Carbonated Sandcrete-Nanographene Oxide Mortar: Investigating Morphology, Phase Formation, and CO2 Sequestration for Enhance Durability

The escalating trend in carbon dioxide emissions is unequivocally linked to global warming and climate change phenomena. This study investigated the morphological development and phase formation of carbonated sandcrete-nanographene oxide (S-nGO) composite mortar for CO2 sequestration and durability under ambient conditions (30±2 °C; 50% RH) after 28 days. A comprehensive characterization methodology incorporating X-ray Diffractometer (XRD), X-ray Fluorescence (XRF), Thermogravimetry Analysis (TGA), Fourier Transform infrared Spectroscopy (FTIR), Energy-Dispersed Spectroscopy (EDS), and Scanning Electron Microscopy (SEM) was used to establish correlations between microstructural changes, degree of porosity, CO2 sequestration, and carbonate concentration. Incorporating nGO during the carbonation transformation in cement-based composites substantially alters the sandcrete matrix's hydration kinetics and associated hydrates, exerting a profound influence on the hydration mechanism. Unlike the control without nanographene oxide, the SEM of S-nGO matrix composites showed a dense microstructure characterized by a foil-like morphology of calcium silicate hydrate (C-S-H) phase containing more carbon, calcium, oxygen, and silicon. The 0.05% S-nGO composite mixture resulted in the highest carbon dioxide sequestration potential, with a carbonate concentration of 0.0406 kg/m3, whereas that of the 0% nanographene oxide control sample was approximately 0.0128 kg/m3 at 30 °C. The findings demonstrated that early-age carbonation (1–28 days) could enhance the durability of the sandcrete–nanographene oxide composite by refining the microstructure and reducing the porosity, thereby improving the material’s overall properties and carbon sequestration potential.