Maximising the potential use of ground granulated blast-furnace slag (GGBS) in cement: An Irish investigation

The production of cement is estimated to account for around 8% of carbon dioxide (CO2) emissions worldwide, and the Irish construction industry yields fifteen million tonnes of CO2 annually. Measures must be employed to reduce these emissions by incorporating less CO2 intensive admixtures such as blast-furnace slag, however, the Irish construction industry can often be resistant to change. Therefore, this study aims to investigate the potential implementation of ground granulated blast-furnace slag (GGBS) into the use of cement in Ireland, on the basis of maximisation over optimisation. This research is based on the hypothesis that if GGBS produces drastically less CO2 than Ordinary Portland Cement (OPC), then maximising its incorporation into cement in Ireland will significantly reduce the Irish construction industry’s carbon footprint. Data for the research is accumulated using a mixed-methods approach, combining both quantitative and qualitative techniques. Quantitative analysis considers compressive strength testing of concrete, with various combinations of GGBS and OPC, and qualitative analysis investigates the key barriers to implementation in Ireland, through a series of interviews conducted with five industry professionals. Results indicate that a one-to-one replacement of up to 60% was found to be the maximum substitution proportion of GGBS for OPC, before a drop-off in compressive strength begins to occur. Some of the barriers to its implementation identified that a lack of awareness exists, weather conditions, overarching costs, as well as raising some major safety concerns with its current method of use. Overall, the key contribution of this study reveals the levels and factors at which OPC can be replaced by GGBS in a cement mix, under equal conditions, without a reduction in compressive strength, during cement production in Ireland.