Sustainable criterion selection framework for green building materials – An optimisation based study of fly-ash Geopolymer concrete

Green materials are considered as one of the prominent elements in designing an environmentally sustainable construction project. Studies have highlighted cement replacement is a popular method of reducing greenhouse gas (GHG) emissions and replacing virgin materials in concrete. These options incur cost implications through sophisticated designs and technologies. The importance of maintaining a balance between environmental and economic benefits of a green design is critical for the decision making stakeholders in a construction project. However, designers often lack the resources and tools to initiate informed decision making for the optimum selection of a green material. In order to systemize the optimising process, the current study suggests a multi-objective optimisation based decision making framework for optimising the cement replacement materials in concrete. The study aims to present a sustainable criterion optimisation framework that could well be adopted to assess the sustainability of green materials in concrete production. A case study using fly ash geopolymer concrete in Melbourne demonstrated a reduction of 3.63% to 41.57% and 23.80% to 30.25% can be achieved for GHG emissions and production cost respectively if the developed optimisation based framework is implemented. The scenario results highlighted around 3% to 8% GHG and cost increase if material is not available locally. A similar approach can be utilised to optimise the environmental and cost savings of other cement replacement materials. Further studies are encouraged on comparing environmental and cost savings of other cement replacement materials using the developed framework. The framework will be valuable for designers in making decisions on sustainable cement replacement materials.