Experimental Study On Marble Powder Used As Roadbed Filler

Hezhou has the largest white marble mineral resources in Central South and South area,and is the largest artificial mineral resource business.However,local enterprises also produce a large amount of marble waste every year.This waste continue to accumulate and cannot be used,which not only causes a waste of resource,but also causes serious environmental pressure in the local area.Therefore,how to make reasonable use of the waste has become an urgent problem that needs to be solved in the local area.This paper studies the feasibility of marble powder as roadbed filler.Firstly,according to the source of the marble powder,the soil samples are named MP1(without binder)and MP2(with binder).Secondly,the type of soil samples are determined through particle analysis test and limit water content test;the mineral composition and element content of marble powder are analyzed through X-ray diffraction test and chemical analysis test.Finally,the mechanical properties and road performances of the soil samples were tested by direct shear test,penetration test,compaction test and California bearing ratio test.The specific experimental conclusions are as follows:(1)The chemical composition of the two soil samples is mainly calcium carbonate,and the mineral composition is calcite.According to the classification standard of soil type,both soil samples are silt.Among them,the MP2 soil sample has a higher plasticity index,in which the properties are closer to clay soil.(2)The permeability coefficients of sample MP1 and sample MP2 in the range of 1.4～1.6 g/cm~3,are weak water permeability.The higher the plasticity index of soil,the more obvious the influence of dry density and void ratio on its permeability coefficient.The internal friction angle of the two soil samples is no obvious difference,but the cohesion force of the MP2 soil sample is 9.33k Pa,which is larger than that of the MP1 soil sample.(3)The optimum water content of the MP1 soil sample is 14%,and that of MP2 soil sample is 18%.MP2 waste powder can meet the requirements of CBR under most moisture content,while MP1 waste powder can only meet the requirements of CBR when the moisture content is within the range of 13%to 16%.(4)After the two soil samples are mixed in different proportions,it is concluded that the main factor affecting the road performance of waste powder is the binder content.The higher the binder content in the soil sample,the flatter the compaction curve,indicating that the dry density of the soil sample is less affected by the change of water content,and the water stability of the soil sample is gradually enhanced;the higher the binder content in soil samples,the greater the optimum water content.(5)By comparing the properties of stone powder with silt and red clay subgrade fillers,it is concluded that the physical and mechanical properties of stone powder waste are between silt and clay.Based on the analysis of the bearing capacity of two kinds of stone powder wastes,discussion from the angle of economy and environmental safety,it is suggested that the two soil samples can be mixed according to a certain mixing ratio to be used as subgrade filler in the actual construction process.