Effect of Curing Methods on the Performance of UHPC

Curing significantly affects the properties of hardened concrete, including its mechanical properties, shrinkage, and durability characteristics. Consequently, it is cured using one or more techniques, such as water ponding, steam curing, and application of a curing compound. While moist curing requires long time, steam curing is the quickest for achieving a required degree of maturity of concrete. However, steam curing requires water and energy to generate steam, that could adversely affect the sustainable production of concrete. Recently, accelerated curing of concrete utilizing carbon dioxide is reported to be an effective and environment-friendly option. However, not much information is available on the efficacy of this method, particularly for curing ultra-high-performance concrete (UHPC). In the present work, the effect of three curing methods, namely steam curing (SC), burlap curing (BC), and accelerated carbonation curing (ACC), on the properties of hardened UHPC was investigated to enable in adopting a most suitable curing method. The impact of selected curing techniques was evaluated in terms of compressive and tensile strength, elastic modulus, fracture toughness, drying shrinkage strain, chloride permeability, and morphology of the UHPC. The strength and elastic modulus of UHPC subjected to 6-h SC was much higher than the case of ACC and BC. Furthermore, the strength and elastic modulus of UHPC subjected to ACC and BC, followed by air exposure, were almost similar. On a long-term basis, the properties of UHPC cured by ACC were found to be marginally better than those cured by BC and slightly less than that cured by SC. Consequently, ACC can be used for the production of environment-friendly UHPC since it leads to the sequestration of CO 2 and conservation of energy and water used in SC and water consumed in BC.