Cementing efficiencies and synergistic roles of silica fume and nano-silica in sulphate and chloride resistance of concrete

• Published in: Construction & building materials Vol. 223; pp. 965 - 975
• Main Authors: Li, L.G., Zheng, J.Y., Ng, P.L., Zhu, J., Kwan, A.K.H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30.10.2019
• Subjects: Cementing efficiency; Chloride resistance; Nano-silica; Silica fume; Sulphate resistance; Synergistic effect; Cementing efficiency; Chloride resistance; Synergistic effect; Sulphate resistance; Nano-silica; Silica fume
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.07.241

•Adding MS and/or NS can improve sulphate and chloride resistance of concrete.•Cementing efficiencies and synergistic effects evaluated by new formulas.•Cementing efficiency factors of MS and NS are much higher than 1.0.•Synergistic effect is larger in sulphate resistance than in chloride resistance. It has been proven by various studies that adding silica fume (SF) alone or nano-silica (NS) alone can provide significant beneficial effects on the durability of concrete. In theory, SF and NS may also be added together, but up to now, such possible combined usage of SF and NS for improving the durability of concrete, especially the sulphate and chloride resistance, has not been deeply explored. In this paper, the individual and synergistic roles of SF and NS in the sulphate and chloride resistance of concrete were investigated by producing a series of concrete mixes containing varying SF, NS and water contents for strength test, sulphate attack test and rapid chloride permeability test. It was found that the combined addition of SF and NS can further enhance the sulphate and chloride resistance to higher than possible with the single addition of SF or NS. From the experimental results, the cementing efficiencies of SF and NS were evaluated, from which it was revealed that there exist certain synergistic effects offered by the combined addition of SF and NS on the sulphate and chloride resistance.