When exposed to temperatures that are progressively and rapidly raised, large dimension fibre cement boards tend to crack. This occurrence is analysed and explained for a specific issue of asymmetric growth of a curvilinear crack in high temperatures. This phenomenon occurred while performing Single Burning Item (SBI) experiments at fire loads which are higher than those used in countries of the European Union, which better reflect fire events that may occur in high-rise buildings. In such conditions, fibre cement boards crack, allowing the fire to reach the thermal insulating material which then combusts, thereby helping to spread the conflagration to upper floors. This experiment investigated the temperatures at which fibre cement boards crack, and why. Thermal analysis methods and thermogravimetric experiments were conducted on the fibre boards, followed by X-ray phase analysis investigations. During this phase, X-ray structural analysis was performed while the fibre cement was exposed to temperatures of 1000 °C. The article also presents ongoing change results when heating only composite fibre-cement board materials; phase changes that take place in high temperatures are discussed.

In case of a fire, the flame can spread from the building through the outer openings to the outside. In such cases, the fire temperature thermal effect determines the façade fibrocement tile thermal destruction, while the flammable thermo-insulating systems used for building energy effectiveness ensures it sets on fire. The spread of such a fire becomes uncontrollable and raises an immediate danger to the people inside the building, while such event dynamics delay and make it harder to put out the fire. Extra additive usage in façade fibrocement tiles can raise its resistance to fire temperature effect. Carbon fiber is widely known as a material resistant to the high temperature destructive effect. An investigation was conducted on the influence that carbon fiber has on the properties of autoclaved fiber cement samples. The autoclaved fiber cement samples were made from the raw materials, typical for façade fiber cement plates, produced in an industrial way (using the same proportions). In the samples, carbon fiber was used instead of mix cellulose fiber in 0.5%, 0.75%, 1% proportions. After completing the density research, it was determined that the carbon fiber effect had no general effect on the sample density. Ultrasound speed spreading research showed that the carbon fiber insignificantly makes sample structure denser; however, after the fire temperature effect, sample structure is less dense when using carbon fiber. The results of both these investigations could be within the margin of error. Insignificant sample structure density rise was confirmed with water absorption research, which during the 1% carbon fiber usage case was lower by 4.3%. It was found that up to 1% carbon fiber usage instead of mix cellulose fiber creates a dense structure of autoclaved fiber cement samples, and the carbon fiber in the microstructure influences the mechanical properties of the autoclaved fiber cement samples. After using carbon fiber in ambient temperature, the sample compressive strength and bending strength increased. However, the results of mechanical properties were completely different after experiencing fire temperature effect. Scanning electron microscopy research showed that the bond between the carbon fiber and the cement matrix was not resistant to high temperature effect, due to which the structure of the samples with carbon fiber weakened. Research showed that carbon fiber lowers the mechanical properties of the autoclaved fiber cement samples after high temperature effect. After analyzing the density, ultrasound speed spreading, water absorption, microstructure and macrostructure, compressive strength, and bending strength, the authors determined the main CF usage for AFK dependencies: 1. CF usage up to 1% replacing MCF makes the AFK structure more dense up to 1.5%, and lowers the water absorption up to 4.3%; 2. CF incorporates itself densely into the AFC microstructure; 3. CF usage up to replacing MCF improves the AFK strength properties up to until the fire temperature effect. Compression strength increases up 7.3% while bending strength increases up to 14.9%. 4. AFK hydrate amount on CF surface is lower than on MCF; 5. Fire temperature effect on AFK with CF causes dehydration by removing water vapor from the microstructure, resulting in a lot of microcracks due to stress; 6. The CF and cement matrix contact zone is not resistant to fire temperature effect. SEM experiments were used to determine the CF “self-removing” effect; 7. Due to complex changes happening in the AFK during fire temperature effect, CF usage does not improve strength properties in the microstructure. Compression strength decreases to 66.7% while bending strength decreases to 20% when compared with E samples.

There were gathered four facades with external thermal insulation composite system with rendering for researches. All of the four samples reveals were arranged differently by changing the thickness of decorative render or by changing the technology of installation. Researches helped determine the fact that external thermal insulation composite system with rendering equivalent for DIN 4102-20 (project) standart does not depend from the type and technology of the installation of reveal. As well as determinated that the reveal which was formed from plastic angular profile with dripstone sustained longer impact of the fire than the reveal which was armed with fabric glass. After researches being acomplished and the data being analyzed it is assumed that destruction of ventilated facade reveal can fate not controlled fire spreading into open space of construction facade. Gaisro poveikio tyrimas tinkuojamo fasado angokraščiui Santrauka Tyrimams atlikti buvo įrengti keturi tinkuojamieji fasadai su termoizoliacinėmis medžiagomis po tinku. Visų keturių bandinių angokraščiai buvo įrengti skirtingai: keičiant dekoratyvinio tinko storį arba keičiant įrengimo technologiją. Tyrimais nustatyta, kad tinkuojamo fasado sistemos atitiktis DIN 4102-20 (projektas) standartui nepriklauso nuo angokraščio įrengimo tipo ir technologijos. Taip pat nustatyta, kad angokraštis, kuris buvo suformuotas iš plastikinio kampinio profiliuočio su laštakiu, išlaikė ilgesnį gaisro poveikį negu angokraštis, kuris buvo armuojamas stiklo audiniu. Atlikus tyrimus ir išanalizavus duomenis prognozuojama, kad kitos konstrukcijos – vėdinamojo fasado – angokraščio destrukcija gali lemti nekontroliuojamą ugnies plitimą fasado konstrukcijos tuštuma. Reikšminiai žodžiai: fasadas, tinkuojamojo fasado sistema, gaisras, degumo bandymai, angokraštis, polistireninis putplastis. Keyword : facade, plastered facade system, fire, flammability tests, embrasures, polystyrene