Monday, 21 December 2015

Things Site Engineers must Know

Minimum thickness of slab is 125mm.
Water absorption should not be more than 15 %.
Dimension tolerance for cubes + or– 2 mm.
Compressive strength of Bricks is 3.5 N /mm
Maximum Free fall of concrete allowed is1.50 m.
In soil filling as per IS code for every 100sqm 3 sample for core cutting test should betaken.
Electrical conduits shall not run in column Earth work excavation for basement above 3m should be stepped formAny 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 F 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.
Cement shall be tested for its setting.
1. The initial setting time shall not be less than 30 minutes.
2. The final setting time shall not be more than 10 hours.
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 – 5 M : 1 No.
6 – 15 M : 2 No’s
16 – 30 M : 3 No’s
31 – 50 M : 4 No’s
Above 50 M : 4 + 1 No of addition sample for each 50 M .

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