Study on Improving Performance of Concrete Subjected to Acid Rain and Deicers

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Cement composites incorporating ground granulated blast furnace slag, whch were reinforced with carbon fibers or aramid fibers, were investigated to develop material for protecting concrete surface. The cement composites were immersed in combined solutions of sulfuric acid and deicing chemicals such as NaCl and calcium magnesium acetate (CMA). The residual amounts of calcium hydroxide decreased with increasing in immersion period in the combined solutions. The lowest value in microhardness was observed on any specimen immersed in the mixed solution of acid and CMA.It is found that the combined action of the sulfuric acid and the deicer solution is more deleterious to the cement composite materials than the action of solely sulfuric acid solution. Permeability and freeze-thaw resistance of the cement composites were investigated against acid and deicer solutions. Coefficient of permeability was calculated on the basis of the measured weight of permeated solution by using a centrifuge. Freeze-thaw tests were performed for the specimens which were immersed in the specified solutions. The coefficient of permeability decreases with increasing in the slag replacement ratio and the freeze-thaw resistance increases, although the freeze-thaw resistance decreases in the case of the slag replacement ratio of 70%. Although the coefficient of permeability increases with increasing in the fiber volume fraction, the freeze-thaw resistance become remarkably higher.