Effects of steel chips on the microstructure, mechanical property, and durability of ultra-high-performance concrete with high elastic modulus

Although ultra-high-performance concrete (UHPC) performs well in terms of strength and durability properties, it is still limited by the low elastic modulus. To overcome this limitation, for the first time, a system investigation was carried out to validate the feasibility of producing UHPC with high elastic modulus (HEMUHPC) by using steel chips (SC) and alumina micro-powder. The initial mixture of HEMUHPC was designed via modified Andreasen and Andersen particle packing model, and the effects of different contents of steel chips on the workability, mechanical properties and durability of HEMUHPC were systematically investigated. Besides, the influence of SC on the microstructure of HEMUHPC was also studied. It was found that, 1) the flexural strength, compressive strength, and elastic modulus of HEMUHPC were increased by 15.49%, 18.33%, and 18.84%, respectively, when the SC content was 50 wt%; 2) when the steel chips content was 50 wt%, the chloride migration coefficient of HEMUHPC was reduced by 12.22%; 3) appropriate amount of SC could lead to a reduction in the porosity and threshold pore diameter of HEMUHPC; 4) the optimal content of SC in HEMUHPC was 50 wt%, considering the effects of SC on the mechanical properties, microstructure, and durability.