly ash addition is in the range of 15% - 35% (replacement of portland cement)
b. Fly ash can be used with other materials to produce building blocks for construcing masonry walls
c. In alkali activated fly ash concretes, cement is completely replaced by fly ash
d. In the manufacture of portland pozzolona cement with fly ash addition, the fly ash is added during the grinding of clinker
2. Identify the TRUE statement with regard to the classification of fly ash
a. Fly ash of lignitic variety usually contains higher amounts of (S + A + F) as compared to other fly ashes
b. As per Indian Standards, the (S+A+F) content should be less than 70% for siliceous fuel ash
c. As per Indian Standards, calcareous fuel ash should contain at least 25% SiO2
d. Class F fly ashes have higher iron content and lower calcium content than Class C fly ashes
3. Identify the FALSE statement with regard to the use of fly ash as partial replacement for portland cement in concrete
a. Fly ash particles of size greater than 45 micron in diameter do not usually take part in the strength development process and only act as filler in concrete
b. With the addition of fly ash, the porosity of portland cement based paste systems (PCBPSs) and the pore size distribution are refined
c. Flow and compressive strength tests are the only characterization tests for fly ash, which are mentioned in Indian Standardsd. One factor that affects the air content of PCBPS due to fly ash addition is its carbon content
4. Identify the FALSE statement with regard to fly ash
a. Moisture content in fly ash causes significant problems during handling and transportation
b. Sulfate resistance of portland cement based paste systems (PCBPSs) is reduced with fly ash addition due to reduction in their porosity and permeability
c. Addition of fly ash to concrete decreases the heat of hydration and increases the setting time
d. The use of fly ash in PCBPSs is usually preferred for cold weather concreting
5. Identify the TRUE statement with regard to the physical requirements of fly ash
a. As per IS, the minimum fineness specified for fly ash is lower than the minimum fineness specified for ordinary portland cement
b. Minimum expansion by Le Chatelier specified in Indian Standard is 0.80%
c. As per IS, the reduction in compressive strength of concrete mixtures containing fly ash upto 20% as compared to the control or reference mixture is acceptabled. As per IS, at least 34% (by weight) of the particles should be retained on the 45 micron sieve after wet sieving the fly ash
6. Identify the TRUE statement with regard to the physical and chemical requirements given in relevant Indian Standards for the use of silica fume as a pozzolonic material
a. The maximum SiO2 content of silica fume should be 85%
b. The mean particle diameter is approximately 1/100 times of the average particle diameter of ordinary portland cementc. The minimum compressive strength at 28 days of silica fume mixture as a percentage of control mixture should be 85%
d. Minimum specific surface area of silica fume should be 15 cm2/g
7. Identify the TRUE statement with regard to the use of silica fume as a pozzolonic material
a. Silica fume is not recommended as an admixture in grouts because it reduces the cohesiveness and plasticity of the mixture
b. Silica fume can be white in colour if its oxide compositions are appropriately modified
c. The C/S ratio of secondary C-S-H gel produced during the pozzolanic reaction of silica fume is equal to 2.0
d. The spherical shape of silica fume particles helps in decreasing water demand or requirement in concrete of a given or required workability
8. Identify the TRUE statement with regard to the use of ground granulated blast furnace slag (GGBFS) as a pozzolonic material
a. If the average 28-day strength of control or reference mixture is upto 20% lower than that of a similar concrete mixture containing GGBFS, the slag is classified as “Grade 80” slag
b. Slag particles are angular in shape like ordinary portland cement
c. Addition of GGBFS to an ordinary portland cement system increases its water demand for a given workability
d. GGBFS is preferred for the situation that requires the quick removal of formwork
9. Identify the TRUE statement with regard to the use of ground granulated blast furnace slag (GGBFS) as a pozzolonic material
a. The addition of GGBFS reduces the compressive strength of concrete at 0 to 56 day curing period
b. At higher replacement level of GGBFS, the setting time of portland cement based paste systems reduces
c. The addition to GGBFS to ordinary portland cement system is independent of the system’s ability to entrain air
d. GGBFS contains higher amounts of magnesia and free lime than silica fume
10. Identify the FALSE statement with regard to pozzolans
a. Silica fume reduces the bleeding in a concrete mixture due to high specific surface area
b. Ground granulated blast furnace slag usually contains higher amounts of calcium oxide than fly ash
c. The specific gravity and fineness of ground granulated blast furnace slag is higher and lower than that of silica fume, respectively
d. Silica fume is used in mass construction as it significantly reduces heat of hydration
7S-7A
1.Identify the TRUE statement with regards to the portland cement based paste systems (PCBPS)
a. As per IS 12600, both initial and final setting time of low heat cement are higher than the ordinary portland cement
b. Low heat cement has higher C2S content than any other types of portland cement
c. Sulfate resistance cement has higher C3A content than the ordinary portland cement
d. High early strength cement has larger average particle size than the ordinary portland cement
2. Identify the TRUE statement with regards to the mercury intrusion porosimetry and its use in porosity related studies of cement paste and concrete
a. As the age of concrete increases, the threshold diameter of pores decreases
b. The total intrusion volume data cannot be used to obtain the differential intrusion volume data
c. Mercury is preferred for use because it wets the surface of the pore walls
d. The ‘critical diameter’ indicates the average size of pores at which the onset of permeation of mercury into the sample occurs
3. Identify the TRUE statement with regards to the porosity studies of cementitious materials
a. If two different cement paste samples have same porosity (in terms of grams per cc), it implies that the pore size distribution of the two samples should also be identical
b. Porosity is directly related to the amount of capillary pores in the system
c. A higher range of pore size in portland cement based paste systems (PCBPSs) can be observed with the increase in the curing period
d. Porosity and permeability can be related to each other when the pore connectivity in the pore system is low
4. Identify the FALSE statement with regards to the porosity studies of cementitious materials
a. The addition of fly ash results in the refinement of porosity and pore size distribution of portland cement based paste systems (PCBPSs)
b. When comparing cement pastes of same porosity, the paste with lower volume of larger pores will have higher strength
c. At early curing periods, the porosity is low because the capillary pores have lesser connectivity
d. The refinement of pore structure of PCBPS is the result of the continued hydration
5. Identify the FALSE statement with regard to the permeability of concrete
a. The strength of concrete increases as its permeability decreases
b. The macropores and large mesopores both affect the permeability of concrete
c. Inter connected pores allow more transport of deleterious materials in concrete during the service life of the structure
d. At early curing periods, the permeability is low because the capillary pores have lower connectivity
6. Identify the TRUE statement with regard to the rapid chloride permeability test used for concrete
a. Classification of concrete based on the rapid chloride permeability test is based on charge passed expressed in ‘Coulombs’
d. Reservoirs used in the test are filled with 0.3M NaCl and 0.3M NaOH solutions
c. The method for carrying out the test is given in ASTM C1201
d. In the test, a potential difference of 60V is applied across the two faces of concrete disc for a 3-hour period
7. Identify the FALSE statement with regard to the salt ponding test used for concrete
a. The ponding in the test is carried out for a period of 90 days
b. A 3% NaCl solution is used for ponding the surface
c. Specimens are moist cured for 14 days and then stored in drying room at 100% relative humidity for 50 days before testing
d. The method for carrying out the test is given in AASHTO T259
8. Identify the FALSE statement with regard to the determination of water permeability of concrete
a. The method is mostly suited for concrete with high permeability
b. In modified water permeability test method, the test is carried out on concrete disc
c. In modified water permeability test, the depth of penetration is taken as a measure of permeability
d. The test is carried out by applying pressure on water to accelerate and facilitate penetration of water into the concrete
9. Consider the information given in the following table regarding the different types of cement as per ASTM standards, and properties or use of the cement.
Which of the following correctly matches the types and the properties of the cement?
1-A, 2-C, 3-B, 4-E, 5-D
1-E, 2-A, 3-D, 4-C, 5-B
1-B, 2-D, 3-A, 4-C, 5-E
1-D, 2-E, 3-B, 4-A, 5-C
10. Consider the following table giving the constituents of concrete in one column and approximate range of volume occupied by different constituents.
Which of the following correctly matches the different constituents and their volume fractions in normal concrete?
1-D, 2-C, 3-A, 4-E, 5-B
1-E, 2-D, 3-A, 4-B, 5-C
1-E, 2-D, 3-A, 4-B, 5-C
1-C, 2-D, 3-E, 4-A, 5-B
You may submit any number of times before the due date. The final submission will be considered for grading.
8W-8A
1. Identify the FALSE statement with regard to the stress strain curve of concrete
a. Prior to the external loading, micro-cracks are not present in hydrated cement paste of the concrete
b. Concrete can be reasonably assumed to show linear elastic behavior until stress level of 30% of ultimate stress
c. At the stress level of 50% of ultimate stress, micro cracks start propagating but not in mortar phase
d. The stress-strain curve of concrete doesn’t show a definite yield point
2. Identify the TRUE statement with regard to the modulus of elasticity of concrete
a. As per IS 456:2000, the modulus of elasticity of concrete can be estimated using the actual strength of cubes determined during construction
b. Modulus of elasticity of concrete is influenced by the moisture condition of specimen
c. Dynamic modulus of elasticity is obtained from the slope of the tangent drawn at the non-linear part of the stress-strain curve
d. Modulus of elasticity of concrete is independent of the modulus of elasticity of aggregate
3. Identify the FALSE statement with regard to the strength of concrete
a. The strength measured using a cylindrical specimen (100mm x 200mm) is higher than that measured using a cube (150mm side).
b. The size of the specimen used depends on the maximum size of the aggregate used in the concrete
c. The strength obtained is not affected by steps taken to minimize the friction between the platens and the specimen.
d. The observed strength is related to the rate of loading
4. Identify the TRUE statement with regard to the strength of the concrete
a. Strength of concrete (S) can be modelled as S = S0[exp(-kp)], where S0 and p are the strength of coarse aggregate and the porosity of hardened cement paste, respectively, with k being an empirical constant
b. Under moist curing condition, complete hydration is achieved when concrete achieves more or less its 100% strength
c. If the rate of application of load is low, the strength of specimen will be low due to the effect of creep
d. Strength gained by concrete is directly proportional to the w/c ratio in concrete
5. Identify the FALSE statement with regard to the curing of concrete
a. Curing is performed to prevent the loss of moisture from the concrete
b. Steam curing is used in case where higher early strength is required
c. Gain in strength of concrete will happen only when concrete remains moist with a minimum relative humidity of 80% and favorable ambient temperature
d. Membrane curing is achieved by covering the surface of concrete with wet cloth or by wet sand
6. Identify the FALSE statement with regard to the maturity of concrete
a. The datum temperature for computing maturity is considered as -5°C
b. Maturity is the function of time and temperature
c. As maturity of concrete increases, its strength gain also increases
d. Batches of same concrete mixtures of same maturity will attain the same strength regardless of the time-temperature combinations
7. Identify the TRUE statement with regard to the durability of concrete
a. Permeability of concrete is independent of the durability of concrete
b. Ingress of harmful material occurs through the pores and not from the ITZ of the concrete
c. Concrete in tidal zone generally cracks due to freeze-thaw or chemical decomposition of hydrated cement
d. Concrete in submerged zone generally cracks due to the corrosion in steel
8. Identify the TRUE statement with regard to the environmental exposure condition of concrete
a. IS 456:2000 classifies four environmental exposure conditions based on the exposure of concrete to environment
b. Japanese code classify three environmental exposure conditions based on the corrosive nature of environment
c. Only EN-1992 includes sulfates in the classification of environmental exposure condition
d. Only ACI 318M includes chemical attack in the classification of environmental exposure condition
9. Identify the TRUE statement with regard to the IS 456:2000 durability specification
a. Plain and reinforced concrete exposed to extreme environmental condition require a minimum grade of M25 concrete to be used
b. In order to mitigate AAR, the maximum alkali content is specified as 0.8 kg/m3 of concrete
c. In RCC, the maximum total acid soluble chloride content in cement is specified as 0.60%
d. In order to mitigate sulfate attack, the maximum total water soluble sulfate content is specified as 4% by mass of cement
10. Identify the FALSE statement with regard to the durability of concrete
a. Map cracking is the pattern of cracking observed in alkali aggregate reaction distress
b. With cyclic exposure to freezing and thawing, ‘pop-outs’ of aggregates are often seen in damaged concrete
c. In sulfate attack, cracks are often seen on hydrated cement paste as well as on the aggregate of concrete
d. Chloride attack result in reinforcement corrosion which causes the spalling of concrete along the reinforcement
