Guide to Curing Concrete

Description

This guide reviews and describes the state of the art for curing concrete and provides guidance for specifying curing procedures. Curing practices, procedures, materials, and monitoring methods are described. Although the principles and practices of curing discussed in this guide are applicable to all types of concrete construction, this document does not specifically address high-temperature or high-pressure accelerated curing,

The term “curing” is frequently used to describe the processby which hydraulic-cement concrete matures and developshardened properties over time as a result of the continuedhydration of the cement in the presence of sufficient water andheat. While all concrete cures to varying levels of maturity withtime, the rate at which this development takes place depends onthe natural environment surrounding the concrete and on themeasures taken to modify this environment by limiting the lossof water, heat, or both, from the concrete, or by externallyproviding moisture and heat.

The term “curing” is also used todescribe the action taken to maintain moisture and temperatureconditions in a freshly placed cementitious mixture to allowhydraulic-cement hydration and, if applicable, pozzolanicreactions to occur so that the potential properties of the mixturemay develop (ACI 116R and ASTM C 125). (A mixture isproperly proportioned and adequately cured when the potentialproperties of the mixture are achieved and equal or exceed thedesired properties of the concrete.)

The curing period is definedas the time period beginning at placing, through consolidationand finishing, and extending until the desired concreteproperties have developed. The objectives of curing are toprevent the loss of moisture from concrete and, when needed,supply additional moisture and maintain a favorable concretetemperature for a sufficient period of time. Proper curingallows the cementitious material within the concrete toproperly hydrate.

Hydration refers to the chemical and physical changes that take place when portland cement reacts withwater or participates in a pozzolanic reaction. Both at depthand near the surface, curing has a significant influence on theproperties of hardened concrete, such as strength, perme-ability, abrasion resistance, volume stability, and resistanceto freezing and thawing, and deicing chemicals.