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.
Pure aluminium oxide vacuum-formed fibreboards were obtained from new generation of alumina fibres synthesized by the sol-gel method. The effect of the chemical composition and the particle size of ...the binder on the vacuum-formed boards was examined. High-temperature testing took place at 1500 °C for 24 h. The mechanical properties (both modulus and compressive strength) are better with Boehmite than with aluminium hydroxide. Decreasing the size of the binder particles enhances these mechanical properties. Field emission scanning electron microscopy was used to study the micro-scale morphology. Well-developed crystals can be found in both the fibres and binders, regardless of the binder system used, after the prolonged high-temperature treatment. The smaller binder particles cause decreased crystal size. The most stable α-aluminium oxide phase was identified by XRD in all systems.
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To improve the thermal performance of conventional single span greenhouses (SPGs), two types of greenhouses with removable back walls that are suitable for the climate in southern Jiangsu province, ...China were investigated, one with fully-removable back wall (FRG) and one with half-removable back wall (HRG). The removable back walls are made of jute fibre boards and installed in winter for heat preservation. They were removed in summer for ventilation. The thermal environment of the new greenhouses were studied experimentally. Results suggest the air temperature in the greenhouse with removable back walls could be maintained above 8.2 °C while the lowest temperature in the single span polyethylene greenhouse was only 2.9 °C, on sunny days in winter. During summer the highest indoor–outdoor air temperature difference of the SPG was 9.0 °C whereas with the HRG and FRG they were 6.8 °C and 6.1 °C, respectively. No significant difference of heat release was found inside room between HRG and FRG. The removable wall combined with jute fibre boards represents a potential design improvement for the back wall of solar greenhouses.
•Thermal performance of greenhouses with removable back walls investigated.•Heat transfer inside greenhouses were measured and analysed.•The removable wall combined by jute fibre boards represents a potential design.
High levels of Volatile Organic Compounds (VOCs) and extremes of Relative Humidity (RH) commonly reduce indoor air quality with associated negative effects on human health and wellbeing. Interior ...materials are known to be one of the main contributors to poor indoor air quality. Notwithstanding, they can also act as a sink for airborne pollutants and excess moisture through adsorption. In this paper, we evaluate the ability of Medium Density Fibreboard (MDF) modified with walnut shell to regulate RH, toluene, limonene, dodecane and formaldehyde. The physicochemical properties, including molecular size/shape, vapour pressure, polarity and boiling point of VOCs allowed them to represent a range of pollutants. Adsorption and desorption behaviour of MDF containing up to 15% walnut shell was evaluated in 2-L environmental chambers under dynamic conditions at 23 °C and 50% RH. The porous microstructure of the MDF and walnut shell and their chemical composition were analysed using SEM, XRD and FTIR. Compared to a control panel, walnut shell additions showed an improved ability to remove VOCs and formaldehyde from the indoor air and buffer humidity. Of particular significance was the irreversible sink effect of formaldehyde and dodecane. This was attributed to the porous surface of walnut shell increasing the specific surface area of the panel and thus its adsorption capacity. The improved capacity of buffer humidity also increased the ability to adsorb water soluble VOCs such as formaldehyde. This research provides for the first time significant evidence that walnut shell modified MDF can improve indoor air quality.
•Addition of walnut shell to the MDF panel improved the ability to remove gas pollutants from the indoor air and buffer humidity.•Greater ability to remove air pollutants from the air and buffer moisture was attributed to the porous surface of the walnut shell.•The irreversible sink effect was observed for formaldehyde and dodecane.
The combustibility of natural wood presents a negative impact for using this material in buildings. Timber elements can be cladded with boards made of non-combustible materials. This study represents ...a group of options for increasing the resistance of timber against the effects of fire and the possibility of slowing down the effect of thermal degradation of wood. The aim of this study is focused on an experimental testing of structures with timber elements protected by cement fibre boards as a non-combustible fire retardant. Cement fibre boards are fibre-reinforced composite materials used for systems of dry constructions. These boards present the highest degree of fire reaction class (A1). The behaviour of the structure, loaded by the effects of fire, was monitored during the experiment. The specimen was tested with reduced dimensions. The temperature loading corresponded to the procedure according to the standards. The final fire resistant (FR) results were evaluated in accordance with the requirements for the selected limit states of FR. This was assessed based on the measured temperatures and the whole condition of the tested specimen. The specimen fulfilled the fire-separating function of the structure for the classification times.
The phenolic content in lignin makes it a potential substitute for formaldehyde-based synthetic wood adhesives. In the present work, lignin isolated from Hevea brasiliensis was treated with laccase ...enzyme to obtain active lignin. The activated lignin (NaOH treated) was further formulated with natural rubber latex (NR-latex) to prepare bio-adhesive. Complementary analysis such as modulus of rupture (MoR), modules of elasticity (MoE), internal bonding (IB), Fourier transform infrared (FTIR) spectroscopy, thickness swelling (TS), and scanning electron microscopy (SEM) were applied to characterize a medium density fibre-board (MDF) prepared based on bio-adhesive formulation. It was found that bio-adhesive formulation of 10 g NR-latex with 10 g of lignin has the highest MoR of 16 MPa, while the formulation of 15 g NR-latex with 5 g lignin showed the highest MoE of 15 MPa. The TS result showed that there is a weight gain on MDFs with a lower proportion of NR-latex content which consequently increases the density of the composites. The FTIR analysis of formulated bio-adhesive revealed the significant difference in chemical composition with different proportions of lignin and NR-latex in bio-adhesive. Finally, SEM examination of the interfaces of formulated bio-adhesive and wood fibre material showed the better dispersion with no adhesive lumps.
Paper-tubes as a building material Hirpara, Sapan; Shah, Anand
Journal of sustainable construction materials and technologies,
06/2017, Letnik:
2, Številka:
1
Journal Article
Recenzirano
Odprti dostop
There has always been a need for recyclable materials in the construction industry. Taking this fact into consideration anexploration using paper tubes and medium density fiber-board (M.D.F) as ...construction materials was ventured. In order tounderstand these materials, a temporary space frame was made. The paper describes in detail the entire process of making thespace frame. Issues related to shape and size of the structure, connection detail and its material, wind forces etc., which occurfrequently during the making of such structures are discussed in depth. At last the strengths, weaknesses, and scope of papertubes as a building construction material in coming future have been discussed.
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