Influence of Activation Methods on Strength and Chloride Resistance of Concrete Using Calcium Carbide Residue–Fly Ash Mixture as a New Binder

Abstract

This research aimed to investigate the compressive strength and chloride resistance of concrete made with 30% of calcium carbide residue (CCR) and 70% fly ash (FA) as a binder without portland cement. There were three activation methods to promote strength development of a new cementing material: (1) adding 1% of NaOH by weight of binder; (2) curing concrete at elevated temperature of 60°C; and (3) increasing the fineness of binder by grinding. All concretes were tested to determine the compressive strengths at 1, 3, 7, 28, and 90 days. The chloride resistance of the concrete was also investigated at 28 and 90 days. The results revealed that three activation methods used in this study could improve the compressive strength of concrete made from CCR and FA mixture, with more significant effects occurring at the early age than at the later age. Increasing the fineness of a new cementing material was found be the most effective method compared with the other methods. The compressive strength of concrete activated by increasing the fineness of a new cementing material could be as high as 55.0 MPa at 28 days and increased to 65.1 MPa at 90 days. Moreover, the chloride resistance of concrete in terms of the chloride ion penetration and corrosion resistance of reinforcing steel in concrete could be considerably improved by three activation methods used in this study.