Title:
Performance of Various Test Methods for Assessing the Potential Alkali Reactivity of Some Canadian Aggregates
Author(s):
M. M. Alasali, V. M. Malhotra, and J. A. Soles
Publication:
Materials Journal
Volume:
88
Issue:
6
Appears on pages(s):
613-619
Keywords:
accelerated tests; alkali-aggregate reactions; alkali content; cements; concretes; mix proportioning; temperature; tests; Materials Research
DOI:
10.14359/1199
Date:
11/1/1992
Abstract:
Three Canadian aggregates that display the three types of alkali reactivity (alkali-silica, alkali-silicate/silica, and alkali-carbonate reactions) were used to study the influence of normal and accelerated test conditions on the behavior of concrete made with them. Prisms of dimensions 75 x 75 x 300 mm were made with high-alkali portland cement (1.13 percent Na 2O equivalent), high-alkali cement with enhanced alkali content, and with low-alkali cement (0.54 percent Na 2O equivalent). The water-cement ratio in all mixtures was kept in the range of 0.53 to 0.60. Expansion of the concrete specimens was monitored under standard and accelerated test conditions. The concrete prisms for standard conditions were kept in a fog room at 23 C; the prisms for accelerated testing were immersed in solutions of NaCl, KCl, NaOH, and KOH, and exposed to temperatures of 38 or 80 C; and another series was subjected to wetting and drying cycles at 38 C. Test results up to 275 days indicate that the expansion of concrete containing different aggregates varies widely in the different conditions. Also, the rate of expansion of concrete containing similar aggregates is greatly affected by the types of chemical solution and the storage temperature. Highest expansions, at 80 C, were in NaCl solution for the dolomitic aggregate, in NaOH solution for the silica-rich limestone aggregate, and in KOH solution for the silicate aggregate.