山田 宏

The factors which affect drying shrinkage of concrete are material properties and environmental conditions, and so on. It is said that the type of coarse aggregate is one of the most dominant factors which affect concrete drying shrinkage. Therefore, it is important that the length-change properties of coarse aggregate particle are grasped when concrete drying shrinkage strain is estimated. Moreover, it is a practical benefit that concrete drying shrinkage strain is estimated by using coarse aggregate properties to be obtained the result early, regardless of the mix proportion of concrete. From the above backgrounds, in this research, we tried to estimate concrete drying shrinkage strain by composite model which has been proposed by KISHITANI &amp BABA, and investigated applicability of the model by using the initial tangent modulus or the secant modulus for coarse aggregate. For this study we used 19 types of crushed stone from different regions and of different qualities. As a result, the estimation of concrete drying shrinkage strain by KISHITANI &amp BABA equation was made different results of accuracy due to types of modulus of elasticity to be used for calculation. The calculated value against the experimental value was a range of -30 to +10% when using the initial tangent modulus, and was a range of -30 to +30% when using the secant modulus.

The factors which affect drying shrinkage of concrete are material properties and environmental conditions, and so on. It is said that the type of coarse aggregate is one of the most dominant factors which affect concrete drying shrinkage. It has also been pointed out that the pore structure of coarse aggregate affects drying shrinkage strain of concrete. From the above backgrounds, in this research, we focused on the pore structure of pore radius of 1 μ m or less for coarse aggregate and investigated the relationship between the coarse aggregate pore characteristics obtained by using mercury porosimetry and the drying shrinkage strain of coarse aggregate and concrete. For this study we used 10 types of crushed stone from different regions and of different qualities. As a result, we indicated a mutual relationship could be identified between the pore characteristics of coarse aggregate and the drying shrinkage strain of coarse aggregate or concrete when categorization by rock type was used. We also demonstrated that the average pore size of coarse aggregate, calculated from the pore characteristics obtained by using mercury porosimetry, was related to the drying shrinkage strain of coarse aggregate and concrete, and that it is possible that this relationship could be uniformly expressed by a power function.

本論文は,トンネル内部のコンクリートの汚れ洗浄に関する基礎的資料を得ることを目的として,実構造物内壁の汚れ付着特性を把握するとともに,汚れ付着量,光源および視線入射角をパラメータとする試料を用いて,トンネル環境下での見かけの汚れ評価について実験的に研究を行ったものである。その結果,実構造物壁面では汚れ付着の経時変化の推定が可能となり,汚れ洗浄を行う際の指標を明らかとした。また,トンネル内の汚れ評価は実態よりも過大に評価される傾向にあることから,汚れ洗浄を短い周期で計画する必要がある。