International Conference on Environment 2010 (ICENV 2010) 1 A REVIEW ON THE USE OF SEWAGE SLUDGE ASH (SSA) IN THE PRODUCTION OF CEMENT AND CONCRETE RAFIU O. YUSUF 1 , ZAINURA ZAINON NOON 1 , MOH’D FADHIL MOH’D DIN 2 , AHMAD A. ABBA 1 , NADZIRAH OTHMAN 1 , HAFIZAN HASSAN 1 1 Environmental Engineering Research Laboratory, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia. 2 Institute of Environmental and Water Resources, Faculty of Civil Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia. E-mail: 1 oyrafiu2@live.utm.my, 1 yusuf.ro@unilorin.edu.ng ABSTRACT The use of recycled sewage sludge ash (SSA) in Portland cement and concrete has attracted a lot of global interest due the increase in sludge production and the limitation of land availability where it is used as a soil conditioner. These are in addition to rising environmental concerns. The major components of SSA are SiO 2 , CaO, Al 2 O 3 , Fe 2 O 3 and MgO. These compounds, in theory, make SSA a good pozzolanic material because SSA is found to be cementitious when finely ground. Thus it can be used as cement replacement in Portland cement and concrete. Though SSA has disadvantages as mortar in terms of pozzolanic activity and strength coupled with high water demand, adequate modification and treatment could provide solution to the problems envisaged. This paper reviews the various use of SSA and summarises the progress made in the development of SSA as a partial replacement for Portland cement and concrete. Keywords: Pozzolanic; Cement; Concrete; Sewage sludge ash; Waste INTRODUCTION Sewage sludge ash (SSA) is primarily a silty material with some sand-size particles. It is the by-product of the combustion of dewatered sewage sludge in an incinerator. SSA is a polyphasic material made of several crystalline minerals (≈60%) and a vitreous phase (≈40%), characterized by a diffusion hump ranging between 25 and 45° 2θ Co (d between 4.14 and 2.34 Å) [1]. The specific size range and properties of the sludge ash depend to a great extent on the type of incineration system and the chemical additives introduced in the wastewater treatment process. The major components in SSA are SiO 2 , CaO, Al 2 O 3 , and Fe 2 O 3 [2] which [3] added MgO. The rapid expansion in sewage treatment plants has led to the production of large quantities of organic sludge – a by-product of the treatment process. This waste is generated continuously and in relatively large amounts in treatment plants. Traditionally, sewage sludge has been used in agriculture as a soil conditioner [4, 5]. Legislative barriers for sewage sludge disposal to sea and a negative public perception regarding the application of sewage sludge in agriculture have led to an increase in sludge incineration which reduces the sludge volume by 95% [6]. The ash generated is separated from exhaust gases in filter bags or via electrostatic precipitators prior to gas scrubbing. The separated fly ash contains high levels of phosphate, typically 10–20% mass as P 2 O 5 [6]. It is estimated that 1.2 million tonnes of incinerator sewage sludge ash (ISSA) are currently produced annually in the EU and North America [1] and a further 0.5 million tonnes/yr in Japan alone [7]. However, continuous application of sewage sludge to land without appropriate management might have adverse impacts on human health and the environment, especially leachate and soil contamination [8]. It is