Sustainability assessment model for concrete formwork system

Abstract

The construction industry is recognised as the world’s least sustainable industries with high rates consumption of resources and contribution towards global pollution. A major contributor to the unsustainable construction is the use of concrete materials. The formwork system is the central technique in the construction discipline when concrete is used. However, the sustainability performance of concrete formwork system has not received the same amount of attention as in other construction activities because it lacks of suitable sustainability assessment tools. The aim of this research is to develop an assessment model for sustainability performance of concrete formwork system. A quantitative approach using multi-phases questionnaire is employed to identify the sustainability principles and indicators related to formwork system which are then linked to sustainability categories. Covariance analysis method is used to develop and validate the assessment model using structural equation modelling technique. A Formwork Sustainability Assessment Model (FSAM) is proposed which consists of three sustainability categories namely Economic, Environmental, and Social. A total of 20 sustainability performance indicators for the formwork system is identified. Results from the FSAM model validation indicated that the model is well fit with values of GFI=0.976>0.95, P=0.000; RMR=0.014, and RMSEA=0.033. The economic pillar is the major contributor to sustainability with direct effect of ß =0.85 on an overall sustainability and indirect effect 0.31 and 0.22 through environment and social pillars respectively. The environment pillar is the second contributor with direct effect of ß = 0.72 and indirect effect 0.18. The BREEAM is also used as standard tool to perform criterion validation using the receiver operating curve technique (ROC). The FSAM model and BREEAM are used to assess three types of formwork system i.e. conventional formwork, steel formwork, and aluminium formwork. The ROC shows that FSAM has high accuracy (ACC=0.98) with high sensitivity and specificity at 0.94 and 0.96. The FSAM results show that the aluminium formwork system is more responsive to sustainability with total score 69.15. Meanwhile, the steel formwork system achieved 59.93 and conventional formwork has 42.76. The research results demonstrate that the assessment model can provide evidence of a valid and reliable designed tool to assess the sustainability performance of the concrete formwork system. Significantly, this newly developed FSAM could become a useful tool to help engineers and other stakeholders to evaluate and select the most appropriate sustainable system for their projects as well as to improve and enhance the existing formwork systems.