SEA AS A RESOURCE POOL TO REDUCE THE WATER FOOTPRINT OF THE CONSTRUCTION SECTOR

To ensure access to clean water for everyone is among the sustainable development goals promoted by the United Nations. Water scarcity, strictly linked to global warming, is one of the main hindrances to reach this goal. One... [ view full abstract ]

To ensure access to clean water for everyone is among the sustainable development goals promoted by the United Nations. Water scarcity, strictly linked to global warming, is one of the main hindrances to reach this goal. One way to increase the availability of clean water for human consumption in regions affected by water scarcity might be to reduce the amount of freshwater used for industrial purposes. Although rarely assessed, construction industry is a major consumer of water resources. Concrete, i.e. the most used construction material, consumes water in different stages of its life-cycle: from the extraction and processing of the raw constituents (i.e. cement and aggregates) to the final mixing. Recent researches estimate that the production of one ton of concrete embodies up to one ton of freshwater. In the present study, the adoption of innovative concrete mixtures was investigated in order to estimate the potential freshwater savings. In particular, the use of resources extracted from sea (i.e. marine aggregates as substitutes of crushed stones or river aggregates and seawater instead of freshwater) was examined. The main practical issue arising from the use of materials with high chloride contents is the shortening of the corrosion initiation time of the carbon steel bars typically employed as reinforcing elements in the concrete structures. However, if alternative non-corrosive reinforcing elements were employed (e.g. stainless steel or fibre reinforced polymers bars), the main deterrent to the application of seawater and chloride-contaminated aggregates would be removed. The goal of the study was hence to assess the water footprint of traditional and innovative mixture via the Life Cycle Assessment (LCA) tool. To improve the validity of the analysis, the applicability to a real context (i.e. Italy) using georeferenced data for the distance to the coastline and the availability of freshwater was explored. In this way, a hypothetical line separating the areas where it would be more sustainable to use materials extracted from sea could be drawn. Preliminary results confirmed the positive effect that the use of seawater and marine aggregates might have in reducing the water footprint of the Italian construction sector, leaving freshwater available for human consumption. Nevertheless, results were highly affected by the season in which the construction was supposed to be built. Finally, further studies on the potential use of this technology in the existing concrete batching plants need to be performed.

KEYWORDS: water footprint; concrete; seawater; aggregates; water scarcity