Experimental Study On The Influence Of Re-dispersible Latex Powder On The Performance Of Cement Stabilized Macadam

Cement stabilized macadam is widely used in highway construction at all levels in China due to its high strength,good integrity and mature construction technology.However,cracks are also easy to occur in cement stabilized macadam base course.Crack resistance of semi-rigid base course has always been the focus of scientific and technical personnel.On the basis of experimental research,this paper explores the properties of redispersible latex powder and its influence on the properties of cement stabilized macadam with the improvement of crack resistance as the core.The main research contents of this paper are:(1)Basic properties of re-dispersible latex powder,preliminary exploration of the influence of the powder on the strength and crack resistance of cement mortar.(2)Re-dispersible latex powder mortar performance,strength,porosity and fluidity test of cement powder mortar,determine the suitable amount of cement powder and strength mechanism of cement mortar.(3)Mix ratio design of cement stabilized macadam,determine gradation and dry density based on crack resistance requirements.(4)Performance test of cement stabilized macadam base including dry shrinkage test,bending tensile strength test and compressive rebound modulus of cement-stabilized macadam,etc.to explore the influence of re-dispersible latex powder on road performance such as cracking resistance of cement-stabilized macadam.Main research conclusions:(1)Crack resistance test results of cement mortar show that re-dispersible latex powder can significantly improve the crack resistance of cement mortar.(2)According to the index of pressure-refraction ratio of cement mortar,1%-2%of re-dispersible latex powder are the appropriate amount.(3)Adding re-dispersible latex powder will increase the fluidity of mortar specimens.Adding re-dispersible latex powder can reduce the water consumption of cement mortar and thus improve the strength of cement mortar.After adding re-dispersible latex powder,the pore size in the section of cement mortar specimens will generally increase,but the number of large-size pores will decrease.(4)With the addition of re-dispersible latex powder,the shrinkage strain of cement stabilized macadam specimens decreases(crack-resistant grading and compactness grading are reduced by 32.7% and 50.6% respectively),and the shrinkage coefficient decreases(crack-resistant grading and compactness grading are reduced by50.1% and 54.1% respectively).(5)With the addition of re-dispersible latex powder,the bending tensile strength of cement stabilized macadam increases(crack-resistant type grading increases by 61.5%),the bending tensile strain increases(crack-resistant type grading increases by 83.6%),the strain energy density increases(crack-resistant type grading increases by 226.8%),and the crack-resistant type grading is obviously better than the compactness grading.(6)With the addition of re-dispersible latex powder,the compressive rebound modulus of cement stabilized macadam decreases by 7%-18%.The research results show that the crack resistance of cement stabilized macadam can be significantly improved by adding re-dispersible latex powder.