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Ishikawa Y.,Chigasaki Research Institute | Kasami H.,Japan Association for Building Research Promotion
AIJ Journal of Technology and Design | Year: 2012

The imperfect placing joint of concrete not only spoils the fine sight of a concrete structure, but has serious influence on the durability of concrete. In this study, the specimens of concrete which is used moderate heat cement and fly ash are prepared to have same compressive strength which is used normal portland cement, and the placing time interval and the placing method is selected as examination index. The quality of the placing joint of the concrete which is used moderate heat cement and fly ash is good as compared with that of ordinary portland cement. Source


Quan H.,Qingdao Agricultural University | Kasami H.,Japan Association for Building Research Promotion
Open Civil Engineering Journal | Year: 2013

This paper presents the test results of a series of experimental studies on the effects of type and replacement ratio of fly ash on strength and durability of concrete. 3 types of fly ashes are used in this research, the specific surface area of which are 5070 cm2/g, 3760 cm2/g and 1970 cm2/g, respectively. They satisfy the requirement of Type-1, Type-2 and Type-4 fly ashes in Japanese Industrial Standard. Ordinary Portland cement, river sand, crushed sandstone, water reducer and air entraining agent are used as well. The results indicate that drying shrinkage of concrete is reduced when cement is partially replaced by fly ash. Comparatively, Type-2 fly ash's addition leads to a more effective drying shrinkage reduction, and those with replacement ratios result in larger dry shrinkage reduction. Carbonation increases with the increase of replacement ratio of fly ash, and concrete with Type-1 fly ash has higher carbonation than those with Type-2 and Type-4 fly ashes. The carbonation rate is found to be linear with water cement ratio regardless of replacement ratio of fly ash. Durability factor decreases with the replacement ratio of fly ash after 300 freezing and thawing cycles. Also, durability factor of concrete containing Type-1 and Type-2 fly ashes with replacement ratio of 25% to 55% is higher than 80%. However, those with Type-4 fly ash show lower durability factor after 300 cycles. Concretes with 70% replacement of fly ash are not durable in spite of the type of fly ash or specific surface area. © Quan and Kasami; Licensee Bentham Open. Source


Quan H.-Z.,Qingdao Agricultural University | Kasami H.,Japan Association for Building Research Promotion
Scientific World Journal | Year: 2014

In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%-20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized. © 2014 Hong-zhu Quan and Hideo Kasami. Source


Yamada K.,Toyota National College of Technology | Nakao M.,Yokohama National University | Yamazaki Y.,Japan Association for Building Research Promotion | Suzuki Y.,Ritsumeikan University
11th World Conference on Timber Engineering 2010, WCTE 2010 | Year: 2010

The horizontal resistant force of a mud plastered wall is influenced by mud plaster and lath, especially the strength of mud plaster. The relation between the mud plaster strength and the horizontal resistant force of mud plastered wall for Japanese traditional wooden structures is clarified by a finite element method. Source


Quan H.,Qingdao Agricultural University | Kasami H.,Japan Association for Building Research Promotion
Advanced Materials Research | Year: 2011

In order to make clear of the effects of the change in fineness of fly ash on air-entrained concrete, 2 series of laboratory experiments were carried out using 6 kinds fly ash with the specific surface area in the range from 2500 to 4400cm 2/g. The test results indicated higher slump and lower air-entraining content and higher dosage of air-entraining agent for fly ash with higher specific surface area. Compressive strength was found to increase with the increases of specific surface area of fly ash, while drying shrinkage and carbonation were found to show different tendency with change in fineness of fly ash. Source

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