• Journal of the Korean Geotechnical Society
• /
• v.25 no.8
• /
• pp.65-76
• /
• 2009

Little attention has been paid to Brazilian test for the estimation of uniaxial compressive strength and elastic modulus of rocks as an indirect method despite high availability of civil engineering parameters. This paper employed Brazilian test value to estimate two parameters of igneous rocks (granite, andesite, rhyolite) of Korea. High reliability of Brazilian test has been supported by the conclusions drawn from point load test and Schmidt hammer strike values. It has also been found that this method can be applied easily and rapidly to the estimation of uniaxial compressive strength and elastic modulus of rock cores when direct tests are not available.

• Journal of Biosystems Engineering
• /
• v.37 no.1
• /
• pp.28-35
• /
• 2012

Purpose: This study performed the oscillatory test using the texture analyzer to characterize the viscoelastic behavior of apples such as the storage modulus (E'), the loss modulus (E"), the complex modulus (${\mid}E^*{\mid}$) and the energy dissipated per cycle ($W_{diss}$). Methods: The sinusoidal deformation with the frequency of 1-10 Hz and the maximum displacement of 0.1 mm were applied to the flesh tissues of Fuji, Golden Delicious and Red Delicious apples. The Lissajous figure was used to measure the phase angle(${\delta}$) between stress and strain curve. Results: Trigger force was critical to the measurement of the phase angle. E', E", ${\mid}E^*{\mid}$ and Wdiss were measured using the Lissajous figure and the phase angle. The complex modulus of Golden Delicious apple was significantly lower than those of Fuji apple and Red Delicious apple. Conclusions: Apple flesh was exhibiting more elasticity at low frequency, and more viscosity at high frequency. Dynamic compressive properties of Fuji apple were similar to those of Red Delicious apple but significantly different from those of Golden Delicious apple.

• Computers and Concrete
• /
• v.9 no.5
• /
• pp.389-402
• /
• 2012

In this study, the modulus of elasticity of low, normal and high strength steel fiber reinforced concrete has been predicted by developing a fuzzy logic model. The fuzzy models were formed as simple rules using only linguistic variables. A fuzzy logic algorithm was devised for estimating the elastic modulus of SFRC from compressive strength. Fibers used in all of the mixes were made of steel, and they were in different volume fractions and aspect ratios. Fiber volume fractions of the concrete mixtures have changed between 0.25%-6%. The results of the proposed approach in this study were compared with the results of equations in standards and codes for elastic modulus of SFRC. Error estimation was also carried out for each approach. In the study, the lowest error deviation was obtained in proposed fuzzy logic approach. The fuzzy logic approach was rather useful to quickly and easily predict the elastic modulus of SFRC.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.38 no.4
• /
• pp.147-154
• /
• 1996

This study wag performed to evaluate the engineering properties of permeable polymer concrete with stone dust and fly ash and unsaturated polyester resin. The following conclusions were drawn. 1. The highest strength was achieved by stone dust filled permeable polymer concrete, it was increased 17% by compressive strength, 188% by bending strength than that of the normal cement concrete, respectively. 2. The water permeability was in the range of 3.O76~4.152${\ell}/ cm{^2}/h$, and it was largely dependent upon the mix design. These concrete can be used to the structures which need water permeability. 3. The static modulus of elasticity was in the range of $1.15{\times} 10^5kg/cm^2$, which was approximately 53 56% of that of the normal cement concrete. 4. The poisson's number of permeable polymer concrete was in the range of 5.106~5.833, which was less than that of the normal cement concrete. 5. The dynamic modulus of elasticity was in the range of $1.29{\times} 10^5~1.5{\times} 10^5 kg/cm^2$, which was approximately less compared to that of the normal cement concrete. Stone dust filled permeable polymer concrete was showed higher dynamic modulus. The dynamic modulus of elasticity were increased approximately 7~13% than that of the static modulus. 6. The compressive strength, bending strength, elastic modulus, poisson's ratio, longitudinal strain and horizontal strain were decreased with the increase of poisson's number and water permeability at those concrete.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.438-441
• /
• 2004

In this study, we investigated compressive characteristics of seawater-absorbed carbon-epoxy composite under hydrostatic pressure environment. The hydrostatic pressures applied were 0.1 MPa, 100 MPa, 200 MPa, and 270 MPa. The results showed that the compressive elastic modulus increased about 10 ％ as the hydrostatic pressure increased from 0.1 MPa to 200 MPa. The modulus increased 2.3 ％ more as the pressure increased to 270 MPa. Fracture strength and fracture strain increased with pressure in a linear fashion. Fracture strength increased 28 ％ and fracture strain increased 8.5 ％ as the hydrostatic pressure increased from 0.1 MPa to 270 MPa.

• Computers and Concrete
• /
• v.12 no.4
• /
• pp.377-392
• /
• 2013

This paper investigates prediction models estimating the hydration properties of concrete, such as the compressive strength, the splitting tensile strength, the elastic modulus,and the autogenous shrinkage. A prediction model is suggested on the basis of an equation that is formulated to predict the compressive strength. Based on the assumption that the apparent activation energy is a characteristic property of concrete, a prediction model for the compressive strength is applied to hydration-related properties. The hydration properties predicted by the model are compared with experimental results, and it is concluded that the prediction model properly estimates the splitting tensile strength, elastic modulus, and autogenous shrinkage as well as the compressive strength of concrete.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04b
• /
• pp.661-664
• /
• 1998

In this paper, the properties of inter-lacking block by the kind of aggregate and fineness modulus are investigated. According to the experimental results, compressive strength and flexural strength increase and absorption ratio decrease with larger fineness modulus in the range of 2.15~4.20. Flexural strength with river sand is higher than that with crushed sand by about 19%, compressive strength with river sand, that with crushed sand by about 11% and absorption ratio with river sand is smaller than that with crushed sand by abort 2%.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.10a
• /
• pp.159-163
• /
• 1995

The purpose of this experimental research is to not only devlop the high-strength concrete using sea and river sand, but also investigatc mechanical properites of the high-strength concrete, such as the elastic modulus, the compressive strength of concrete cyllinder, and etc. Also, rational analytical formula for elastic modulus has been proposed together with those for the splitting tensile strength and the flexural strength to be predicted from compressive strength of conccrete cyllinder.

• Computers and Concrete
• /
• v.20 no.4
• /
• pp.491-502
• /
• 2017

In this research, the application of ultrasonic pulse velocity (UPV) test as a nondestructive method for estimating some of the mechanical and dynamic properties of reactive powder concrete (RPC) containing steel and polyvinyl alcohol (PVA) fibers, as well as their combination was explored. In doing so, ten different mix designs were prepared in 19 experimental groups of specimens containing three different volume contents of steel fibers (i.e., 1, 2, and 3 %) and PVA fibers (i.e., 0.25, 0.5, and 0.75 %), as well as hybrid fibers (i.e., 0.25-0.75, 0.5-0.5, and 0.75-0.25 %). The specimens in these groups were prepared under the two curing regimes of normal and heat treatment. Moreover, the UPV test results were employed to estimate the compressive strength, dynamic modulus, shear modulus, and Poisson's ratio of the RPC concrete and to investigate the quality level of the used concrete. At the end, the effect of the specimen shape and in fact the measuring distance length on the UPV results was explored. The results of this research suggest that the steel fiber-containing RPC specimens demonstrate the highest level of ultrasonic pulse velocity as well as the highest values of the mechanical and dynamic properties. Moreover, heat treatment has a positive effect on the density, UPV, dynamic modulus, Poisson's ratio, and compressive strength of the RPC specimens, whereas it leads to a negligible increase or decrease in the shear modulus and static modulus of elasticity. Furthermore, the specimen shape affects the UPV of fiber-lacking specimens while negligibly affecting that of fiber-reinforced specimens.

• Journal of the Society of Disaster Information
• /
• v.15 no.2
• /
• pp.249-258
• /
• 2019

Purpose: The purpose of this study is to attain the correlation analysis and thereby to deduce the uniaxial compressive strength of rock specimens through the elastic wave velocity and the elastic modulus among the physical characteristics measured from the rock specimens collected during drilling investigations in Seoul and Gyeonggi region. Method: Experiments were conducted in the laboratory with 119 granite specimens in order to derive the correlation between the compressive strength of the rocks and elastic wave velocity and elastic modulus. Results: In the case of granite, the results of the analysis of the interaction between the compressive strength of a rock and the elastic wave velocity and elastic modulus were found to be less reliable in the relation equation as a whole. And it is believed that the estimation of the compressive strength by the elastic wave velocity and elastic modulus is less used because of the composition of non-homogeneous particles of granite. Conclusion: In this study, the analysis of correlation between the compressive strength of a rock and the elastic wave velocity and elastic modulus was performed with simple regression analysis and multiple regression analysis. The coefficient determination ($R^2$) of simple regression analysis was shown between 0.61 and 0.67. Multiple regression analysis was 0.71. Thus, using multiple regression analysis when estimating compressive strength can increase the reliability of the correlation. Also, in the future, a variety of statistical analysis techniques such as recovery analysis, and artificial neural network analysis, and big data analysis can lead to more reliable results when estimating the compressive sterength of a rock based on the elastic wave velocity and elastic modulus.