Thermal Performance of LSF Wall Systems with Vacuum Insulation Panels

Lightweight Steel Frames (LSF) in building construction are becoming more popular due to their fast, clean, and flexible constructability. Typical LSF wall panels are made of cold-formed and thin-walled steel lipped channel studs with plasterboard linings. Due to the high thermal conductivity of steel, these LSF components must be well engineered and covered against unintended thermal bridges. Therefore, it is essential to investigate the heat transfer of the LSF wall of different configurations and reduce heat loss through walls by lowering the thermal transmittance, which would ultimately minimise the energy consumption in buildings. The effect of novel thermal insulation material, Vacuum Insulation Panels (VIP), their position on the LSF wall configuration, and Oriented Strand Board (OSB) and plasterboard’s effect on the thermal transmittance of LSF walls were investigated through numerical analysis. A total of 56 wall configurations and 112 finite element models were analysed and compared with the minimum U-value requirements of UK building regulations. Numerical model results exhibited that using plasterboards instead of OSB has no considerable effect on the U-value of the LSF walls. However, 77% (4 times) of U-value reduction was exhibited by introducing the 20 mm VIP. Moreover, the position of the VIP to the U-value of LSF was negligible. Based on the results, optimum LSF wall configurations were proposed by highlighting the construction methods. Additionally, this study, through literature, seeks to identify other areas in which additional research can be conducted to achieve the desired thermal efficiency of buildings using LSF wall systems.

Experimental and numerical study on the screw connection strength of bamboo-oriented strand board compared with wood-oriented strand board

The utilization of resourceful bamboo can alleviate the wood shortage problem. Bamboo-oriented strand board (BOSB) with the highest utilization of bamboo ratio and excellent mechanical properties was considered as a good engineering and furniture material. The strength of joints affects the safety of BOSB structure. This study aims to investigate the effect of screw spacing on the tensile and compressive stiffness and strength of corner joints from BOSB by experimental method combined with finite element method (FEM) compared with wood-oriented strand board (WOSB). The results showed that (1) the strength and stiffness of the corner joint was significantly affected by the screw spacing, and it affected the compressive strength and stiffness of WOSB more significantly; (2) the bending moment and stiffness coefficient of BOSB compressed joint decreased with the increase of spacing, while that of tensile joint increased first and then decreased, and it reached the maximum value, when the spacing was 48 mm; (3) compared with WOSB joint, BOSB joint had higher strength and stiffness, and the failure of the joint was due to the yielding of self-drilling screws. This was also verified by numerical analysis results; (4) the bending moment of BOSB joints was about 2.5 times that of WOSB joints, while the difference between stiffness coefficient was small; (5) the elastic deformations resulted from experimental tests and FEM are similar. It was shown that when the screw spacing is 48 mm, the Von Mises stresses on the BOSB joint were smaller, and the bending strength and stiffness were larger, which was the most suitable screw spacing.

The Analysis of Erosive Wear Resistance of WC-Co Carbides Obtained by Spark Plasma Sintering Method

WC-Co (tungsten carbide-cobalt) composites are widely used in industry, wear-resistant parts, and cutting tools. As successful tool materials, WC-Co carbides are widely applied in metal cutting, wear applications, chipless forming, stoneworking, wood, and plastic working. These materials are exposed to severe solid particle erosion by sand particles, such as in the wood industry. During the production of furniture with HDF (High Density Fibreboard), MDF (Medium Density Fibreboard), or OSB (Oriented Strand Board), there are observed problems with tool erosion. Contamination, mainly of the HDF by sand, is quite often, which is why all tools used for the machining of such materials are exposed to erosion by sand particles. Although many studies have been performed on the erosion of various metals, and erosion models exist to predict their erosion behavior, the issue is still relevant. The aim of the study was to determine the effect of grain size (submicron, ultrafine) and the manufacturing technology (SPS—Spark Plasma Sintering, conventional) used on the erosive properties of WC-Co sintered carbides. Sinters produced by the SPS method with different sizes of WC grains and commercial samples were used for the tests. Ten two-hour cycles were carried out under medium conditions of quartz sand and quartz sand with 10% SiC added. Used samples were characterised using scanning electron microscopy (SEM) and roughness was determined. Furthermore, erosion studies allowed individuating a wear mechanism as well as the possibility to foresee cutting performance in prospective application.

Optimization of Production Parameters in Oriented Strand Board (OSB) Manufacturing by Using Taguchi Method

Optimization of process conditions in oriented strand board (OSB) manufacturing is a very important issue for both reducing cost and improving the quality of panels. Taguchi experimental design technique was applied to determination and optimization of the most influential controlling parameters of OSB panels such as press condition (pressure-time-temperature) and the ratio of adhesive parameters on modulus of elasticity (MOE). The value of the MOE is one of the very important mechanical properties of OSB panels. For this purpose, several experiments were conducted according to Taguchi L27 orthogonal design. The signal-to-noise (S/N) and the analysis of variance (ANOVA) were used to find the optimum levels and to indicate the impact of the controlling parameters on MOE. A verification test was also performed to prove the effectiveness of Taguchi technique. Since the predicted and the measured values were very close to each other, it was concluded that the Taguchi method was very successful in the optimization of effective parameters in OSB’s manufacturing.

Effects of Strands Pre-treatment and Adhesive Type on the Properties of Oriented Strand Board Made from Gmelina (Gmelina arborea) Wood

The objective of this study was to evaluate the effects of steam treatment of strands on the physical and mechanical properties of oriented strand board (OSB) from gmelina wood (Gmelina arborea) bonded with two types of adhesive. Strands of gmelina wood were steamed at 126°C and pressure of 0.14 MPa for 1 h. OSBs were prepared with a 0.6 g/cm3 target density using two types of adhesives, namely methylene diphenyl diisocyanate (MDI) and phenol-formaldehyde (PF) resins. The resin content used was 5% for MDI and 10% for PF. The physical and mechanical properties of the OSB were evaluated referring to the JIS A 5908-2003 standard, and the values were compared with CSA 0437.0 (Grade O-1) standard. The results showed that the steam treatment improved the dimensional stability of OSB, as shown from the decrease of water absorption and thickness swelling. Steam treatment also increased the mechanical properties of the OSB, such as modulus of elasticity, modulus of rupture, internal bonding strength, and screw holding power. The results revealed that gmelina wood OSB bonded with MDI adhesives produced better OSB than bonded with PF resin. Keywords: gmelina, methylene diphenyl diisocyanate, oriented strand board, phenol-formaldehyde, steam treatment

Effects of Resin Content on the Characteristics of Bamboo Oriented Strand Board Prepared from Strands of Betung, Ampel, and Their Mixtures

The objectives of this research were to evaluate bamboo-oriented strand board (BOSB) characteristics made from betung (Dendrocalamus asper), ampel (Bambusa vulgaris), and their mixtures at two different contents (3% and 5%) of methylene diphenyl di-isocyanate (MDI) adhesives. The strands were steam-treated at 126°C for 1 h under the pressure of 0.14 MPa. Three-layered BOSBs with a target density of 0.7 g/cm3 were made with the size of 30 cm x 30 cm x 0.9 cm and a shelling ratio of 1:2:1 (face:core:back layers). The physical and mechanical properties of BOSB were evaluated following JIS A 5908 (2003) standard, and the results were compared with the CSA 0437.0 Grade O-1 standard. The results show that BOSB from the mixtures of betung and ampel bamboo strands has higher dimensional stability as shown by the decrease in water absorption and thickness swelling and higher mechanical properties than single BOSB. All BOSBs with 5% resin content have higher dimensional stability, MOE, and MOR than BOSB with 3% resin content. The physical and mechanical properties of all BOSB manufactured met the CSA 0437.0 Grade O-1 standard. This study proved that BOSBs from the mixture of betung and ampel strands have the potential to be developed due to having better physical and mechanical qualities than a single BOSB. Keywords: ampel (Bambusa vulgaris), bamboo oriented strand board, betung (Dendrocalamus asper), resin content, strand mixtures

Hygrothermal Monitoring of Two Pilot Prefabricated Exterior Energy Retrofit Panel Designs

NRCan undertook a proof-of-concept project to retrofit a small building with prefabricated wall panels in 2017 in Ottawa, Canada. The retrofit used two wall panel designs: nailbase and woodframe. The Nailbase panel consisted of fiberglass batt, an expanded polystyrene (EPS) core, oriented strand board (OSB) sheathing, a rainscreen, and cladding. The Woodframe panel also featured OSB sheathing and included a 90 mm stand-off gap filled with dense-packed, fibrous insulation. A side-by-side comparison of cost, constructability, and performance was performed. The wall assemblies were instrumented to monitor the temperature, relative humidity, and moisture content of sensitive layers. The data was used to evaluate the hygrothermal performance, moisture accumulation, and risk of associated problems such as mould growth. This paper presents the monitored hygrothermal data from 2017 to 2021, compares the two approaches and assesses their feasibility. During construction, some of the fibrous insulation may have been wetted by wind-driven snow before completion. The data showed that this moisture was able to dissipate without significant risk. The sheathing of the Woodframe panel experienced a higher peak moisture content during the dry-out period. Otherwise, both panel designs showed limited potential for mould growth on monitored surfaces over the monitored period.

The Effect of Surface Finishes on Rising Damp in Oriented Strand Board

It is known that oriented strand board (OSB) is prone to water absorption. This characteristic of OSB is undesirable, it can have a negative impact on the physical and mechanical properties of the material and it can also make it prone to attack from wood-destroying insects, rot or mould. The research follows previous work of the authors related to optimisation of surface finishes for OSB in order to increase its moisture resistance. The aim of the research is to compare the rise of dampness in test specimens with different types of coating, spray, primer and waterproofing under predefined conditions. The paper contains a definition of the basic material, test specimens and test methods, and covers 8 different types of surface finish materials selected for application to the test specimens. The results include graphs showing rise of dampness in the test specimens for each day of observation. The results are also discussed and in the conclusion the results are evaluated. The results of the experiments confirm the assumption that the choice of surface finish has a significant effect on slowing down the rise of dampness in OSB.

Pengaruh Modifikasi Steam dan Pembilasan NaOH terhadap Keasaman Enam Jenis Bambu

Perlakuan steam dan bilas NaOH 1% telah diketahui meningkatkan sifat fisis dan mekanis Oriented Strand Board (OSB) bambu. Peningkatan tersebut disebabkan oleh menurunnya kadar zat ekstraktif dan komponen berbobot molekul rendah lainnya pada bambu. Selain itu, steam dan bilas NaOH 1% juga diduga mempengaruhi keasaman bambu. Penelitian ini bertujuan untuk menentukan perubahan keasaman yang terjadi akibat perlakuan steam dan bilas NaOH 1% pada enam jenis bambu Indonesia. Enam jenis bambu meliputi bambu andong, betung, tali, ampel, kuning, dan hitam digunakan pada penelitian ini. Sampel bambu dicacah hingga berbentuk partikel dan diberikan dua perlakuan berbeda yaitu steam dan steam + bilas NaOH 1%. Partikel bambu kemudian digiling hingga didapatkan serbuk berukuran 40-60 mesh. Serbuk bambu diekstrak dengan air panas selama 1 jam. Nilai pH filtrat ekstrak diukur menggunakan pH meter. Ekstrak kemudian dititrasi dengan larutan H2SO4 0,025 N hingga pH 4 dan larutan NaOH 0,025 N hingga pH 10. Jumlah larutan penyangga yang ditambahkan ke dalam ekstrak dinyatakan sebagai kapasitas penyangga asam dan basa. Hasil penelitian menunjukkan bahwa jenis bambu dan perlakuan berpengaruh terhadap nilai pH dan kapasitas penyangga. Nilai rata-rata pH enam jenis bambu berkisar 5,20-6,67 dan meningkat setelah perlakuan steam dan Steam + bilas NaOH 1% berturut-turut menjadi 5,97-6,78 dan 7,02-7,63. Kapasitas penyangga asam dan basa enam jenis bambu masing-masing berkisar 0.404-0.525 mmeq dan 0.095-0.1750 mmeq dan meningkat setelah perlakuan steam dan Steam + bilas NaOH 1%.