The Use of Pessimum Effect to Reduce the Expansion of Concretes Based on ASR Reactive Aggregates

Moundoungou, I; Bulteel, D.; Garcia-Diaz, E.; Dégrugilliers, P.

doi:10.14359/51663213

Cited by 2 publications

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“…This strong decrease of pH and alkali concentrations in the pore solution indicates a strong reaction of the Bend aggregate, in contrast to the Cal, U, P, and B aggregate. The observed strong decrease in pH and alkali concentrations could explain the so-called pessimum effect (= low ASR expansion) observed for fast-reacting [ 43 , 44 ] and very fine aggregates [ 45 , 46 ]. In fact, the samples made of PC and Bend aggregate showed no significant expansion (Fig.…”

Section: Resultsmentioning

confidence: 99%

The effect of paste composition, aggregate mineralogy and temperature on the pore solution composition and the extent of ASR expansion

2022

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The reaction kinetics of the alkali silica reaction depends on the composition of the pore solution. The evolution of the pore solution composition in different cement pastes and concretes was studied. Pastes containing silica fume or metakaolin had the lowest amount of alkalis in the pore solution. In addition, metakaolin increased the aluminium concentrations. The lowest expansion was measured for the concretes made of blended cement pastes with low alkali and hydroxide content in their pore solution, for the duration of the present study, no additional aluminium effect was observed due to the already low pH. Addition of 400 mM of Li slowed down expansion rate of concrete prisms at 40 and 60 °C, however, similar expansion was observed for samples with and without Li at 60 °C after 1 year. Temperature, alkali concentration and pH of pore solution all have a major effect on ASR expansion.

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