A comprehensive investigation into the effect of water to cement ratios and cement contents on the physical and mechanical properties of Roller Compacted Concrete Pavement (RCCP)

Abstract

The use of Roller Compacted Concrete Pavement (RCCP) is rapidly expanding all around the world. Thus, it is important to investigate its various physical and mechanical properties and compare them with those of Normal Vibrated Concrete (NVC). This paper aims to evaluate the validity of existing relations and hypotheses about NVC as applied to RCCP. In addition, the mechanical properties of RCCP are evaluated and compared with those of NVC, using existing international codes and predictive models. In this experimental study, 11 mixtures of RCCP with various water-to-cement (W/C) ratios (0.3–0.55) and various cement content values (240–340 kg/m3 or in another word 12% to 17% cement-to-aggregate (C/A) ratios) are constructed for the purpose of evaluating the mechanical/physical properties of RCCP in its both fresh and hardened states. The properties examined in this paper are Vebe time, dry unit weight, compressive strength (fc), splitting tensile strength (ft), modulus of rupture (fr), static modulus of elasticity (Ec), dynamic modulus of elasticity (ED), and ultrasonic pulse velocity (UPV). Extensive data collected from literature on the properties of NVC and RCC are used to validate the results of this study. The test results showed that decreasing the W/C ratios from 0.55 to 0.3 increased the Vebe time up to two times, while increasing the cement content from 12% to 17% decreased the Vebe time by 34%. In addition, the results showed that decreasing the W/C ratios and increasing the cement content cause the physical and mechanical properties of RCCP to improve. The results also showed that the relation presented by IMCP manual, Raphael, and Legeron for NVC can provide acceptable estimates of the Ec, ft and fr of RCCP for different W/C ratios as well as different cement contents. On the other hand, in this experimental study, the relationships between the Ec, ft, fr and fc were obtained as Ec=5240fc, ft=0.69fc, fr=1.13fc.