Study On Crack Resistance Of Cement Stabilized Macadam Base Mixed With Waste Plastic Fiber

The waste plastic fiber is a filamentous fiber.It is made by mechanically pulverizing waste plastics,including waste cables,woven and plastic bags.In road engineering,it can not only reduce the environmental pollution,but also achieve the reuse of waste resources,thus reducing engineering costs.In order to improve the crack resistance of cement stabilized macadam,waste plastic fibers were mixed into the cement stabilized macadam composite,and the fiber content and the curing time were taken as variables.The research on the mechanical properties,dry shrinkage,thermal shrinkage and crack resistance reinforcement mechanism of waste plastic fiber modified cement stabilized macadam composite was carried out.At the same time,according to the requirements of "Research on road performance of composite polymer modified semi-rigid base" of Hunan Transportation Science and technology project,the test road section is paved in Luoj iu interchange ramp A(AK0+000～AK0+100)of Huaihua to Zhijiang Highway in Hunan Province to study the feasibility of application of waste plastic fiber in the actual project.Main conclusions of this study are drawn as follows:(1)The surface of raw materials of waste plastic fibers is contaminated during the recycling process so that its adhesion to the cement is poor;At the same time,fibers entangled with each other are easily agglomerated during the mixing process.In terms of these problems,a method for surface modification of waste plastic fibers was proposed in this study,that is,light calcium carbonate was prepared to cover and modify waste plastic fiber.It was found that light calcium carbonate improved the density of waste plastic fiber,and its surface flatness,thus reducing the situation of agglomeration in the mixing of mixture;At the same time,it significantly improved the hydrophilicity of waste plastic fiber and the adhesion of waste plastic fiber to cement.(2)When the content of waste plastic fiber in the cement stabilized macadam composite is 0.30%,its mechanical properties are the best in the same age;Compared with ordinary cement stabilized macadam composite at the age of 7 d,28 d,and 90 d,the compressive strength of composite in this study increased by 5.9%,12.2%,and 15.6%respectively;Its tensile strength increased by 71.4%,111.1%,and 136.3%respectively;Its flexural tensile strength increased by 13.0%,15.8%,and 16.0%respectively;Its compressive modulus of resilience decreased by 1.0%,2.4%,2.7%respectively.(3)After continuously recording the dry shrinkage and thermal shrinkage of cement stabilized macadam composite for 90 d,it was found that when the content of waste plastic fiber was less than 0.45%,the coefficients of dry shrinkage and thermal shrinkage of waste plastic fiber modified cement stabilized macadam composite were significantly lower than those of ordinary cement stabilized macadam composite’s.(4)The fiber stress transmission theory,fiber composite laminate theory,and flexible fiber crack resistance theory were used to analyze and discuss the effect of plastic fiber volume content,elastic modulus and length diameter ratio to the crack resistance of matrix composite.(5)Through laying test sections and subsequent follow-up tests,the construction technology of waste plastic fiber modified cement stabilized macadam composite was summarized;Laboratory test and engineering practice prove that the mixing of waste plastic fiber has a good inhibiting effect on the cracking of cement stabilized macadam,reduces the number and length of cracks,and improves the anti cracking performance of cement stabilized macadam base.