The paper deals with determination and classification of the mechanical parameters of cement fibre boards (CFB) with cellulose and PVA reinforcing fibres. The cement fibre material with reinforcing ...fibres is produced using the Hatschek process, where the fibres are arranged in the production direction and the curing is subsequently verified. Test experimental samples, specimens are created from the same production batch, and are produced orienting all of them in the production direction to determine the characteristic for an orthotropic material. The fracture mechanical parameters such as fracture energy and work of fracture were then determined and verified as well. Records will be made for the determined crack mouth opening displacement (CMOD) and displacement (d) of test specimens. The loading directions are given to cover the determination of the mechanical parameters of the material. These measurements are intended to complement the mathematical model that uses FEA modelling for subsequent implementation of the material into civil engineering structures or details.
Display omitted
•Determination of fracture properties of CFB with cellulose and PVA fibre.•A new CMOD measurement method was developed for smaller test specimens.•The obtained fracture energy values were implemented in the FE Analysis.•Validation of the numerical model with fracture parameters via experimental tests.
The paper aims to determine selected basic material and elasticity constants of cement fibre boards (CFB) with organic cellulose fibres produced with the use of Hatschek process and thus extend ...potential field of application of CFB in the field of civil engineering for supporting structure designs. Modulus of rupture and modulus of elasticity determination was performed with the use of a three-point and four-point bend test, and tensile strength and compressive strengths were tested. During loading the orientation of testing specimens was distinguished, while taking into account the production method. The loading was applied with regard to a potential use of the boards in supporting structures perpendicularly or parallel to the mid-plane of the board. An innovative approach to distinguishing board orientation during loading was selected in order to extend the scope of application of this special group of cement composites even outside the usual field of application, particularly with a focus on bearing structures of building construction.
The testing specimen orientation had a significant effect on failure and course of loading diagrams. The biggest differences occurred under tensile loading, when delamination of thin layers (monolayers) of the cement fibre board occurred during perpendicular loading to the board mid-plane.
The aim of this paper was to analyze selected properties of beech wood (Fagus sylvatica L.) treated by one-sided surface charring. Specimens were one-side charred with a hot plate using several ...time-temperature combinations (from 200 to 400 °C). Characteristics such as colour, discoloration, surface roughness, fire resistance, total carbohydrate content at several wood layers and decay resistance were evaluated. Surface charring was applied to the radial and tangential surfaces. Colour measurements showed that the surface of the wood turned grey due to charring. In addition to colour measurements, other experiments showed significant differences between radial and tangential specimens due to their different structures. The higher the temperature used in treating them, the lower the roughness values for radial specimens, while the trend for tangential specimens was the opposite. A smoother surface is more fire resistant, so radial specimens are generally better in this regard. Tangential specimens are more susceptible during preparation to forming cracks that impair flame resistance because a continuous protective densified layer is not formed. The determination of total carbohydrates revealed significant changes at various wood depths after surface charring. These changes were more predictable in radial specimens due to the annual ring orientation, because each layer consisted of a similar earlywood/latewood ratio. Finally, when decay resistance was assessed, weight loss was found to be lower in all specimens than in the references. The results suggest that charring at a particular combination of temperature and time improved the investigated properties of the surface-modified beech.
The aim of this work was to verify the behavior of hybrid hardwood glue-laminated beams and the possibility of replacing Norway spruce (Picea abies) construction elements, especially in roof and ...ceiling structures. The samples were six lamellae homogeneous beech (Fagus sylvatica) beams and six-lamellae hybrid beech-poplar (Fagus sylvatica–Poplar spp.) beams; each beam had a cross-section of 60 × 120 mm and was glued with polyurethane adhesive. The samples were loaded using destructive four-point bending tests according to EN 408; the obtained bending strength and modulus of elasticity were statistically evaluated and compared to each other in both types of samples. The results showed that the examined properties of the hybrid beams (with a 16% weight reduction) are comparable to the properties of homogeneous beech glue-laminated beams. Based on the obtained data, the timber elements that are currently used can be successfully replaced by hardwood glue-laminated elements. Based on their higher load-bearing capacity, the cross-section depth can be reduced compared to a larger cross-section depth in spruce beams; this means that hardwood could be suitable in building renovations.
The study presents a possible innovative use of cement fiber boards (CFBs) reinforced with cellulose fibers for construction of an interior prefabricated staircase. Regarding the unusual use of ...traditional material that was used in all bearing elements of the staircase, a numerical simulation with the use of a material model SBETA was carried out and, subsequently, multiple experimental static loading was applied. In order to carry out experimental testing of static load capacity, a full-scale experiment method was chosen and performed on a real staircase structure for family houses. The full-scale experiment is considered the most precise method to test structures or material behavior. The obtained results show that the designed and tested staircase structure of CFBs is able to meet the requirements of technical standards related to static loading of staircases. The load test confirmed the potential use of cement fiber boards produced by the Hatschek process for real bearing structures under static loading.
Although international trade is an incontestable driver of economic development, scientific literature still lacks the studies to assess the impact of the international trade in agricultural products ...on the EU economic growth. The agricultural sector is treated as specific in comparison to other economic sectors as the EU subsidisation policies causes distorted competition in both local and global agricultural markets. The main purpose of this article is to assess the impact of the international trade in agricultural products on the economic growth of EU28. The results of the correlation and regression analyses have revealed that the international trade in agricultural products (in particular, section I and III products) contributes only insignificant part, to the economic growth of EU 28 through the following indicators: GDP in market prices, seif-employment, employment in the agricultural sector, labour force rate, subsidies and other transfers. The results have also disclosed that while analysing the impact of the international trade in agricultural products on economic growth, there is no necessity to research export and import volumes in separate as agricultural export and import show nearly the same (only with insignificant value differences) determinants of economic growth promotion. Another important conclusion is that the international trade in agricultural products mainly comprises the trade in live animals and animal products (meat and edible meat offal, fish and crustaceans, molluscs and other aquatic invertebrates, dairy produce, birds' eggs, natural honey, edible products of animal origin, not elsewhere specified or included, and products of animal origin, not elsewhere specified or included) as well as animal or vegetable fats and oils and their cleavage products, prepared edible fats, and animator vegetable waxes.
A waste-based particle polymer composite (WPPCs) made of foam glass and polypropylene was developed as a low-cost construction material. Thermomechanical properties of the composite, including creep ...properties of WPPC and polypropylene binder, were examined. By adding a relatively small amount of polypropylene to foam glass (about 2:8 in volume parts), the maximum bearing capacity at room temperature of the composite increased from 1.9 (pure foam glass) to 15 MPa. A significant creep strain accumulated during compressive loading of WPPC (5 MPa) in the first 2000 s at elevated temperatures (40, 60 °C). In the study, Kafka’s mesomechanical model was used to simulate creep strain changes in time for various temperatures. The applicability of Kafka’s mesomechanical model for simulating creep properties of the studied composite material was demonstrated.
Analysis of Unreinforced Ceramic Wall Panels in the Mounting State Karlik, Stepan; Lavicky, Milos; Pencik, Jan
Applied mechanics and materials,
12/2016, Volume:
861, Issue:
Buildings and Environment - Energy Performance, Smart Materials and Buildings
Journal Article
Peer reviewed
Properties of building materials used for the construction of surrounding structures significantly contribute to creating a healthy and comfortable microclimate inside the rooms. Ceramics belong ...among materials which exhibit very suitable properties for the formation of the healthy environment. It is also one of the reasons that the fired clay structures remain popular among builders and that recovery of ceramic prefabrication can be seen in the Czech Republic. The important step towards rediscovering the benefits of the prefabricated ceramic elements is forthcoming production of unreinforced ceramic wall panels made of fired clay masonry units with tongue and groove, connected in the bed joints by two-component adhesives. Conventional analytical model for vertical loads is used in the operating state. However, in the transport and mounting state it is a structure stressed by bending in its own plane. This paper is focused on the issue of load-bearing capacity of structures with masonry units cross-sections that are not filled in head joints and therefore are unable to transfer either tensile or compressive stresses. On the segment of the wall panel is performed numerical model analysis using the finite element method in the computing program ANSYS and comparison of this analysis results with the results of the experimental tests.
PDF
