In order to achjeve the objective. it was impor­tant to develop a mix lhat would rapidly generate a high heac of hydration. The cold ambient air would cool down 1he shotcrete but the heat released dur­ing the hydration process would allow 1he hydra­tion of ccmem 10 proceed unril Lhe remperature of fresh shotcrete decreased lo the freezing tempera¢ ture of the brine solution (brine is a solution of cal­
cium chloride). Al that 1empera1ure, brine freezes and the process of hydration remains suspended until thawing takes place. A laborntory test progi-am (not presented in 1his paper) was used to develop two dry-mix shotcrcte mixes for performance evaluation at a mine near the Arctic Circle under permafros1 conditions. The mixes evaluated had very shon initial and final set times. generated the most heat of hydration during the first 1rtinu1es, and developed the highest com­pressive strcnglh during the first few hours.[2] It. was lherefore. expected I.hat these mixes could be ap­plied on frozen surfaces and would be able lo set and develop adequate mechanical properties.