Effect of belite-rich cement replacement on the properties enhancement of eco-friendly ultra-high performance concrete containing limestone powder and slag

Abstract

Cement-slag-limestone (CSL) powder concrete is a new type of ternary concrete. Thus far, CSL powder application in ultra-high performance concrete (UHPC) remains relatively limited. Furthermore, the effects of different types of cements, including belite-rich Portland cement (BRC), on CSL concrete have not been investigated. Therefore, in this study, a new CSL-UHPC was designed, where the sustainability of CSL-UHPC was systematically improved by using BRC to replace the ordinary Portland cement (OPC) in CLS cementitious materials and realize a UHPC with a low heat of hydration, low autogenous shrinkage, low CO2 emissions, and high strength. According to the experimental data, the heat released by the hydration reaction during the early stages of BRC concrete was less than that released in the early stages of OPC concrete. The cumulative heat release from hydration and the maximum heat release rate were minimal, approximately 171.8 J/g and 1.41 mW/g of the binder, respectively, for 100% BRC replacement. Moreover, the autogenous shrinkage generation in the early stages was effectively reduced; notably, the reductions autogenous shrinkage were particularly pronounced (approximately 39.5–36.7%) for 66% and 100% BRC replacement. After 56 days of curing, the compressive strength of the BRC-infused concrete was similar to or higher than that of OPC concrete. In addition, the CO2 emissions and the CO2 emissions per unit strength decreased by 2.6–7.8% and 7.0%, respectively, as the percentage of BRC replacement increased. Thus, CSL-UHPC combined with BRC is more effective than OPC in terms of promoting a sustainable concrete industry.

Keywords

• Eco-efficient UHPC
• CO2 emissions
• Cement hydration
• Autogenous shrinkage
• Late strength