Characterization and predictive reaction model for cement-sand-kaolin. composite for CO2 sequestration

The sustainability and sturdiness of cement based composite is increasingly coming to the forefront of infrastructural design, maintenance and as a green material that is environmentally benign. This paper seeks to develop a predictive mathematical global reaction rate model for atmospheric carbon dioxide sequestration in sandcrete composite of cement, mineral kaolin as supplementary aggregate material (SAM), sand and water. Standard experimental techniques and procedures were used. MatCad Professional (R14) software was used to simulate the developed model equation. Results obtained indicate that the overall global reaction rates for CO2 sequestration was higher in both experimental and simulated for the developed sandcrete-kaolin (S-K) composite (9.064 x 10(-6) and 9.532 x 10(-6) mol/kg s) at 30 degrees C compared to the reference kaolin-free sandcrete (S-S) composite (4.058 x 10(-7) and 4.056 x 10(-7) mol/kg s) at an early stage of setting (9 h). The quantity of carbon dioxide sequestered after 9 h of carbonation ranges between 0.0185-0.0214 kg/m(3) for sandcrete-kaolin composite, while for the reference specimen it ranges from 0.0128 to 0.011 kg/m(3) at 30-45 degrees C. The simulated results based on the developed overall global reaction rates compared strongly with the experimental in most of the parameters investigated. The mineralogical compositions and microstructure changes of the carbonated samples characterized using X-ray Diffractometer (XRD), X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM) and Diffraction Spectrometer (EDS) showed that addition of mineral kaolin to sandcrete enhanced the rate of CO2 sequestration. (C) 2016 Elsevier Ltd. All rights reserved.