Creep behaviour of single hemp fibres. Part II: Influence of loading level, moisture content and moisture variation

2014 ◽  
Vol 50 (5) ◽  
pp. 2061-2072 ◽  
Author(s):  
Violaine Guicheret-Retel ◽  
Ousseynou Cisse ◽  
Vincent Placet ◽  
Johnny Beaugrand ◽  
Miguel Pernes ◽  
...  
Keyword(s):  
Moisture Content ◽  
Creep Behaviour ◽  
Loading Level ◽  
Moisture Variation ◽  
Hemp Fibres

Examination of moisture content variation within an operational wet deck

TAPPI Journal ◽  
2013 ◽  
Vol 12 (1) ◽  
pp. 45-50 ◽  
Author(s):  
LAURENCE SCHIMLECK ◽  
KIM LOVE-MYERS ◽  
JOE SANDERS ◽  
HEATH RAYBON ◽  
RICHARD DANIELS ◽  
...  
Keyword(s):  
Moisture Content ◽  
Southeastern United States ◽  
Forest Products ◽  
Time Domain Reflectometry ◽  
Water Application ◽  
Wood Moisture ◽  
International Paper ◽  
Content Variation ◽  
Moisture Variation

Many forest products companies in the southeastern United States store large volumes of roundwood under wet storage. Log quality depends on maintaining a high and constant wood moisture content; however, limited knowledge exists regarding moisture variation within individual logs, and within wet decks as a whole, making it impossible to recommend appropriate water application strategies. To better understand moisture variation within a wet deck, time domain reflectometry (TDR) was used to monitor the moisture variation of 30 southern pine logs over an 11-week period for a wet deck at the International Paper McBean woodyard. Three 125 mm long TDR probes were inserted into each log (before the deck was built) at 3, 4.5, and 7.5 m from the butt. The position of each log within the stack was also recorded. Mixed-effects analysis of variance (ANOVA) was used to examine moisture variation over the study period. Moisture content varied within the log, while position within the stack was generally not significant. The performance of the TDR probes was consistent throughout the study, indicating that they would be suitable for long term (e.g., 12 months) monitoring.

scholarly journals Non-destructive evaluation of moisture content in wood by using Ground Penetrating Radar

2016 ◽  
Author(s):  
Hamza Reci ◽  
Tien Chinh Maï ◽  
Zoubir Mehdi Sbartaï ◽  
Lara Pajewski ◽  
Emanuela Kiri
Keyword(s):  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Wood Fiber ◽  
Fiber Direction ◽  
Direct Wave ◽  
Reflected Waves ◽  
Moisture Variation ◽  
Reflection Configuration ◽  
Ground Penetrating ◽  
Non Destructive

Abstract. This paper presents the results of a series of laboratory measurements carried out to study how the Ground Penetrating Radar (GPR) signal is affected by moisture variation in wood material. The effects of the wood fiber direction, with respect to the polarisation of the electromagnetic field, are investigated. The relative permittivity of wood and the amplitude of the electric field received by the radar are measured for different humidity levels, by using the direct-wave method in Wide Angle Radar Reflection configuration, where one GPR antenna is moved while the other is kept in a fixed position. The received signal is recorded for different separations between transmitting and receiving antennas. Direct waves are compared to reflected waves: it is observed that they show a different behaviour when the moisture content varies, due to their different propagation paths.

Properties of thermally modified medium-density fibreboards

Holzforschung ◽  
2012 ◽  
Vol 66 (1) ◽  
Author(s):  
Jürgen Bonigut ◽  
Detlef Krug ◽  
Beate Stephani
Keyword(s):  
Thermal Treatment ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Phenol Formaldehyde ◽  
Creep Behaviour ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Thickness Swelling ◽  
Short Term ◽  
European Standards

Abstract Thermal treatment of solid timber and oriented strandboards (OSB) improves durability against fungal decay and dimensional stability (swelling and shrinking). It is not clear whether thermal treatment of medium-density fibreboards (MDF) has the same effects. In this work, four variants of phenol-formaldehyde (PF)-bonded MDF with varying contents of resin and hydrophobing agent were thermally post-treated according to the Mühlböck procedure at three different maxi-mum temperatures. The short-term properties internal bond, modulus of rupture, modulus of elasticity, thickness swelling and equilibrium moisture content and the long-term property creep behaviour of treated variants and of one untreated variant have been tested. The results are presented and discussed in comparison with the respective European standards. Altogether, the thermal treatment had a positive effect on most of the tested mechanical short-term properties. The moisture-related properties, i.e., thickness swelling and equilibrium moisture content, were also positively influenced. The creep behaviour of heat-treated MDF could also be improved by thermal modification.

scholarly journals The Influence of Moisture Content on the Time-Dependent Characteristics of Rock Material and Its Application to the Construction of a Tunnel Portal

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaojun Liu ◽  
Chao Yang ◽  
Jing Yu
Keyword(s):  
Moisture Content ◽  
Deformation Behaviour ◽  
Creep Behaviour ◽  
Three Dimensional ◽  
Viscosity Coefficient ◽  
Guizhou Province ◽  
Creep Model ◽  
Low Grade ◽  
Saturation Degree ◽  
Moisture Contents

Uniaxial compression creep experiments were carried out for low-grade metamorphic slate samples (located in the southeastern area of Guizhou province, China) with different moisture contents, using an Instron electric-fluid servo-compression machine. Based on the experimental results, a detailed analysis was made of the effect of moisture content on the strength and deformation behaviour of the slate specimens. The three-parameter generalised Kelvin model was identified to describe the creep behaviour of the low-grade metamorphic slate with different moisture contents. There is an approximately linear negative correlation between the elastic modulus and the saturation degree, and the viscoelastic modulus and viscosity coefficient show a negative exponent correlation with the saturation degree. The Kelvin creep model considering the moisture degradation effect was established and a three-dimensional finite difference model was developed with the softwareFLAC3Dto validate the creep model. A three-dimensional numerical analysis was then performed to simulate the tunnel excavation process. The results show that the influence of moisture and creep of the surrounding rocks is needed for estimating the deformation of complex tunnel portals.

X-Lam Panels in Swimming-Pool Building – Monitoring the Environment and the Performance

2013 ◽  
Vol 778 ◽  
pp. 779-785 ◽  
Author(s):  
Luís Jorge ◽  
Alfredo M.P.G. Dias
Keyword(s):  
Moisture Content ◽  
Dimensional Stability ◽  
Plane Deformation ◽  
Monitoring Program ◽  
Swimming Pool ◽  
Service Class ◽  
Cross Laminated Timber ◽  
Building Monitoring ◽  
Moisture Variation ◽  
High Level

The cross-laminated timber panels (X-Lam panels) are produced for structural use in Service Classes 1 and 2 conditions, in accordance with what is established on Eurocode 5 [. Timber boards are glued together on orthogonal layers, allowing the panel to perform two important characteristics: good dimensional stability and loading in two-way directions. The influence of wood moisture content on the feasibility of cross-laminated timber is described in this paper regarding the dimensional stability of the panels when applied in high moisture locations. Several European Technical Approvals, state the low importance of the dimensional variations with moisture content of this type of panel, but some reference values can be found in other technical documents. The French Avis Technique [[[1 reference the value of 0.01mm/m for in-plane deformation (per percentage of timber moisture variation) and the TRADA Wood Information Sheet, WIS 2/3-62 [1, refers the maximum value of 0.02mm/m for the same conditions.The use of the X-Lam panels in Service Class 3 can not be used, concerning the high level of stressing in glue lines, and no producer has yet certified it for this Service Class. Moreover, the French Avis Technique doesnt allow the use of X-Lam panels in swimming-pools due to high hygrometry, even for conditions corresponding to Service Class 2.Cross laminated timber panels are widely used across Europe but are giving the first steps in Portugal at the moment. The first big project was finished in spring 2012 in Almada, comprising a building integrating a 25 meter in-door swimming-pool and a gym. In order to assess the behavior of the timber structure, due to the non-conventional using of the X-Lam panels, a monitoring program was started immediately after building construction. The results obtained are presented and discussed in this paper.

scholarly journals Soil moisture monitoring at the field scale using neutron probe

2014 ◽  
Vol 51 (3) ◽  
pp. 332-345 ◽  
Author(s):  
J. Kodikara ◽  
P. Rajeev ◽  
D. Chan ◽  
C. Gallage
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Layer ◽  
Calibration Method ◽  
Flow Equation ◽  
Wetting Front ◽  
Wet Season ◽  
Buried Structures ◽  
Neutron Probe ◽  
Moisture Variation

Measurement of the moisture variation in soils is required for geotechnical design and research because soil properties and behavior can vary as moisture content changes. The neutron probe, which was developed more than 40 years ago, is commonly used to monitor soil moisture variation in the field. This study reports a full-scale field monitoring of soil moisture using a neutron moisture probe for a period of more than 2 years in the Melbourne (Australia) region. On the basis of soil types available in the Melbourne region, 23 sites were chosen for moisture monitoring down to a depth of 1500 mm. The field calibration method was used to develop correlations relating the volumetric moisture content and neutron counts. Observed results showed that the deepest “wetting front” during the wet season was limited to the top 800 to 1000 mm of soil whilst the top soil layer down to about 550 mm responded almost immediately to the rainfall events. At greater depths (550 to 800 mm and below 800 mm), the moisture variations were relatively low and displayed predominantly periodic fluctuations. This periodic nature was captured with Fourier analysis to develop a cyclic moisture model on the basis of an analytical solution of a one-dimensional moisture flow equation for homogeneous soils. It is argued that the model developed can be used to predict the soil moisture variations as applicable to buried structures such as pipes.

scholarly journals Effect of Moisture Content on Calculated Dielectric Properties of Asphalt Concrete Pavements from Ground-Penetrating Radar Measurements

2021 ◽  
Vol 14 (1) ◽  
pp. 34
Author(s):  
Qingqing Cao ◽  
Imad L. Al-Qadi
Keyword(s):  
Dielectric Properties ◽  
Numerical Model ◽  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Asphalt Concrete ◽  
Concrete Pavements ◽  
Proposed Model ◽  
Moisture Variation ◽  
Ground Penetrating ◽  
Non Destructive

Moisture presence in asphalt concrete (AC) pavement is a major cause of damage to the pavement. In recent decades, an increasing need exists for non-destructive detection and monitoring of the moisture content in AC pavement. This paper provides a simulated approach to quantify the effect of internal moisture content on AC pavement dielectric properties using ground-penetrating radar (GPR). A heterogeneous numerical model was developed to simulate AC pavement with internal moisture at various saturation levels. The numerical model was validated using GPR surveys on cold-in-place recycling treated pavements. An empirical formula was derived from the simulation to correlate the dielectric constant with the moisture content for non-dry AC pavement. The results validated the proposed model and, hence, demonstrated the ability of GPR to monitor moisture variation in AC pavements.

Estimating moisture content variation in kiln dried Pacific coast hemlock

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sohrab Rahimi ◽  
Stavros Avramidis ◽  
Ciprian Lazarescu
Keyword(s):  
Moisture Content ◽  
Linear Model ◽  
Coefficient Of Variation ◽  
Pacific Coast ◽  
Closed Formula ◽  
Kiln Drying ◽  
Content Variation ◽  
Moisture Variation ◽  
Polynomial Models

Abstract Kiln drying is admittedly a significant value-adding step in timber processing where the importance of predicting moisture within a dried batch cannot be overemphasized. This study predicts and characterizes the moisture variation in kiln-dried wood based on the initial and target moisture values using polynomial models. Four polynomial models are used to correlate initial and final moisture characteristics. First model is linear while the three others are nonlinear. The robustness of the three best models is analyzed and a closed formula is proposed to evaluate the final moisture coefficient of variation based on the target moisture and initial moisture coefficient of variation. Three models could successfully characterize the final moisture variation with the best one showing an R 2 > 96%. However, the first (linear) model is the most resilient and, thus recommended for estimating final moisture variation.

Relationships between seasonal patterns of live fuel moisture and meteorological drought indices for Mediterranean shrubland species

2007 ◽  
Vol 16 (2) ◽  
pp. 232 ◽  
Author(s):  
G. Pellizzaro ◽  
C. Cesaraccio ◽  
P. Duce ◽  
A. Ventura ◽  
P. Zara
Keyword(s):  
Moisture Content ◽  
Meteorological Drought ◽  
Meteorological Conditions ◽  
Drought Indices ◽  
Seasonal Patterns ◽  
Fuel Moisture ◽  
Fire Weather Index ◽  
Moisture Variation ◽  
Live Fuel Moisture ◽  
Fuel Moisture Content

Measurements of seasonal patterns of live fuel moisture content and ignitability (in terms of time to ignition) of four Mediterranean shrub species were performed in North Western Sardinia (Italy). Relationships between the two variables were evaluated. Relationships between live fuel moisture content and environmental conditions (i.e. rainfall, air temperature and soil moisture) were analysed. Two groups of species were identified in relation to the different response of live fuel moisture content to seasonal meteorological conditions. Seasonal patterns of live fuel moisture content were also compared with five meteorological drought indices: Duff Moisture Code and Drought Code of the Canadian Forest Fire Weather Index System, Keetch–Byram Drought Index, Canopy Drought Stress Index and Cumulative Water Balance Index. In addition, the capability of the meteorological drought indices to describe moisture variation for each species was evaluated. Although the Drought Code was formulated to describe changes in the moisture content of dead fuel, it was shown to have a good potential for modelling live fuel moisture variation of a group of shrubland species that are sensitive to meteorological conditions, with a clear and large decrease of moisture content during the drought season.

Creep deformation of clay masonry structures: a parametric study

1998 ◽  
Vol 25 (1) ◽  
pp. 67-80 ◽  
Author(s):  
Ezzeldin Y Sayed-Ahmed ◽  
Nigel G Shrive ◽  
Dan Tilleman
Keyword(s):  
Moisture Content ◽  
Creep Behaviour ◽  
Masonry Structure ◽  
Time Dependent ◽  
Masonry Structures ◽  
Moisture Condition ◽  
Test Setup ◽  
Elastic Part ◽  
Masonry Construction ◽  
Dependent Part

When loads are applied to a masonry structure, viscoelastic behaviour is exhibited where the response can be divided into two distinct parts: an instantaneous elastic part and a time-dependent part. With the change in masonry construction during the last century, the latter portion of the response is becoming more important in the design of masonry structures. The effects of mortar type, stress level, age at loading, moisture condition, and masonry strength on the creep behaviour of clay masonry structures are examined. The results of a continuing experimental programme, begun in 1988, were used to evaluate the variations in specific creep of clay masonry with the different parameters considered. The test setup and the effect of moisture content on the creep behaviour of clay masonry are also described briefly.Key words: masonry, creep, specific creep, creep ratio, mortar type, moisture condition.

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