Research On Performance Influence Of Stone Powder On Manufactured Sand And Its Mortar And Concrete

Stone powder is one of the important components formed in the process of rock crushing and sand making.The content of stone powder directly affects the material characteristic of manufactured sand and the properties of mortar and concrete.Therefore,relying on the Li-rong Expressway construction project in Guizhou Province,this paper studies the influence of stone powder on the properties of manufactured sand,mortar and concrete,in order to reveal the action mechanism of stone powder in the concrete system of manufactured sand,so as to promote the popularization and application of manufactured sand instead of natural sand.(1)The differences between manufactured sand and natural sand in material properties were compared and analyzed,and the influence of stone powder content on the characteristic of manufactured sand was tested.The results show that the content of stone powder of the relying project manufactured sand is above 10%,the granules angularity of manufactured sand is rich and the gradation is characterized by "more at both ends and less in the middle".In addition,the voidage decreases gradually with the increase of stone powder content,which indicates that stone powder plays a role in filling voids with micro-aggregates and lubricating between particles in manufactured sand system.(2)The influence of stone powder content on the properties of manufactured sand mortar was tested.The results show that the working performance and mechanical strength of mortar first increase and then decrease with the increase of stone powder content,indicating that stone powder plays a role of physical water reduction,water retention and thickening,and filling voids with micro-aggregate in the system of manufactured sand mortar.(3)The mix proportion design of manufactured sand concrete is carried out by using the concept of orthogonal experiment design and optimization.Combing with the actual situation of relying on project construction,the optimum mix proportion of two typical strength grade manufactured sand concrete,low strength grade C35 and high strength grade C50,is determined.Finally,a mix proportion design method of manufactured sand concrete based on orthogonal experiment design and optimization is proposed.(4)The influence of stone powder content on the properties of manufactured sand concrete was tested.The results show that increasing the content of stone powder properly is helpful to improve the working performance,mechanical strength and shrinkage resistance of concrete,indicating that stone powder also has the effect of accelerating the early hydration of cement by microcrystalline nucleus in the system of manufactured sand concrete.Therefore,the stone powder content of C35 and C50 strength grade manufactured sand concrete should be controlled in the range of 8%～16%and 4%～12%respectively.(5)The effect of sand ratio on the properties of manufactured sand concrete was tested.The results show that the suitable sand ratio can improve the working performance and mechanical strength of concrete.In the concrete system,the manufactured sand and cement paste form mortar,which has the function of filling skeleton pore,encapsulating bond and balling.Therefore,the sand ratio of C35 and C50 strength grade manufactured sand concrete should be controlled in the range of 0.47-0.53 and 0.39-0.42 respectively.In conclusion,the results of this paper can provide references for mix proportion design of manufactured sand concrete and reasonable control of stone powder content and sand ratio in manufactured sand concrete.