An experimental study was conducted to evaluate the effects of crumb rubber (CR) on mechanical properties of roller compacted concrete (RCC) for use in pavements. In the experiment, proportions of 0%, 10%, 20% and 30% by volume (vol) CR, were incorporated into RCC as sand replacement material. Mixtures were made at cement contents of 275 kg/m3 (11%) and 201 kg/m3 (8.6%). The water content quantities used to prepare RCC mixtures, were determined from the moisture-dry density relationship obtained based on the soil compaction approach. Various mechanical properties were measured comprising compressive strength, splitting tensile strength, ultrasonic pulse velocity, static and dynamic moduli of elasticity. Also measured were pore-related physical tests consisting of water absorption and volume of permeable pores. It was found that cement content has significant influence on the amount of CR that can be suitably utilized in RCC mixtures. The RCCs prepared at the adequate cement content of 275 kg/m3, exhibited suitable performance for all mixtures containing up to 20% vol CR content. Results showed that the standard relationships between compressive strength, static and elastic moduli as established for normal concretes, are also applicable to RCCs.

Roller Compacted Concrete Pavements (RCCP) are mostly designed by soil-compaction technique. However, the shortcomings associated with the soil-compaction method warrant a scientific way of designing RCCP mixtures based on the paste volume requirements considering the compactness and morphology of aggregates. To evaluate the optimum binder ratio (ratio of paste volume to the volume of void) for RCCP, several mixes were prepared following the particle packing approach by varying the binder ratio at a constant water-cement ratio (0.42). Fresh density, consistency, compactability, hardened density, and compressive strength were considered for binder ratio optimization. It was observed that there exists a linear relationship between the binder ratio and hardened properties up to a ratio of one; post this, a significant decrease in the considered hardened properties was observed. The results indicate that the RCCP mixtures could achieve higher strength and good workability with a binder ratio of 1.