The organic–inorganic hybrid sol for the consolidation of decayed wood in architectural heritage

Generally, the mechanical property defects and surface cracks are often presented in partly decayed wood components that are treated with silicon-based inorganic consilidants. To solve the problem, an organic–inorganic hybrid sol for the conservation of decayed wood was developed in this work, in which the polyvinyl alcohol (PVA) was introduced into the silicon inorganic sol formed by the sol–gel process of ethyl orthosilicate and methyl triethoxysilane. The properties of decayed wood treated with the organic–inorganic hybrid sol were characterized by performance tester, microcomputer control electron universal tester, simulation of swelling-shrinkage and thermal gravimetric analyzer. The consolidation mechanism was affirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. The results revealed that the introduction of PVA into the hybrid sol led to a great improvement in comprehensive mechanical properties of the treated wood, accomplishing the swelling-shrinkage properties of the decayed area closer to those of sound area in wood. The improved properties could be ascribed to the hybrid gel coats formed on the surfaces of wood cells, which displayed a good performance in enhancing mechanical properties and thermostability. The hybrid sol can be used as a potential material to consolidate the partly decayed wood components for the protection of ancient wooden buildings.