Effect of molybdenum tailings aggregate on mechanical properties of engineered cementitious composites and stirrup-confined ECC stub columns

Abstract

Abstract Engineered cementitious composites (ECC) exhibit behaviors of multiple cracking and strain-hardening compared to ordinary concrete. However, the use of ultrafine silica sand (S) to produce ECC results in increased cost and environmental overload. This study was to develop an eco-friendly and cheaper ECC by incorporating different replacement ratios of industrial byproduct molybdenum tailings (MT). The mechanical properties of ECC with MT were evaluated. Based on industrial computer technology, nuclear magnetic resonance, and scanning electron microscope techniques, the three-dimensional spatial distribution and fluid distribution of pores and the microstructure of the ECC were investigated, respectively. The mechanical properties of stirrup-confined ECC stub columns were also investigated. Results indicated that the ECC incorporating 25% MT exhibited the best mechanical properties, in which the tensile strength (f t) increased by 32.16% and exhibited well strain-hardening behaviors. Under a 25% MT replacement ratio, ECC had the lowest porosity and good interfacial transition zone, and bonding interface between polyvinyl alcohol (PVA) fiber (PF) and matrix. Moreover, the stirrup-confined ECC stub column with 25% MT can ensure better both the peak stress (f cc) and peak strain (ε cc). The assessment of environmental impact and cost further indicated that the incorporation of MT to prepare ECC is a promising method.