RESEARCH ARTICLE


Experimental Study on Effects of Type and Replacement Ratio of Fly Ash on Strength and Durability of Concrete



Hongzhu Quan*, 1, Hideo Kasami2
1 School of Civil Engineering, Qingdao Agricultural University, Qingdao, Shandong, 266109, China
2 Japan Association for Building Research Promotion, Tokyo, 108-0014, Japan


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© 2013 Quan and Kasami;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the School of Civil Engineering, Qingdao Agricultural University, Qingdao, Shandong, 266109, China; Tel: +86-532-88030416; +86-13792443322; Fax: +86-532-88030411; E-mail: quanhz719@yahoo.com.cn


Abstract

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.

Keywords: Carbonation, Compressive strength, Drying shrinkage, Fly ash, Freezing and thawing, Replacement ratio.