New concrete should be allowed to dry until moisture content is below 12% as measured with protimeter, which usually takes about 2-4 weeks after plastering subject to weather conditions . The presence of form release agents and laitance deposits on new plastering must be considered and thoroughly removed before painting. All dirt, algae, fungus, loose paint films etc, on the old substrate can be removed by high pressure water jet cleaning. Apply KCC fungicidal solution on area infested with algae and/or fungus. All cracks and minor surfaces damage shall be repaired with appropriate sealant or putty and allowed to dry prior to painting.