Material design and structural optimization of a High-RAP large-size recycled asphalt-stabilized macadam mixture

Abstract

Semi-rigid asphalt pavement bases are subject to dry shrinkage and thermal shrinkage cracking during the service life and may develop upward and reflect as well. At the same time, a large amount of reclaimed asphalt pavement (RAP) is produced during road maintenance, and its resource-efficient use is now urgently needed. Therefore, this study constructed a high-RAP recycled asphalt-stabilised large-size macadam mixture, denoted as RLGATB-40, by adding a large amount of RAP to the large-size aggregate reinforced system. First, a one-step filling method was used to find the ideal blending ratios of RAP fractions at all particle sizes. Then, compressive strength and splitting strength tests were carried out to optimise the content of large-size aggregates, rejuvenator dosage, and virgin asphalt-aggregate ratio. Subsequently, microstructural analysis, dynamic modulus determination and pavement structure modelling in HPDS2017 were carried out to examine the performance of the proposed material from all sides. Based on the above analysis, although the new mixture has a higher dynamic modulus than the old one, the pavement performance will be almost the same. In addition, the degree of compaction, deflection and smoothness of the built test section all met the requirements specified in the contract, and RLGATB-40 is suitable for use as a flexible base material.