Influence of stone powder on working and mechanical properties of high-strength manufactured sand concrete

In order to explore the influence of fly ash,silica fume and different contents of stone powder on the working and mechanical properties of high-strength manufactured sand concrete,C70 manufactured sand concrete with different stone powder contents（ 3%, 5%, 7%, 9%, 11%） was prepared,with the help of nuclear magnetic resonance（ NMR）,differential thermal-thermogravimetry（ TG） synchronous test and field emission scanning electron microscope test（ SEM）,to study its mechanical properties and microscopic evolution. The research results show that the high-strength manufactured sand concrete that meets the mechanical property requirements can be prepared by using stone powder and other qualities instead of manufactured sand. Under the condition that the water-binder ratio remains unchanged,the mechanical property of the concrete with a stone powder content of 5% to7% is the best. The good micro-aggregate filling effect of stone powder and the formation of basic calcium carbonate make the hydration products C₃ S and CaCO₃ micro-interface structure more compact,and Ca（ OH）₂ generates a large number of crystals on the surface of CaCO₃,resulting in Ca（ OH）₂ crystal grains refinement,thereby improving the interfacial bonding effect,so that the interface transition zone is significantly improved. The research results can provide a theoretical reference for the use of stone powder in the design of high-strength manufactured sand concrete mix ratio.