Development of reactive MgO-based Engineered Cementitious Composite (ECC) through accelerated carbonation curing

Abstract

The use of reactive magnesium oxide (MgO) is widely recognized in carbonated concrete formulations associated with permanent sequestration of CO2. Engineered Cementitious Composite (ECC) is an advanced fiber reinforced cement-based composite with high tensile ductility and intrinsically tight crack width. In this paper, we investigate an alternative binary binding system for ECC: reactive MgO and fly ash cured with an accelerated carbonation process. Compressive strength, density, carbonation depth, tensile performance and crack pattern of the carbonated reactive MgO-based ECC were investigated at various curing ages. In addition, the CO2 uptake and materials sustainability, in terms of energy consumption, net CO2 emission and cost of the newly developed ECC were assessed. The objective of this research is to further advance the application of reactive MgO and utilization of CO2 in the construction industry through novel ECC material. It was observed that carbonation curing densifies the binding system, thus leading to an increase in both compressive and first cracking tensile strengths of ECC. The tensile strain capacity of the carbonated reactive MgO-based ECC achieved up to 6% with an average crack width below 60 μm after 1-day carbonation. Compared to conventional ECC (M45) and concrete, the 1-day carbonated reactive MgO-based ECC could reduce the net CO2 emission by 65% and 45%, respectively. It is concluded that environmental and technical benefits could be simultaneously achieved for the 1-day carbonated reactive MgO-based ECC incorporated with 50% fly ash. The findings of this research shed light on further applications of reactive MgO cement in the precast industry.