Experimental Study On Road Performance Of Fiber Cement Stabilized Macadam Base

Cement stabilized macadam base is the most widely used form of road base in China.With the increase of using time of cement stabilized material base course,under the influence of vehicle load and environmental conditions,some diseases will also appear on the base course,the typical disease form is crack.Based on the experiment,this paper explores the influence of different fibers,such as polyvinyl alcohol,on the mechanical properties of cement stabilized macadam base material.In terms of road performance,the core index of attention is to improve its crack resistance.This paper mainly studies:(1)Raw material selection and test;(2)Mix proportion design of fiber cement stabilized macadam mixture.According to the traffic grade,two types of mixture gradation(c-b-2,c-c-2)are selected in this paper;(3)Mechanical properties test of fiber cement stabilized macadam.Tests of unconfined compressive strength,splitting strength and freeze-thaw splitting strength of single and mixed fiber cement stabilized macadam.(4)Crack resistance test of fiber cement stabilized macadam mixture.The bending tensile strength(different age)and dry shrinkage property of fiber cement stabilized macadam were tested,and the effect of different fiber and fiber adding methods on the crack resistance of cement stabilized macadam was analyzed.The main conclusions of this paper are as follows:(1)Compared with that without fiber,the water content and the maximum dry density of cement stabilized macadam with fiber are very small.(2)The unconfined compressive strength of cement stabilized macadam mixture can be improved by adding different fibers.The effect of adding polyester polyvinyl alcohol mixed fiber is the best,and polyvinyl alcohol fiber and glass fiber powder also have good effect.(3)The splitting strength of cement stabilized macadam is improved by adding fiber.The cleavage strength of the fiber is increased most by adding polyester polyvinyl alcohol mixed fiber,followed by polyvinyl alcohol fiber.(4)After BDR(5 freeze-thaw cycles),the loss of compressive strength of cement stabilized macadam is the smallest(90.8%)、 Then PVA fiber(80.39%)、Glass fiber powder(72.41%),that is to say,after adding fiber,the water stability and frost resistance of cement stabilized macadam are improved,and the best effect is polyester polyvinyl alcohol mixed fiber.(5)The flexural tensile strength of cement stabilized macadam is improved by adding fiber.The strength of the fiber increased by 44.6%;the strength of PVA fiber increased by 33.9%;the flexural tensile strength of glass fiber powder increased by 28.6%;The strength of polyester fiber increased by 24.1%.(6)With the addition of fiber,the dry shrinkage coefficient of cement stabilized macadam mixture is reduced and its crack resistance is improved.The dry shrinkage coefficient of cement stabilized macadam mixed with polyester polyvinyl alcohol fiber decreased the most,and the value of dry shrinkage coefficient decreased between 40-43%.