Low Temperature Effects on the Properties of Shotcrete Accelerators and Potential Remedies

The effect of subzero temperatures on the stability and thereafter performance of three different shotcrete accelerators were investigated here. It was found that decreasing in its fluidity, the non-alkaline shotcrete accelerator (no F ions in formula) was not affected by freezing temperature of as low as −15 ℃, thus may be used as it is for all applications. On the other hand, fluorosilicate-based shotcrete accelerator should only be employed till a temperature of −10 ℃ to −5 ℃. When fully froze at −15 ℃, fluorosilicate shotcrete accelerators undergo an irreversible change where solidified product cannot be fully redissolved. Lastly, cryolite based shotcrete accelerators freeze the fastest but may be employed when heating facilities are available at point of application.