ABSTRACT
This paper is aimed at developing the accelerated mortar bar test to assess the potential deleterious effect of iron sulfide-bearing aggregate in concrete. The modified ASTM C1260 (accelerated mortar bar test for ASR) was adopted in this study. Some factors that can accelerate the oxidation reaction of the iron sulfide-bearing aggregate were evaluated to reduce the time of testing such as particle sizes of the aggregates, storing temperatures and wet-dry cycles. In this study, 4 types of aggregate including pure pyrrhotite mineral (PR), pure pyrite mineral (PY), aggregate with pyrite mineral (CB) and limestone aggregate without sulfide mineral (NA), were used. The test results suggest that the test conditions by using aggregates with a size range of 2.36 to 4.75 mm, storing temperature of 60°C, 80% RH and wetting and drying cycles of 7 cycles per 2 weeks are recommended for practical application. Different types of aggregate exhibit different expansion of mortar bars. The mortar bar containing CB has the highest expansion, followed by the mortar bars with PR, PY, and NA. The mortar bar test results also correspond with the results obtained by the chemical tests to identify deleterious iron sulfide-bearing aggregates.
