Abstract
Alkali silica reaction (ASR) is influenced by external factors such as the surrounding environment of high alkalinity. Countries with cold climate have a high probability to be exposed to high concentrations of NaCl solution by the deicing salt. This condition will lead to serious ASR problems in concrete, if the aggregates contain reactive silica. The main research work in this paper is to investigate the effect of 15% replacement ratio of high quality fine fly ash (FA15%) and 42% replacement ratio of blast furnace slag (BFS42%) on the ASR mitigation in concrete with different alkali amount inside the pore solution. The experiments were conducted according to the accelerated mortar bars experiment following the JIS A1146 mortar bar test method. In addition, post-analysis such as observation of ASR gel formation by the Uranyl Acetate Fluorescence Method and observation of thin sections using a Polarizing Microscope were also conducted. The mortar bar tests show a very good mitigation effect of supplementary cementitious materials (SCMs). The results show that only small ASR expansions, which can be categorized as “innocuous”, occurred for specimens with 1.2% Na2Oeq using FA15% and BFS42%. However, larger alkali amount inside the system will require more SCMs amount.
Highlights
Alkali silica reaction (ASR) is influenced by internal factors such as alkali, aggregates contain reactive silica and moisture
ASR expansion is completed in just 4 weeks for Ordinary portland cement (OPC) specimens, and around 12 weeks for specimens using fly ash (FA) and blast furnace slag (BFS)
It was delayed, around 12 weeks, for specimens using FA and BFS. (2) The crushed andesite stone and crushed andesite sand aggregate have the same level of reactivity, which is high reactivity
Summary
Alkali silica reaction (ASR) is influenced by internal factors such as alkali, aggregates contain reactive silica and moisture. ASR is influenced by external factors such as the surrounding environment condition and the use of the structures. In terms of reactive aggregates, in Hokuriku district, Japan, there are records that show that the reactive crushed andesite stone has been used throughout the Noto Peninsula. In the Joganji river in Toyama Prefecture, in the Tedori river in Ishikawa Prefecture, and in aggregate production from the basin of the river on top of the Kuzuryu river in Fukui Prefecture, the andesite particles contained in river sand and/or gravel show a high reactivity. The Hokuriku district has a lot of local companies that make PC Girder and PCa Product
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