Effect of GU vs. GUL Cement on AAR Testing of Concrete Aggregates

The Ministry of Transportation (MTO) evaluates the reactivity of concrete aggregates using the MTO laboratory methods, Accelerated Mortar Bar Test (LS-620) and Concrete Prism Test (LS-635), demanding the use of Portland Cement (GU). The introduction of Portland-limestone (GUL) cement in the industry calls for an investigation of its effect on the two methods. This paper reports on LS-620 test data on two MTO reference aggregates (a quarried dolomitic limestone (ACR CA1) from Kingston area and a quarried siliceous limestone (ASR CA6) from Eastern Ontario) using both GU and GUL cements. The data were produced through 4 years of MTO Aggregate and Soil Proficiency Programs. 2019 and 2022 programs involved testing of ACR CA1 using GU (2019) and GUL (2022). The expansion of mortar bars at 14 days produced by GU and GUL from the same supplier are very similar. ANOVA analysis of the expansion data showed no significant difference. However, the precision estimates calculated for ACR CA1 suggested that the variations in expansion with GUL cement are much greater than the variations for GU cement from the same supplier. The findings from the 2021 program showed that with ASR CA6, the use of GUL cement has no significant impact on the test method. The expansion range produced by using GU cement should only be exceeded one time in twenty if GUL cement of the same supplier is used. The paper also includes analysis of the data from 2023 program involving testing of ASR CA6 using GU and GUL cements from different suppliers. The analysis further verifies the effect of GU vs. GUL on LS-620 testing of aggregate reactivity and supports establishment of expansion ranges for the AMBT of ASR CA6.