Abstract
The process of drying of many materials is accompanied by dimensional changes, which induce cracks in the structure. This phenomenon is particularly significant in acrated concrete owing to its high total porosity and specific surface of pores. The factors influencing drying shrinkage of aerated concrete are widely different from that of normal concrete because of the presence of coarse aggregates in the latter. This paper discusses the results of statistically designed experiments conducted to ascertain the influence of composition on the drying shrinkage of non-autoclaved and autoclaved aerated concrete. Detailed single factor experiments were conducted to assess the influence of basic constituents of the mix on drying shrinkage whereas fractional factorial experiments were used for the interaction effects and the influence of some additives. It was observed that increase in lime-cement ratio and fly ash content increases drying shrinkage. Significant shrinkage reduction is obtained by autoclaving, suggesting that drying shrinkage is predominantly a function of the physical structure of the hydration product.
Résumé
Un grand nombre de matériaux subissent des modifications dans leurs dimensions lors du séchage, ce qui entraîne une fissuration dans la structure. Ce phénomène est particulièrement significatif dans le cas du béton-gaz en raison de sa porosité générale élevée et de la surface spécifique des pores. Les facteurs qui influencent le retrait de séchage du béton-gaz sont très différents de ceux du béton ordinaire en raison de la présence d’agrégats grossiers dans ce dernier. Cet article traite des résultats d’expériences statistiquement conçues pour étudier les effets de la composition sur le retrait de séchage du béton-gaz non-passé à l’autoclave. Certaines expériences avaient pour but d’étudier l’influence d’un seul facteur: les composants de base du mélange, alors que pour étudier les effets d’interaction et l’influence de certains additifs, plusieurs facteurs ont été pris en compte. On a observé que l’augmentation de la proportion chaux/ciment et de la teneur en cendres volantes fait augmenter le retrait de séchage. Une réduction significative du retrait est obtenue par l’autoclavage, ce qui implique que le retrait de séchage est essentiellement une fonction de la structure physique du produit hydratation.
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Ramamurthy, K., Narayanan, N. Influence of composition and curing on drying shrinkage of aerated concrete. Mat. Struct. 33, 243–250 (2000). https://doi.org/10.1007/BF02479334
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DOI: https://doi.org/10.1007/BF02479334