Green composite plaster with modified morphology for enhanced thermal comfort in buildings

Abstract

Partially replacement of constituent materials in cementitious products using waste materials leads to reduce the CO2 emissions while saving the natural resources and minimize the environmental hazards caused by waste disposal. Development of such an alternative for conventional plaster with better thermal performance, strength and durability characteristics will result in energy savings in the construction and operational phases of buildings. A composite plaster was developed by dry mixing of fine aggregate, bottom ash (BA), Portland cement and poly-carboxylic ether-based admixture. Their phase composition and microstructure morphologies were evaluated using XRD and SEM for a range of compositions and comparisons were made by varying water to cement ratios on the development of the best composition. The results indicate that the morphology and grain dimensions of the developed composite plaster can save 60 % of fine aggregate with effective replacement of bottom ash while maintaining the water to cement ratio of 1.15. A reduction of thermal conductivity by 76 % was noted concerning to the conventional plaster. The application of this waste based composite plaster in model units indicated good adhesion properties with better surface texture and good water resistance characteristics. No thermal or shrinkage cracks appeared in the operational phase of the models under outdoor exposure of two years to the tropical environment. A numerical model was also developed to predict the indoor wall temperature variation of a compartment finished with the said composite plaster and a comparison was made with the measured temperature cycle during outdoor exposure. A parametric study was conducted to compare the heat balance of the developed models with available systems and different climate variations.