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

研究了用碳纤维或芳纶纤维增强磨细高炉矿渣的水泥复合材料，以开发混凝土表面防护材料。将水泥复合材料浸泡在硫酸和除冰化学品(如氯化钠和醋酸钙镁(CMA))的组合溶液中。在复合溶液中，氢氧化钙残留量随浸泡时间的增加而减少。在酸和CMA的混合溶液中浸泡的试件的显微硬度最低，发现硫酸和除冰剂溶液的联合作用比单独的硫酸溶液作用对水泥复合材料的危害更大。研究了水泥复合材料在酸性溶液和除冰液中的渗透性和抗冻融性。根据离心机测得的渗透溶液重量计算渗透系数。对浸泡在指定溶液中的试件进行冻融试验。当矿渣取代率为70%时，混凝土的抗冻融性能降低，但渗透系数随矿渣取代率的增加而减小。虽然渗透系数随纤维体积分数的增加而增大，但抗冻融性能显著提高。

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.