Nov 2018 METHODS FOR CONCRETE CURING
In cooking, curing sees the preservation of food by drawing moisture out of meat, fish, chicken and other items by way of osmosis/induced evaporation. In construction, the curing of cement shares a similar explanation whereby moisture / water must not evaporate from the concrete in order for it to gain strength. With that said however, the process of curing in concrete and construction is a delicate one that must be closely administered so as to ensure this process does not happen in some places and not in other sections of the concrete. Maintaining the appropriate amount of water along with the temperature. Curing concrete especially in the early phases of this process will see the desired strength and durability as the end result. While the curing process begins almost immediately after pouring concrete, it’s important to maintain moisture for a specified period of time to prevent the concrete from drying out too fast resulting in flaky and crack prone concrete with a soft sandy/dusty surface.
Based on the type of construction work, curing can be done by the following methods. Each offering their own unique benefits, Sephaku Cement shares these methods of curing when working with concrete.
Making use of hessian or wet gunny bags or plastic sheeting are an effective method in ensuring that recently placed concrete does not dry out too quickly by covering up the wet concrete mix. Ideally practiced on horizontal and vertical installations, covering the wet concrete helps to regulate surface moisture and is especially effective in windy and hot climates.
Protecting the concrete from losing moisture too quickly, curing concrete by way of ponding sees poured concrete segregated into squares or rectangular ponds by using clay or sand to create a pond that can be filled with water. The ponds are filled with water daily keeping the curing concrete continually wet. This curing method is ideally applied to flat horizontal concrete installations.
As the name suggests concrete can also be cured by submerging pre-cast concrete into water at a temperature above 20oC but not much more than 30oC.
- Steam Curing
Steam curing concrete sees wet steam distributed over, and underneath if precast concrete, various concrete or cement based surfaces. Ideal when looking to achieve early strength as well as on prefabricated concrete installations and frameworks, steam curing is also especially effective in cold weather conditions. (ensure to follow the rules for steam curing)
Ensuring that moisture levels of curing concrete is maintained as it sets, by repeatedly sprinkling all concrete surfaces with water on an ongoing bases will ensure maximum strength and durability is achieved, allowing a complete and comprehensive curing process to take place. This process must go on for as long as possible but not less than three days.
- Chemical Curing
Curing cement by way of chemical inclusions sees the application of a specified volume of hygroscopic salt such as NaCI-, CaCl- etc. added to the surface of the concrete. As soon as this is applied the cement is sprayed over with water helping to engross moisture from the surrounding environment. This method is however not recommended where the concrete are in contact with any steel, reinforcing steel, columns and girders.
- Membrane Curing
By wrapping the surface of curing concrete in a waterproof membrane or with a spray on membrane such as a wax or bitumen emulsion, this process hinders the loss of moisture through evaporation ensuring that the surface and internally of the concrete remains moist and able to adequately cure and gain its designed strength and durability.
Offering a wide selection of general purpose and more specialised cement products and mixes contact Sephaku Cement or view our range of products online.