Comparisons of quarry by-products as a partial replacement of portland cement in pastes and mortars

Abstract

Quarry by-products (QB), including screenings, pond fines, and baghouse fines, present a significant surplus, since they are not significantly utilized in other markets and industries. This study explores the use of seven different QB as direct replacements of limestone powder in a portland limestone cement for paste and mortar applications. Cement replacements ranging from 5 % to 20 % by volume were explored, and testing included compressive and flexural strengths, isothermal calorimetry, pore solution analysis, alkali-silica reaction, and reactivity analysis. Expectedly, the results demonstrated that not all QB yielded equivalent performance. All mortars with 5 % and 15 % QB substitution had lower compressive strengths than the control, with the 15 % QB substitution performing worse. However, the mortars with QB had higher flexural strengths than the control. The 5 %, 10 %, 15 %, and 20 % QB substitution samples decreased the cumulative heat at 24 h, 48 h, and 72 h, with a higher substitution having a stronger decreasing effect. QB 2 and QB 7 were found to only slightly decrease the cumulative heat at 5 % substitution. Furthermore, QB 2 was found to significantly accelerate the silicate and aluminate heat evolution peaks, while QB 1, QB 3, QB 4, QB 5, and QB 7 only slightly accelerated the silicate and/or aluminate peaks. The pore solution of mortars with 5 % and 15 % QB substitution were found to have a lower pH and, in general, increased calcium and silicon contents. QB 2 was found to be moderately ASR reactive, while QB 7 was found to be ASR reactive. All QB were found to be non-pozzolanic; however, they may still be of use in other portland cement applications.