Feasibility Study of the Use of Concrete Sludge As Alternative Raw Material for Portland Clinker Production

Abstract

This study aims to examine the use of concrete sludge from water treatment installations of ready-mixed concrete plants as an alternative raw material for portland clinker kilns, and to enumerate possible limitations. By its extensive and representative collection of concrete sludge samples data, it may also be used for other investigations. The chemical variations of this sludge were evaluated by gathering 87 sludge samples over a period of two years. Furthermore, a treatment phase was proposed. Numerical simulations were conducted based on the chemistry of a representative concrete sludge sample, before and after a specific treatment phase, together with classic raw materials of three reference clinker factories to investigate the influence of the sludge on the clinker meal composition. Based on these simulations, experimental clinkers were produced, which were fully analyzed and evaluated for possible mineralogical influences. Based on the findings of this investigation, it was concluded that sludge out of concrete plants could not be classified as a feasible alternative raw material. Nevertheless, this paper has unveiled some attention points for the use of recycled materials or by-products as alternative raw materials for portland clinker production.