Experimental Study On Static And Dynamic Characteristics Of Foamed Cement Banking Mixed By Waste Gypsum

According to the latest development plan of Chinese government,there will be a rapid development period for infrastructure construction such as highways,high-speed railway,and urban rail transit in the following decades.Balance between construction and environmental protection is a problem to be solved.It is an effective method to solve this problem by developing some kinds of engineering material using solid wastes such as waste soil and waste gypsum.In this paper,both efforts of experimental study and theoretical analysis are added on the research of mechanism for performance improving of foamed mixture lightweight soil by adding into waste gypsum.Both static and dynamic characteristics of waste gypsum bubble lightweight soil are studied and analyzed systematically through density test,unconfined compression test,direct shear test and dynamic triaxial test.Improving effects on both static and dynamic strength by the adding of waste gypsum is thus revealed.The effects of waste gypsum mixing ratio,cement mixing ratio,bubble mixing ratio and confining pressure on the static and dynamic properties of Foamed Cement Banking Mixed with Waste Gypsum(FCBMWG)are studied and analyzed,including density,stress-strain relationship,unconfined compressive strength,internal friction angle,cohesion and dynamic shear stress.Main research results are as follows:(1)Through the study and analysis of density test,it can be concluded that FCBMWG is excellent in light quality.According to the density test results,the average value of FCBMWG is about 1.55 g/cm3,which is 0.37 g/cm3 lower than that of raw soil.(2)By analysis of stress-strain curve in static test of FCBMWG,it can be concluded that deformation modulus and strength of sample change synchronously with the change material component.With cement content less than 8%,plastic failure is found to be the main failure mode,while brittle failure is found with cement content larger than 8%.While ratio of air bubbles and waste gypsum are found with no effect on failure mode.(3)With ratio of waste gypsum to cement 1:2,both static and dynamic strength of FCBMWG reach maximum level.Static strength of FCBMWG increased by 27.4%compared with pure FCB,while dynamic strength of FCBMWG increased by 35.3%.Results of this research will have an improvement effect for both physical and mechanical properties of foamed mixture lightweight soil,as well as utilization of waste residue.This research has important significance for understanding the strength mechanism and performance of lightweight soil.