水泥稳定再生集料的性能及其影响因素研究

将再生集料(RCA)按0%,30%,60%和100%的掺量(质量分数,下同)替代天然碎石,设计了4种水泥稳定再生集料(CSRCA);用掺量为5%的水泥拌和后,成型了CSRCA试件.测试了CSRCA试件的击实特性、无侧限抗压强度、劈裂强度、抗压回弹模量、干缩性能、抗冲刷性能和抗冻性能,以研究CSRCA的路用性能变化规律及其影响因素.结果表明,RCA存在孔隙与微裂缝,强度低、吸水率大,导致CSRCA试件的最大干密度随RCA掺量的增加而降低,最佳含水量则逐渐增大;CSRCA试件的7,28d无侧限抗压强度和抗压回弹模量随RCA掺量的增加而增大,90d无侧限抗压强度和抗压回弹模量随RCA掺量的增加而降低;当水泥掺量为5%时,任意RCA掺量的CSRCA试件无侧限抗压强度均满足高等级公路基层的使用要求.CSRCA试件的7,28和90d劈裂强度随着RCA掺量的增加而增大.CSRCA试件的干缩性能、抗冲刷性能和抗冻性能均随着RCA掺量的增加而降低.RCA存在一定的未水化水泥颗粒和活性物质,能发生水化和火山灰反应,对CSRCA试件的早期强度有改善作用.

Performances and Influencing Factors of Cement Stabilized Recycled Concrete Aggregate

Four types of cement stabilized recycled concrete aggregate(CSRCA) with RCA content(by mass, the same below) of 0%, 30%, 60% and 100% were applied, and specimens were prepared with 5% cement content. Properties of CSRCA, including compacting character, unconfined compressive strength, splitting strength, compressive resilient modulus, drying shrinkage property, erosion resistance and freezing resistance, were tested so as to see the variation rule of CSRCA pavement performance and influencing factors. The result shows that the maximum density of CSRCA decreases and the optimum water content increases as RCA content increases, because of low density and high water absorption of RCA and existence of voids and microfractures in RCA. With RCA content increasing, 7, 28d unconfined compressive strength and compressive resilient modulus of CSRCA increase, while 90d unconfined compressive strength and compressive resilient modulus decrease. Unconfined compressive strength of CSRCA with arbitrary RCA content can satisfy base layer requirement of high grade highway when cement content is fixed to 5%. 7, 28, 90d splitting strength of CSRCA increase with the increase of RCA content. Drying shrinkage property, erosion resistance and freezing resistance of CSRCA all increase as RCA content increases. A certain amount of unhydrated cement particles and certain active substances included in RCA can lead to cement hydration reaction and pozzolanic reaction, which will enhance the early strength of CSRCA.