Concrete or concrete plaster should be cured for minimum 28 days. Moisture content in concrete should not be more than 15%. Check for presence of laitance, oil/grease and efflorescence. Any oil/ grease should be removed by using a proper emulsifying agent followed by rinsing with sweet water. Allow to dry. Any efflorescence should be removed by high pressure water hosing (min 150 bar). Small areas can be mechanically cleaned. Removal of laitance would be by Sand/ Grit Sweep Blast or by using a Diamond Disc Grinder. Remove all dust and contaminants. When sweep blasting use abrasive of 90% - 50 –60 mesh, nozzle pressure of approx. 50- 70 psi. Movement should be by a fast motion and with distance of at least min. 20 inch from the substrate.

Surface should be primed with a suitable primer sealer. This could be either a clear coat or a diluted pigmented coating, which, would show off all the pinholes and other imperfections in the concrete surface. Fill all pinholes and cracks (cracks should be V cut) with a suitable filler. Abrade all areas again where ever filler was used. Remove all dust and contaminants. This surface preparation would be followed by application of 1st coat of paint system.

Tape 18 by 18 inch of polyethylene sheet or plastic tightly to the concrete surface, ensure that all edges are sealed for minimum 16 hours. Visually, check for moisture on underneath of plastic sheet and on concrete surface after removal.

Is a cemetitious sludge layer often formed on concrete surface during casting. It is a weak layer on the concrete surface and if not removed, easily peels off together with any paint on it. Scrape using a blunt knife to check for presence of laitance.

Form oil is used in casting forms to allow easy removal after casting of concrete. It has properties similar to oil and grease. Usually checked visually oily surface would have a darker surface than other dry surface.

Using a Chalk. Draw a line from a clean area through the suspected oil area to another clean area. If the line through suspect area decreases in intensity, but intensity is regained in the second clean area again, the suspected area is contaminated to the extend, that degreasing is required.

Means water soluble salts brought to the surface by water moving from the interior of concrete. It has the effect of salt. Using a conductivity meter or by using a Bessler Sampler, for immersion service chlorides less than 7 micrograms/ sq.cm. For nonimmersion service – Chlorides less than 20 micrograms/ sq.cm Maximum level acceptable – Chlorides less than 50 micrograms/ sq.cm.