The Use of Geopolymer Concrete in the Place of Cement Based Concrete in Coastal Infrastructures

Abstract

The emission of greenhouse gases during its production, and the poor performance of cementbased concrete in marine environments has raised the need for alternative eco-friendly materials. This study investigated the strength and durability of Geopolymer concrete cured in marine water. The Slag/Metakaolin-based geopolymer concrete was used in this study. Two curing regimes were adopted; a sample was cured in marine water while the control was air-cured and designated as GPCW and GPCD respectively. Geopolymer beams, cubes, and cylinders were used for flexural, compressive, and tensile tests, respectively, at 7, 28, 90, 180, 270, and 365 days. Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to determine the microstructural and elemental compositions. Results showed an increase in compressive, flexural and tensile strengths between 7 to 180 days, with a gradual decrease at 365th days for the GPCD samples. The GPCW showed a 43% reduction in strength between the 7th and 28th days, with a further decrease of 11% from 28 to 365 days. The average strength of both samples was above C40 grade concrete. SEM revealed differences in GPCD and GPCW with the latter displaying less dense structures with larger voids, consistent with the reduction in compressive strength over time. The EDS analysis showed that there was <1% ingress of Sulphate into GPCW on average, this revealed its resistance to the deterioration-causing agent in cement-based concrete. This study concluded that GPC can be used for coastal marine concrete structures.