Preparation And Performance Testing Of Composite Materials Based On SiO₂ For Consolidation Of Stone Heritages

There are four representative grottoes in China and they possess greatly history values, art values and science values. However, as stone monuments located outdoors, they are always exposing themselves to natural environment and are suffering from natural factors and human factors so that weathering phenomenon of them becomes more and more serious day by day. Stone heritages are precious cultural resources and unrenewable resources in order that many countries are trying their best to research excellent materials to protect them.However, the stone heritages have their own special characters so that the protective materials must have excellent properties. At present, nanocomposite materials are exensively paid more attentions to because of their excellent performances. In the experiment, sol-gel method was used to prepare organic/inorganic composite materials which can consolidate weathered stone heritages.The experiment demonstrates that these concentrations of reactants including water , TEOS, ETOH and ammonia have direct influences on the stability of sol. Stirring velocity and dropping rate also affect that. Water concentration and surfactant affect seperately the size of nanoparticle and their dispersion.Methyltrimethoxysilane have excellent performances which had alidated by my partner so the material was chosen to prepare composite materials. When its weight perceng is 15, the sol has high consolidation uptake, low viscosity, short gel time and better stability. Wacker OH100 and KSE OH300 which are commercial consolidate materials are chosen as contrasts. SEM images show that there are many cracks on the surface of Wacker OH100 and KSE OH300 gel after laying for 10 days.As consolidate materials to protect weathered gritstone stone heritages, penetrability and consolidation strength are the main standards to value its properties. However, other properties must also be assured. The tests done on stone samples show that color variation caused by the composite material is small and it is limited to related standards; the composite material has low viscosity which is near to that of water; the consolidant uptake of the composite material is much better than pure organic materials; its breathability is higher than commercial consolidants; its acid-resistance and alkaline-resistance are better than other materials and especially its salt tolerance is very distinct; the composite materials can effectively decrease water absorption and surface absorption and increase hydrophobic, the aging resistance improves highly. The results above show that the composite materials prepared in the experiment have excellent comprehensive performance.