Investigations on design and durability characteristics of cement treated reclaimed asphalt for base and subbase layers

This paper presents the mechanical, durability and microstructure characteristics of cement treated recycled asphalt (CTRA) bases and sub-bases material produced by varying the percentage of virgin aggregate (VA), recycled asphalt aggregate (RA), and cement content. Modified proctor method of compaction was used to prepare cylindrical specimens at 2.5, 5.0, 7.5, and 10.0% cement contents (% by wt. of aggregate) with different blends of VA and RA. Durability tests were carried out to evaluate the performance of mixtures under repeated wetting and drying in the tropical climate. Experimental results revealed that the addition of cement in CTRA had more effect on mechanical and durability properties compared to RA content. The CTRA mixtures were found to be more ductile albeit lower values of elastic modulus. Scanning Electronic Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis manifest that large amount of Ettringite and higher the Si/Ca ratio in CTRA compared to cement treated mixtures without RA. The higher proportion of these products signify the detrimental effect in mechanical properties. Cost analysis for a typical pavement section demonstrate that the cost-saving of the pavement section with CTRA mixtures observed to be in the range of 26-32% under varying cement and RA contents compared to the pavement section without CTRA. It was found that these mixtures can be used as a replacement for granular bases and sub-bases in flexible pavements and/or bases for concrete pavements instead of roller-compacted concrete. (C) 2020 Elsevier Ltd. All rights reserved.