Anchor Bars in Frozen Bedrock - Curing Techniques for Backfill Grout

Abstract

As part of a power plant expansion project at the Diavik DiamondMine in the Northwest Territories of Canada, forty eight (48) rock anchors for six (6) exhaust stack foundations were designed, installed and pull-tested. The Diavik Diamond Mine is located in a region of continuous permafrost which presents unique challenges for design and construction. In particular, frozen bedrock is known to slow the curing time of grout, and if incorrectly cured, significantly reduce the strength of the cured grout. In an effort to accurately replicate the in-situ ground temperature conditions while curing grout samples, single node thermistors were installed to monitor ground temperatures and the samples of the cold weather anchor grout were cured in a calcium chloride ice-bath.The anchor installation procedure, cold weather anchor grout formulation, in-situ ground temperature measurements, unconfined compressive strength (UCS) test results of the ice-bath cured grout and a summary of the anchor pull-test results are presented.