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The Auto-Shrink system measures the unrestrained autogenous shrinkage of a specimen of cement paste or mortar cured under sealed conditions as per standard ASTM C1698.
When cement hydrates through chemical reactions with water, the volume occupied by the products of hydration is less than the original volume of cement and water. This phenomenon is known as “chemical shrinkage.”
Auto-Shrink is intended primarily for measurements after setting of cement pastes or mortars with a maximum aggregate size of 2 mm. To minimize the influence of temperature variations, the dilatometer should be used in a thermostatically controlled room. Background information on the measurement technique used in Auto-Shrink.
No matter what the application, a sealant has three basic
functions:
1. It fills a gap between two or more substrates.
2. It forms a barrier by the physical properties of the
sealant itself and by its adhesion to the substrate.
3. It maintains its sealing property for the expected
lifetime, service conditions, and environments.
More details what can be applied as sealant, where?
Typical Application Areas for Generic Sealants:
Generic Base
Typical Uses
Oil
Small wooden window sash
Oil and Resin
Metal windows
Butyl Noncuring
With polybutene for Metal buildings, slip joints, interlocking curtain walls, sound deadening, tapes
Butyl Curing
Home sealants, repair of lock-strip gasket, tapes- With resins for hot melts on insulating glass
Polyisobutylene
Primary seal on insulating glass
Asphalts
With bitumen on gutters, driveway repair; with neoprene on gutters, waterstops, and adhesives
Acrylic Nonplasticized
Water-based for interior-use joints on wallboard
Acrylic Plasticized
Caulks for exterior joints on low-rise housing, With good movement capabilities, excellent weathering
Acrylic Solvent-based
Exterior joints on Highrise construction, around doors and windows With low movement
Block-polymer Solvent- based
For low-rise buildings With good movement
Hypalon Solvent-based
Exterior joints on Highrise construction, around doors and windows
PVC-coal-tar
As a hot melt on airfield runways and highways
Polysulfide One-part
Highrise building joints
Polysulfide Two-part
Highrise building joints, aircraft fuel tank, boating, insulating glass sealant for remedial housing; with coal tar for airport aprons
Urethane One-part
Highrise building joints
Urethane Two-part
Highrise building joints, insulating glass sealant, With coal tar and asphalt for membrane waterproofing compounds
Silicone One-part
Low and medium modulus for Highrise building joints; low modulus for highways and difficult building joints; medium and high modulus for insulating glass with polyisobutylene; structural glazing; home use as bathtub caulk
Silicone Two-part
Mostly in-plant use on prefab units and insulating glass
Neoprene
Fire resistant gaskets, lock-strip gaskets, foam gaskets
EPDM
Gaskets, lock-strip gaskets, foam gaskets
Nitrile Solvent-based
For Small cracks and narrow joints
Epoxy
Concrete repair, complex beam construction; potting, molding, sealing transformers; high voltage splicing, capacitor sealant; with polymers as a concrete coating on bridges
This
testing is conducted on the concrete as per IS 13311 – part 1 and 2 and is used
to know:
1. The
homogeneity of the concrete
2. The
presence of cracks, voids and other imperfections,
3. Changes
in the structure of the concrete which may occur with time,
4. The
quality of the concrete in relation to standard requirements,
5. The
quality of one element of concrete in relation to another
6. The
values of dynamic elastic modulus of the concrete.
In
this test method, if the concrete is not compacted as thoroughly as possible,
or if there is segregation of concrete during placing or there are internal
cracks or flaws, the pulse velocity will be lower, although the same materials
and mix proportions are used.
The
quality of concrete in terms of uniformity, incidence or absence of internal
flaws, cracks and segregation, etc, indicative of the level of workmanship
employed; can thus be declared by the below table, which have been evolved for
characterising the quality of concrete in structures in terms of the ultrasonic
pulse velocity.
The
assessment of compressive strength of concrete from ultrasonic pulse velocity
values is not adequate because the statistical confidence of the correlation
between ultrasonic pulse velocity and the compressive strength of concrete is
not very high. The estimated strength may vary from the actual strength by f 20
percent.
The
dynamic Young’s modulus of elasticity (E) of the concrete may be determined
from the pulse velocity and the dynamic Poisson’s ratio as follows:
E ={
[Density of mix (1+ Poisson’s ratio) (1-2 X Poisson’s ratio) ] / (1- Poisson’s ratio)
} X Square of pulse velocity.
Let
see the testing method using REBOUND HAMMER TEST:
Conversion of rebound hammer no to compression test: Locate the reading as per the direction of test and read the Cop strength using this chart:
For more details about the Poisson's Ratio, watch this:
Let
see the testing method using ULTRASONIC PULSE VELOCITY:
Let
us understand the technique of ultrasonic pulse testing:
Let see the compression of results of ultrasonic, rebound and compression strength:
By the test result, may it be compressive strength, young’s modulus it shall match with the designed parameters tested in the lab by other direct methods.
Many
thanks for google.com and www.masterbuilder.co.in from where the details are collected.
Standard
BS EN 8204 -2 says to test the slip resistance as per BS 7976-2 and the result
of the slip resistance value [PTV (pendulum test value)] of the floor surface
is not less than 40.
When
flooring / coatings are wet, the slip resistance depends on the depth of the
surface micro-texture. The smoother the surface, the lower the slip resistance.
Slip resistance is only retained if the floor is cleaned correctly by regular
washing and cleaning with suitable cleaning products and techniques. Generally,
the more slip resistant the floor when wet, the more difficult it is to clean.
Existing floor surfaces that have become slippery despite cleaning may be
roughened by mechanical treatment, e.g. shot-blasting the surface.
Alternatively, a resin coating containing hard angular granules of natural or
synthetic material may be applied to a cleaned and textured floor surface to increase
slip resistance.
Testing can be conducted in 2 different
methods:
Standard
BS EN 8204 -2 says to test the slip resistance by roller coaster method and convert
the readings to PVT values and the result of the slip resistance value [PTV
(pendulum test value)] of the floor surface is not less than 40.
Determination of slip resistance of
pedestrian surfaces by the ramp/trolley method, alternatively known as the
roller coaster method:
The
device consists of a trolley having four wheels and a slider, together with a
ramp. The trolley is given an initial velocity by running down the ramp under
the action of gravity. The trolley then runs across the floor area to be
tested. The friction generated by the slider traversing the floor causes the
trolley to come to rest. The dynamic coefficient of friction is calculated from
the distance it takes for the trolley to come to rest.
The
device is used to determine the slip resistance of a floor surface by measuring
the dynamic coefficient of friction. It might be used, particularly by floor
end users, to detect changes in the dynamic coefficient of friction caused by
contamination or wear of the floor surface and/or changes caused by the method
of cleaning the floor.
The reading shall be more than 130.
Pendulum test for slip:
Standard
BS EN 8204 -2 says to test the slip resistance as per BS 7976-2 and the result
of the slip resistance value [PTV (pendulum test value)] of the floor surface
is not less than 40.
Let
see the Pendulum test:
The reading shall be more than 40.
BOT-3000E Floor Slip Resistance Tester - as per ANSI B 101.1, ANSI B 101.3 and ANSI A 137.1 slip test standards able to measure the static / dynamic slip resistance also. Let see the testing method:
Many thanks for google.com from there the details are collected.
As per BS EN 14617-1, water absorption can be tested as follows specially Agglomerated stones:
Water absorption is maximum amount of water absorbed by the material when soaked in deionised water at room temperature and pressure according to the procedure described below, expressed as a percentage of the dry mass of the sample.
Specimen of 6 No's of 100 x 100) mm length and width and (10 ± 2) mm thickness.
Dry the specimen at 70 ± 5°C for 24 Hrs and cool them at 20 ± 5°C.
Place the specimens in a tank on two supports in order to reduce the support contact surface to a minimum area.
Slowly pour the deionised water into a container until the specimens are completely immersed and covered by 2 cm of water. After (1 ± 0,25) h, (8 ± 0,5) h and (24 ± 1) h from the beginning of the tests, and later at regular intervals of (24 ± 1) h, take the specimens out of the water, wipe with a damp cloth and weigh them in air.
Continue to immerse the specimens in water and repeat the tests until the weight the specimens.
Find out the water absorption in % using the below formula:
Mo - is sample mass weighed in air after drying, in kilograms
Mt - is sample mass soaked in water (6), wiped by a damp cloth and weighed in air, in kilograms.
From these values, we can decide the subsequent application product nature, Ex.. the material used to bond should have water retention strength, Coverage of top coating material, Spreadability of the material, Stain catching time, Cleaning time, etc.
One more popular test to find out the water absorption is one minute COBB test. Let see the testing process:
As per ASTM C 570, water absorption can be tested as follows for Plastics and other type of sheet membranes:
Here ash is a material / filler content. An ash content test cannot identify individual
percentages in multi-filled materials without additional test procedures being
performed. An ash test cannot be used to determine the percent carbon fiber or
percent carbon black since carbon burns off during the Ash test.
Refer standards: UNI EN15403, UNI EN ISO18122, ISO 18123,
UNI EN15148, ASTM D2584, ASTM D5630, ISO 3451.
Let see how the testing is conducted as per IS 101 : Part 8
: Sec 3 : 1993, Title: Methods of sampling and test for paints, varnishes and
related products: Part 8 Tests for pigments and other solids: Sec 3 Ash content:
The percent volume solids of a paint is related to the covering capacity and wet film thickness in the following manner: Theoretical coverage in meter square per Ltr = Percentage of solids / DFT in microns X 10. OR Wet film thickness ( microns ) = (Dry film thickness in microns / Percent Volume Solids) X 100 Reference IS 101 - part 8 sec g - page no 2. Many thanks to google.com
As you all know that the cement and cement-based mortar as
well as concrete undergoes shrinkage. But, for some of the applications like,
bore hole filling, baseplate grouting, pressure grouting in the concrete to
fill the voids, it is necessary to have the expansion property. Modern technology
has invented the cement-based products which can expand by its volume.
Expansion of the newly installed material can be tested as
per standard ASTM C 827.
In this testing, cast
iron, rigid, strong, watertight mould is used to restrain the volumetric
expansion from all sides and allow to expand at top. Testing material will be
mixed and placed in the mould of different height and the increase in the
height is measured.
Note:
1. For cement pastes, grouts, and mortars where all the
aggregate will pass through a 4.75-mm sieve, use the 100-mm high mould.
2. For cementitious mixtures containing aggregate
that will not all pass through a 4.75-mm sieve, but which will all pass the 12.5-mm
sieve, use the 150-mm high mould.
3. For concrete mixtures having particles retained on
the 12.5-mm sieve or larger, use the 300-mm mould.
For accurate reading
purpose, make the following arrangement:
Result, the expansion property,
i.e. the change in height is expressed in terms of percentage.
For site use, arrangement can be made as follows:
Many thanks for
google.com from there the details are collected.
There are various types of
concrete admixtures like accelerators admixtures, retarders admixtures,
water-proofing admixtures and air entraining admixtures. Some of these
admixtures are likely to contain water soluble chlorides which are likely to
cause corrosion of reinforcement in the reinforced concrete. In fact, the use
of such chlorides containing admixtures has been prohibited by IS: 456-1964, IS
2645, etc to 2% of the total mass.
Test can be conducted in 3 methods as IS 6925 and are as follows:
A. The volumetric method may be used when the chloride concentration
is nearly 1 percent or above.
B. The gravimetric method may be used when the chloride concentration
is more than 2.5 percent.
C. The turbidimetric method may be used when the concentration of chloride
is as low as 2 ppm and above. This is adopted when chloride ions are very low.
