CONCRETE CURING COMPOUND

Concrete curing compound consists essentially of waxes, natural and synthetic resins, and solvents of high volatility at atmospheric temperatures. The compound forms a moisture retentive film shortly after being applied on fresh concrete surface. White or gray pigments are often incorporated to provide heat reflectance, and to make the compound visible on the structure for inspection purpose. Curing compound should not be used on surfaces that are to receive additional concrete, paint, or tile which require a positive bond, unless it has been demonstrated that the membrane can be satisfactorily removed before the subsequent application is made, or that the membrane can serve satisfactorily as a base for the later application.
The compound should be applied at a uniform rate. The usual values for coverage range from 0.20 to 0.25 m2/lit. Curing compound can be applied in two applications at right angles to each other by hand or power sprayer usually at about 0.5 to 0.7 MPa pressure. For small areas, the compound can be applied with a wide, soft-bristled brush or paint roller.
For maximum beneficial effect on open concrete surfaces, compound must be applied after finishing and as soon as the free water on the surface has disappeared and no water is visible, but not so late that the liquid curing compound will be absorbed by the concrete.
When forms are removed, the exposed concrete surface should be wetted with water immediately and kept moist until the curing compound is applied. Just prior to application, the concrete should be allowed to reach to a uniformly damp appearance with no free water on the surface and then application of the compound should begun at once.
USES
Curing compound can be used with advantage where wet curing is not possible. It is very suitable for large areas of concrete which are directly exposed to sunlight, heavy winds and other environmental influences. It can be used for curing of:
•Concrete pavements, airport runways, bridge decks, industrial floors.
•Canal linings, dams and other irrigation related structures.
•Sport arenas and ice ring.
•Precast concrete components
•Roof slabs, columns  and beams
•Chimneys, cooling towers and other tall structures.
TESTING OF CURING COMPOUND
The curing compound should be tested in accordance to ASTM for the following tests:
a)     Water retention – The test should be conducted in accordance with test method C 156.
b)     Reflectance – Determine the daylight reflectance of white – pigmented compound in accordance with test method E 97.
c)      Drying time – The test should be conducted in accordance to ASTM C 309 clause 10.3
d)     Long term setting – For routine testing use test method D 1309. In case of dispute use method D 869.
e)     Nonvolatite content – Test in accordance with test method D 1644 method 4.