軽量コンクリート特性に及ぼす骨材含水量の影響

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The artificial lightweight aggregate has higher porosity and absorption than those of natural aggregate. It has been recognized that the higher water absorption property of artificial lightweight aggregate has a great deal to do with the mixing proportion of concrete and also with the properties of hardened concrete, such as drying shrinkage, durability and so on. In this study, the authors made some experiments relating to the effect of absorbed water of aggregate on the properties of artificial lightweight aggregate concrete. Three kinds of commercial lightweight aggregate, namely two kinds of expanded shale (coated type) and expanded clay (pelletized type) were used as coarse aggregate. In order to clarify the efficacy of absorbed water content, these aggregates were made to contain different amount of absorbed water by keeping them in water for different length of time. Fine aggregate was river sand in all the mixes. Fresh concrete was tested for consistency, and hardened concrete for compressive strength, tensile strength, flexural strength, Young's modulus, drying shrinkage and durability against freezing and thawing. The main results of the experiments are summerized as follows : (1) The consistency of fresh concrete is not affected by water absorbed in the aggregate. (2) The compressive strength of hardened concrete is little affected by absorbed water. (3) The flexural strength of concrete is little affected by absorbed water when it is cured in water. but when it is cured in air is remarkably deteriorated by the increase of water absorbed in it.(4) The shrinkage of concrete is smaller in an early stage of. drying, when the aggregate containing absorbed water to a higher quantity is used instead of the aggregate in which water is absorbed for 24 hours. But in a later stage the shrinkage in question becomes larger than in the concrete in which the aggregate with water absorbed in it for 24 hours is used. (5) The durability of concrete against freezing and thawing depends very much on the quantity of the water absorbed in its aggregate. The durability becomes remarkably poor by using aggregate in which water is absorbed over 5〜6%.
社団法人日本材料学会の論文
1969-02-15

軽量コンクリート特性に及ぼす骨材含水量の影響

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