The Adjusted Dynamic Modulus of Elasticity Above the Fiber Saturation Point in Taiwania Plantation Wood by Ultrasonic-Wave Measurement

Holzforschung ◽  
2003 ◽  
Vol 57 (5) ◽  
pp. 547-552 ◽  
Author(s):  
S.-Y. S.-Y.Wang ◽  
C.-J. Lin ◽  
C.-M. Chiu
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Ultrasonic Wave ◽  
Ultrasonic Velocity ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Dynamic Modulus Of Elasticity

Summary In this study, the effects of moisture content and bulk density on the ultrasonic velocity of Taiwania (Taiwania cryptomerioides Hay.) plantation wood in the longitudinal and radial directions are investigated. The dynamic modulus of elasticity is adjusted above the fiber saturation point by a simple method. It was observed that ultrasonic velocity tended to increase with a decrease in moisture content, and the effect of moisture content on the ultrasonic speed below the fiber saturation point was stronger than that above. Moreover, for this species ultrasonic speed in the longitudinal direction decreased with increasing bulk density, while that in the radial direction increased. The correlations between ultrasonic velocity, moisture and bulk density could be represented by a polynomial regression model. The K value for ultrasonic wave was affected by density. The adjusted dynamic modulus of elasticity remained fairly constant above the fiber saturation point using this simple method. Therefore, the results obtained by the ultrasonic-wave technique should be adjusted before estimating some physical properties of standing trees.

ANALYSIS OF SOUND SPEED IN LONGITUDINAL DIRECTION AT REFERENCE MOISTURE CONTENT (w = 12 %) IN SAWMILL ASSORTMENTS (FAGUS SYLVATICA, L.)

Akustika ◽  
2020 ◽  
pp. 45-50
Author(s):  
Alena Rohanová
Keyword(s):  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Sound Speed ◽  
Longitudinal Direction ◽  
Structural Timber ◽  
Sound Speeds ◽  
Dynamic Modulus Of Elasticity ◽  
Round Timber

This paper explores the analysis of sound speeds in the longitudinal direction and their reduction to the reference moisture content w = 12 %. The sound speed cw was determined with Sylvatest Duo device. Moisture content of beech sawmill assortments (round timber: N = 16, logs: N = 2 × 16, structural boards: N = 54) in the range of 12 – 72 % was measured. For the analysis purposes, the sound speed was converted to reference conditions (c12, uref = 12%). A second-degree polynomial (parabola) with a regression equation of the form: c// = 5649 - 27,371 × w + 0.0735 × w2 was used to convert cw to c12, and correction of measured and calculated values was used as well. The sound speeds c12 in sawmill assortments (c12,round, c12,log, c12,board) were evaluated by linear dependences. Dependence was not confirmed for c12,round and c12,board1 (r = 0.168), in contrast for c12,round and c12,log2 the dependence is statistically very significant (r = 0.634). The results of testing showed that the most suitable procedure for predicting quality of structural timber is the first step round timber – log2, the second step: log2 - board2. More exact results of the construction boards were obtained from log2 than from log1. The sound speed is used in the calculation of dynamic modulus of elasticity (Edyn). EN 408 mentions the possibility of using dynamic modulus of elasticity as an alternative method in predicting the quality of structural timber.

Fiber-Reinforced Mortar Incorporating Pig Hair

2017 ◽  
Vol 21 ◽  
pp. 219-225 ◽  
Author(s):  
Gerardo Araya-Letelier ◽  
Federico C. Antico ◽  
Pablo Fernado Parra ◽  
Miguel Carrasco
Keyword(s):  
Impact Strength ◽  
Bulk Density ◽  
Environmental Impacts ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Food Industry ◽  
Fiber Reinforced ◽  
Dynamic Modulus Of Elasticity ◽  
Cement Based Materials ◽  
The Impact

Recycled fibers from food-industry could be added as reinforcement to cement-based materials. Cement-based materials perform well under compression, but tensile strength and post-cracking ductility in tension are poor. Fibers produced from steel, glass and synthetic materials, have been successfully used to overcome some of these shortcomings. Fiber-reinforced mortar has shown an increased post-cracking ductility and improved long-term serviceability due to the crack control provided by fibers. Food-industry waste disposal is globally a major concern because of its environmental impacts. For these reasons, the use of recycled materials in construction applications has been investigated over the last decades. This investigation deals with the incorporation of pig hair, which is a waste produced by the food-industry worldwide, in fiber-reinforced mortars. This composite material is intended to reduce the environmental impacts by valuing waste materials in construction applications while improving mechanical properties. To determine compressive, flexural and impact strength, bulk density, porosity and dynamic modulus of elasticity laboratory tests were conducted in mortar specimens with 0%, and 2% of pig-hair content in weight of cement. The results of this research show that the impact strength can increase up to five times when compared to plain mortar. Moreover, the compressive and flexural strengths, bulk density, porosity and the dynamic modulus of elasticity of fiber-reinforced mortar, with the aforementioned pig-hair content, are not significantly affected.

scholarly journals Influence of the moisture content on the dynamic modulus of elasticity of concrete made with recycled aggregate

2019 ◽  
Vol 19 (2) ◽  
pp. 79-89
Author(s):  
Claudio de Souza Kazmierczak ◽  
Joana Kirchner Benetti Boaro ◽  
Monique Palavro Lunardi ◽  
Marlova Piva Kulakowski ◽  
Mauricio Mancio
Keyword(s):  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Coarse Aggregates ◽  
Codes Of Practice ◽  
Dynamic Modulus Of Elasticity

Abstract The elastic behavior of the concrete is estimated from its strength or determined by static or dynamic tests. However, because the codes of practice do not standardize the internal moisture content of the concrete and disregard the use of recycled aggregates when proposing equations for the estimation of the modulus of elasticity, discrepancies between the values measured and estimated are frequent. The influence of the moisture content of concrete containing basaltic coarse aggregates and coarse recycled concrete aggregate in the dynamic modulus of elasticity is discussed in this paper. A basalt coarse aggregate and two recycled coarse aggregates where used. For each type of coarse aggregate, concrete with compression strength between 25 MPa and 55 MPa were produced. The dynamic modulus of elasticity of the saturated samples were determined and range from 26 GPa to 46 GPa. There is a significant difference in the value of the dynamic modulus of elasticity for dry concrete versus saturated concrete, also influenced by the type of aggregate. Estimations of the modulus of elasticity from the compressive strength equations proposed by the codes of practice must be improved considering its characteristics.

scholarly journals Investigation of the fiber saturation point of tropical Brazilian wood species

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 5379-5387
Author(s):  
Tiago H. Almeida ◽  
Diego H. Almeida ◽  
Vinicius B. M. Aquino ◽  
Eduardo Chahud ◽  
Roberto V. Pinheiro ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wood Species ◽  
Wood Specimen ◽  
Basic Density ◽  
Fiber Saturation Point ◽  
Coefficient Of Determination ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Standard Code ◽  
Brazilian Standard

The fiber saturation point (FSP) is an important parameter of wood material, related to dimensional stability and variations of mechanical performance. This paper investigated the FSP values of 15 tropical Brazilian wood species covering all strength classes of the Brazilian standard code. An additional goal was to estimate FSP value based on the wood’s apparent density. The FSP values were determined by measuring the wood specimen dimensions during moisture content reduction from the saturated state. Wood densities at 0% and 12% moisture contents and basic density were determined according to the Brazilian standard code. The average FSP for all wood species was 21.6% moisture content. Among density values, good correlations were observed, and a multivariate regression model for FSP estimation based on wood densities presented a coefficient of determination equal to 13.07%. There was no correlation between FSP and wood densities, suggesting that this parameter is almost constant regardless of the wood species.

Experimental Data Correction of the Dynamic Elastic Moduli, Velocity and Density of Solid Wood as a Function of Moisture Content above the Fiber Saturation Point

Holzforschung ◽  
2000 ◽  
Vol 54 (3) ◽  
pp. 309-314 ◽  
Author(s):  
Song-Yung Wang ◽  
Shih-Tzu Chuang
Keyword(s):  
Moisture Content ◽  
Wave Velocity ◽  
Stress Wave ◽  
Elastic Moduli ◽  
Free Water ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Static Tests ◽  
Simulation Procedure ◽  
Fiber Saturation

Summary Experimentally it was observed that the dynamic modulus of elasticity calculated from the velocity of stress wave or ultrasonic wave and the density of wood in green condition increased with increasing moisture content. This statement disagrees with the physical meaning of data observed with static tests, namely the decreasing of all mechanical properties of wood with increasing moisture content. To elucidate this discrepancy a simulation procedure was developed to study the effect of free water, present in wood above the fiber saturation point on wave velocity. For this purpose the coefficient k, related to the mobility of free water was defined, as a ratio of free water vibrating simultaneously with water present in cellular wall (k = 0.6 for stress wave velocity and k = 0.7 for ultrasonic velocity). The simulation procedure using corrected values of velocity and density showed that the elastic moduli are relatively constant above the FSP, as all the mechanical parameters determined with static tests.

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