Coarse aggregate sand and gravel should mainly control its particle size, gradation, grain shape, stone powder content, mud content, and mud content. Each vehicle undergoes a macro inspection, and the vehicle shall not be unloaded if it is unqualified; in addition, various indicators shall be inspected in batches according to the requirements of the specification. Fine aggregate should be controlled fineness modulus, mud content and mud content. Each vehicle shall undergo a macro inspection, and the unqualified vehicle shall not be unloaded; it shall also be inspected in batches according to the specifications.

Sand and gravel aggregate sand is too fine, the water demand of concrete will increase, and the pumpability and plasticity retention of concrete prepared with fine sand are extremely poor, the concrete strength will decrease and it is easy to crack. Concrete needs to use medium sand. In addition to the standard requirements for sand gradation, mud content and mud content, it is also important to note that the sand that passes through the 0.315mm sieve is not less than 15%. This has a great influence on the pumpability of concrete. If the value is too low, it will easily block the pump and make the concrete have poor water retention and bleeding.

The above introduction about sand and gravel aggregates is here first, I hope it will be helpful to you.