Requirements for concrete base course

Grading. After removing the formwork, defects such as uneven board surface, dislocation of formwork joints and local protrusion shall be repaired according to the characteristics of coating method and coating type, and adjusted to the scope of construction. Generally, the dislocation is controlled below 3mm, and the surface accuracy is limited to 5mm. The basic yin and yang corners and corner lines should be dense and well-defined. If there are missing edges and corners, they must be repaired.

Alkalinity of concrete PH value should be below 10. Under normal circumstances, after the completion of the construction of the external wall, the summer maintenance period is more than 2-3 weeks, and the winter maintenance period is more than 4 weeks to meet the alkalinity requirements.

Concrete surface should be dry, the general requirements of the moisture content of 8-10% below, the moisture content of solvent-based coatings is generally required to be below 8%. The water content of water-based coatings is generally required to be below 10%. Remove the reinforcement, nails, wood chips and other sundries that hinder the coating construction, and fill them with mortar or putty. In order to avoid the expansion of corrosion caused by steel and other coating off and pollution. For concrete joints, construction joints and cracks caused by concrete shrinkage, etc., may cause water leakage, so should choose the appropriate method for waterproof treatment, and fill with putty.

If it is found that the surface hardening is poor and the strength is obviously insufficient, the low strength part shall be removed by steel wire brush and other tools, and then the cement polymer putty or polymer mortar shall be repaired. At the expansion joints reserved on the surface of the outer wall (including those reserved during construction), closed materials shall be used for waterproofing. Demoulding contaminants, grease, dust, splashes and mortar flow marks on the base surface shall be thoroughly removed.