• Journal of the Korean Wood Science and Technology
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• 제24권2호
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• pp.42-45
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• 1996

A residue from the newsprint waste was investigated as a filler in adhesive for bonding southern pine plywood. The residue was prepared by drying the wet residue to 8% moisture content and grinding the dry material using a laboratory Wiley mitt with a 75-${\mu}m$(200-mesh) screen. The residue was compared to a commercial filler commonly used in structural plywood adhesives. A total of 48 three-ply panels. 12.7mm nominal thickness and 0.3 by 0.3 m in size, were fabricated at two press times(4 and 5 min) and three assembly times(20, 40 and 60 min). Evaluations of the residue were carried out by performance tension shear tests after two 4-hour boil accelerated aging tests on plywood. The test results included tension shear strength and estimated wood failure values. All plywood made with the residue filler were comparable to the control-bonded plywood. These results indicate that residue from the newsprint waste streams would be suitable as filler for plywood adhesives.

• Structural Engineering and Mechanics
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• 제72권2호
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• pp.155-168
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• 2019

This paper presents the results of an experimental investigation on the compressive strength of small scale concentrically axially loaded fiber-reinforced polymer (FRP) confined plain concrete columns, with cylinder concrete strength 19 MPa. For columns with circular (150-mm diameter) and square (150-mm side) cross sections wrapped with glass- and carbon-FRP sheets (GFRP and CFRP, respectively) applied with dry lay-up the effect of different jacket schemes and different overlap configurations on the confined characteristics is investigated. Test results indicate that the most cost effective jacket configuration among those tested is for one layer of CFRP, for both types of sections. In square sections the location of the lap length, either in the corner or along the side, does not seem to affect the confined performance. Furthermore, in circular sections, the presence of an extra wrap with FRP fibers parallel to the column's axis enhances the concrete strength proportionally to the axial rigidity of the FRP jacket. The recorded strains and the distributions of lateral confining pressures are discussed. Existing design equations are used to assess the lateral confining stresses and the confined concrete strength making use of the measured hoop strains.

• Advances in concrete construction
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• 제3권1호
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• pp.39-54
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• 2015

Relative humidity and strains within a massive concrete cylinder (${\varphi}450mm{\times}900mm$) in the drying and the re-saturating process were measured for elucidating the process of ASR surface cracking in concrete. The expansion behavior of mortars in dry atmospheres with various R.H. values and the resaturating process was revealed. Non- or less-expansive layers were formed in near-surface regions in the concrete cylinder in the drying process, but ASR expansions actively progressed in inner portions. After resaturating, R.H. values of near-surface regions rapidly increased with time, but expansions in the regions were found to be very small. However, in the middle portions, of which R.H. values were kept 80% ~ 90% R.H. in the drying process, expansion actively progressed, resulting in further development of surface cracks in the re-saturating process.

• Advances in concrete construction
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• 제5권1호
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• pp.1-15
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• 2017

This research project aimed at evaluating experimentally the effect of natural perlite powder as an alternative supplementary cementing material (SCM) on the performance of fiber reinforced self-consolidating repair mortars (FR-SCRMs). For this purpose, four FR-SCRMs mixes incorporating 0%, 10%, 20%, and 30% of natural perlite powder as cement replacements were prepared. The evaluation was based on fresh (slump flow, flow time, and unit weight), hardened (air-dry unit weight, compressive and flexural strengths, dynamic modulus of elasticity), and durability (water absorption test) performances. The results reveal that structural repair mortars confronting the performance requirements of class R4 materials (European Standard EN 1504-3) could be designed using 10%, 20%, and 30% of perlite powder as cement substitutions. Bonding results between repair mortars containing perlite powder and old concrete substrate investigated by the slant shear test showed good interlocking justifying the effectiveness of these produced mortars.

• Membrane and Water Treatment
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• 제10권1호
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• pp.83-89
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• 2019

The most common way of reducing non-point source pollutants from agricultural areas is the installation of reservoirs. However, this method is only effective for surface runoff of settleable pollutants. This study was conducted to estimate the effect of interflow, baseflow, and surface runoff on pollutant runoff in a small agricultural catchment. Runoff of organic matters, SS, and T-P were directly proportional to the rainfall variation, while ammonia and nitrate were inversely proportional to the amount of rainfall. The interflow and baseflow was only 46% of the total stream flow, but the nitrate load reached 78%. The interflow as a nutrient transport pathway should be considered for managing a stream water quality. It requires careful attention and appropriate control methodology such as vegetation to consider the influence by interflow. The reservoir as a dry extended detention pond (DEDP) has function of nutrient captor.

• Earthquakes and Structures
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• 제23권4호
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• pp.353-361
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• 2022

The dynamic behavior of a single pile was investigated by using analytical and numerical studies. The focus of this study was to develop the dynamic p-y curve of a pile for pseudo-static analysis considering the shear wave velocity of the soil by using three-dimensional numerical analyses. Numerical analyses were conducted for a single pile in dry sand under changing conditions such as the shear wave velocity of the soil and the acceleration amplitudes. The proposed dynamic p-y curve is a shape of hyperbolic function that was developed to take into account the influence of the shear wave velocity of soil. The applicability of pseudo-static analysis using the proposed dynamic p-y curve shows good agreement with the general trends observed by dynamic analysis. Therefore, the proposed dynamic p-y curve represents practical improvements for the seismic design of piles.

• Structural Engineering and Mechanics
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• 제84권4호
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• pp.465-477
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• 2022

The formation of biopolymer-soil matrices mainly depends on biopolymer type and concentration, soil type, pore fluid and phase transfer to influence its strengthening efficiency. In this study, the physical and mechanical properties of sodium alginate (SA) treated kaolinite are investigated through compaction test, thread rolling teat, fall cone test and unconfined compression test with considering biopolymer concentration, curing time, initial water content, mixing method. The results show that the liquid limit slightly decreases from 69.9% to 68.3% at 0.2% SA and then gradually increases to 98.3% at 5% SA. At hydrated condition, the unconfined compressive strength (UCS) of SA treated clay at 0.5%, 1%, 2% and 3% concentrations is 2.57, 4.5, 7.1 and 5.48 times of untreated clay (15.7 kPa) at the same initial water content. In addition, the optimum biopolymer concentration, curing time, mixing method and initial water content can be regarded as 2%, 28 days, room temperature water-dry mixing (RD), 50%-55% to achieve the maximum unconfined compressive strength, which corresponds to the UCS increment of 593%, compared to the maximum UCS of untreated clay (780 kPa).

• Geomechanics and Engineering
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• 제35권2호
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• pp.165-179
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• 2023

This study investigates the uplift capacity of a single vertical belled pile buried at shallow depth in dry sand. The laboratory model experiments are conducted with different pile-tip angles and relative densities. In addition, image and FEM analyses are performed to observe the failure surface of the belled pile for different pile-tip angles and relative densities. Accordingly, the uplift capacity and failure angle in the failure surface of the belled pile were found to depend on the belled pile-tip angle and relative density. A predictive model for the uplift capacity of the belled pile was proposed considering the relative density and belled pile-tip angle based on a previous limit equilibrium equation. To validate the applicability of the proposed model, the values calculated using the proposed and previous models were compared to those obtained through a laboratory model experiment. The proposed model had the best agreement with the laboratory model experiment.

• Earthquakes and Structures
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• 제14권4호
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• pp.323-336
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• 2018

Machine foundations with impact loads are common powerful sources of industrial vibrations. These foundations are generally transferring vertical dynamic loads to the soil and generate ground vibrations which may harmfully affect the surrounding structures or buildings. Dynamic effects range from severe trouble of working conditions for some sensitive instruments or devices to visible structural damage. This work includes an experimental study on the behavior of dry dense sand under the action of a single impulsive load. The objective of this research is to predict the dry sand response under impact loads. Emphasis will be made on attenuation of waves induced by impact loads through the soil. The research also includes studying the effect of footing embedment, and footing area on the soil behavior and its dynamic response. Different falling masses from different heights were conducted using the falling weight deflectometer (FWD) to provide the single pulse energy. The responses of different soils were evaluated at different locations (vertically below the impact plate and horizontally away from it). These responses include; displacements, velocities, and accelerations that are developed due to the impact acting at top and different depths within the soil using the falling weight deflectometer (FWD) and accelerometers (ARH-500A Waterproof, and Low capacity Acceleration Transducer) that are embedded in the soil in addition to soil pressure gauges. It was concluded that increasing the footing embedment depth results in increase in the amplitude of the force-time history by about 10-30% due to increase in the degree of confinement. This is accompanied by a decrease in the displacement response of the soil by about 40-50% due to increase in the overburden pressure when the embedment depth increased which leads to increasing the stiffness of sandy soil. There is also increase in the natural frequency of the soil-foundation system by about 20-45%. For surface foundation, the foundation is free to oscillate in vertical, horizontal and rocking modes. But, when embedding a footing, the surrounding soil restricts oscillation due to confinement which leads to increasing the natural frequency. Moreover, the soil density increases with depth because of compaction, which makes the soil behave as a solid medium. Increasing the footing embedment depth results in an increase in the damping ratio by about 50-150% due to the increase of soil density as D/B increases, hence the soil tends to behave as a solid medium which activates both viscous and strain damping.

• Asian-Australasian Journal of Animal Sciences
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• 제18권6호
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• pp.802-806
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• 2005

The objective of this study was to determine the effects of processing method and rapeseed variety on ruminal and intestinal protein digestibility of rapeseed meal in steers. Intestinal amino acid digestibility was assessed with an in situ ruminal incubation and precision-fed rooster bioassay. In this experiment one traditional rapeseed meal sample (sample A, prepress extraction) and three double low rapeseed meal samples (sample B, prepress extraction, sample C, screw press and sample D, low temperature press) were placed in polyester bags(8 cm${\times}$12 cm) and suspended in the ventral rumen of steers for 16 h. The residues of in situ incubations were intubated to roosters. Total excreta were collected for 48 h after incubation and then desiccated and amino acid concentrations were determined. Results showed that in ruminal incubation the degradation rate of amino acid and crude protein was higher for traditional rapeseed meal sample A than for double low rapeseed meal sample B, but was much lower than for double low sample C and D. In the group of double low rapeseed meal samples, sample D processed by low temperature press had the highest degradation rate of amino acids in the rumen. For all amino acids, the digestibility of the residual protein as measured by the precision-fed rooster bioassay tended to be lower for sample B than for sample A, which had the same processing method with sample B, and in the group of double low rapeseed meals, sample B had similar digestibility of amino acid in residual protein to sample D and higher than that of sample C. However, although the total amino acid availability involving the digestibility of amino acids in the rumen and rooster bioassay of double low rapeseed meal sample D (low temperature press) was higher than those of the other three samples by 7 to 9 percent, there were no significant differences. Results indicated that processing method markedly affected ruminal and post ruminal amino acid digestibility of rapeseed meal when the temperature exceeded 110$^{\circ}C$. Rapeseed meal that had a high content of fiber was not suitable for dry heat treatment at higher temperatures or the amino acids digestibility in rumen and total availability of amino acids could be reduced. Results also suggested the variety of rapeseed meal had no significant effect on the digestibility and availability of amino acids.