Innovative air entraining and air content measurement methods for roller compacted concrete in pavement applications

Abstract

Roller compacted concrete pavement (RCCP) is a widely used paving infrastructure for regular and heavy duties. The durability against cyclic freezing and thawing in cold regions is an important issue in lifetime performance of RCCPs. The necessity of using air entraining agents to achieve durable RCCP against freezing and thawing cycles is a controversial subject amongst the researchers. The utilization of appropriate air measurement and entraining methods are two other challenges that RCCPs face in practice. In this study, 8 non-air entrained RCCPs have been designated with 3 paste volumes and different water to cement ratios. In addition, an innovative air entraining method has been used to entrain air in RCCP mixtures by incorporating 1.5–1.9 wt% cement weight of air entraining admixture (AEA). Furthermore, an innovative modified volumetric (IMV) method for air content measurement of fresh RCCP mixtures has been suggested and the results compared with the pressure method (ASTM C231) and microscopical analysis based on ASTM C457 (procedure C). Besides, the modified Vebe and compressive strength tests have been conducted to evaluate the fresh and mechanical properties of RCCPs, respectively. The ASTM C666 test method has also been carried out to assess the durability against cyclic freezing and thawing. The results indicate that both suggested air entraining and IMV methods seem to be efficient in air entrainment and air content measurement, respectively. Adding 1% entrained air bubbles by utilizing AEA could lead to 6.34% lower Vebe time. The air entrainment could result in the reduction of compressive strength up to 15.5% and spacing factor down to 96 μm. The effectiveness of air entrainment on frost resistance of RCCPs can be concluded, as well.