CPT as an evaluation method of concrete mixture for ASR expansion

• Compositional and size pessimum effects can be detected by CPT.
• CPT according to RILEM AAR-4 shows larger amount of alkali leaching from specimens.
• Wet paper wrapping for 100 × 100 × 400 mm specimens can reduce the alkali leaching.
• There are positive relations between mass gain of specimens and expansion.
• Paper wrapping with alkaline solution could be suitable for detecting ASR reactivity.

Highly reactive andesite aggregates including opal or tridymite were evaluated by concrete prism test (CPT) in two ways and the suitable conditions of CPT were discussed. 18 concrete mixtures were used to examine the effect of the type and content of aggregate, the type of cementitious material. Two methods for detecting for ASR reactivity were used; RILEM AAR-4 and JASS 5N, and the latter one is of which authors revised few points. As the results, different performances of andesite depending on the size and the different required amounts of fly ash suppressing ASR depending on the mixture proportion were well demonstrated by CPT that is difficult for mortar bar test. As a curing method to avoid alkali leaching, wrapping with wet paper showed much less leaching than curing in a sealed box. From the viewpoint of easiness of operation, small size 75 × 75 × 250 mm is suitable than large size 100 × 100 × 400 mm.