Properties of cement made by partially replacing cement raw materials with municipal solid waste ashes and calcium carbide waste P. Krammart, S. Tangtermsirikul * Sirindhorn International Institute of Technology, Thammasat University, Pathumthani 12121, Thailand Received 15 October 2003; received in revised form 5 April 2004; accepted 6 April 2004 Available online 15 June 2004 Abstract An investigation on using municipal solid waste incinerator bottom ash (MSWI) and calcium carbide waste (CCW) as a part of the cement raw materials was performed. Cement raw meals were replaced by 5% and 10% of MSWI and CCW to study properties of the laboratory produced MSWI and CCW cements. Chemical composition, setting times, compressive strength and expansion in sulfate solution of the pastes and mortars made of MSWI cements and CCW cements were tested and compared with these made of conventional cement. It was found from the study that the chemical compositions of MSWI cements and CCW cements were similar to that of the control cement. However, SiO 2 content of MSWI cements was higher than that of the control cement, whereas CaO content was lower. Setting times of cement pastes were slightly delayed when MSWI or CCW were used to replace a part of raw meal in cement production. The longer setting times of these cement pastes were observed due to the lower C 3 S but higher C 2 S content than those in the control cement. Compressive strength of CCW cement mortars was close to that of the control cement. However, compressive strength of the mortars produced from MSWI cements was smaller than that of the control cement mortar, especially when the percentage of MSWI in the raw meal was increased. When compared to the control cement, the performance of MSWI cement and CCW cement in sodium sulfate solution was superior due to the lower C 3 S and C 3 A. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Municipal solid waste ash; Calcium carbide waste; Chemical composition; Setting time; Compressive strength; Sulfate attack 1. Introduction The incineration of municipal solid waste (MSW), as a method for reducing volume of the waste, is currently receiving widespread attention. There are presently two methods of incineration of MSW [1] i.e. mass-burning and burning processed refuse-derived fuel (RDF). The mass-burning is the process to incinerate all MSW in the as-received condition, while the RDF process requires the removal of ferrous materials and shredding of the remaining MSW prior to burning. Volume reduction of MSW by either method of incineration ranges from 60% to 75%. The incineration of MSW creates two general types of ash: fly ash and bottom ash. MSW generation in Thailand is of critical concern, especially in big cities. Bangkok, alone, produced ap- proximately 8000 tons per day in 2002. The incineration of MSW is presently receiving attention as an effective disposal method for MSW in Bangkok. Like MSW, calcium carbide waste (CCW), another by-product from production of acetylene gas (C 2 H 2 ), was produced ap- proximately 30,000 tons in recent years. In general, CCW or calcium hydroxide (Ca(OH) 2 ) is obtained from the reaction between water and calcium carbide (CaC 2 ) as CaC 2 þ 2H 2 O ! C 2 H 2 þ CaðOHÞ 2 ð1Þ CaC 2 is produced by burning limestone (CaCO 3 ) to yield lime (CaO) and carbondioxide (CO 2 ) (CaCO 3 !CaO + CO 2 ). Then CaO reacts with coal (C) and CaC 2 are obtained together with carbonmonoxide (CO) (CaO + 3C! CaC 2 + CO). * Corresponding author. Tel.: +662-986-9009x1908; fax: +662-986- 9009x1900. E-mail address: somnuk@siit.tu.ac.th (S. Tangtermsirikul). 0950-0618/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2004.04.014 Construction and Building Materials 18 (2004) 579–583 Construction and Building MATERIALS www.elsevier.com/locate/conbuildmat