Dredged sediments used as novel supply of raw material to produce Portland cement clinker G. Aouad ⇑ , A. Laboudigue, N. Gineys, N.E. Abriak Univ Lille Nord de France, F-59000 Lille, France Ecole des Mines de Douai, EMDouai, LGCgE-MPE-GCE, F-59508 Douai, France article info Article history: Received 6 May 2011 Received in revised form 6 February 2012 Accepted 17 February 2012 Available online 28 February 2012 Keywords: Portland cement Recycling Sediment Clinkering Sustainable development abstract The maintenance of waterways generates large amounts of dredged sediments that are an environmental issue. This paper focuses on the use of fluvial sediment to replace a portion of the raw materials of Portland cement clinker, which would otherwise come from natural resources. The mineralogy of the synthetic cement was characterised using X-ray diffraction and scanning electron microscopy and its reactivity was followed by isothermal calorimetry. Comparisons were made to a commercial ordinary Portland cement (CEM I 52.5). Compressive strength measurements were conducted on cement pastes at 1, 2, 4, 7, 14, 28 and 56 days to study strength development. The results showed that Portland cement clinker can be successfully synthesised by using up to 39% sediment. The compressive strengths devel- oped by the cement made from sediment were equivalent to those obtained with the reference at early ages and 20% higher at long term. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction With more than 10 billion metric tons of concrete being produced worldwide per year, the cement industry has a large envi- ronmental footprint. The tools and strategies to meet the environ- mental challenges should involve the use of recycled materials in place of natural resources. This study focuses on the recycling of sediment to replace a portion of raw materials in conventional Port- land cement manufacture. Waterway sediments are dredged either to maintain navigability, prevent flooding or, more recently, to improve the environmental quality of the aquatic ecosystem. Pres- ently, in France about 60% of waterway-dredged sediments are deposed in dedicated sites. However, this style of management is unacceptable to most local communities. In addition, several tech- nologies, including the thermal elimination of organic matter, the stabilisation of heavy metals [1], mineral processing [2] and phyto- remediation [3] have been explored either to treat sediments or to manage the risk of pollution transfer to surrounding environments. Most of these treatments are under validation but are either too expensive or not available at this stage. From the viewpoint of resource recovery and recycling, the use of by-products or wastes as raw materials for cement production is of interest and has been widely investigated [4–13]. Judging by the chemical composition, sediment could also be used as substitute for cement raw materials. Dredged sediments present the advanta- ges of a renewable resource and are available in huge quantities, easily transportable through waterways, which is in accordance with cement industry needs. Research conducted on the valorisa- tion of sediment in cement-based materials has mostly focused on the classical sand substitution for mortar production [1 and citations therein]. This type of recovery requires treated or unpol- luted sediment. Dalton et al. [14] demonstrate the potential of using contaminated marine sediment as feedstock replacement in Portland cement manufacture. A bench scale manufacture was carried out with feedstock mixtures containing up to 12% of dredged material from the New York/New Jersey harbour. Results showed a decrease of alite and increase of belite for contents high- er than 6%. In addition, this study treated marine sediment with a high chloride content, which causes two difficulties. First, chloride trapped in the clinker is well known to reduce the concrete strength and may speed up the corrosion of reinforcing steel in concrete [15]. Second, large fractions of chloride are volatilised at approximately 980 °C and travel up the kiln to cooler regions to finally precipitate along the kiln walls. Thus, periodic maintenance is needed, and production time is lost [16]. Here we present the use of fluvial contaminated sediment to replace a portion of raw materials in conventional Portland cement manufacture. The sediment is classified as contaminated because of the presence of organic and inorganic contaminants. At the high temperature required for cement manufacture (1450 °C), organic contaminants are degraded, and heavy metals are stabilised [7–19]. In addition, previous research indicates that the heavy 0958-9465/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.cemconcomp.2012.02.008 ⇑ Corresponding author. Address: Ecole des Mines de Douai, 941 rue Charles Bourseul, 59500 Douai, France. Tel.: +33 (0)327 712 430; fax: +33 (0)327 712 916. E-mail address: georges.aouad@mines-douai.fr (G. Aouad). Cement & Concrete Composites 34 (2012) 788–793 Contents lists available at SciVerse ScienceDirect Cement & Concrete Composites journal homepage: www.elsevier.com/locate/cemconcomp