A review of concrete exposed to low-temperature environments at early ages: mechanical properties and durability

Abstract

Cold weather concreting can slow down the hydration of cement, hindering the development of microstructure and strength gain of concrete materials and resulting in poor durability of concrete. This paper reviews the recent progress in mechanical properties and durability of concrete exposed to low-temperature environments. The effects of low-temperature conditions, including exposure time, temperature, and duration, on the mechanical properties and durability of early-age concrete are evaluated. The mechanical properties involve compressive, steel-concrete and/or fiber-matrix bond, tensile, flexural, and shear properties, while durability mainly focuses on water permeability, chloride permeability, and frost durability based on the available literature. Several improvement strategies for the mechanical properties of concrete are proposed through considering the influences of w/b ratio, mixture proportion, and use of advanced temperature regulating techniques. The underlying mechanisms, advantages, and disadvantages associated with these improvement strategies are discussed. It is found that with the decrease in exposure temperature and increase in exposure duration, the mechanical properties and durability of early-age concrete gradually decreased. Compared to compressive strength, the flexural/tensile strengths are less sensitive to ambient temperature changes. The uses of proper pre-curing and optimal contents of antifreeze admixture, high-early strength cement, nano-materials, alkali-activator, and phase change materials are effective in enhancing the early-age properties of concrete subjected to low temperature. This paper aims to enhance the fundamental knowledge of cold weather concreting to facilitate its highly efficient design and construction, as well as to extend the service life of concrete infrastructures.