Influences on Compaction of Cold Mix Cement Emulsified Asphalt Using the Superpave Gyratory Compaction

Abstract

It is well known that cold mix cement emulsified asphalt (CMCEA) exhibits good mechanical performance even when paved at room temperature. In this study, the compactibility and mechanical properties of CMCEA specimens were studied using a Superpave gyratory compactor. To analyze CMCEA compaction dynamics, two indices based on indexes of compaction quality (ICQ) and parameters of the compaction process (PCP) were considered. ICQ included the compressive strength and air voids, while PCP included the compaction energy index and compaction rate. Tests were conducted on CMCEA specimens to estimate the effect of process variables, such as compaction temperature, time interval before compaction, and gyration parameters, on ICQ and PCP. It was determined that CMCEA could be molded satisfactorily at temperatures below 40°C. Experimental results showed that the compressive strength and densification of CMCEA specimens were positively correlated in the range of °C10–40°C and negatively correlated beyond 40°C. Process variables play an important role in controlling the compaction characteristics, such as the compressive strength and air voids. Furthermore, choosing a suitable time interval before compaction (TIBC) at a given compaction temperature helps in saving compaction energy and achieving an appropriate compaction rate. To achieve a CMCEA compressive strength >2.4 MPa and densification >92% at 25°C, as mandated by practical design requirements, the TIBC, number of gyrations, and gyration angle were optimized at 12–35 min, 140–160, and 1.15°, respectively. The method used to determine these parameters and the obtained optimal values serve as a benchmark for actual pavement construction.