Effects of plastic coating on the physical and mechanical properties of the artificial aggregate made by fly ash

The production methods of artificial aggregate (AA) and plastic-coated AA are explored. Fly ash (FA), sodium hydroxide, sodium silicate, and water were used as raw materials for geopolymerization. The geopolymerization characteristics and granulation efficiency were analyzed. The physical, mechanical, and durability properties of the AA were evaluated. The enhancement mechanism of plastic coating on AA was discussed. The mechanical and thermal properties of the concretes were assessed. Results showed that the geopolymerization is not a crystallization process, and the granulated AA would deteriorate during the soak-dry cycles. Furthermore, coating AA with plastic could enhance the AA and protect it from water damage, and plastic with different strengths and ductility would have different strengthening modes. Lastly, the plastic-coated AA concrete showed a better performance than AA concrete and better thermal insulation than ordinary concrete. And the cost and benefit analysis indicated that plastic-coated AA was a promising building material in the future for carbon neutrality.