Environmental impact of carbon fibre-reinforced polymer flexural strengthening solutions of reinforced concrete beams

The properties of fibre-reinforced polymer (FRP) composites have led to a significant increase of civil engineering applications based on the usage of these materials. In the construction sector, FRP are mainly used for strengthening existing buildings, thus creating the possibility of avoiding the environmental problems resulting from demolishing these structures and constructing new ones. In the light of this new opportunity, the present paper aims at evaluating and comparing the environmental performances of an unstrengthened reinforced concrete (RC) beam with those of different carbon fibre-reinforced polymer (CFRP) flexural strengthening techniques. The paper uses Life Cycle Assessment (LCA) methodology in order to determine the most environmentally friendly solution in the case of an existing RC beam which does not properly satisfy the structural demands. The authors have decided to use the Cradle-to-Gate LCA type of study, considering that the primary goal of the paper is to establish whether strengthening and reusing an existing RC beam can be considered a more viable environmentally friendly proposal in contrast with demolishing the existing structural element and constructing a new one. The following impact categories are used with the purpose of achieving a clear understanding of the products' environmental influence: Climate Change, Human Toxicity, and Ozone Depletion. Their environmental performances are evaluated using the GaBi 6 software. The obtained results show that all the assessed CFRP strengthening solutions have a significantly lower environmental impact in comparison with those of the RC beam. In the case of the analysed RC structural element, the highest impact is attributed to the manufacturing stage of the cement and to the steel reinforcements. In most of the CFRP strengthening schemes, the environmental impact is mainly influenced by the amount of component materials (fibre and resin) used for manufacturing the considered composite elements. The resulted values for the environmental parameters in the assessed case studies encourage the authors to assert that the usage of composite materials in specific civil engineering applications can represent an environmentally friendly solution. The environmental aspect of sustainability can thus be achieved in this industry by using particular FRP strengthening applications. Moreover, the negative effects of modern society over Earth can be reduced. The paper concludes that the usage of composite materials can represent an important step towards the sustainable development of the construction sector.