Things Site Engineer must know ~ After Civil..

11/4/2014

Things Site Engineer must know ~ After Civil...?

Plastering quantity calculation for 1 Cu.m : RATIO (1:6) NOTE = 1:6: 0.55(Water) = + (7.55) Cement = 1m3/7.55 x 1 = 0.132m3 (No of Kg = 0.132 x1506 =198.792kg) Sand = 1m3/7.55 x 6 = 0.794m3 (No of Kg = 0.132 x 1650 =437.250 kg) Water = 1m3/7.55 x 0.55 = 0.072 m3 ( No of Kg = 0.072 x1000 = 72liter)

1.

Calculation of sand , cement & aggregate quantities in 1m3 - M20

, 1m3 20cm/ 1m2 of 10cm brick wall, paint quantity for 1m2 snowcem and lime painting? Grade of concrete M20 so ratio is 1:1.5:3 let volume of concrete - 1cum total ratio- 1+1.5+3 = 5.5 cement = 1x1.54/5.5 = 0.28 cum so cement is =0.28x1440Kg/cum = 403.2 Kg = 8.064 bags sand = 0.28*1.5= 0.42cum aggregate = 2.8*3= 0.84 cum

2.

1m2 of 6mm/12mm/20mm plaster

Plaster = suppose 12mm plaster consider 1 sqm ratio is 1:6 volume of concrete= 0.012x1= .012cum ( per 1sqm) increase 20% for joint, filling and wastage=.012*20%=.0144 calculate 1/3rd of mortar when dry= .0144*1/3+.0144= .0192cum summation of ratio = 7 cement= 0.0192/7= 0.00274cum = 0.0789bags sand= 0.00274*6= 0.0164cum this formula applied for 6mm and 20mm also. plaster area= paint area http://www.aftercivil.in/2014/06/things-site-engineer-must-know.html

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11/4/2014

Things Site Engineer must know ~ After Civil...?

Things Site Engineer must know Hook for stirrups is 9D for one side No. of stirrups = (clear span/Spanning) + 1 For Cantilever anchorage length for main steel is 69D “L” for column main rod in footing is minimum of 300mm Chairs of minimum 12 mm diameter bars should be used. Minimum diameter of dowel bars should be 12 mm Lap slices should not be used for bar larger than 36 mm. In steel reinforcement binding wire required is 8 kg per MT. Lapping is not allowed for the bars having diameters more than 36 mm. Minimum number of bars for a square column are 4 and for circular column are 6. Longitudinal reinforcement should not be less than 0.8% and more than 6% of gross C/S. Weight of rod per meter length = d2/162 where d is the diameter in mm All reinforcement shall be free from mill scales, loose rust & coats of paints, oil or any other substances. 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. In case of spacing of bars -Provide the diameter of the bar, if the diameter of the bar is equal. -Provide the diameter of the larger bar, if the diameter is unequal. -5mm more than the nominal maximum size of the coarse aggregate. Minimum thickness of slab is 125 mm. Water absorption should not be more than 15 %. Dimension tolerance for cubes + – 2 mm. Compressive strength of Bricks is 3.5 N /mm2 Maximum Free fall of concrete allowed is 1.50 m. In soil filling as per IS code for every 100 sqm 3 sample for core cutting test should be taken. http://www.aftercivil.in/2014/06/things-site-engineer-must-know.html

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11/4/2014

Things Site Engineer must know ~ After Civil...?

Electrical conduits shall not run in column Earth work excavation for basement above 3 m should be stepped form Any back filling shall be compacted 95% of dry density at the optimum moisture content and in layers not more than 200mm for filling above structure and 300 mm for no structure For soling is specified the soling stones shall be laid at 45° to 60° inclination (and not vertical) with interstices filled with sand or moorum. A set of cube tests shall be carried out for each 30 cum of concrete / each levels of casting / each batch of cement. Water cement ratio for different grades of concrete shall not exceed 0.45 for M20 and above and 0.50 For M10 / M15 contractor For concrete grades M20 and above approved admixture shall be used as per mix design requirements. Cement shall be stored in dry places on a raised platform about 200mm above floor level and 300mm away from walls. Bags to be stacked not more than 10 bags high in such a manner that it is adequately protected from moisture and contamination. Samples from fresh concrete shall be taken and at least a set of 6 cubes of 150mm shall be prepared and cured. 3 Cubes each at 7 days and 28 days shall be tested for compressive strength. The test results should be submitted to engineer for approval. If results are unsatisfactory necessary action/rectification/remedial measures has to be exercised. Water used for both mixing and curing shall be clean and free from injurious amounts of oils, acids, alkalies, salts, sugar and organic materials or other substances that may be deleterious to concrete or steel. The ph shall be generally between 6 and 8. Slump IS 456 -Lightly reinforced 25 – 75 mm -Heavily reinforced 75 – 100 mm -Trench fill (insitu & Tremie) 100 – 150 mm (For Tremie no need of vibrator) Curing Days Required -Super Sulphate cement : 7 days -Ordinary Portland cement OPC : 10 days -Minerals and Admixture added cement : 14 days Cube Samples -1 to 5 M3 : 1 No. -6 to 15 M3 : 2 No’s -16 to 30 M3 : 3 No’s -31 to 50 M3 : 4 No’s

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11/4/2014

Things Site Engineer must know ~ After Civil...?

-Above 50 M3 : 4 + 1 No of addition sample for each 50 M3. Tolerance Limits on Construction Site i)Accuracy of measuring equipment in batching plant. -Cement : + – 2% -Aggregate : + – 3% -Admixture : + – 3% -Water : + – 3% -Mixing time : 2 minutes for one mixing. (Mixing which is being done on site) ii)Tolerance in 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).

iii)Tolerance in 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. iv)Tolerance on diameter in length -0-25mm = +- 0.5 % -25-35mm = +- 0.6 % -35-50mm = +- 0.8 % v)Tolerance on weight per metre -0-10mm = +- 7% -10-16mm = +- 5% -16 and above = +- 3% vi)Tolerance for cutting Length

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11/4/2014

Things Site Engineer must know ~ After Civil...?

- When the specified length is not given = + 75mm (or) – 25 mm - When the minimum length is specified = + 50 mm (or) – 0 mm Cement setting tests: i) The initial setting time shall not be less than 30 minutes. ii) The final setting time shall not be more than 10 hours. samples from fresh Concrete shall be taken and at least a set of 6 cubes of 150mm shall be Prepared and cured. iii) Cubes each at 7 days and 28 days shall be tested for compressive strength. Water cement ratio for different grades of concrete shall not exceed 0.45 For m20 and above and 0.50 for m10 / m15 contractor / mix designer to Carry out the necessary initial (preliminary) tests. For concrete grades m20 and above approved admixture shall be used as per Mix design requirements. Min. periods – Removing shuttering (OPC in normal weather) a.

Walls, columns, & vertical sides of beam

b.

Slabs (props left under)

c.

Beam soffits (props left under)

d.

Removal of props to slabs :

e.

24 to 48 hours 3 days 7 days

i)

Spanning upto 4.5m

7 days

ii)

Spanning over 4.5m

14 days

Removal of props to beams & arches : i)

Spanning upto 4.5m

ii)

Spanning over 6m

7 days 21 days

For rapid hardening cement, 3/7 of the above period will be sufficient in all cases except vertical sides of the slabs, beams and columns which should be retained for 24 hrs. Reduction in strength of Cement (as a result of storage) a.

Freshly procured cement strength

100%

b.

Cement after 3 months storage, strength reduced by

20%

c.

Cement after 6 months storage, strength reduced by

30%

d.

Cement after 12 months storage, strength reduced by

41%

e.

Cement after 24 months storage, strength reduced by

50%

Strength of Ordinary Portland Cement Concrete at various Periods (Approx.) 3 days

-20%

7 days

-40%

3 months

-80%

6 months -95%

28 days 1 year

-60% -100%

Calculation of weight of rod with respect to dia. in Kg/m § Wt. of rod = d²/162 Upto 36mm size rod dia. only we can use lapping system to extend the rods. Above 36mm we should provide Mechanical joints (coupler, welding)# The max. differential settlement of foundation on sandy soils is limited to 15mm. In case of raft foundations on clayey soils, the max. total settlement is limited to 100m. The max. differential settlement for foundations on clayey soils is limited to 40mm. The slump recommended for concrete for column is 75 to 125mm. The recommended angle of slope for a flat roof of reinforced cement concrete is 2 to 5 degrees. The Red color indicates proposed work according to National building code. http://www.aftercivil.in/2014/06/things-site-engineer-must-know.html

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Things Site Engineer must know ~ After Civil...?

The normal height of door in residential buildings is 2.0m. The bearing of lintel should be the minimum of 10cm. 1/10 to 1/12 of span and height of the lintel. In a building, the plinth area is the total buildup and is calculated by taking outer dimensions of the building but excludes any offset of columns extending beyond wall/wall finishes, staircase, internal shafts for services (restricted to 2 sqm. area), lift well including landing and machine room. Area of porch, if not cantilevered, is also considered in plinth area. Floor area is the plinth area minus area of walls (walls inclusive of finishings if more than 1 m from finished floor level.) Floor area is thus area of all rooms, corridors, (excluding pillars, kitchen, toilets, stores excluding area of walls and structuring which occupy any area on plinth. Carpet area is the floor area less area for staircase and mounty, toilets, kitchen, store, verandah, corridor and passage, entrance hall and porch. Covered area is the area covered by a building at plinth level as the ground areas covered by watchman’s booth and other services are excluded from covered area. Circulation area is the area for free movement of people frequenting a building and to have access to different rooms, kitchen, toilets etc. This area is formed by verandahs, corridors, staircase, entrance lobby etc

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