Location

University of Leeds

Keywords

Concrete, Nano-silica, Slag, Frost resistance, Synergistic effect

Abstract

The frost resistance of concrete is one of the most important factors for its durability. Supplementary cementitious materials could effectively improve the frost resistance of concrete. On this basis, the synergistic effect of nano-silica (NS) with slag on the frost resistance of concrete is better than the single, which was investigated. Nano-silica and slag were employed as a partial substitute of cement. The effect of these on the related indexes, including the mass loss, relative dynamic elastic modulus and porosity of concrete were measured after specified number of freeze and thaw cycles. Results show that the frost resistance of nano-silica modified concrete was obviously improved. The mass loss of control concrete was 2.5 % after 300 freeze-thaw cycles while that of the nano-silica modified concrete was as low as 1%. Further, the anti-freeze durability factor can reach up to 89.55% for the nano-silica modified concrete. The reasons are that the activity and nucleation effects of nano-silica accelerate the hydration of cement and the filling effect leads to more compact matrix. All of these made concrete better frost resistant. This was also proven by the porosity analysis. When the nano-silica was added, the total porosity of nano-silica modified concrete decreased from 14.57 % to 11.39 % compared with the control concrete. So, the synergistic effect of nanosilica with slag can enhance the frost resistance of concrete and improve its durability.

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The Synergistic Effect of Nano-Silica with Slag on Frost Resistance of Concrete

University of Leeds

The frost resistance of concrete is one of the most important factors for its durability. Supplementary cementitious materials could effectively improve the frost resistance of concrete. On this basis, the synergistic effect of nano-silica (NS) with slag on the frost resistance of concrete is better than the single, which was investigated. Nano-silica and slag were employed as a partial substitute of cement. The effect of these on the related indexes, including the mass loss, relative dynamic elastic modulus and porosity of concrete were measured after specified number of freeze and thaw cycles. Results show that the frost resistance of nano-silica modified concrete was obviously improved. The mass loss of control concrete was 2.5 % after 300 freeze-thaw cycles while that of the nano-silica modified concrete was as low as 1%. Further, the anti-freeze durability factor can reach up to 89.55% for the nano-silica modified concrete. The reasons are that the activity and nucleation effects of nano-silica accelerate the hydration of cement and the filling effect leads to more compact matrix. All of these made concrete better frost resistant. This was also proven by the porosity analysis. When the nano-silica was added, the total porosity of nano-silica modified concrete decreased from 14.57 % to 11.39 % compared with the control concrete. So, the synergistic effect of nanosilica with slag can enhance the frost resistance of concrete and improve its durability.