Curing concrete is the process that controls the rate and amount of moisture concrete loses during cement hydration. When concrete is properly cured, it can attain its optimal strength and durability. Curing can be done at the jobsite once the concrete is placed and finished or during the manufacturing of concrete products.
There are several different methods for curing concrete that are determined by factors such as the type of construction, the concrete mix, and outside temperature and humidity. Regardless of the technique used, they all strive to keep concrete moist and to prevent the loss of moisture. Other considerations taken into account are project specifications and/or parameters of the jobsite. The Portland Cement Association explains that the purpose of curing is to provide the “adequate amount of moisture for continued hydration and development of strength, volume stability, resistance to freezing and thawing, and abrasion and scaling resistance.”
Concrete attains its full strength and durability after curing for a number of days, or in some cases, weeks. Concrete contractors prevent the loss of moisture during curing by leaving the formwork in place and/or to cover the concrete with an impervious paper, plastic sheeting or membrane-forming compounds. In addition methods such as spraying (or fogging), ponding or wet coverings that cool the concrete as the water evaporates are used.
When temperatures are 40ºF and above, the American Concrete Institute (ACI) recommends a curing period of a minimum of 7 days, or until 70% of the specified compressive strength is achieved for most concrete structures. In temperatures above 50ºF, an accelerant can be used to speed up the hardening process and reduce the curing period to only 3 days. Additional variables are determined by the weather conditions the concrete will be exposed to during its life-cycle as well as the size, shape and strength requirements.
The Conco Companies are a leading supplier of concrete services for the Western U.S. and got our start in the Bay Area in 1959 by offering clients the best value on a wide range of concrete services and products. Since that time, we have taken a leading role as one of the top concrete contractors in the region. Our offices serve California, Colorado, Oregon, Washington and Nevada.