The effectiveness of the incineration of sewage sludge on the evolution of physicochemical and mechanical properties of Portland cement Sara Naamane ⇑ , Zakia Rais, Mustapha Taleb Laboratory of Electrochemical Engineering, Modeling and Environmental, Faculty of Sciences Dhar El Mehraz, BP 1796, 30000 Atlas, Fez, Morocco highlights  Extensive and detailed characterization of sewage sludge treated thermally at temperatures between 300 and 800 °C.  Monitor the evolution of the properties of sewage sludge during the thermal treatment.  Study the influence of varying the calcination temperature of sewage sludge on Portland cement properties. article info Article history: Received 30 September 2015 Received in revised form 12 January 2016 Accepted 22 February 2016 Keywords: Sewage sludge Calcination Cement Mortar Physico-chemical and mechanical characterization abstract The influence of sewage sludge, treated at temperatures between 300 and 800 °C, on cement-based mate- rials has been studied in this paper. The clinker of CPJ 45 cement was partially replaced by sewage sludge ash (SSA) admixture in mortar at various percentages. The sewage sludge ashes were characterized chemically, physically and mineralogically. In addition, the influences of SSA on mortar properties, including Blaine fineness, specific gravity, water demand, time of setting, compressive strength and degree of hydration were also investigated. Results show that calcination influences the microstructure of sewage sludge and increases its poz- zolanic activity that reaches its maximum at 800 °C. The presence of absorbed water and organic matter in sewage sludge calcined in temperature range 300–500 °C prolongs strongly the setting time and affects negatively the compressive strength and the hydration degree of mortars. While the high amounts of P 2 O 5 and SO 3 in sewage sludge calcined in temperature range 700–800 °C increase also water demand and setting time compared to the control mortar, however, the compressive strengths and the degree of hydration increase with time and become superior to the control mortar at 90 days, for a replacement rate of 15%. The best mechanical results are obtained for the substitution of 5% of calcined sewage sludge at 28 days. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction The production of sewage sludge is one of the major issues in wastewater treatment that requires proper, effective and environ- mentally safe management. After several years of experience in handling with sewage sludge, many countries start to reconsider or minimize the use of this waste as natural fertilizer in landfilling or in agriculture because of the limited availability of suitable land- fill space, concerns over the accumulation of heavy metals in soils, and the potentially pathogenic organisms [1–3]. In the mean time, incineration has become a growing option and an attractive dis- posal method of sewage sludge, especially for large cities, as it reduce the waste volume, eliminate the pathogenic organisms and the volatile contents, and can also produce energy recovery profits [1,4]. However, another environmental problem has emerged because of the substantial amounts of sewage sludge ashes (SSA) produced after the firing process, which must be disposed by other means [5]. To avoid eventual environmental impact, the use of SSA in building materials is therefore a smart solution, given that the technology of manufacturing cement needs to conserve the resources, reduce CO 2 emissions and preserve energy [6–8]; and that the cement matrix can immobilize the SSA contents [9,10]. Accordingly, SSA has been used in concrete mixtures ([11–13], in lightweight aggregates [14,15], in ceramic products [16–18], in asphaltic paving mixes [19], in cement mortars ([20–22]; and as raw material in clinker production [23,24]. The purpose of the present work is to deepen the characteriza- tion of SSA and to better understand the effect of varying the http://dx.doi.org/10.1016/j.conbuildmat.2016.02.121 0950-0618/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: saranaamane@hotmail.com (S. Naamane). Construction and Building Materials 112 (2016) 783–789 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat