Multi-criteria optimization of concrete mixes incorporating cenosphere waste and multi-minerals

Following the requirements of sustainable development, this paper aims to develop a sustainable concrete mix by replacing part of the cement with cenosphere waste and multi-minerals. The cenosphere was chemically treated to provide internal curing effect to enhance concrete performance. The sensitivity of cenospheres and multi -minerals on concrete strengths, microstructures, economic benefits and environmental sustainability were evaluated. To simultaneously consider these factors, concrete mixes were optimized using TOPSIS, a multicriteria optimization method. Results show that the surface-treated cenosphere offers a good internal curing effect to improve the mechanical properties of concrete. A more considerable amount of minerals, i.e., 40%, is observed to have sound performance since the additional curing water provided by the treated cenospheres can accelerate the hydration of cement and minerals, contributing to a densified microstructure with abundant hydrates. Additionally, the addition of cenosphere and multi-minerals also brings a noticeable decline in the direct cost given a maximum decrease of 7.6%, and a significant advantageous effect on environmental sustainability given a maximum decrease of 37.4%, 34.0% and 6.34% in CO2 emissions, energy consumption and raw material ratio, respectively. Furthermore, mixture G11 with 20% cenosphere, 6% MK and 14% GGBS is suggested when an equal priority is determined for mechanical properties, cost and environmental sustainability.

Automated summary

This study aims to develop a sustainable concrete mix by replacing part of the cement with cenosphere waste and multi-minerals. The results show that the surface-treated cenosphere offers a good internal curing effect to improve concrete performance, while the addition of cenosphere and multi-minerals also brings cost savings and has a positive impact on environmental sustainability.