Utilization of ultra-fine copper slag to prepare eco-friendly ultrahigh performance concrete by replacing silica fume

Abstract

The present study aims to determine the feasibility of using ultra-fine copper slag (WCS) to prepare eco-friendly ultrahigh performance concrete (UHPC) by replacing silica fume (SF). The variation of hydration progress, mechanical property and microstructure development of UHPC as function of WCS was evaluated. Experimental results indicated that WCS could be prepared and the fayalite could be decomposed by using wet-grinding method. The UHPC pastes behaved like Herschel-Bulkley (H-B) fluids and the shear-thickening behavior was more pronounced as the increase of WCS dosage, implying that WCS has negative impact on workability of UHPC to some extent. WCS had no negative impact on the hydration of UHPC pastes at the early stage and exhibited good pozzolanic activity at the later stage, so as to generate more hydration products to refine the pore structure, thus making UHPC with WCS to obtain better mechanical strength than that without WCS. Replacing SF in UHPC by WCS has significant economic benefits, while the negative impact on CO2 emissions can be negligible.