amardeep s

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                 =                  ...

Aggregates occupy ¾ space in the concrete mass and have following functions ( a ) provide a filler for concreting material ( b) provides mass to the concrete and reduce volume changes while setting and hardening of concrete.  ( c ) the rest ¼ is occupied by the paste ( water + cement ) binder which is an active component of concrete and having following functions:  ( a)  it fills the voids between aggregates ( b ) it gives strength to hardened concrete             The Reinforced Concrete ( R.C.C.) , the steel and concrete forms a very good combination because the co-eff of expansion of concrete and steel are nearly equal.             Concrete has low tensile strength & hence cracks easily .Therefore  concrete is to be reinforced with mild steel bars, high tensile steel bars or mesh .             Co...