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Showing papers by "Marc-André Bérubé published in 2002"


Journal ArticleDOI
TL;DR: In this article, particles from 17 different aggregates, 1.25-5 mm in size, were immersed in continuously agitated solutions at 38 °C: distilled water, Ca(OH)2-saturated solution, 0.7 M NaOH (measurement of K supply), and 0.5 M KOH (metric measurement of Na supply).

119 citations


Journal ArticleDOI
TL;DR: In this article, low and high-alkali, plain and air-entrained large concrete cylinders, 255 mm in diameter by 310 mm in length, were made with a highly alkali–silica reactive limestone and subjected to 14-day exposure cycles, including in the most severe case periods of humid storage in air, drying, wetting in salt water, and freezing and thawing cycles.
Abstract: Low- and high-alkali, plain and air-entrained large concrete cylinders, 255 mm in diameter by 310 mm in length, were made with a highly alkali–silica reactive limestone. After curing, a number of cylinders were sealed with silane, oligosiloxane, polysiloxane, linseed oil, or epoxy, with others subjected to 179 freezing and thawing cycles in humid air (one cycle per day). All cylinders were then subjected to 14-day exposure cycles, including in the most severe case periods of humid storage in air, drying, wetting in salt water, and freezing and thawing cycles. All low-alkali specimens did not either expand or develop surface cracking, even those with a deficient air void system and exposed to freezing and thawing cycles. All unsealed high-alkali cylinders subjected early to a series of freezing and thawing cycles did not significantly expand during these cycles, but presented high expansion afterwards. Wetting and drying significantly reduced alkali–silica reaction (ASR) expansion compared with constant hu...

36 citations


Journal ArticleDOI
TL;DR: In this article, a method was applied to 17 aggregates and 8 concretes incorporating aggregates presenting different degrees of alkali-silica or alkali carbonate reactivity.
Abstract: The knowledge of the active- or soluble-alkali content of concrete is useful in the diagnosis and prognosis of alkali-aggregate reactivity (AAR). A method often used for determining this content is hot-water extraction from ground concrete samples. This method was applied to 17 aggregates and 8 concretes incorporating aggregates presenting different degrees of alkali-silica or alkali-carbonate reactivity. The following conclusions can be drawn: (1) a correction must be made to take account for the alkalies released by the aggregates in the test; (2) using cold water rather than hot water has no significant effect on the results; (3) grinding to

29 citations


Journal ArticleDOI
TL;DR: In this paper, different types of sealers were applied on plain and air-entrained large concrete cylinders made with high-alkali contents and highly alkali-silica reactive limestone aggregates.
Abstract: This study follows another experimental study where different types of sealers were applied on plain and air-entrained large concrete cylinders made with high-alkali contents and highly alkali–silica reactive limestone aggregates. The main objective was to determine the effectiveness of these sealers in counteracting concrete expansion and surface deterioration due to alkali–silica reaction under various exposure conditions. This study indicated that all three sealers tested, the silane-, oligosiloxane-, and polysiloxane-based sealers, could stop concrete expansion due to ASR and even produced contraction, even for concrete cylinders subjected to wetting and drying, freezing and thawing, and sodium chloride solutions. In 1991, the same silane, oligosiloxane, and polysiloxane were applied on sections of median barriers showing various degrees of deterioration due to ASR. These sections were subjected to wetting and drying, freezing and thawing, and, during winter, to deicing salt. The silane was also appli...

26 citations


Journal ArticleDOI
TL;DR: In this paper, the potential expansion and damage due to alkali-silica reactivity (ASR) can be reasonably assessed in the laboratory from the inherent expansivity of the concrete under study, which is determined by testing core samples in air at 100% RH and 38°C.
Abstract: In-situ monitoring of concrete deformations and movements is the best way to assess the current expansion of concrete members affected by alkali-silica reactivity (ASR). However, laboratory tests on cores are less expensive and more rapid, and are commonly used to assess the potential for further expansion due to ASR. The risk of expansion and damage due to ASR can be reasonably assessed in the laboratory from: (1), the inherent expansivity of the concrete under study, which is determined by testing core samples in air at 100% RH and 38°C; (2), the residual absolute reactivity of the aggregates present in the concrete under study, which can be determined by testing core samples in 1N NaOH solution at 38°C or, even better for coarse aggregates, by testing aggregates extracted from cores through the concrete prism test CSA A23.2-14A or ASTM C 1293; (3), the amount of alkalies that are still active in the concrete, i.e. in the pore solution, which is estimated by a hot-water extraction method on ground concrete, and (4), humidity, (5), temperature, and (6), stress conditions (confinement, reinforcement, pretensioning, postensioning) in service. The individual risk indices corresponding to each of the above parameters are combined to determine the potential rate of ASR expansion of concrete members in service, either already affected by ASR or not.

16 citations