Study on preparation and performance of alkali-activated low carbon recycled concrete: Corn cob biomass aggregate

Abstract

The burning or accumulation of a large number of corn cobs in the countryside not only pollutes the environment but also takes up land, and it is of great significance to use agricultural solid waste to prepare green ecological construction materials for liveable villages. Therefore, in this study, the agricultural solid waste-corn cob is used as coarse aggregate, the recycled sand as fine aggregate, and industrial solid waste-mineral powder is used as cementitious material to prepare a green low carbon recycled concrete (LCRC). Regarding the alkali exciter concentrations, fine aggregate type and pre-wetting degree of aggregate as key variables, the time-varying laws of mechanical property, thermal insulation property, drying shrinkage property and CO2 emission of LCRC were studied. The results show that LCRC with a higher concentration of alkali exciter has better mechanical and thermal insulation properties, but poorer shrinkage properties. The mechanical property and shrinkage property of LCRC by manufactured sand are more excellent but poor insulation property. 80% pre-wetted LCRC has better mechanical and shrinkage properties, but lower thermal insulation property. The 28 days compressive strength and flexural strength of LCRC can reach up to 11.6 and 1.6 MPa. The bending compression ratio and 90 days shrinkage of LCRC are between 0.07 and 0.18 and 625.9∼977.7 × 10−6, which are comparable to or even better than normal concrete. The thermal conductivity of LCRC ranges from 0.108 to 0.300 W/(m·K) and can be used as a preparation insulation material. Meanwhile, LCRC can reduce carbon emissions by up to 31% than ordinary cement.

Keywords

• Alkali-activated
• Corn cob aggregate
• Low carbon concrete
• Solid waste
• Thermal insulation performance