Synergistic influence of micro-nano silica mixture on durability performance of cementious materials

Although works have been carried out to explore the influence of adding micro silica (MS) and nano silica (NS) mixture on the main characteristics of cementious materials, the synergistic role of micro-nano silica mixture was rarely studied on the direct corrosion protection performance of concrete. This research is to investigate the efficiency of using MS and NS mixture, as cement partial replacement, on corrosion protection and sulphate resistance of cementious materials. In addition, the influence of this silica multi-sized mixture was also studied on some durability characteristics related to corrosion and sulphate protection. Based on the maximum mortar compressive strength, 10% MS and 2% NS were the optimum cement replacement ratios for each size separately. For the comparative purposes, the total cement replacement ratio of MS and NS mixture was kept equal to the optimum MS (i.e.10%) and hence the optimum mixing ratios for combining MS and NS in a mixture were equal 8% and 2% respectively. Concrete corrosion protection and mortar sulphate resistance were remarkably enhanced by using 2%NS + 8%MS mixture, instead of the optimum MS or NS cement replacement ratios. Further sensitivity study is recommended for the proposed MS + NS mixture considering more controlling factors.