Mechanical Properties of Polyurethane Adhesive Bonds in a Mineral Wool-Based External Thermal Insulation Composite System for Timber Frame Buildings

Resistance of External Thermal Insulation Systems with Fire Barriers to Long-Lasting Weathering

Fire barriers are used to reduce the risk of fire spreading over façades. External thermal insulation composite systems consist of mineral wool strips embedded in a layer of another thermal insulation material. A system configured in this manner, beyond standard solutions, can be more susceptible to environmental factors. In this study, an expanded polystyrene-based system with a mineral wool fire barrier was subjected to weathering conditions. In view of climate change, nonconventional long-lasting exposure simulating the effects of intensive atmospheric factors was applied. Two exposure sequences were used, each covering 80 cycles of heating and wetting, five cycles of heating and cooling, and 30 cycles of wetting, freezing, and thawing. Significant changes were observed in the first sequence. The second sequence caused rendering system cracks wider than 0.2 mm. This indicated a loss of watertightness. A new approach of 3D scanning with inspection analysis was used to assess the deformations. It showed deformation amounted to 0.7 mm within the MW strip. The methods used previously did not allow this level of deformation to be recorded.

The Effect of Openings' Size and Location on Selected Dynamical Properties of Typical Wood Frame Walls

The wooden frame constructions are now popular in many developed countries of the world. Many of these locations where such buildings are constructed are exposed to seismic and other shocks which are generated by human activities. This paper discusses the effect of the size and location of openings in the wooden frame walls under dynamic loadings. Natural frequencies of such frames with and without openings have been determined. Three 14 m high walls with different widths, including 3, 6, and 12 m, have been considered. Dynamic analysis has been made using finite element method structural analysis software Dlubal RFEM 5.17. The results show that the effect of the size and location of the openings on the natural frequency is significant. Numerically speaking, the relative change of the natural frequencies of a wall without and with an opening in a specific place could be up to 30%. In addition, the change of the natural frequency for the location of the openings is more sensitive than that to the sizes. Furthermore, the appropriate sizes and locations of openings of the wooden frame walls have been suggested. The appropriate size and place were found to be small openings in the top of the walls.

Experimental Verification of a Highly Simplified, Preliminary Machinability Test for Wood-Based Boards in the Case of Drilling

In contrast to metalworking there are no standardized or (at least) generally accepted, relative machinability tests for innovative or less known wood-based panels. The most reliable testing procedures are based on the use of a specialized, accurate system for measuring cutting forces and on conducting all tests in conditions that are similar to real industrial conditions (machine tool, cutting parameters etc.). However, the need for a more simplified testing procedure has often been voiced—not all scientists specializing in wood-based materials development have a machine tool comparable to one that can be found in a real furniture factory and piezoelectric force sensors at their unlimited disposal. To meet this need, the highly simplified, preliminary machinability test for wood-based boards in the case of drilling was developed and tried. The results of experimental research suggest that the simplified way of testing of relative machinability of wood-based boards (i.e., testing based on the photoelectric measurement of the time needed to make a 10 mm deep hole under constant feed force) can be a useful substitute of standard machinability testing procedure (based on accurate cutting forces measurements carried out in the standard industrial conditions). When verifying the simplified testing procedure, samples from each of the three basic groups of wood-based materials of substantially different internal structures (fiberboard, particleboard, and veneer boards) were tested. The relationship between significantly reliable and highly simplified machinability indexes turned out to be at a satisfactory level (R2 = 0.97 for particleboards and R2 = 0.95 for fiberboards or boards made of veneer or solid wood). The use of a simplified procedure can be especially pragmatic in case of any preliminary testing of innovative wood-based boards during the material development work.

Porosity of Calcium Silicate Hydrates Synthesized from Natural Rocks

In this work, the suitability of natural raw materials with various modifications of SiO₂—granite sawing waste (quartz) and opoka (a mixture of cristobalite, tridymite, quartz, and an amorphous part)—for the 1.13 nm tobermorite and xonotlite synthesis is examined, and their specific surface area, pore diameter and volume, and the predominant pores are determined. Hydrothermal syntheses were carried out at 200 °C for 12 and 72 h from mixtures with a molar ratio of CaO/SiO₂ = 1.0. X-ray diffraction analysis, simultaneous thermal analysis, and scanning electronic microscopy were used, which showed that in the lime–calcined opoka mixture the formation of crystalline calcium silicate hydrates takes place much faster than in the lime–granite sawing waste mixture. The high reactivity of amorphous SiO₂ results in the rapid formation of 1.13 nm tobermorite and xonotlite (12 h). According to Brunauer, Emmet and Taller (BET) analysis data, this product features a specific surface area of ~68 m²/g, a total pore volume of 245 × 10⁻³ cm³/g, and has dominating 1–2.5 nm and 5–20 nm diameter pores. This porosity of the material should provide good thermal insulation properties of the products made from it as no air convection occurs in the fine pores.