Influence of curing on durability performance of concrete

Durable concrete experiences a long service life in most natural environments without deterioration. One of the important factors that influence the durability of concrete is curing. This paper represents a comprehensive investigation to study the effect of method and duration of curing on concrete durability. The techniques of curing used in this study encompass the majority of methods commonly encountered on site. The methods of curing were freshwater wet burlap, plastic film, liquid membrane and air (no curing). The study considered different durations of curing of 3, 7 14, 21 and 28 days. Concrete specimens were exposed to various conditions of deterioration: sulphate attack, cycles of wetting and drying; temperature changes, high temperature, fire and corrosion of reinforcing steel. Compression, tensile strength, weight and corrosion of steel were then monitored. Each of these parameters is utilized to evaluate the durability performance. Durability performance is defined as the ratio between a monitored parameter under one of the aforementioned conditions of curing and deterioration factors, and the counterpart parameter of a standard reference specimen. A corresponding standard reference specimen was cured for 28 days in freshwater and subjected to the same deterioration condition. The study demonstrates that the method and the duration of curing heavily affect the durability performance. For the same method of curing the increase in the duration of curing increases the durability of concrete. The effect of the various curing methods on the increase of the durability of concrete for the same duration can be put into the following hierarchy: air (no curing), liquid membrane, plastic film, wet burlap and finally freshwater. Due to the tremendous impact of curing on the durability of concrete, quality control for proper field curing is of the utmost importance.