Coarse aggregates used in granular base and asphaltic and portland cement concrete must be sound and capable of withstanding the prevailing environment. In canada, aggregates must be frost resistant. Durability of coarse aggregate is normally evaluated in the sulfate soundness test and water absorption tests, and by measuring resistance to impact in the los angeles abrasion and impact test. These tests suffer from some disadvantages: poor precision and inadequate correlation with field performance. The ministry of transportation has been developing and evaluating new test procedures for a number of years. Some of the major findings are summarized. The likely performance of aggregates in granular base is best measured by the micro-deval test and water absorption. The physical quality of portland cementconcrete aggregates is best measured by the micro-deval test, waterabsorption, and unconfined freezing and thawing. The quality of asphaltic concrete aggregates is best measured by the micro-deval test, polished-stone value test, and unconfined freezing and thawing test. Petrographic examination is also an essential tool in the evaluation of aggregate quality. This paper appears in transportation research record no. 1301, Factors affecting properties and performance of pavements and bridges 1991
Samenvatting