Silica colloid based inorganic-organic hybrid materials for stone monuments conservation and anti-weathering evaluation

The colloid with nano-size silica particles was synthesized by conventional sol-gel process. Based on the fact that the stability of colloid and the size of nano-silica particle are mainly determined by TEOS content, ammonia concentration, water content, ethanol content and titration speed parameters, as-synthesized colloid was mechanically mixed with methyl trimethoxysilane, an organic with relatively good anti-weathering properties to prepare the organic-inorganic hybrid consolidant (SiO2-OIHC). When OIHC contains 15%-20% methyl trimethoxysilane, the viscosity of SiO2-OIHC with good stability is low, which is close to the viscosity of water, and the gel time is shorter. The SiO2-OIHC hybrid consolidant avoids the tendency to crack inside the pores of stones and drawback that often appears in traditional organic consolidant. Additionally, the color changes of SiO2-OIHC coated stones is small, and the consolidant absorption rate and air permeability are significantly higher than those of single organic consolidant. The ability to resist the acid and salt corrosion of SiO2-OIHC coated stones are improved significantly.