Experimental study on the influence of the different percentage of nanoparticles on strength and freeze–thaw durability of shotcrete

Abstract

Shotcrete is widely used in mining, tunneling, and construction engineering. In cold areas, shotcrete layers expose to freeze–thaw cycles which affect its durability. The effects of nanoparticles on the mechanical properties and the frost resistance of shotcrete were examined. Thus nano-silica and nano-clay were used, as a cement replacement, at 0, 2, 4, and 6% by weight for preparing the samples. Different mix designs were exposed to freeze–thaw conditions based on ASTM C666-A and compressive strength, dynamic elastic modulus, water absorption, mass loss, length change, and physical appearances were monitored. The experimental results demonstrate that the sample containing 6% nano-silica has the best mechanical properties and the most resistant against freeze–thaw cycles. Adding nano-clay provides a lower enhancement than nano-silica; however, its effect on mechanical and durability properties is significant compared with the control sample. The optimum percentage for nano-clay was established to be 4%. Eventually, the results revealed that the application of the nanomaterials improves mechanical properties and frost durability of shotcrete due to these materials have pozzolanic and filling effects and resulted in less porous and denser structure.