Purpose The concrete industry faces challenges to create concrete mix designs that reduce negative environmental impacts but also maintain high performance. This has led to ‘greener’ cementitious materials being developed which can decrease the use of traditional Portland cement (PC). This study intended to carry out a ‘cradle-to-gate’ life cycle assessment (LCA) on concrete mix designs containing different cementitious blends. Methods The aim of this study was to obtain the overall environmental impact, with a particular focus on carbon dioxide (CO₂) emissions of three concrete mix designs: CEM I (100 % PC content), CEM II/B-V (65 % PC content, 35 % Fly Ash (FA) content) and CEM III/B (30 % PC content, 70 % ground granulated blast furnace slag (GGBS) content). Evaluations of the three concrete mixes were performed using ‘SimaPro 8’ LCA software. A comparative cradle-to-gate LCA of these mixes has not currently been explored and could present a new insight into improving the environmental impact of concrete with the use of secondary materials. Recommendations from this work would help the industry make key decisions about concrete mix designs. Results and discussion Results show that Mix 2 (CEM II/B-V) and Mix 3 (CEM III/B) could potentially be taken forwards to improve their environmental impacts of concrete production. With respect to optimum mix design, it is strongly recommended that GGBS is selected as the addition of choice for reducing CO₂ emissions. FA does still considerably improve sustainability when compared to PC, but this work proved that inclusion of GGBS environmentally optimises the mix design even further. Advantages of using GGBS include lower CO₂ emissions, a substantial reduction of environmental impacts and an increased scope for sustainability due to the higher PC replacement levels that are permitted for GGBS. Due to mix designs enabling a higher contribution of GGBS additions, it would also indicate an increased positive effect regarding waste scenarios. Conclusions and recommendations The main contribution of this work demonstrated that concrete can be produced without loss of performance whilst significantly reducing the negative environmental impacts incurred in its production. The results obtained from this work would help to define the available options for optimising concrete mix design. The only material variations in each mix were the different cementitious blends. So, by determining the best option, a platform to make recommendations can be established based upon cementitious materials.

The article aims to identify the scientific challenges and point out future research directions on Cost Engineering. The research areas covered in this article include Design Cost; Manufacturing Cost; Operating Cost; Life Cycle Cost; Risk and Uncertainty management and Affordability Engineering. Collected information at the Academic Forum on Cost Engineering held at Cranfield University in 2008 and further literature review findings are presented. The forum set the scope of the Cost Engineering research, a brainstorming was held on the forum and literatures were further reviewed to understand the current and future practices in cost engineering. The main benefits of the article include coverage of the current research on cost engineering from different perspectives and the future research areas on Cost Engineering.