Concrete requirements for stone powder content in sand

Stone powder refers to particles less than 75μm in artificial sand and mixed sand. Most of the stone powder in artificial sand is fine particles of broken parent rock. Unlike mud in natural sand, their role in concrete is also very different. On the one hand, high stone powder content increases the specific surface area of sand and increases water consumption; on the other hand, the ball effect produced by fine spherical particles will improve the workability of concrete. Therefore, stone powder in artificial sand cannot be regarded as a harmful substance.

The comprehensive impact of stone powder content on artificial sand has been proved by decades of experiments: Guizhou Province began to study the use of artificial sand in the 1970s. When the stone powder content in artificial sand is 0-30%, it has little effect on the performance of concrete, has no effect on the compressive and tensile strength of medium and low-grade concrete, and has little effect on the strength of C50 grade concrete. The shrinkage is close to that of river sand. The experimental research of the Railway Science Institute also proved that the mechanical properties of concrete prepared with artificial sand are better than those of river sand concrete (under the condition that the cement dosage and the consistency of the concrete mixture are equal).

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