A green drying powder inorganic coating based on geopolymer technology

A geopolymer-based drying powder decorative coating was successfully prepared from metakaolin and solid type water glass by using simple powder mixing process, and the coating was successfully applied in engineering. The compressive strength and rheological performances of coating were studied. To improve the coating anti-cracking performance, the quartz sand and polycondensed aluminum phosphate (PAP) were applied and studied. The experiment results showed that water glass and water content significantly influenced the viscosity and compressive strength of drying powder coating, 3 wt% PAP improved the 3 d compressive strength from 23 to 29 MPa and prolonged surface drying time from 0.6 to 3 h, no crack in 500 μm thickness coating including quartz sand. The coating performances, including surface drying time, hardness, water resistance, and scrub resistance, were systematically tested based on the Chinese construction coating standards. The optimal coating formula (WG/MK = 0.8, W/P = 0.5, PAP = 3 wt%) was obtained for a coating that has excellent properties of high strength, artificial aging resistance, high temperature resistance, good workability, etc. The coating has good prospects of development and application due to its outstanding advantages, low manufacturing cost, simple manufacturing technology, environment friendly, etc.