Effect on mechanical properties and microstructure of high-strength eco-friendly concrete with waste glass powder-eggshell particles

Abstract

Waste glass and discarded eggshells are common solid waste materials. In order to explore a new type of high-strength eco-friendly concrete, waste eggshell particles (ESP) combined with waste glass powder (GP) to replace the same mass of cement was used to prepare waste eggshell particles-waste glass powder concrete (ESGPC) in this study. The compressive strength and splitting strength of the specimens were tested using a universal testing machine. Meanwhile, the NMR technique was applied to test the pore structure of the specimens, the scanning electron microscope was used to investigate the microscopic morphology of the hydration products, and the distribution of GP and ESP in the specimens was investigated by the energy spectrum analyzer. The modification mechanisms of GP and ESP on the workability and mechanical properties of ordinary high-strength concrete were summarized. The results showed that as the content of ESP-GP increased, the slump of fresh concrete gradually increased, the compressive strength and splitting tensile strength first increased and then decreased, and the best replacement rate of ESGPC was 20%; the porosity of concrete initially decreased and then increased, and the number of gel pores (<10 nm) and transition pores (10 nm∼100 nm) increased with the increase of ESP-GP content. When the substitution rate of ESGPC reaches 40%, there is a significant decrease in the number of macropores (>1000 nm) and capillary pores (100 nm∼1000 nm). After analysis by the grey entropy correlation comprehensive analysis method, it was discovered that the volume of transition pores had the strongest correlation with the compressive strength of ESGPC; ESP-GP formed an amorphous film to compensate for the characteristics of weak bond in the transition zone of concrete.