Development of a universal accelerated test for alkali-silica and alkali-carbonate reactivity of concrete aggregates |
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| Authors: | Duyou Lu Benoit Fournier P E Grattan-Bellew Zhongzi Xu Mingshu Tang |
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| Affiliation: | (1) College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xin Mofan Road, Nanjing, Jiangsu, 210009, China;(2) ICON/CANMET-MTL, Natural Resources Canada, 3484 Limebank Road, Ottawa, ON, Canada, K1A 0E4;(3) Institute for Research in Construction, National Research Council of Canada, Building M-20, Ottawa, ON, Canada, K1A 0R6;(4) Present address: Department of Civil Engineering, Hong Kong University of Science and Engineering, The Clear Water Bay, Kowloon, Hong Kong |
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| Abstract: | A universal accelerated test for both alkali-silica and alkali-carbonate reactivity was proposed based on extensive comparative
studies on existed Accelerated Mortar Bar Test (AMBT), (e.g., ASTM C1260, CSA A23. 2–25A, RILEM TC191-ARP-AAR02) and Chinese
accelerated procedures. A single size fraction of 2.5–5.0 mm aggregate particles is used in the test instead of five-graded
requirements in the AMBT, and 0.15–0.80 mm fine particles for ASR, 5–10 mm particles for ACR in existed Chinese accelerated
tests. Three short-fat bars, 40 × 40 × 160 mm, made at fixed cement-aggregate ratio of 1:1, and water-cement ratio of 0.33
are used and the length change of the bars is monitored till 28 days in 1 M NaOH solution at 80°C after being soaked in 80°C
water for 24 h. Over 40 kinds of aggregates from various origins, which include both ASR and ACR aggregates and show a broad
range of reactivity levels in the concrete prism test (CPT), were used to evaluate the reliability of the new test in this
study. Experimental results indicate that, for ASR aggregates, the new test gives a better indication than the AMBT does of
both the reactive/nonreactive characteristic and reactive levels of almost all tested aggregates based on an acceptance criteria
of 0.093% at 14 days, although some very highly reactive aggregates show low expansions relative to the CPT. The “abnormal”
low expansion of some highly reactive aggregate in the test is mainly due to the rapid formation and loss of fair amount of
low viscosity ASR product into the soaking alkali solution. The results on some typical ACR aggregates usually undetected
by the AMBT show that the new test gives the same outcome as using 5–10 mm particles in the Chinese Accelerated Concrete Microbar
Test for ACR aggregates and is in agreement with the CPT, which suggests that it has good potentials to be used for ACR aggregate
when an expansion criteria of 0.1% after 28 days is used. |
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| Keywords: | Alkali-silica reaction Alkali-carbonate reaction Accelerated testing method |
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