Life cycle costing for obtaining concrete credits in green star rating system in Australia

Cement is one of the widely used materials in construction. Due to the adverse impacts towards the environment from cement manufacturing, green building rating tools always give a significant consideration towards concrete usage in green buildings. Irrespective of its significance in green buildings, there is a clear lack of research on life-cycle cost (LCC) impact of using supplementary cementitious materials (SCMs) in cement as required by green building rating tools. Therefore, this research analyses the life cycle costs of concrete using SCMs in obtaining concrete credits according to Green Star rating system in Australia. This research used fly ash, slag and silica fume as SCM for concrete. The SCM replacement percentage in concrete ranges from 10% to 60% as higher than 60% substitution is impractical. This research calculated LCC for each replacement percentage and specific building elements in different strength categories. LCC of concrete decreases with higher SCM replacement percentages. Further, there are only slight differences in LCC when comparing the three SCMs. In LCC, the contribution from the initial material cost is approximately 85%–87%, and in an exceptional situation such as in columns, this lowers to 66%. In larger columns, the cost of demolition is greater than that of the initial cost whereas it contributed to 61%–68% of the LCC.