amardeep singh sohal

All reinforcement shall be furnished in full lengths as indicated on the drawing. No splicing of bars, except where shown on the drawing, shall be permitted without approval of the Engineer. Where practicable, overlapping bars shall not touch each other, and shall be kept apart by 25 mm or 1.25 times the maximum size of coarse aggregate, whichever is greater . If this is not feasible, overlapping bars shall be bound with annealed steel binding wire not less than 1 mm diameter and twisted tight in such a manner as to maintain minimum clear cover to the reinforcement from the concrete surface. Lapped splices shall be staggered or located at points, along the span where stresses are low.

Concrete shall be transported and placed as near as practicable to its final position, so that no contamination, segregation or loss of its constituent materials takes place. Concrete shall not be freely dropped into place from a height exceeding 1.5 mtr

When it is necessary to deposit concrete under water, the methods, equipment, materials and proportions of mix to be used shall be got approved from the Engineer before any work is started. Concrete shall contain 10 percent more cement than that required for the same mix placed in the dry to compensate the loss due to wash. Concrete shall not be placed in water having a temperature below 5oC. The temperature of the concrete, when deposited, shall not be less than 16oC, nor more than 40oC. Coffer dams or forms shall be sufficiently tight to ensure still water conditions, if practicable, and in any case to reduce the flow of water to less than 3 m per minute through the space into which concrete is to be deposited. Coffer dams or forms in still water shall be sufficiently tight to prevent loss of mortar through the joints in the walls. Pumping shall not be done while concrete is being placed, or until 24 hours thereafter. To minimise the formation of laitance, care shall be exercised

                                              By hand the concrete cube should be filled by 3 layers 35 tampings on each layer by rod 16 mm dia The no of tampings are between 100 – 105 while preparing the concrete cube the no of tampings divides the no of layers                       For eg cube is casted in 3 layers  ( 150 mm cubes )                       105/3                 =                     35 nos of tampings                       If cube is to be casted in 4 layers then ( 100 mm cubes )                       100/4                 =                      25 nos of tampings However the total no of tampings should be between 100 – 105 nos                       Loading on the cube on strength machine should be 14/N/mm 2 / per min Rate of loading of concrete cube Loading should be applied @ 14/N/mm 2 /min                                            Or 140 kg / cm 2 /min        140*15*15/101*60               =          5.198 KN/sec                       Note: to convert 140 kg