Technical Questions

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What is curing?

Q. What is curing?


A. Curing is action taken to maintain moisture and temperature conditions in a freshly placed cementitious mixture to allow hydraulic cement hydration and, if applicable, pozzolanic reactions to occur so that the potential properties of the mixture may develop (ACI 308). The presence of sufficient moisture to maintain a relative humidity (RH) over 80% within the concrete and favorable temperatures exceeding 10°C (50°F) are necessary for the continuation of the chemical reactions on which the increase in strength depends (ACI 308R). Moisture and temperature control also reduce adverse volumetric changes that may cause cracking in structures and slabs (ACI 209R, ACI 302.1R).

During early curing, the internal structure of the concrete is built up to provide strength and low permeability. Simply retaining moisture within the concrete may be sufficient for w/cm greater than 0.4; however, for mixtures with w/cm less than 0.4, water is needed during curing. With such concrete, water curing should begin as soon as possible, with free water kept on the concrete to replace any lost moisture and to help dissipate heat.


References: SP-1(02); ACI 308R-16; ACI 209R-92; ACI 302.1R-15

Topics in Concrete: Concrete Fundamentals; Curing; Placing

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