Influences and Mechanisms of Ordinary Portland Cement on Properties of Asphalt Emulsion Composites

Abstract

Asphalt emulsion composites are energy-saving, ecologically safe materials because they do not need any heating processes which can emit gas and fire hazard in their use. Their use for highway structural layers has attracted relatively little attention largely in China because of the problems associated with the time taken for full strength to be achieved after paving and the susceptibility to early life damage by rainfall. This research work aims at studying influences of using ordinary Portland cement to asphalt emulsion composites. The asphalt emulsion composites were prepared using a three step; road properties were studied and mechanisms were analyzed with Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDXA). The results indicate that ordinary Portland cement addition improves road properties of the composites, such as Marshall stability, compressive strength, dynamic stability and ratio of splitting strength after freezing-thawing cycles. Splitting strength at low temperature of the composites increases with the cement increase, but if the cement dosage surpasses 3.0%, the composites become brittle. So optimal cement dosage is 3.0% in aggregate mass. There is much hydrated calcium silicate(C-S-H) gel in the composites with the cement, which can increase mass and atom percentage of Ca element and Si element, decrease proportions of free asphalt and make mastics in the composites more dense. Road properties of asphalt emulsion composites can be improved.