Materials for Curing Concrete

Burlap

• One method for curing concrete is to cover it with fabric saturated with water. Many moisture-retaining fabrics are effective, including cotton mats or rugs, but the most common material used is burlap. Burlap sheets treated to reflect sunlight and resist fire and rot are ideal for concrete curing. Ensure that the burlap you plan to use is free of any residue that might prevent proper curing or stain the concrete. Rinse new burlap sheets with water to get rid of any residual manufacturing substances that might leach into the concrete. Apply the wet burlap once the concrete has hardened enough that the surface cannot be easily indented. Cover the concrete completely with the wet burlap, and continue to moisten it as the concrete cures so the surface always has a film of water on top of it.

Plastic Sheets

• Plastic sheets are another effective option for curing concrete. They are made from lightweight polyethylene film that does not damage the surface when placed atop it, and help prevent moisture loss from the concrete. However, plastic sheets may cause stains or discoloration on the surface. As a result, it is best to use this curing method in combination with another material, such as wet burlap, so that the plastic does not touch the surface directly. Place the burlap on top of the concrete and the plastic sheet over the burlap -- the plastic holds the moisture in. Polyethylene sheets are available in clear, white and black. Use a white sheet when temperatures are high, so sunlight reflects off the surface. In cooler weather, a black sheet helps absorb sunlight to keep the concrete warm. Clear plastic sheets do not affect heat absorption either way. Plastic is also an effective option for interior curing.

Impervious Paper

• Concrete is also cured using a double layer of kraft paper held together by a bituminous adhesive. This type of impervious paper also contains fiber reinforcement to strengthen it and is an ideal option for curing horizontal concrete surfaces in basic shapes. It is a convenient curing method because the paper does not require constant moistening to ensure an effective result; it blocks moisture loss once the surface is saturated. Apply the impervious paper after the cement has hardened enough that the surface cannot be easily damaged and you have thoroughly saturated the concrete. Weigh down the sheets so they remain in contact with the concrete surface throughout the curing process.

Chemical Membranes

• The easiest method for curing concrete may be the application of a chemical membrane. This method utilizes a chemical compound containing chlorinated rubber, resins, waxes and other substances that help control moisture loss. When applied to the surface, the compound forms a membrane that keeps the concrete moist. Apply the compound as soon as the concrete is finished. Chemical membranes are typically applied as a spray, and may require two thin coats to effectively cover the surface.