2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference
Dr. M. T. Bassuoni, University of Manitoba
Efficient repair of concrete pavements typically requires a rapid setting material that can be placed and hardened within a relatively short period of time for quick opening of traffic. While numerous high early-strength cementitious repair materials are commercially available, many of these materials are vulnerable to early-age cracking, poor bonding, and premature deterioration, for example due to incompatibility with the existing pavement. On the other hand, concrete incorporating fly ash, which is known for its improved long-term performance, is not typically recommended as a repair material. The delay in setting time, strength gain and microstructural development at early-age of fly ash concrete impede its wider acceptance as a repair material for concrete pavements. Nevertheless, these performance limitations can be mitigated by incorporation of nanoparticles in the mixture design of fly ash concrete. In the present study, an effort was made to develop nano-modified fly ash concrete as a repair material for concrete pavements. The performance of the newly developed mixtures was compared to that of two commercial cementitious products customarily used by the regulatory bodies in Manitoba, Canada for partial depth repair of concrete pavements. The experimental scheme comprises tests on fresh, hardened and durability properties relevant to the performance of repair materials for concrete pavements. Due to their ultrafine nature, the addition of a small dosage of nano-silica particles efficiently catalyzed the kinetics of hydration reactions in the cementitious matrix at early-age. The results indicate that nano-modified fly ash concrete has superior performance in terms of strength development, bonding, and resistance to salt-frost scaling, and thus it presents a viable option for repair of concrete pavements.