Compressive Strength and Heat Evolution of Concretes Containing Palm Oil Fuel Ash Vanchai Sata 1 ; Chai Jaturapitakkul 2 ; and Chaiyanunt Rattanashotinunt 3 Abstract: The study of using palm oil fuel ash POFA in concrete work is just the beginning, and obtained data are very little as compared to fly ash and silica fume. In order to collect experimental data, the effects of ground POFA GPOFA replacement rate up to 30 wt % and water/binder W/B ratios of 0.50, 0.55, and 0.60 on normal concrete properties were studied. GPOFA with high fineness was found to be a possible pozzolanic material in concrete. Cement replacement of GPOFA at rates of 10 and 20% yielded higher compressive strength than that of control concrete after 28 days of curing. In addition, heat evolution in terms of temperature rise of fresh concrete decreased with an increased of GPOFA replacement. For concrete with a W/B ratio of 0.50, the use of 30% GPOFA as a cement replacement exhibited the lowest peak temperature rise. However, a decrease compressive strength at early age might be considered if a high replacement rate of GPOFA was used. DOI: 10.1061/ASCEMT.1943-5533.0000104 CE Database subject headings: Ashes; Concrete; Biomass; Compressive strength. Author keywords: Palm oil fuel ash; Pozzolan; Concrete; Heat evolution; Biomass ash. Introduction It is known that there are several causes of global warming, in- cluding CO 2 from cement. Approximately 5% of total CO 2 emis- sion is released to atmosphere, with about 0.7–1.1 t of CO 2 being emitted for every ton of cement production. CO 2 emitted by ce- ment industry is composed of the following: 50% result from the calcination of limestone; 40% from combustion of fuel in the kiln; and 10% from transportation and manufacturing operations Bosoaga et al. 2009. In order to reduce the amount of CO 2 emission, cement manufactures can help by improving production process. For concrete production, the reduction of cement content in concrete by utilization of supplementary cementitious materials such as fly ash, blast-furnace slag, silica fume, metakaolin, natural pozzolans, and biomass ash to replace cement is one of the solu- tions. Palm oil is extracted from the fruit and copra of the palm oil tree. After the extraction process, waste products such as palm oil fibers, shells, and empty fruit brunches are burnt as biomass fuel to boil water, which generates steam for electricity and the extrac- tion process in palm oil mills. The result is palm oil fuel ash POFA, which is about 5%, by weight, of solid waste product. In Thailand, a total of 5.4  10 6 t of fresh fruit brunches was pro- duced in 2005, resulting in high amount of solid waste and bio- mass ash, which tends to increase every year Rangsan and Titida 2007. This biomass ash is not used, and most of it has to be deposited in landfills, creating environmental problems. However, many researchers Tay 1990; Hussin and Awal 1996; Awal and Hussin 1997; Sukantapree et al. 2002; Sata et al. 2004 have found that POFA can be used in the construction industry, specifi- cally as a supplementary cementitious material in concrete. In 1990, Tay 1990 investigated the use of ash derived from oil- palm waste incineration in making blended cement; the results showed that replacing 10–50% ash by weight of cementitious material in blended cement had no significant effect on segrega- tion, shrinkage, water absorption, density, or soundness of con- crete. Within the 20–50% replacement rate range, the decrease in the compressive strength of concrete at various ages was almost proportional to the amount of ash in the blended cement, with the exception of 10% replacement. A few years later, Hussin and Awal 1996 studied the compressive strength of concrete con- taining POFA. The results revealed that it was possible to replace at a level of 40% POFA without affecting compressive strength. The maximum compressive strength gain occurred at a replace- ment level of 30% by weight of binder. In addition, Awal and Hussin 1997 revealed that POFA has good potential for sup- pressing expansion due to alkali-silica reactions. In Thailand, Sukantapree et al. 2002 revealed that the com- pressive strength of mortar containing original POFA was low due to the large particle size and high porosity of POFA. However, mortar containing ground POFA GPOFA with particles retained on a 45-m sieve No. 325 of 4.3% gave a compressive strength higher than 100% of control mortar at the curing ages of 7 and 28 days. Furthermore, a previous investigation Sata et al. 2004 in- dicated that POFA with high fineness has a highly pozzolanic reaction and can be used as a supplementary cementitious mate- rial for producing high strength concrete. However, study of POFA is just the beginning, and the ob- tained data are scarce compared to studies of fly ash and silica 1 Lecturer, Dept. of Civil Engineering, Khon Kaen Univ. KKU, Khon Kaen 40002, Thailand corresponding author. E-mail: vancsa@kku.ac.th 2 Professor, Dept. of Civil Engineering, King Mongkut’s Univ. of Technology Thonburi KMUTT, Bangkok 10140, Thailand. E-mail: chai.jat@kmutt.ac.th 3 Ph.D. Student, Dept. of Civil Engineering, King Mongkut’s Univ. of Technology Thonburi KMUTT, Bangkok 10140, Thailand. E-mail: mengt_t@hotmail.com Note. This manuscript was submitted on May 21, 2009; approved on March 17, 2010; published online on March 22, 2010. Discussion period open until March 1, 2011; separate discussions must be submitted for individual papers. This paper is part of the Journal of Materials in Civil Engineering, Vol. 22, No. 10, October 1, 2010. ©ASCE, ISSN 0899- 1561/2010/10-1033–1038/$25.00. JOURNAL OF MATERIALS IN CIVIL ENGINEERING © ASCE / OCTOBER 2010 / 1033 Downloaded 15 Sep 2010 to 202.12.97.120. Redistribution subject to ASCE license or copyright. Visit http://www.ascelibrary.org