橡胶-水泥稳定碎石持强增韧特性研究

Strength and Toughness of Rubber-cement Stabilized Macadam

为了增加水泥稳定碎石半刚性基层材料的韧性,有效提高其抗裂性能,以减少因基层开裂引起的路面反射裂缝,以粒径为2.36~4.75mm的橡胶颗粒等体积替换同粒径的集料,制备了持强增韧型橡胶-水泥稳定碎石材料。橡胶颗粒掺量分别为该粒径集料总体积的38%、57%、76%和95%。采用材料试验系统(MTS)开展了7d无侧限抗压强度试验、四点弯曲强度试验和劈裂强度与模量试验,揭示了无侧限抗压强度、最大劈裂与弯拉应变及劈裂动态模量随橡胶颗粒掺量的变化规律,提出了一种强度满足规范要求、模量可调控的水泥稳定碎石材料制备方法。研究结果表明:橡胶-水泥稳定碎石的7d无侧限抗压强度随橡胶颗粒掺量的增加而减小,且两者呈幂函数关系,当掺量在80%以下时可满足规范中的强度要求;最大劈裂应变随橡胶颗粒掺量的增加而逐渐增大,在保证强度的基础上,极限应变最大可达到传统水泥稳定碎石的1.9倍,而弯拉应变则先增大后减小,在保证设计强度的前提下,极限应变最大可达到传统水泥稳定碎石的3.79倍;劈裂动态模量随橡胶颗粒掺量的增加而减小,两者呈幂函数关系;橡胶-水泥稳定碎石的韧性较传统水泥稳定碎石显著增强,从而提高了其作为半刚性基层材料的抗裂性能;橡胶颗粒的掺入使水泥稳定碎石在保证强度的前提下,实现了破坏应变显著增大(即断裂能显著增大)、模量可调可设计的功能。

Rubber cement stabilized macadam,with properties of strength and toughness,was prepared by replacing similar-sized aggregate with 2.36-4.75 mm rubber particles.The content of the rubber particles was 38%,57%,76%and 95%of the total volume of the aggregate.The 7-day unconfined compressive strength test,four-point bending strength test,splitting strength test,and modulus test were carried out using the materials test system(MTS).The results show that the 7-day unconfined compressive strength of rubber-cement stabilized macadam decreases with the increase in the content of rubber particles,and a power function governs the relationship between the two parameters.When the content is below 80%,the 7-day unconfined compressive strength can meet the requirements of the specification.The maximum splitting strain increases with the increase in the content of rubber particles.Based on ensuring the design strength,the maximum splitting strain is 1.9 times that of the traditional cement stabilized macadam.However,the bending tensile strain increases first and then decreases.Based upon the premise of ensuring the design strength,the maximum bending strain is 3.79 times that of the traditional cement stabilized macadam.The splitting dynamic modulus decreases with the increase in the content of rubber particles,and a power function governs the relationship between the two parameters.Compared with traditional cement stabilized macadam,the toughness of rubbercement stabilized macadam is significantly enhanced,improving its crack resistance as a semi-rigid base material.The addition of rubber particles enables the cement stabilized macadam to increase the failure strain(increasing the fracture energy significantly),adjusts the modulus,and ensures strength.