Life cycle assessment of precast and cast ln-situ concrete

Abstract

A life cycle assessment methodology for concrete structures is developed in this study. The study compares the environmental impacts of a concrete frame office structure, built with different construction techniques, including cast in-situ, precast and semi-precast method of constructions. The use of precast concrete elements is increasingly becoming more used in the local construction industry due to several reasons such as quality control, efficiency and cost during the manufacturing and construction phases. In addition, this study illustrates from an environmental point of view which of these technologies have the highest impact. The analysis adopts the CML 2001 characterization method to present and compare the environmental impacts from cradle to gate, therefore, the extraction and production of raw materials, manufacturing and construction phases of these technologies. Results show that the total energy consumption for the three methods of construction is similar, with a variation of less than 5%. The highest energy consumption phase is associated to the extraction and production of cement. In fact, precast and semi-precast were found to have almost 30% higher global warming potential (C02 eq.) than cast in-situ per functional unit due to the utilisation of higher cement content in the mix. This study also provides an assessment of energy use on a local aspect. In fact, it has been found that semi-precast construction consumes around 30% additional energy than precast and cast in-situ construction techniques. The environmental impacts associated each individual phase will help the concrete construction industry to develop and improve its efficiency while adopting more sustainable measures.