PORTLAND CEMENT CONCRETE - Materials for Civil and Construction Engineers - page 271

FIGURE 7.24 Curing concrete with plastic sheets.

and simply shaped concrete structures, while plastic sheets are effective and
easily applied to various shapes. Periodic watering is not required when im-
pervious papers or plastic sheets are used. Discoloration, however, can
occur on the concrete surface.

■ 7.3.5 Membrane-Forming Compounds

Various types of liquid membrane-forming compounds can be applied to the
concrete surface to reduce or retard moisture loss. These can be used to cure
fresh concrete, as well as to hardened concrete, after removal of forms or
after moist curing. Curing compounds can be applied by hand or by using
spray equipment (see Figures 7.25 and 7.26). Either one coat or two coats
(applied perpendicular to each other) are used. Normally, the concrete sur-
face should be damp when the curing compound is applied. Curing com-
pounds should not be used when subsequent concrete layers are to be
placed, since the compound hinders the bond between successive layers.
Also, some compounds affect the bond between the concrete surface and
paint.