DURABILITY OF BLAST-FURNACE SLAG CEMENT CONCRETE WITH DIFFERENT CURING METHODS

Abstract

The concrete industry in Egypt has incorporated Blast Furnace Slag Cement Concrete, BFSCC, as a replacement to Ordinary Portland Cement Concrete, OPCC, in favor to resist harsh conditions related to water hydraulic structures. The practice cannot follow the strict requirements of curing according to the Egyptian code of practice (ECP), where in such cases it was necessary to evaluate the mechanical behavior of such concretes experimentally with practical curing methodologies. Two different methods were used to cure concrete specimens; IC samples were immersed in water until testing time, and secondly, FC samples were kept at a certain relative humidity and temperature and sprinkled with water every twelve hours for one week, simulating practical field curing conditions. The slump, flow, air content, and unit weight of fresh concrete were measured. Compressive strength, dynamic elastic modulus, and pulse velocity are investigated for hardened concrete. The main characteristics of the concrete pore structure were determined. The chloride content of the concrete was evaluated via titration analysis after 1-, 3-, and 5-months’ immersion in sodium chloride solution. Moreover, the concrete specimens were immersed in a 10% sodium sulfate solution for 360 days to test their sulfate resistance. The carbonation depths of the concrete sample were measured at 1, 2, 4, 8, and 12 weeks. The results indicated good agreement between the destructive and non-destructive tests. In addition, as the curing methods and cement type were changed, the pore structure characteristics, sulfate resistance, carbonations, chloride penetration, and diffusion coefficients were significantly study show a lower percentage of soluble/total chloride than Gaynor's range. The BFSC soluble/total chloride ratios are lower than the OPC mix ratios. Furthermore, the data shows that there are no significant changes in soluble and total chloride for zone 20~30 mm.