Mechanical Strength Indicators of Polyurethane Adhesive in Lightweight Floor Systems

The article describes the basic features of the lightweight floor system with heat-dissipating lamellas (LFS-L) that do not require screeds and are used in the design of radiant heating. It was assumed that reactive polyurethane adhesive constitute the connection layer between the ceramic tile floor and the thermal insulation substrate, which is covered with aluminium foil. This type of construction has not been fully tested for mechanical strength. To define it, for example, using the finite element method, strength indicators of the tested adhesives which were not used in any of the previous studies discussed in this paper should be determined, such as Young’s modulus E, Poisson’s ratio ν and linear thermal expansion coefficient α. This article presents research methods by which these data were determined. Module E and the ν ratio were determined in the compression strength test of cylindrical samples of polyurethane adhesive. Coefficient α was determined by using digital image correlation in the Aramis system, placing the prepared adhesive samples in a thermal chamber

Selection of floor heating by MCDA method

Using Multiple-criteria Decision Analysis (MCDA), the most favorable floor heating system of a detached house has been selected. The analysis also includes an assessment of the performance of this type of heating on small surfaces (up to 20m2). The choice was made among eight heating variants, adopting various systems available on the construction market powered by water or electricity, including traditional with "wet" screeds, "dry" screeds and lightweight floor heating systems without Screeds. From the set of 14 evaluation criteria, the eight most important ones were identified. Using the summed corrected indicator of mathematical analysis, it was assessed that the best variant is a lightweight floor water heating system on a reactive adhesive without screeds with aluminum foil

The effects of various parameters on the strengths of adhesives layer in a lightweight floor system

The article presents the results of shear and tensile strength of deformable cement adhesives, reinforced by fiberglass mesh with a different weight in a lightweight floor system without screeds. The substrate under adhesive was EPS and XPS thermal insulation. Tests were carried out in dry, wet conditions as well as during freezing and thawing. On their basis, it can be concluded that the larger contact surface of the EPS thermal insulation with the deformable adhesive C2S1 increases the adhesive’s tensile strength. This surface is not important using C2S2 adhesives or when the substrate is made from rough insulation XPS. It was generally found that the higher weight of the fibreglass mesh in deformable cement adhesives has a more favorable effect on their shear strength. Water absorption does not significantly affect the adhesion of terracotta, and in some configurations of components in this system increases it. The adhesive with the symbol C2S2 compared to C2S1 has a higher tensile and shear strength using the same materials. Frost conditions do not allow for long-term use of this type of floor construction in snow and ice protection systems. This experimental research shows that an economical solution with optimal strength consists of XPS insulation, 205 g/m2 mesh, C2S1 adhesive

Young’s modulus and Poisson’s ratio of the deformable cement adhesives

The article outlines the methods, which has designated Young’s Modulus and Poisson’s Ratio of deformable cement adhesives. These indicators are necessary for the strength calculation of the lightweight floor systems (LFS), that do not require screeds with and without heating, using the finite element method. It was noticed that the diagrams of the dependence the stress on deformation in deformable cement adhesives are similar to the model of the ‘Madrid parabola’ used in testing concrete and cement mortar. In order to determine that the theory of ‘Madrid parabola’ is correct, calculations were performed using the least amount of squares approximation method. The data of the experimental studies combined with the formula calculations, allowed the study to achieve a reliable result, together to determine whether the theory of relative approximation is correct or not. All these actions have allowed determining the smallest deformations εc2 in deformable cement adhesives type C2S1 and C2S2 and their compressive strength. Thanks, these two methods (experimental and calculation) the functions describing deformable cement adhesives are defined. They were named S1 and S2 Evola and can be used by designers and producers of floor systems that do not require screeds

Numerical Analysis of Experimental Research in a Lightweight Floor System (LFS) with Heat Diffuser

The article presents the results of research on a lightweight floor system (LFS) with a heat diffuser made of metal lamellae. It differs from traditional layered floors in the absence of a screed layer, which reduces thermal inertia and predisposes it to be used with renewable energy sources. As part of the research, a real model of the floor, consisting of nine ceramic tiles, was made. Polyurethane adhesive was used to connect the individual layers of this composite. The model was subjected to a thermal action. It was constructed with the measuring equipment consisting of strain gauges. These were located at the boundaries of the composite layers and measured the material’s deformation. The measurement results were verified by numerical calculations. For this purpose, a computational model was made using FEM (finite element method). Comparable results of deformations were obtained (the differences did not exceed 6.1%), which made it possible to perform numerical calculations of light floor materials stresses. Additionally, the displacement of the tested model was measured and numerically verified. The results of these verifications can be useful not only in the heated/cooled LFS with aluminium lamellae, but also in other building partitions inside and outside the building

Patterns of Diversity of Fusarium Fungi Contaminating Soybean Grains

Soybean is an important, high protein source of food and feed. However, like other agricultural grains, soybean may pose a risk to human and animal health due to contamination of the grains with toxigenic Fusaria and associated mycotoxins. In this study, we investigated the diversity of Fusaria on a panel of 104 field isolates obtained from soybean grains during the growing seasons in 2017–2020. The results of species-specific PCR analyses showed that Fusarium avenaceum was the most common (n = 40) species associated with soybean grains in Poland, followed by F. equiseti (n = 22) and F. sporotrichioides (11 isolates). A set of isolates, which was not determined based on PCR analyses, was whole genome sequenced. Multiple sequence analyses using tef-1α, top1, rpb1, rpb2, tub2, pgk, cam and lsu genes showed that most of them belonged to Equiseti clade. Three cryptic species from this clade: F. clavum, F. flagelliforme and FIESC 31 (lacking Latin binomial) were found on soybean for the first time. This is the first report demonstrating the prevalence of Fusaria on soybean grains in Poland