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Showing papers by "Marc-André Bérubé published in 2007"


Journal ArticleDOI
TL;DR: In this article, the pore solution was systematically expressed (i.e. ex tracted at high pressures) from concrete speci- mens tested at 38� C over water (Canadian standard).
Abstract: Knowledge of alkali concentration in concrete pore solution is key for long-term eval- uation of alkali-silica reaction (ASR) expansion. This study aimed at providing experimental data on the alkalinity evolution in concrete tested for ASR in order to determine critical alkalinity values that stop concrete expansion. The pore solution was systematically expressed (i.e. ex- tracted at high pressures) from concrete speci- mens tested at 38� C over water (Canadian standard). Alkali concentration showed a decreasing trend with time, which can be mainly explained by alkali leaching. After 52 weeks, the decrease in alkalinity was up to 25% of the ori- ginal Na2Oeq content in the concrete, contributing to underestimate long-term expansion of reactive concrete. Comparisons were also made between pore solution expressed out of cement paste specimens and concrete specimens; differences (from 25% to 43% higher for cement paste) suggest that results obtained from cement paste are not suitable for concrete as they tend to overestimate the concrete pore solution alkalin- ity. The alkali concentration threshold varied from one mixture to another (205-335 mmol/l).

54 citations


Journal ArticleDOI
TL;DR: In this article, a total of 87 concrete mixtures were made incorporating 12 reactive aggregates of various types and degrees of alkali-silica reaction (ASR), and using various dosages of LiNO 3 and Li glass in combination or not with supplementary cementing materials (SCM).
Abstract: To evaluate the effectiveness of lithium-based products to counteract alkali-silica reaction (ASR), a total of 87 concrete mixtures were made incorporating 12 reactive aggregates of various types and degrees of ASR, and using various dosages of LiNO 3 and Li glass in combination or not with supplementary cementing materials (SCM) The concrete prisms were tested at 38 °C (100 °F), according to CSA A232-14A or ASTM C 1293, and also at 60 °C (140 °F) to evaluate the possibility of accelerating the testing procedure Using LiNO 3 at the [Li]/[Na + KJ ratio of 074 recommended by the manufacturer, satisfied the 2-year 004% expansion limit criterion (CSA A232-28A) at 38 °C (100 °F) for six aggregates; three aggregates required a ratio between 074 and 111, while a ratio 111 was not effective with the other three aggregates The lithium glass was not effective The ternary silica fume/slag cement tested was effective and the fly ashes and slag as well provided they were in sufficient quantities and they had a proper composition Most LiNO 3 -SCM combinations did not show significant synergetic effect The required LiNO 3 dosage is not related to the aggregate reactivity The 6-month expansion at 60 °C (140 °F) correlated well with the 2-year expansion at 38 °C (100 °F) for the control and SCM mixtures, but not for the LiNO 3 mixtures

22 citations