Building and Environment 40 (2005) 1261–1266 Use of incinerator ash as a replacement for cement and sand in cement mortars Amer Ali Al-Rawas à , Abdel Wahid Hago, Ramzi Taha, Khalid Al-Kharousi Department of Civil and Architectural Engineering, Sultan Qaboos University, P.O. Box 33 Al-Khod 123, Sultanate of Oman Received 30 June 2003; received in revised form 8 October 2004; accepted 15 October 2004 Abstract Incinerator ash was investigated for its potential use as a replacement for sand and cement in cement mortars. The physical and chemical characteristics of the raw materials were determined. Two sets of mixes were prepared. For the first set, cement and water quantities were fixed while incinerator ash was used at 0%, 10%, 20%, 30% and 40% replacement by weight for sand. In the second set, incinerator ash was used at 0%, 10%, 20% and 30% replacement by weight for cement while sand and water quantities were kept constant. The cement, sand and water mixing proportions were 1:3:0.7, respectively. Slump, compressive strength and unit weight tests were performed on all specimens. Results indicate that incinerator ash caused a reduction in slump values when it was used as a replacement for sand while an opposite trend was observed when it was used as a replacement for cement. The replacement of sand by incinerator ash up to 40% exhibited a higher compressive strength than the control mix (0% incinerator ash) for most curing periods. The maximum compressive strength of 36.4 N/mm 2 was achieved using 20% incinerator ash after 28 days of curing. Specimens prepared using 20% incinerator ash replacement for cement yielded a higher compressive strength than the control mix after 14 and 28 days of curing. The maximum compressive strength of 27:4N=mm 2 was achieved at 28 days curing period. r 2004 Elsevier Ltd. All rights reserved. 1. Background Incinerator ash results from burning municipal solid waste and has two components, bottom ash and fly ash. Bottom ash and fly ash constitute approximately 80% and 20%, respectively, of the total burnt ash [1]. Bottom ash generally consists of coarse particles (0.1–100 mm) of slag, glass, rocks, metals and unburnt organic matters [2] while fly ash consists of small dia- meter particles (1–500 mm) of burnt or partially burnt organic matters, on which various components of the flue gas have condensed. At present, most operating facilities combine bottom ash and fly ash for disposal. The high cost of treatment and disposal, the shortage of landfill space, and increased environmental awareness prompted the search for finding alternative uses of the ash other than disposal. The use of incinerator ash in various engineering applications has gained a consider- able worldwide attention. Several studies were con- ducted on the use of incinerator ash in various engineering applications such as: (1) partial replacement for cement [3,4], (2) a replacement for natural aggregates in structural grade concrete [5,1], (3) a soil stabilizing agent [6], and (4) an aggregate substitute in roads and highway construction [7,8]. Rivard-Lentz et al. [1] evaluated the physical behavior of incinerator bottom ash and reported that it is similar in grain size distribution to a well-graded gravelly sand. Results also showed that bottom ash has lower compacted density and specific gravity than a typical well-graded coarse grained natural aggregate but has equivalent or higher strength properties. Concrete containing washed mass-burnt ash to replace 50% of the sand yields reasonable strength [9]. ARTICLE IN PRESS www.elsevier.com/locate/buildenv 0360-1323/$ - see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2004.10.009 à Corresponding author. Tel.: +968 244 15300; fax:+968 244 13416. E-mail address: ameraar@squ.edu.om (A.A. Al-Rawas).