Preliminary testing of timber consolidants applied by impregnation

Abstract

This paper presents the initial laboratory work developed with the aim of consolidating timber that has been subjected to the action of rot fungi, by impregnation with polymeric products. This technique has been largely used in restoration of works of art but not so much in civil engineering. Indeed, structural wooden elements in buildings are often subjected to degradation by rot fungi due to the accidental presence of water from various causes such as deficiencies in plumbing, broken tiles, clogging of guttering or degradation of exterior masonry. In these situations the question arises about which repair action to take: replace the whole element? Replace only the damaged part by inserting prosthesis? Maintain the damaged element, strengthening or consolidating it? The option of maintaining in the building the original (even though deteriorated) timber has been gaining more and more importance, because the loss of the element contributes to the loss of its historical identity. Consolidation by impregnation falls within this context, thus justifying deeper studies. The laboratorial work, developed using degraded maritime pine (Pinus pinaster) specimens, is presented. The test-specimens were prepared in the laboratory, to reach different decay levels by varying the exposure time to brown-rot fungi (Coniophora puteana). Three commercial low-viscosity products, specific for the impregnation of timber deteriorated by rot fungi, were tested: two epoxy-based and one acrylic. The efficiency of these products was assessed through compression tests parallel to the grain and hardness tests, involving both impregnated and non impregnated wood. Their influence, when applied to degraded timber, on its water absorption behavior was also tested.