構造系 707 号 カテゴリー Ⅱ 日本建築学会構造系論文集第 80 巻第 707 号,9-18,2015 年 ₁ 月 J. Struct. Constr. Eng., AIJ, Vol. 80 No. 707, 9-18, Jan., 2015 細骨材および調合がコンクリートのワーカビリティーに及ぼす影響 EFFECTS OF FINE AGGREGATE AND MIX PROPORTION ON WORKABILITY OF CONCRETE 寺西浩司 *1, 桝田佳寛 *2, 陣内浩 *3, 鹿毛忠継 *4 *5, 伊藤智章 Kohji TERANISHI, Yoshihiro MASUDA, Hiroshi JINNAI, Tadatsugu KAGE and Tomoaki ITO A slump test and a cylinder penetration test were conducted for 155 kinds of concrete with different grading of fine aggregate and different mix proportion, and a flow test was conducted simultaneously for wet-screened mortar. Additionally, the consideration based on the excess paste theory was conducted. The following findings were obtained as the results. (1) The segregation degree of concrete is evaluated quantitatively by an inflow mortar value, the result of the cylinder penetration test, and the inflow mortar value corresponding to the limit of segregation is 30 mm. (2) The fluidity of matrix mortar has a dominant influence on the segregation degree of concrete. Furthermore, the new procedure of mix design which can reasonably consider the segregation resistance of concrete was proposed based on these findings. Keywords : Fluidity, Segregation resistance, Excess paste theory, Grading, Solid content, Cylinder penetration test *1 *2 *3 *4 *5 名城大学理工学部建築学科 教授 博士 ( 工学 ) Prof., Prof., Dept. Dept. of Architecture, of Architecture, Faculty Faculty of Science of Science and and Engineering, Engineering, Meijo Meijo Univ., Univ., Dr. Dr. Eng. Eng. 日本大学 特任教授 工博 Project Prof., Nihon Univ., Dr. Eng. 大成建設 技術センター 主席研究員 博士 ( 工学 ) Chief Research Engineer, Technology Center, Taisei Co., Ph. D. 国土交通省国土技術政策総合研究所建築研究部 Research Coordinator for Quality Control of Building, Building Dept., National Institute 建築品質研究官 博士 ( 学術 ) for Land and Infrastructure Management (NILIM), Ministry of Land, Infrastructure and Transport, JAPAN, Ph. D. 宇部興産 技術開発研究所 グループリーダー Group Leader, Technical Development Center, Ube Industries - 9 -
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Va Slsa Slsa Slsa Sl s/a - 12 -
Slsa - 13 -
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EFFECTS OF FINE AGGREGATE AND MIX PROPORTION ON WORKABILITY OF CONCRETE Kohji TERANISHI *1, Yoshihiro MASUDA *2, Hiroshi JINNAI *3, Tadatsugu KAGE *4 and Tomoaki ITO *5 *1 Prof., Dept. of Architecture, Faculty of Science and Engineering, Meijo Univ., Dr. Eng. *2 Project Prof., Nihon Univ., Dr. Eng. *3 Chief Research Engineer, Technology Center, Taisei Co., Ph. D. *4 Research Coordinator for Quality Control of Building, Building Dept., National Institute for Land and Infrastructure Management (NILIM), Ministry of Land, Infrastructure and Transport, JAPAN, Ph. D. *5 Group Leader, Technical Development Center, Ube Industries 155 kinds of concrete with different grading of fine aggregate and different mix proportion such as water-cement ratio, unit water content and sand-total aggregate ratio were mixed by the subcommittee for revision of Recommendation for Practice of Mix Design of Concrete organized in Architectural Institute of Japan. Additionally, a slump test and a cylinder penetration test for them and a flow test (JIS R 5201) for their wet-screened mortar were conducted. Furthermore, the following considerations were conducted by applying the excess paste theory, which can comprehensively evaluate the effects of grading of aggregate, aggregate content, sand-total aggregate ratio, etc. on fluidity of concrete, to the experimental results: (1) the effect of grading of fine aggregate on workability of concrete, (2) the optimum combination of unit water content and sand-total aggregate ratio based on the index to evaluate segregation of concrete, (3) the procedure of mix design more reasonable than ever before. The following findings were obtained as the results. (1) A slump value is determined by the combination of unit water content and sand-total aggregate ratio in principal. Besides, the area that a slump value hardly changes with sand-total aggregate ratio in case of constant unit water content exists in the relationship between them, and the area is wider as unit water content increases. (2) The segregation degree estimated by observing the state of fresh concrete of the slump test can be evaluated quantitatively by an inflow mortar value, the result of the cylinder penetration test. Moreover, the inflow mortar value corresponding to the limit of segregation of concrete is 30 mm. (3) The fluidity of matrix mortar has a dominant influence on the segregation degree of concrete. Moreover, the threshold of the flow value, that is the measure without falling motion, of wet-screened mortar corresponding to the limit of segregation of concrete is 160 (163). (4) Depending on grading of fine aggregate and mix proportion, the concrete with a given slump value and the minimum unit water content may segregate, and in that case, the optimum combination of unit water content and sand-total aggregate ratio need to be determined with the aim of ensuring segregation resistance of concrete. (5) In light of the considered results in this study, the following procedure of mix design of concrete is reasonable: First, sand-cement ratio and dosage of chemical admixture of matrix mortar should be set so that its flow value is that (160 + the difference of flow value between wet-screened mortar and ordinary mortar) corresponding to the limit of segregation of concrete. Next, the ratio of coarse aggregate to matrix mortar should be set so that a given slump value of concrete is obtained. (2014 年 ₆ 月 ₄ 日原稿受理,2014 年 10 月 ₈ 日採用決定 ) - 18 -