Professor, University of Windsor, Windsor, Ontario
Ph.D. Candidate, University of Missouri-Rolla, Rolla, MO
Petrographic examination of coarse aggregate is accepted as a viable method for predicting its durability in concrete. No similar quantitative method existed for fine aggregate, although Guide for Petrographic Examination of Aggregates for Concrete (ASTM C 295) does yield preliminary information of durability of fine aggregate. This paper proposes a quantitative petrographic analysis that can be used to quickly assess the natural fine aggregate's durability when used in concrete. The method of analysis is essentially the Ministry of Transportation, Ontario LS-616, which separates the fine aggregate into silicate, carbonate, shale and chert fractions. The weighted percentages of these fractions were statistically compared to standard physical tests, including water adsorption and absorption, dry density, magnesium sulfate loss, and micro-Deval abrasion loss. Step-wise multiple regression equations were developed, which allowed calculation of expected magnesium sulfate and micro-Deval abrasion losses based on the proportion of the petrographic types. Mathematical and statistical techniques were also used to establish a petrographic number for sand (PNS) that allows the classification of aggregate into good or poor categories based on their petrographic composition.
Paper ID: CCA10135J