Coating for building and bridges

External coating undergoes many harsh condition of environmental changes so it must have the property of UV resistant, anti-carbonation, breathability, waterproofness, crack bridge-ability, etc. Generally, coatings like on Acrylic elastomeric coating, Epoxy polyurethane paint system and Epoxy phenolic coating systems are proven as best.

IRC: SP-20, has clarified and put the specification requirement for Acrylic elastomeric coatings:

Coating requirement:

Sl No	Parameters	Requirement	Reference
1	Specific gravity	1.35 – 1.4	IS 345
2	Solid content	70 ± 3%	IS 345
3	UV resistant	No colour change	ASTM G 53 / DIN EN 150 – 105
4	IR Spectrum	As per Acrylic polymer	IR – Spectrum Meter standard
5	Adhesion with concrete	1.5 N/Sqmm	ASTM D 4541 -02 DIN 500014
6	Dry film thickness	200-225 micron per min 2 coats
7	Coverage	400-500 gm/Sqm for 2 coats
8	Physical properties diffusion resistance against carbon-dioxide	Equivalent to air thickness SD CO2 shall be > 50m	DIN 53122 Part 1
9	Diffusion resistance against water vapour	Equivalent to air thickness SD CO2 shall be > 4m	DIN 52615
10	Waterproofing characteristics	Percentage reduction in flux should be > 50%
11	Re-coat-ability	Min 2-72 Hrs or as per manufacturer specification with the approval of engineer in-charge

 

Primer requirement:

     a.       System – Single component

     b.       Base – Acrylic resin dispersion

     c.       Curing – Air cure

     d.       Colour – Milk white, transparent application

     e.       Shelf life: 6 months or as per manufacturer’s specification

     f.        Coverage – 75-100 Gms per Smtr (depending on surface porosity)

Performance guarantee of coating system: 5 years

Reference: IRC: SP-20 : 2008, page No 37 and 38.

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What is the national language of India?

annayyachandrashekar.blogspot.com

India is a union of states with 28 states and 8 Union Territories has a variety of languages that changes every km. in the formation of new Constitution, there have been several arguments and discussion language that which language can be selected as Nation Language of India.

The Constitution of India has stated the usage of Hindi and English to be the two official languages of communication for the national government. Additionally, it contains a list of 22 official languages (including Hindi and English).

Hence, Hindi is the language used by the Central Government as per Article 343 when communicating with the states of Hindi Belt. And, English is the Associate official language and the language to be used while communicating with the states.

India does not have a national language. However, it has two official languages at the national level: Hindi and English. Hindi is the most widely spoken language in India, and English is often used for official and administrative purposes, as well as in education and business. Additionally, India is a linguistically diverse country with several regional languages spoken across different states. Each state in India can have its own official language(s) as well.

The decision to not designate a single national language was a conscious one, and instead, Hindi and English were chosen as the official languages at the national level to accommodate linguistic diversity. This approach aims to promote inclusivity and respect for the various languages spoken in different regions of the country.

Advocates of this approach argue that it helps in maintaining unity in diversity and fosters a sense of cultural and linguistic tolerance. On the other hand, critics may argue that not having a single national language might pose challenges in terms of communication and administration, as there isn't a common language that everyone speaks.

Ultimately, the question of what should be the national language of India is subjective and involves balancing the interests of different linguistic communities. The current approach of having multiple official languages at the national level seems to be a pragmatic solution to address the linguistic diversity in the country.

So, there is no national language of India. Hindi and English are considered as official languages of India.

Jai Hind.

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Different concrete grade / concrete mix

 There are two type of mix design :

1. Nominal Mix design (For below M20 grade)
2. Design Mix (For above M20 grade)
M stands for Mix and numerical value 20 stands for Mpa or N/mm2 compressive strength of concrete at 28th day.

According to IS 456:2000 code Up to M20 we will go for nominal mix design, like:

M5=1:5:10
M7.5 = 1:4:8
M10 = 1:3:6
M15 = 1:2:4
M20 = 1:1.5:3
Beyond M20, it needs to do design mix with reference of IS 456:2000

For design mix we can refer to IS:456, IS:10262 & IS:1343, we need to consider the following points :

Workability of concrete.

Consistency of concrete.

Strength of concrete.
Water-cement ratio.
Durability of concrete.
Density of concrete.
Generation of heat of hydration.

Recommended Grades of concrete (based on compressive strength) where can be used – Reference: IS 15658.2006, Table: Paver Blocks for Different Traffic Categories: (Which grade of concrete where to be used):

Important NOTES on the above table:

1. Non-traffic areas are defined as areas where no vehicular traffic occurs.
2. Light-traffic is defined as a daily traffic up to 150 commercial vehicles exceeding 30 kN laden weight, or an equivalent up to 0.5 million standard axles (MSA) for a design life of 20 years ( A standard axle is defined as a single axle load of 81.6 kN).
3. Medium traffic is defined as a daily traffic of 150-450 commercial vehicles exceeding 30 kN laden weight, or an equivalent of 0.5 to 2.0 MSA for a design life of 20 years.
4. Heavy traffic is defined as a daily traffic of 450-1500 commercial vehicles exceeding 30 kN laden weight, or an equivalent of 2.0 to 5.0 MSA for a design life of 20 years.
5. Very heavy-traffic is defined as a daily traffic of more than 1500 commercial vehicles exceeding 30 kN laden weight, or an equivalent of more than 5.0 MSA for a design life of 20 years.

Similarly, based on flexural strength / breaking load of concrete, we can decide which concrete can be used where

Suggested values of minimum breaking load for different applications are given below as per IS 15658:

Pigment for concrete:

Synthetic or natural pigments maybe used in concrete mix to obtain paver blocks with desired shades of colours. The pigment used should result in durable colours of paver blocks, but not contain matters detrimental to concrete. Pigments, either singly or in combination, conforming to the following Indian Standards may be referred:

Floor topping:

Since, concrete is dusty, porous, etc., in nature which makes concrete not to leave it exposed for long time; hence, it is best to seal the top surface using floor topping, coating or at least by applying sealers. A variety of different types of synthetic resin systems are available which can form the binder of a flooring system. These include typically epoxy, polyurethane and methacrylate resins. Different resin types give different combinations of application characteristics and in-service performance and the considerations which affect the selection of a particular type are described as follows (reference: FeRFA_GUIDE_TO_SPECIFICATION_&_ APPLICATION_OF_SYNTHETIC_RESIN_FLOORING):

Note:

LD (Light duty) : light foot traffic, occasional rubber tyred vehicles
MD (Medium duty) : regular foot traffic, frequent fork lift truck traffic, occasional hard plastic-wheeled trolleys,
HD (Heavy duty) : constant fork lift truck traffic, hard plastic wheeled trolleys, some impact
VHD (Very heavy duty) : severe heavily loaded traffic and impact

Next blog explains: How to decide what should be the strength of the floor depending on the load / vehicular movement.

You can mention your comment below.

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IMP notes for civil engineers - Part 1

Design Mix:

M10 ( 1 : 3.92 : 5.62)

Cement                       :          210 Kg/ M3

20 mm Jelly                :          708 Kg/ M3

12.5 mm Jelly             :          472 Kg/ M3

River sand                  :          823 Kg/ M3

Total water                 :          185 Kg/ M3

Fresh concrete density:          2398 Kg/M3

 

M20 ( 1 : 2.48 : 3.55)

Cement                       :          320 Kg/ M3

20 mm Jelly                :          683 Kg/ M3

12.5 mm Jelly             :          455 Kg/ M3

River sand                  :          794 Kg/ M3

Total water                 :          176 Kg/ M3

Admixture                  :          0.7%

Fresh concrete density:          2430 Kg/ M3

 

M25 ( 1 : 2.28 : 3.27)

Cement                       :          340 Kg/ M3

20 mm Jelly                :          667 Kg/ M3

12.5 mm Jelly             :          445 Kg/ M3

River sand                  :          775 Kg/ M3

Total water                 :          185 Kg/ M3

Admixture                  :          0.6%

Fresh concrete density:          2414 Kg/ M3

Note: sand 775 + 2% moisture, Water 185 -20.5 = 164 Liters, Admixture = 0.5% is 100ml

 

M30 ( 1 : 2 : 2.87)

Cement                       :          380 Kg/ M3

20 mm Jelly                :          654 Kg/ M3

12.5 mm Jelly             :          436 Kg/ M3

River sand                  :          760 Kg/ M3

Total water                 :          187 Kg/ M3

Admixture                  :          0.7%

Fresh concrete density:          2420 Kg/ M3

Note: Sand = 760 Kg with 2% moisture (170.80+15.20)

 

M35 ( 1 : 1.79 : 2.57)

Cement                       :          410 Kg/ M3

20 mm Jelly                :          632 Kg/ M3

12.5 mm Jelly             :          421 Kg/ M3

River sand                  :          735 Kg/ M3

Total water                 :          200 Kg/ M3

Admixture                  :          0.7%

Fresh concrete density:          2400 Kg/ M3

Note: sand = 735 + 2%, Water = 200- 14.7 = 185.30,

Admixture = 0.7%

 

M40 ( 1 : 1.67 : 2.39)

Cement                       :          430 Kg/ M3

20 mm Jelly                :          618 Kg/ M3

12.5 mm Jelly             :          412 Kg/ M3

River sand                  :          718 Kg/ M3

Water Cement ratio    :          0.43

Admixture                  :          0.7%

Note: Sand = 718 + Bulkage 1%

 

M45 ( 1 : 1.58 : 2.26)

Cement                       :          450 Kg/ M3

20 mm Jelly                :          626 Kg/ M3

12.5 mm Jelly             :          417 Kg/ M3

River sand                  :          727 Kg/ M3+ Bulkage 1% Water Cement ratio    :          0.43

Admixture                  :          0.7%

 

M50 ( 1 : 1.44 : 2.23)

Cement                       :          450 Kg/ M3

20 mm Jelly                :          590 Kg/ M3

12.5 mm Jelly             :          483 Kg/ M3

River sand                  :          689 Kg/ M3 + Bulkage 12% Water Cement ratio    :          0.36 (188 Kg)

Admixture                  :          1.20%3

Micro silica                :          30 Kg

Super flow      6.7% of cement

 

WEIGHT OF MATERIALS

 

50 mm J bolt               :          751 No’s / 52 Kg

40 mm J bolt               :          883 No’s / 54 Kg

2” nails                       :          385 No’s / Kg

3” nails                       :          118 No’s / Kg

4" nails                       :          72 No’s / Kg

Binding wire               :          170 rings /Kg

 

SIMPLEX FORMULA:-

 

U = (N /L) x {(W x H) / (1 + S)} x Sq.rt {(L/50)}

 

U N	= =	Ultimate load in tones Number of blows
L	=	Pile length in feets
W H	= =	Weight of hammer in tones Height of fall in feet.
S	=	Set for 1 blows in Inch

 

Safe load = (ultimate load/ 2.5) Factor of safety = 2.5

10 blows = below 10 MM

 

Thread couplers:- (For Column lapping)

Couplers for reinforcing bars 20 mm to 28 mm crimped sleeve

 

Slump IS 456

 

Lightly reinforced 25 – 75 mm

 

Heavily reinforced 75 – 100 mm

 

Trench fill (insitu & Tremie) 100 – 150 mm

 

(For Termie vibrator not required)

  

Durability:-

         The Environment

         Cover to Steel

         Type and quality of the constituent material

 

        Cement content and Water Cement ratio.

         Workmanship to obtain full compaction.

         Compaction and efficient curing.

 

 

Accuracy of measuring equipment in batching plant.

 

Cement           :          + 2% Aggregate       :          + 3% Admixture      :          + 3% Water              :          + 3%

Mixing time    :          2 minutes for one mixing.(site Mixing)

 

 TOLERANCE:-

Form work:-

 

In C/S for columns & Beams deviation is     = + 12mm more (or) - 6mm less in size In footing plan                                                = + 50 mm more (or) – 12 mm less size In depth                                                          = + 0.05 D (specified thickness). Reinforcement:-

 

For effective depth D < 200mm                     = + 10mm For effective depth D > 200mm                     = + 15mm For Cover to reinforcement                            = + 10mm Maximum freefall of concrete           = 1.50 m height.

TOLERANCE ON DIA IN LENGTH:-

 

0-25mm                                              = + 0.5 %

 

25-35mm                                            = + 0.6 %

 

35-50mm                                            = + 0.8 %

 

 

 

TOLERANCE ON WEIGHT PER METRE:-

 

0-10mm                                              = +7%

 

10-16mm                                            = + 5%

 

16 and above                                      = + 3%

 

TOLERANCE FOR CUTTING LENGTH :-

 

A)	When the specified length is not given	= + 75mm (or) – 25 mm
B)	When the min. length is specified	= + 50 mm (or) – 0 mm

 

 

GENERAL:-

 

   Lapping is not allowed for the bars having diameters more than 36 mm.

 

   Chair spacing maximum spacing is 1.00 m (or) 1 No per 1 Sq.m

 

   For dowels rod minimum of 12 mm dia should be used.

 

   Chairs minimum of 12 mm dia bars to be used.

 

   Longitudinal reinforcement not less than 0.8% and more than 6% of gross C/S.

 

   Minimum bars for square column is 4 No’s and 6 No’s for circular column.

 

   Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars)

 

and the distributors not less than 8 mm and not more than 1/8 of slab thickness.

 

   Minimum thickness of slab is 125 mm

 

   Dimension tolerance for cubes + 2 mm.

 

   Free fall of concrete is allowed maximum to 1.50m.

 

   Lap slices not be used for bar larger than 36 mm.

 

   Water absorption not more than 15 %.

 

   PH value of the water should not be less than 6.

 

   Compressive strength of Bricks is 3.5 N / mm2

 

    In steel reinforcement binding wire required is 8 kg per MT

 

   In soil filling as per IS code 100 sqm should take 3 sample for core cutting test

DENSITY OF MATERIALS:-

 

Weight of Bricks                                = 1600-1920 Kg/M3

 

Weight of Block work                        = 1920 Kg/M3

 

Weight of R.C.C                                = 2310 – 2700 Kg/M3

 

 

 

CURING:-

 

Super Sulphate cement                       : 7 days Ordinary Portland cement OPC         : 10 days Minerals & Admixture added cement : 14 days

 

 

 

STRIPPING TIME ( De-Shuttering):-

 

For columns, walls, vertical form works       : 16-24 hrs

 

Soffit formwork to slabs                                : 3 days (props to be refixed after removal) Soffit to beams props                                     : 7 days props to refix after removal. Spanning up to 4.50m                                    : 7 days

Spanning over 4.50m                                     : 14 days Arches spanning up to 6m                             : 14 days Arches spanning over 6m                              : 21 days

 

 

 

 

CUBE SAMPLES:-

 

1 – 5 M3               :          1 No.

 

6 – 15 M3       :          2 No’s

 

16 – 30 M3         :          3 No’s

 

31 – 50 M3         :          4 No’s

 

Above 50 M3   :          4 + 1 No of addition sample for each 50 M3

 

 

 

TEST RESULTS OF SAMPLES:-

 

The test results of the samples shall be the average of the strength of three specimens. The individual variation should not be more than + 15 % of the average.

If more the results of the sample are invalid.

 

 

 

COMPRESSIVE STRENGTH:-

 

3 days             :          45 %

7 days             :          67 – 70 %

14 days           :          85 %

28 days           :          100% +

 

 

APPROXIMATE COST PER SQ.FT (MANTRI PROJECT)

 

HIGH RISE BUILDING:-

 

Structure                                                                                             = 979 / Sft

(Concreting, Block work, Plastering, Flooring, Dado, painting)

 

Electrical works (Modular switches)                                                 = 172 / Sft Plumbing (P.H.E)                                                                               = 93 / Sft Fire Fighting                                                                                       = 13 / Sft Lift                                                                                                      = 34 / Sft Common Area                                                                                    = 94 / Sft External development (Landscape, road works, drains etc.,)            = 87 / Sft

 

 

TEST FOR SILT & CLAY:-

 

   Take 200 ml measuring cylinder fill sand up to 100ml mark

 

   Add 150ml of water and shake well

 

   Allow it to settle for 3 hrs.

 

   Measure the total height and height of clay.

 

   Calculate the clay and silt in total sand

 

   Clay and Silt should not exceed 3% by weight (or) 8-10% by volume

 

   For crushed sand Clay and Silt should not exceed 15% by weight

 

 

 

ORGANIC IMPURITIES:-

 

   Don’t dried the specimen before testing

 

   Take 250 ml measuring cylinder.

 

   Add 75 ml of water with 3% of Sodium Hydroxide. Fill sand layer to 125 ml

 

   Make the volume up to 200ml by adding more of sodium hydroxide solution

 

   Shake well allow it to stand for 24 hrs

 

   If the solution becomes darker than straw yellow colour then the sand has to be tested for further by casing mortar cubes for 7 & 28 days is not less than 95%.

   If the solution is lighter or just straw yellow colour the sand can be used for concreting without any further test.

QUANTITIES REQUIRED:-

 

Plastering (CM 1:3)                                       = 1.50 bags / 10 m2

 

Plastering (CM 1:5)                                       = 1.05 bags / 10 m2

 

Ceiling Plastering (CM 1:3)                           = 48 kg / 10 m2

 

Brick work (CM 1:5)                                     = 86 Kg / 10 m3

 

Brick work (CM 1:6) 9” thick                        = 80.64 Kg / 10 m3

 

Brick work (CM 1:3) 4½” thick                     = 15.46 Kg / 10 m3

 

Lime for white washing                                 = 10 Kg/100 m2

 

Painting                                                          = 10 ltr/ 100 m2

 

Distemper 1st coat                                          = 6.5 Kg / 100 m2

 

Distemper 2nd coat                                         = 5.0 kg / 100 m2

 

Snowcem 1st coat                                           = 30 Kg / 100 m2

 

Snowcem 2nd coat                                          = 20 Kg / 100 m2

 

Paint ready mixed one coat                            = 10 ltr / 100 m2

 

Weathering Course                                        = 7.68 Kg / m2

 

Flooring                                                          = 8.10 kg / m2

 

Pressed tiles for weathering course (CM 1:3)= 7.68 Kg / 10 m2

 

Granolithic floor finish                                  = 8.10 Kg / 10 m2

 

 

 

WATER CEMENT RATIO:-

 

M20	=	0.55
M25	=	0.50
M30	=	0.45
M35	=	0.45
M40	=	0.40

 

 

SPACING OF BARS:-

 

   Provide the dia of the bar, if the dia of the bar are equal.

 

   Provide the dia of the larger bar, if the dia are unequal.

 

   5mm more than the nominal maximum size of the coarse aggregate.

 

 

 

CONVERSION:-

1 Acre = 4046.72 m2

 

1 cent  = 40.4672 m2

 

 

 

COVER TO MAIN REINFORCEMENT:- Column                       :          40 mm (D>12mm) Column                       :          25 mm (D= 12mm) Beam                          :          25 mm

Slab                            :          15 mm (or) not less than dia of the bar. Footing                       :          50 mm

Sunshade (Chajja)      :          25 mm

 

 IMP notes for civil engineers - Part 2.... Coming next...