Life cycle analysis of sediment valorization by means of geopolymerization from laboratory to industrial scale

Abstract

Geopolymerization has become a potential competitor to cement over the last 10 years due to its lower carbon impact. However, the development of geopolymerized applications on an industrial scale still faces numerous limits. As an answer, the valorisation of local sources of materials such as dredged sediment as precursors has been identified in the literature of high interest as it could solves sediment management problems as well as reducing geopolymerization environmental and economic cost. Therefore, this study evaluates, through a Life Cycle Analysis (LCA), the impact of mortars developed from untreated dredged sediments mixed with cement or alkalis. The solutions developed in the laboratory were transposed to a hypothetical industrial scale around the Port of Bordeaux area. Four mortars were compared with equivalent mechanical resistance: a classic Ordinary Portland Cement (OPC) mortar and three geopolymer mortars with NaOH and Na2SiO3 alkalis. Results showed that, compared to the use of cement, in this specific case, geopolymerization effectively reduces the impact on climate change by 66% when sediment beneficial recovery was taken into account. This article is a first step in the industrial development adoption of waste geopolymer based mortar for public works as several conclusions were found to justify their implementation on a larger scale. Among them the use of alternative local precursors is effective in order to reduce the environmental cost of geopolymer. However, the market potential of geopolymer mortars will also highly depend on alternatives to silicate as an alkaline reagent.