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12 records – page 1 of 2.

Acoustic Impact Testing and Waveform Analysis for Damage Detection in Glued Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue771
Year of Publication
2017
Topic
Acoustics and Vibration
Serviceability
Material
Glulam (Glue-Laminated Timber)
Author
Xu, Feng
Wang, Xiping
Teder, Marko
Liu, Yunfei
Publisher
De Gruyter
Year of Publication
2017
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Acoustics and Vibration
Serviceability
Keywords
Decay
Delamination
Damage Detection
Moment Analysis
Wavelet Transform
Acoustic Signals
Research Status
Complete
Series
Holzforschung
Summary
Delamination and decay are common structural defects in old glued laminated timber (glulam) buildings, which, if left undetected, could cause severe structural damage. This paper presents a new damage detection method for glulam inspection based on moment analysis and wavelet transform (WT) of impact acoustic signals. Acoustic signals were collected from a glulam arch section removed from service through impact testing at various locations. The presence and positions of internal defects were preliminarily determined by applying time centroid and frequency centroid of the first moment. Acoustic signals were then decomposed by wavelet packet transform (WPT) and the energy of the sub-bands was calculated as characteristics of the response signals. The sub-bands of 0–375 Hz and 375–750 Hz were identified as the most discriminative features that are associated with decay and delamination and therefore are indicative of the presence of delamination or decay defects. A defect diagnosis algorithm was tested for its ability to identify internal decay and delamination in glulam. The results show that depth of delamination in a glulam member can be determined with reasonable accuracy.
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Carbon dynamics of paper, engineered wood products and bamboo in landfills: evidence from reactor studies

https://research.thinkwood.com/en/permalink/catalogue3032
Year of Publication
2018
Topic
Environmental Impact
Author
Ximenes, Fabiano A.
Kathuria, Amrit
Barlaz, Morton A.
Cowie, Annette L.
Organization
North Carolina State University
Publisher
Springer
Year of Publication
2018
Format
Journal Article
Topic
Environmental Impact
Keywords
Carbon
Engineered Wood Products
Decay
Landfill
Greenhouse Gas Inventory
Methane
Research Status
Complete
Series
Carbon Balance and Management
Summary
Background There has been growing interest in the development of waste-specific decay factors for estimation of greenhouse gas emissions from landfills in national greenhouse gas inventories. Although engineered wood products (EWPs) and paper represent a substantial component of the solid waste stream, there is limited information available on their carbon dynamics in landfills. The objective of this study was to determine the extent of carbon loss for EWPs and paper products commonly used in Australia. Experiments were conducted under laboratory conditions designed to simulate optimal anaerobic biodegradation in a landfill. Results Methane generation rates over incubations of 307–677 days ranged from zero for medium-density fibreboard (MDF) to 326 mL CH4 g-1 for copy paper. Carbon losses for particleboard and MDF ranged from 0.7 to 1.6%, consistent with previous estimates. Carbon loss for the exterior wall panel product (2.8%) was consistent with the expected value for blackbutt, the main wood type used in its manufacture. Carbon loss for bamboo (11.4%) was significantly higher than for EWPs. Carbon losses for the three types of copy paper tested ranged from 72.4 to 82.5%, and were significantly higher than for cardboard (27.3–43.8%). Cardboard that had been buried in landfill for 20 years had a carbon loss of 27.3%—indicating that environmental conditions in the landfill did not support complete decomposition of the available carbon. Thus carbon losses for paper products as measured in bioreactors clearly overestimate those in actual landfills. Carbon losses, as estimated by gas generation, were on average lower than those derived by mass balance. The low carbon loss for particleboard and MDF is consistent with carbon loss for Australian wood types described in previous studies. A factor for carbon loss for combined EWPs and wood in landfills in Australia of 1.3% and for paper of 48% is proposed. Conclusions The new suggested combined decay factor for wood and EWPs represents a significant reduction from the current factor used in the Australian greenhouse gas inventory; whereas the suggested decay factor for paper is similar to the current decay factor. Our results improve current understanding of the carbon dynamics of harvested wood products, and allow more refined estimates of methane emissions from landfills.
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Effectiveness of Several NDE Technologies in Detecting Moisture Pockets and: Artificial Defects in Sawn Timber and Glulam

https://research.thinkwood.com/en/permalink/catalogue778
Year of Publication
2016
Topic
Serviceability
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Application
Bridges and Spans
Author
Wacker, James
Senalik, Christopher
Wang, Xping
Jalinoos, Frank
Year of Publication
2016
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Application
Bridges and Spans
Topic
Serviceability
Keywords
Decay
Douglas-Fir
Moisture Pockets
Non-Destructive Evaluation
Scanning
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria
Summary
Several nondestructive evaluation (NDE) technologies were studied to determine their efficacy as scanning devices to detect internal moisture and artificial decay pockets. Large bridge-sized test specimens, including sawn timber and glued-laminated timber members, were fabricated with various internal defects. NDE Technologies evaluated in this research were ground penetrating radar (GPR), microwave scanning, ultrasonic pulse velocity, ultrasonic shear wave tomography, and impact echo methods. Each NDE technology was used to evaluate a set of seven test specimens over a 2-day period and then raw data scans were processed into two-dimensional, internal defect maps. Several parameters were, compared including the relative size, orientation, and moisture conditions of the internal defect. GPR was the most promising NDE technology and is currently being more rigorously evaluated within the laboratory. The study results will be useful in the further development of a reliable NDE scanning technique that can be utilized to inspect the primary structural components in historic covered timber bridges.
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Evaluating Decay Resistance of Mass Timber

https://research.thinkwood.com/en/permalink/catalogue718
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Organization
Forest Products Laboratory Mississippi State University
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Funghi
Decay
Research Status
In Progress
Notes
Project contacts are Grant Kirker (Forest Products Laboratory), Katie Ohno (Forest Products Laboratory) and C. Elizabeth Stokes (Mississippi State University)
Summary
Mass timber, as a renewable prefabricated structural panel material, is seen as highly desirable in the “green” building movement and has excellent thermal insulation, sound insulation, and fire restriction qualities. CLT is one of the more recent additions to the mass timber market worldwide, and although the product has undergone structural property testing in several laboratories, degradation testing of this non-preservative-treated product has only recently been initiated (Singh and Page 2016). Preliminary testing with exposure to Oligoporus placenta and Antrodia xantha indicated that untreated CLT is susceptible to the spread of mold and decay fungi, while treatment with boron somewhat reduced the extent of the decay fungus spread (Singh and Page 2016). These panels are easily handled on-site and have a much higher strength-to-weight ratio than their precast concrete competitors, which make them ideal for rapid construction of modular buildings, including apartment/condominium structures (Van de Kuilen et al. 2011). However, installations using CLT as a primary structural component in humid/damp climates, such as the southeastern United States, may be heavily affected by molds and decay fungi, and effects on CLT strength should be determined prior to widespread use of the product in these areas.
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Evaluation of Coatings Used for Prolonging the Durability of Cross-Laminated Timber Against Weathering and Wood Decay Fungi

https://research.thinkwood.com/en/permalink/catalogue2721
Year of Publication
2020
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Bobadilha, Gabrielly
Publisher
Mississippi State University
Year of Publication
2020
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Weathering
Decay
Funghi
Fungus
Coatings
Research Status
Complete
Summary
The aim of this study was to assess the durability of commercially available coatings on cross- laminated timber (CLT) during natural and artificial weathering and against wood decay fungus. The CLT samples coated with twelve coatings were tested based on their moisture exclusion, water repellency, volumetric swelling and anti-swelling efficiency. Among all the tested coatings, only five (A, C, F, I and J) were able to promote water repellency and limiting dimensional changes. The top five coatings were then tested on CLT blocks exposed to natural (Starkville-MS and Madison-WI) and artificial weathering conditions and brown-rot fungi (G. trabeum). Variables such as visual ratings, water uptake, color and gloss change were determined during both weathering procedures. Damage caused by Gloeophyllum trabeum on uncoated and coated CLT was analyzed based on visual appearance and weight loss. For the coatings C and F, the visual rakings and color change results indicated high consistency during outdoor exposure. The artificial weathering showed that coating C and F were the most resistant to chalking, lightness, color and gloss change. In the soil block test, coating C obtained satisfactory performance against G. trabeum with weight loss of 1.33%. Coatings F and J did not offer any protection to water penetration, which eventually contributed to fungal development. For future, new coatings specifically designed for the protection of high percentages of end-grain in CLT panels should be a target of research and development.
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Field Tests of Treated Thin-Lamina Glulam after Five Years of Exposure

https://research.thinkwood.com/en/permalink/catalogue370
Year of Publication
2015
Topic
Serviceability
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Morris, Paul
Ingram, Janet
Organization
FPInnovations
Year of Publication
2015
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Serviceability
Keywords
Cedar
Decay
Preservative
ACQ
Copper Azole
Fasteners
Research Status
Complete
Summary
Field tests of untreated and preservative-treated glulam beams in outdoor exposure, in ground contact and above ground, were inspected for decay after five years. Copper azole and ACQ-D-treated material was in excellent condition, while moderate to severe decay was present in untreated non-durable material. Early stages of decay were also noted in yellow cedar glulam in the above-ground test. Using galvanized rather than stainless steel fasteners appeared to have a protective effect against decay in untreated material, supporting the hypothesis that zinc from the sacrificial coating on galvanized bolts inhibits germination of basidiospores.
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Hygrothermal Performance Of Highly Insulated Wood Frame Walls With Air Leakage: Field Measurements And Simulations

https://research.thinkwood.com/en/permalink/catalogue2316
Year of Publication
2014
Topic
Moisture
Design and Systems
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Walls
Author
Fox, Michael
Organization
Toronto Metropolitan University
Publisher
Ryerson University
Year of Publication
2014
Format
Thesis
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Walls
Topic
Moisture
Design and Systems
Keywords
Mid-Rise
High Thermal Resistance
High RSI
Condensation
Mould
Decay
Moisture Content
Temperature
Relative Humidity
Heat Flux
Research Status
Complete
Summary
The thesis examines the hygrothermal performance of six types of high thermal resistance (High RSI) wall assemblies during environmental exposure and an air leakage (exfiltration) simulation test. These walls were installed in the Building Engineering Group's test facility (BEG Hut) located at the University of Waterloo. The High-RSI wood-frame walls were assessed by analyzing condensation, mould, and decay risks using the moisture content, temperature, relative humidity and heat flux data collected during the field test. These field-measured data were also used to calibrate one-dimensional WUFI® simulation models for each of the High-RSI assembly for use in future durability assessments using a range of North American climates. Methods were investigated to improve the predictive capacity of these simulation models as well as to increase their utility as a research tool. The design, construction and instrumentation details of the High-RSI study were also documented.
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Identifying Incipient Decay in Douglas-fir Bridge Components using X-Ray Computerized Tomography

https://research.thinkwood.com/en/permalink/catalogue2350
Year of Publication
2019
Topic
Design and Systems
Moisture
Serviceability
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Application
Bridges and Spans
Author
Senalik, Christopher
Wacker, James
Wang, Xiping
Wu, Xi
Year of Publication
2019
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Application
Bridges and Spans
Topic
Design and Systems
Moisture
Serviceability
Keywords
X-ray Computerized Tomography
Wood Timber
Brown Rot Fungus
Incipient Decay
Conference
International Nondestructive Testing and Evaluation of Wood Symposium
Research Status
Complete
Summary
In this report, wooden members of sizes typically used in bridge construction are examined using x-ray computerized tomography (CT) to determine the presence of internal decay. This report is part of an overall study in which Douglas-fir (Pseudotsuga menziesii) glue-laminated (glulam) beams and solid sawn timbers were inoculated with brown rot fungus, Fomitopsis pinicola, and exposed to aboveground conditions approximately 25 miles (40 km) north of Gulfport, Mississippi, USA. The goal of the overall study is to develop interior decay within the test specimens and then identify and characterize the decay using a variety of nondestructive testing (NDT) techniques. One NDT technique used is x-ray CT. The pixel brightness (PB) of CT scan images is proportional to the specific gravity (SG) at that location; high SG materials appear brighter whereas low SG materials appear darker. The consumption of wood by fungus decreases the wood SG; however, fungal progression takes place in areas where sufficient moisture is present. The presence of moisture increases wood SG as detected by the CT scan, which masks the effect of the fungal decay, which is a common co-occurrence with many NDT techniques. To identify incipient decay, it is necessary to examine the ring structure both within and outside of the area of moisture. Quantifying the extent of the decay requires correlating the PB to known SG values for both dry wood and wood of varying moisture content. In this report, the relationship between wood SG, moisture content, and PB was quantified.
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Moisture Response of Wall Assemblies of Cross-Laminated Timber Construction in Cold Canadian Climates

https://research.thinkwood.com/en/permalink/catalogue143
Year of Publication
2012
Topic
Serviceability
Moisture
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Lepage, Robert
Organization
University of Waterloo
Year of Publication
2012
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Serviceability
Moisture
Keywords
Canada
Climate
Decay
Durability
Hem-Fir
Hygrothermal
Mold
Relative Humidity
Rot
Simulation
SPF
Water Vapour Permeability
Research Status
Complete
Summary
Wood is a highly versatile renewable material (with carbon sequestering properties), that is light in weight, has good strength properties in both tension and compression while providing good rigidity and toughness, and good insulating properties (relative to typical structural materials). Engineered wood products combine the benefits of wood with engineering knowledge to create optimized structural elements. Cross-laminated timber (CLT), as one such engineered wood product, is an emerging engineering material which provides great opportunities for the building industry. While building with wood has many benefits, there are also some concerns, particularly decay. Should wood be exposed to elevated amounts of moisture, rots and moulds may damage the product or even risk the health of the occupants. As CLT panels are a relatively new engineered wood product, the moisture characteristics have yet to be properly assessed.
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Nondestructive Evaluation of a 75-Year Old Glulam Arch

https://research.thinkwood.com/en/permalink/catalogue246
Year of Publication
2013
Topic
Serviceability
Material
Glulam (Glue-Laminated Timber)
Author
Teder, Marko
Wang, Xiping
Year of Publication
2013
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Serviceability
Keywords
Decay
Delamination
Modulus of Elasticity
Non-Destructive Evaluation
Stress Wave Timing
Wave Propagation
Strength
Resistance Micro-Drilling
Conference
International Nondestructive Testing and Evaluation of Wood Symposium
Research Status
Complete
Notes
September 24-27, 2013, Madison, Wisconsin, USA
Summary
The purpose of this study was to explore the possibilities of using existing nondestructive evaluation (NDE) methods to assess delamination and decay of glulam structures. A glulam arch removed from a research building after more than 75-year service was used as a test specimen. The glulam arch section was tested using stress wave timing, ultrasonic wave propagation, and resistance microdrilling methods at a series of locations. The arch was subsequently cut open for visual inspection and small compression and shear samples were obtained for strength testing. It was found that wave propagation times or wave velocities measured across the laminations were good indicators of internal decay. Stress wave timing and ultrasonic propagation methods were able to detect moderate to large delamination, but not micro-delamination. Resistance micro-drilling was found not effective in detecting delamination. Further research is planned to evaluate the possibility of using pulse-echo method to detect internal delamination of glulam members. Key words: glued laminated timber (glulam), stress wave, ultrasonic wave, resistance micro-drilling, strength, modulus of elasticity.
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12 records – page 1 of 2.