High-resolution proxies for wood density variations in Terminalia superba

Building and Environment

Windt

et al. 2013

Self Cite

Strength and durability of wood-based products are substantially influenced by moisture. It is, therefore, crucial to monitor the moisture content (MC) distribution in wood products to fully understand their behaviour in dynamic moisture conditions. In this paper, we present a combined X-ray CT method and an adapted version of the electrical resistance MC measurement method for detailed studies on MC distribution in wood products. The X-ray CT method is evaluated using the gravimetrically recorded MC of solid wood. Subsequently, the recorded MC of electrical method is evaluated by using X-ray CT method. Three wood products are used for this purpose, i.e. solid wood, plywood and oriented strand board (OSB) panels. It is proven that X-ray CT method can accurately determine the MC of wood products and thus has great potential for non-destructively measuring the MC distribution in 3D. Furthermore, the results show that electrical method can effectively record the local MC when the MC distribution in this region is even. Otherwise, the position of the electrodes, with regard to specific wood properties has a substantial influence on its performance. Compared with solid wood and OSB, the electrical method performs best in plywood due to its layered structure. The adapted electrical method is an effective tool for continuously monitoring the MC distribution of wood products, taking into account that the electrodes are installed correctly according to the structure of the material and research questions. Combined with X-ray CT scanning, MC distribution of wood-based products under in-service applications, can be monitored.

Section: Data Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combining electrical resistance and 3-D X-ray computed tomography for moisture distribution measurements in wood products exposed in dynamic moisture conditions

Building and Environment

Windt

et al. 2013

Self Cite

“…Magnetic resonance imaging allows monitoring the free water movement in wood materials [9]. Research with X-ray CT scanning revealed the internal structure and density distribution of wood materials [10,11]. Compared with the above two approaches, neutron imaging is more suitable to determine moisture distribution due to the high attenuation of the neutron beam by hydrogen nuclei [12,13].…”

Section: Introductionmentioning

confidence: 99%

Impact of internal structure on water-resistance of plywood studied using neutron radiography and X-ray tomography

Construction and Building Materials

Mannes

et al. 2014

Self Cite

To improve water resistance of plywood, a detailed understanding of the moisture dynamics of plywood and related solid wood is essential. Neutron radiography and X-ray CT were used to monitor water transport and the internal micro-structure respectively. Compared with solid wood, water uptake and release of plywood is, apart from wood species, also influenced by veneer checks and gaps between veneers. Type of adhesive and grain direction of veneers also play a crucial role. According to the findings of this paper and practical requirements, more water resistant plywood can be produced when taking into account abovementioned factors.

“…Studying moisture distribution in function of local properties of plywood is therefore valuable. X-ray CT scanning has been used to investigate the internal structure and density distribution of wood materials (Chen et al 2009, De Ridder et al 2011, Lindgren 1991. Hence, this method is well-suited to monitor the structural changes of plywood, which is essential to understand the influence of moisture distribution on local structure and vice versa.…”

mentioning

confidence: 99%

Moisture behavior and structural changes of plywood during outdoor exposure

Windt

et al. 2015

Eur. J. Wood Prod.

Self Cite

Abstract:Plywood is an important wood-based construction material yet prone to water uptake, as such potentially decreasing mechanical properties and increasing decay risk. It is, therefore, essential to understand the moisture behavior and structural changes of plywood in service. In this research, several plywood specimens were exposed in outdoor weathering conditions for approximately one year. During this period, the average moisture variation of and moisture distribution in different veneer layers of a set of plywood specimens and detailed field weather information were recorded continuously. The internal structure of the specimens was also monitored by periodically scanning using X-ray CT. Measurements indicate that moisture distribution in plywood is not homogeneous in outdoor conditions. The second layer can, in some plywood types, accumulate a significant amount of rain, and long rainy periods and cloudy weather can keep the moisture content of the inner layers of plywood significantly high. Moisture accumulation and moisture dynamics, in combination with wood species, are the main factors causing structural changes, mainly occurring as cracks, of the plywood veneers in service. The glue line between the veneers, however, is not ruptured after one year of outdoor exposure. Plywood with layers having a slow water sorption and fast water desorption could effectively avoid internal moisture accumulation and cracks in service. Based on the knowledge of the interrelationship of weather data, internal moisture behavior and structural changes in service, fit-for-purpose design of plywood could be improved and service life prediction is at hand.