Evaluation of cement-treated mixtures with slow setting bitumen emulsion as base course material for road pavements

This study investigated the effects of the addition of a bitumen emulsion and Portland cement on the long-term performance of road base. The specimens stabilized with Portland cement (0-6%), bitumen emulsion (0-6%) and Portland cement-bitumen emulsion mixture were subjected to different stress sequences in order to study the unconfined compressive strength (UCS), flexural strength (FS), wetting and drying (WD), soaked and unsoaked California bearing ratio (CBR), dynamic creep (DC), and wheel-tracking (WT) characteristics of 7-day-cured specimens. The results of UCS, FS and CBR tests revealed that the additives significantly improved the strength of the mixture. The WD cycling tests showed that the addition of a 4% Portland cement-3% bitumen emulsion mixture resulted in a 179.4% reduction in water absorption, a volume change of 256.3%, and a weight change of 211.95% as compared to the sample with 4% cement after 12 WD cycles. The permanent strain behavior of the samples was assessed by the Zhou three-stage model. The results of DC and WT tests showed that the permanent deformation characteristics were considerably improved by the addition of a 4% Portland cement-3% bitumen emulsion mixture, which resulted in reduction of permanent strain of the mixture. Therefore, this research presents an environmentally friendly additive with outstanding engineering properties for use in road bases.