Life cycle assessment of self-healing geopolymer concrete

• Main Author: Garces, Jerome Ignatius T.
• Format: text
• Language: English
• Published: Animo Repository 2021
• Subjects: Polymer-impregnated concrete; Life cycle costing; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etdm_chemeng/5; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1003&context=etdm_chemeng
• Institution: De La Salle University

Research developments in construction materials are moving towards greener alternatives such as geopolymers, which are promising substitutes to Ordinary Portland Cement (OPC). The application of self-healing in geopolymer concrete can help improve it further, especially with regards to solving the issue related to its proneness to crack propagation leading to durability and serviceability issues. This study proposed a microcapsule-based self-healing technique for geopolymers. Poly(urea-urethane) microcapsules containing alkali-activators were successfully synthesized using in-situ polymerization and characterized. A percentage yield of 81.6230% was obtained. This study also conducted an ex-ante Life Cycle Assessment (LCA) on self-healing geopolymer concrete to assess and quantify the environmental impacts associated with this emerging material. The system boundaries for this LCA study primarily focused on a cradle-to-gate perspective. Coal fly ash (CFA) and ground granulated blast furnace slag (GGBS) were considered as geopolymer precursors. Based on the LCIA results, geopolymer concrete has the capacity for significant reductions in global warming potential of up to 52% compared to its OPC counterpart but performs worse in other categories. Moreover, GGBS/CFA geopolymers is better than pure CFA geopolymers in terms of environmental impacts in all the compressive strengths investigated. The addition of self-healing microcapsules further entails an initial environmental cost during the production phase of the concrete. The primary culprits behind the impacts of the self-healing microcapsules are the toluene solvent and the wall-forming monomer. However, the environmental savings brought about by self-healing through the reduction in concrete repair exceeds its initial impacts, as evidenced by the assessment of the hypothetical scenario on the materials’ usage phase. Reduction in impacts due to the elimination of repairs were calculated to be between 17% and 86% relative to OPC concrete, depending on the impact category considered. At increasing strengths, the benefits of self-healing microcapsules become more apparent because of the increasing costs of repair through damaged concrete replacement.