ABSTRACT
There exists no universally accepted Cold Bituminous Emulsion Mixtures (CBEMs) design procedure. Three design procedures, based on AASHTO and Asphalt Institute guidelines were studied and tested in this investigation. The main obstacles that restrict the adoption of CBEMs as a first option for all road layers include; high porosity, low early life strength and long curing times. The main aim of this investigation was to investigate ways of improving CBEMs volumetric and mechanical properties.
Five different waste materials were incorporated into the cold mixture, i.e. PFA, Red Porphyry Sand, Synthetic Aggregates, Steel Slag and Crumb Rubber. The aggregate gradation was determined using a modified Fuller’s curve. Improvements in all mixture properties were accomplished by increasing the compaction effort and incorporating cement. Three types of cements were tested, namely, OPC, Rapid Setting Cement and Natural Cement. It was found that the Rapid Setting Cement gave higher and faster rates of strength development. Additionally, attempts to accelerate curing times were made by compacting the CBEM specimens in two layers thus allowing the moisture to escape and reducing curing time. These trials provided encouraging results.
The mix design procedure initially adopted in this investigation was found to be complicated, a more simplified cold mixture design procedure is also introduced in this paper. It was concluded that heavier compaction effort and incorporation of cement are very essential for improving the performance of CBEMs. When CBEMs are carefully designed and are allowed to achieve full curing, they become comparable to hot mixes.
