CEMENT COMPOSITES REINFORCED WITH TEOS-TREATED WOOD FIBRES

In this study, wood fibres were extracted from eucalyptus and pine woods, treated by immersion in tetraethyl orthosilicate (TEOS) and incorporated into a cementitious matrix at three weight contents (2 wt%, 5 wt% and 10 wt%). The fibres were characterized using chemical and morphological analyses and the cement-based composites were evaluated using chemical, hygroscopic, mechanical and morphological tests. The morphological and spectroscopic results satisfactorily justified the physical-mechanical properties. The wood fibre-cement composites reached similar water uptake and apparent porosity to those of the neat mortar, but exhibited higher mechanical properties. Furthermore, all treated fibres yielded composites with improved mechanical and hygroscopic properties compared to those with pristine fibres. Overall, the best performance (based on hygroscopic and mechanical results) was obtained for the wood fibre-cement composite with 2 wt% pine fibres.

Test of Adhesion and Cohesion of Silicone Sealants on Facade Cladding Materials within Extreme Weather Conditions

This research was carried out as part of project MPO FR - TI4/332 – New Technologies of Bonded Facade Cladding with Anchor Elements with Increased Resistance to Corrosion.This contribution concerns tests carried out to investigate the tensile properties of silicone sealants for use with facade cladding materials. The experimental part of the research is aimed at ascertaining the technical properties of sealants via the cyclic alternation of extension and compression of test specimens in test moulds. For the tests, industrially manufactured neutral and universal silicones were chosen from three different manufacturers. The aim of the research was to discover any differences that might appear in their resistance against alternating maintained extension and compression of the specimens under extreme temperature conditions, i.e. a high temperature of (70+2) °C and a temperature simulating freezing, i.e. (-20+2) °C. The cladding material used was fibre-cement composite boards (known as Cembonit), ceramic and glass cement facade claddings.The result of the measurements taken is a summary in which effective and unsuitable combinations of sealants and test substrates are outlined. The main conclusion is the fact that it is not possible to responsibly choose a suitable material without taking appropriate measurements or having previous experience. A secondary conclusion to this article is the fact that there are significant differences between individual sealants in the results they provide in combination with specific cladding material.