Effects of aggregate quality on reinforcement corrosion

Abstract

The reduction in the useful-service life of concrete structures in the Arabian Gulf, due to chlorideinduced reinforcement corrosion is of major concern to the construction industry in this region. There are several options available to minimize concrete deterioration due to reinforcement corrosion. Among these alternatives, the use of good quality concrete is the cheapest one. However, it is difficult to produce good quality concrete locally, as the available limestone aggregates are weak and highly absorptive. Therefore, there is a need to improve the quality of concrete by suitable adjustments in the mix design. Further, the performance of high quality concrete when exposed to thermal variations is not very well documented.

This research was conducted to develop high quality concrete utilizing local aggregates. Three types of coarse aggregates, namely limestone aggregates from Abu-Hadriyah and Riyadh, and steel slag aggregates were selected to produce high quality concrete. The tensile strength and reinforcement corrosion of the high quality concrete produced using local aggregates were investigated.

The data developed in this research indicate that the quality of aggregate has a significant effect on the corrosion resistance of concrete. The steel slag aggregate concrete showed better corrosion resistance and tensile strength followed by Riyadh and Abu-Hadriyah aggregate concretes. Exposure to the thermal variations reduced the corrosion resistance of reinforced concrete specimens prepared with the selected aggregates.

The service life of the concrete prepared with the selected aggregates was predicted using two models, namely Bazant's mathematical model and Morinaga empirical formula. The highest service life was recorded in the concrete specimens prepared with steel slag aggregates, silica fume and steel fibers.