Evaluation of Canadian Unconfined Aggregate Freeze-Thaw Tests for Identifying Nondurable Aggregates. Technical Summary.

摘要

The Kansas Department of Transportation (KDOT) wants to construct durable concrete pavements with minimal maintenance needs. This goal can only be achieved by using durable aggregates that are resistant to freezing and thawing damage when used in concrete. There is a critical need for a quick and field representative test method that classifies durable aggregates from the nondurable ones. The current battery of tests used by KDOT to qualify an aggregate for use in on-grade concrete can take up to six months to complete. The Canadian freeze-thaw method CSA A23.2-24A, developed by the Ministry of Transportation Ontario (MTO) (CSA A23.2-24A 2004), was developed to quickly screen aggregates for freezing and thawing durability. The method was developed to use salt solutions instead of water to saturate the aggregates before freezing to be more representative of field conditions. Freeze-thaw deterioration of aggregates in concrete is the biggest durability problem faced by Kansas concrete pavements (Clowers 1999). The main objective of this study is to determine any correlations between the CSA A23.2-24A method and the currently used KDOT aggregate qualification methods to allow for use of the simpler and more rapid CSA test method.