Optimal design and characteristics of sustainable eco-friendly ultra-high-performance concrete

Abstract

Sustainable eco-friendly ultra-high-performance concrete (UHPC) is a remarkable innovation in construction technology. This research aims to develop sustainable UHPC by incorporating various supplementary materials, including silica fume (SF), glass powder (GLP), fly ash (FA), limestone powder (LP), and granite powder (GrP), as partial replacements for cement and fine aggregate. To achieve this goal, a total of twenty-seven concrete mixtures were designed using response surface methodology (RSM) and tested in order to determine the optimal combination of these supplementary materials for enhancing the mechanical properties of UHPC. Mathematical models were constructed using analysis of variance (ANOVA) test. The results of the study suggest that it is indeed possible to produce sustainable UHPC with reduced CO2 emissions and improved mechanical properties by utilizing the suggested supplementary materials. In particular, the compressive and flexural strengths of the concrete significantly improved when high proportions of LP, SF and GLP, and low proportions of FA and GrP were used. Among the various mixtures tested, the mixture containing 12.5% SF, 15% FA, and 10% GLP as partial replacements of cement, along with 12.5% GrP and 50% LP as partial replacements of fine aggregate, exhibited the highest compressive and flexural strength at all curing ages, the compressive strength was 133, 175.8, 180.2 MPa at age 7, 28 and 90 days, respectively, meanwhile the flexural strength was 38.5 MPa at age 28 days. The SEM results revealed that the higher proportion of LP, FA, and GLP contributed to an enhanced concrete microstructure, further validating the positive impact of these supplementary materials on UHPC's mechanical properties.