EFFECT OF LIMESTONE CONTENT IN CEMENT ON ALKALI-SILICA REACTION USING ACCELERATED MORTAR BAR TEST

摘要

This paper reports the effect ofinterground limestone content on Alkali-Silica Reaction (ASR) in binder systems with and without supplementary cementitious materials (SCMs) using commercial Portland cement (Type GP) with no limestone addition and a masonry cement with 17% limestone. Tine results show that increasing cement limestone content up to 17% has no adverse effect on expansion of mortar bars containing reactive greywacke aggregate tested using Australian Standard AS 1141.60.1. The high limestone content of 17% also appears to stabilise the Accelerated Mortar Bar Test (AMBT) expansion after 14 days of immersion in 1M NaOH 80 °C This is possibly because of the formation of monocarboaluminate as detected by X-Ray Diffraction (XRD), resulting from the reaction of limestone with the aluminate phases in the cement, which may lead to reduced porosity in the mortar as well as the reduced amount of portlandite in the Irydrated masonry cement as confirmed by Thermogravimemc Analysis (TGA). Moreover, it was found that the limestone content had no detrimental effect on the efficacy of SCMs to suppress ASR as shown in the expansion of the accelerated mortar bar tests.