Characteristics of mechanized sand
(1) Rough surface, edges and corners.
(2) the fineness modulus is large, and the particle grading is concentrated. The particles passing through the 0.315mm sieve are between 8% and 13%.
(3) Large porosity.
Mechanism of action of stone powder
(1) Micro-aggregate filling effect. Stone powder particles are very small, in concrete can play the role of micro-aggregate, filling into the tiny pores, and participate in the hydration reaction, physical filling and hydration reaction product filling, than inert micro-aggregate simple physical filling effect, make concrete more dense, thus improving the strength of concrete.
(2) water retention and thickening effect. On the one hand, stone powder can absorb water in concrete and increase water consumption per cubic meter of concrete to a certain extent. With the increase of stone powder content, the viscosity of concrete increases continuously, which effectively reduces the risk of concrete mixture segregation and bleeding; On the other hand, during the concrete hardening process, the stone powder will release the water it absorbs, which is used to compensate for the hydration water of the concrete later, thus reducing the shrinkage of the concrete.
