RAP变异对厂拌热再生沥青混合料强度性能的影响分析

Analysis of the Effect of RAP Variation on the Strength Performance of Plant-mixed Hot Recycled Asphalt Mixes

再生沥青混合料受原路面沥青混合料回收料(Reclaimed asphalt pavement,RAP)矿料级配、旧沥青含量和结团率变异的影响,容易出现强度性能不稳定的情况,影响再生沥青混合料的推广应用。针对该情况,生产前对RAP材料进行破碎筛分的预处理,可有效减小RAP组成的变异性,从而减小再生沥青混合料强度性能的变异性。因此,为研究厂拌热再生沥青混合料中RAP组成的变异性及其控制方法,本文以级配偏离度和变异系数为评价指标,讨论破碎筛分前后RAP的矿料级配、旧沥青含量和结团率的变异性与再生沥青混合料马歇尔稳定度、劈裂抗拉强度变异性的相关性。结果表明:在进行再生沥青混合料配合比设计时可通过降低变异性较大档次、提高变异性较小档次RAP掺量的方式,达到减小再生沥青混合料材料组成变异性的目的,从而减小再生沥青混合料的强度性能变异性。

Recycled asphalt mixes are affected by the variability of the mineral gradation,old asphalt content and agglomeration rate of RAP,which can easily lead to unstable strength performance and affect the promotion and application of recycled asphalt mixes.To address this situation,the pre-processing of RAP material by crushing and screening before production can effectively reduce the variability of RAP composition,thus reducing the variability of strength properties of recycled asphalt mixes.Therefore,in order to study the variability of RAP composition and its control method,this paper discusses the correlation between the variability of mineral grade,old asphalt content and agglomeration rate of RAP and the variability of Marshall stability and splitting tensile strength of recycled asphalt mixture before and after crushing and screening,using grade deviation and coefficient of variation as evaluation indexes.The results show that the variability of recycled asphalt mixes can be reduced by controlling the amount of RAP in the grades with higher variability and those with lower variability,thus reducing the variability of the strength properties of recycled asphalt mixes.