Experimental and computational analysis of the thermal degradation and the loss of strength of engineered wood-based panels
(2022) In LUTVDG/TVBB VBRM05 20221Division of Fire Safety Engineering
- Abstract
- The current trends in the construction industry push toward materials that are more sustainable and environmentally friendlier than more traditional building materials such as concrete and steel. Timber and timber composites are one of the most popular materials on this list, due to both their mechanical strength and pleasant aesthetics. Oriented strand board (OSB) is one of these timber composites gaining traction in the construction field due to its low cost and sustainable use of timber products in manufacturing.
The major barrier to the effective use of OSB panels in construction is their susceptibility to fire and high thermal conditions. The impact of high thermal conditions on the mechanical strength of OSB must be quantified, so... (More) - The current trends in the construction industry push toward materials that are more sustainable and environmentally friendlier than more traditional building materials such as concrete and steel. Timber and timber composites are one of the most popular materials on this list, due to both their mechanical strength and pleasant aesthetics. Oriented strand board (OSB) is one of these timber composites gaining traction in the construction field due to its low cost and sustainable use of timber products in manufacturing.
The major barrier to the effective use of OSB panels in construction is their susceptibility to fire and high thermal conditions. The impact of high thermal conditions on the mechanical strength of OSB must be quantified, so that accurate predictions can be made. This would allow the timber composite manufacturing industries to develop thermal and fire-retardant solutions to improve the thermal-mechanical behavior of OSB.
The goal of this research work was to gain an understanding of the thermal degradation of OSB and its relative impact on the behavior of thermal material properties and mechanical degradation. The scope of the research was limited to pre-ignition behavior. The work in this thesis was split into three major parts. First, a series of thermal material property tests (TGA, thermal conductivity, and cone calorimeter tests) were performed to gain an understanding of the thermal degradation of the OSB. Second, a series of thermal-mechanical combination experiments were conducted to identify a trend between thermal -decomposition and mechanical degradation of OSB. Finally, a heat transfer model based on the cone calorimeter test was simulated and compared with results from experimental measurements.
Major findings from the research work include the trend of thermal degradation of OSB. Until a temperature of 225 °C, the mass loss is minimal (1.9 ± 0.1 %) after which, a large mass loss of a further 66% is observed by the temperature range 380 ± 10 °C. Another finding is regarding the thermal decomposition-mechanical degradation behavior of OSB. The failure stress trend associated with thermal degradation was found to be different for specimens tested immediately after removing from the furnace and for specimens tested after a 24-hour period of cooling. For specimens tested immediately after removal from the furnace, the failure stress had a continuous, non-linear degradation for the test temperature range of room temperature to 200 °C. However, for the specimens allowed to cool for 24 hours, an upward trend was observed between 75 ° and 100 °C for the failure stress. For the specimens heated at 100 °C, 150 °C, 175 °C, and 200 °C, it was also found that the 24-hour cooling period allowed strength to be regained in the OSB. (Less) - Popular Abstract
- In the present-day world, there is a large demand for sustainable practices in the construction industry. This mean balancing the needs of the environment, society and economy for both the current and future generations. Timber and timber composites are touted as sustainable construction material. Timber composites have gained interest over natural timber due to reasons such as lower number of defects, higher consistency and higher strength.
The use of timber composites in construction is being blocked due to their low tolerance to fire and high temperatures by organizations governing construction practices. To promote the use of timber composites, it is first needed to understand their behaviour under high thermal conditions. This... (More) - In the present-day world, there is a large demand for sustainable practices in the construction industry. This mean balancing the needs of the environment, society and economy for both the current and future generations. Timber and timber composites are touted as sustainable construction material. Timber composites have gained interest over natural timber due to reasons such as lower number of defects, higher consistency and higher strength.
The use of timber composites in construction is being blocked due to their low tolerance to fire and high temperatures by organizations governing construction practices. To promote the use of timber composites, it is first needed to understand their behaviour under high thermal conditions. This knowledge can be used to develop methods that can improve the behaviour of timber composites under high temperatures.
In this study, a timber composite panel called Oriented Strand Board (OSB) was studied. OSB is used in construction in various capacity: for walls, floors, roofs, and furniture. The study consisted of several experiments and computer modelling of the material.
The first experiment heated a microscopic amount of OSB in a nitrogen atmosphere at a constant heat to observe the mass loss occurring with temperature. It was observed that until about 225 °C, the mass loss was very small (less than 2%).
The second experiment observed how the thermal conductivity of the material, which is a measure of the material’s ability to conduct heat changes with the temperature of the material. It was observed that for a low temperature (less than 85 °C), this thermal property increases linearly with temperature.
The third experiment performed is named cone calorimeter tests. This allowed to subject the OSB material to different levels of heat and observe the time taken to ignite the OSB and the heat released from the fire.
The fourth experiment composed of heating OSB samples at different temperatures (50 °C – 200 °C) for roughly two hours and then bending the samples until they fail. For half of the samples, the bending test was performed immediately after removing from the furnace and for the other half, after allowing 24 hours to cool down the samples. The results showed that increasing temperature increased the loss of strength in OSB and the 24 hours of cooling allowed a change in the strength of the material.
The results from the experiments were compared with results found in previous studies. This comparison showed a degree of similarity between experimental and literature results.
The computer modelling section attempted to simulate the heat transfer occurring inside the OSB material using data from the experimental results and literature study. The results did not fully represent the actual results, meaning that more data and work is needed. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9086703
- author
- Kularatne, Wickramasooriyage Devmini LU
- supervisor
- organization
- course
- VBRM05 20221
- year
- 2022
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Oriented strand board, thermal decomposition, mechanical degradation, heat transfer modelling
- publication/series
- LUTVDG/TVBB
- report number
- 5672
- other publication id
- LUTVDG/TVBB—5672--SE
- language
- English
- id
- 9086703
- date added to LUP
- 2022-06-10 15:27:35
- date last changed
- 2022-06-10 15:27:35
@misc{9086703,
abstract = {{The current trends in the construction industry push toward materials that are more sustainable and environmentally friendlier than more traditional building materials such as concrete and steel. Timber and timber composites are one of the most popular materials on this list, due to both their mechanical strength and pleasant aesthetics. Oriented strand board (OSB) is one of these timber composites gaining traction in the construction field due to its low cost and sustainable use of timber products in manufacturing.
The major barrier to the effective use of OSB panels in construction is their susceptibility to fire and high thermal conditions. The impact of high thermal conditions on the mechanical strength of OSB must be quantified, so that accurate predictions can be made. This would allow the timber composite manufacturing industries to develop thermal and fire-retardant solutions to improve the thermal-mechanical behavior of OSB.
The goal of this research work was to gain an understanding of the thermal degradation of OSB and its relative impact on the behavior of thermal material properties and mechanical degradation. The scope of the research was limited to pre-ignition behavior. The work in this thesis was split into three major parts. First, a series of thermal material property tests (TGA, thermal conductivity, and cone calorimeter tests) were performed to gain an understanding of the thermal degradation of the OSB. Second, a series of thermal-mechanical combination experiments were conducted to identify a trend between thermal -decomposition and mechanical degradation of OSB. Finally, a heat transfer model based on the cone calorimeter test was simulated and compared with results from experimental measurements.
Major findings from the research work include the trend of thermal degradation of OSB. Until a temperature of 225 °C, the mass loss is minimal (1.9 ± 0.1 %) after which, a large mass loss of a further 66% is observed by the temperature range 380 ± 10 °C. Another finding is regarding the thermal decomposition-mechanical degradation behavior of OSB. The failure stress trend associated with thermal degradation was found to be different for specimens tested immediately after removing from the furnace and for specimens tested after a 24-hour period of cooling. For specimens tested immediately after removal from the furnace, the failure stress had a continuous, non-linear degradation for the test temperature range of room temperature to 200 °C. However, for the specimens allowed to cool for 24 hours, an upward trend was observed between 75 ° and 100 °C for the failure stress. For the specimens heated at 100 °C, 150 °C, 175 °C, and 200 °C, it was also found that the 24-hour cooling period allowed strength to be regained in the OSB.}},
author = {{Kularatne, Wickramasooriyage Devmini}},
language = {{eng}},
note = {{Student Paper}},
series = {{LUTVDG/TVBB}},
title = {{Experimental and computational analysis of the thermal degradation and the loss of strength of engineered wood-based panels}},
year = {{2022}},
}