Potential Alkali-Silica reaction in some Malaysian rock aggregate and their test results

Abstract

It is widely known that the deterioration of concrete due to alkali-silica reaction (ASR) will occur when aggregates containing pessimum amounts of reactive silica minerals are used with high alkali cement. Petrographic examination and expansion tests on several natural rock aggregates collected throughout Peninsular Malaysia indicate some to be potentially alkali-silica-reactive. Petrographic evidences confirm that potential alkali silica reactive minerals in the aggregates consist of chalcedonic (spherulitic) quartz in volcanics, chert clasts in sandstone, strained quartz in quartzite and microcrystalline and cryptocrystalline quartz in hornfels, volcanics and schists are the likely causative factors in the expansion of the concrete bar used in the tests. The hot and humid climatic condition of this country is conducive for the occurrence of alkali-silica reaction in concrete. Therefore, appropriate precautions should be taken when using the Malaysian aggregates for the production of concrete to avoid the risk of alkali-silica reaction.