• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.93-101
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• 2010

The purpose of this study is to provide basic data for utilization in environment-friendly and economically outstanding CSG construction method by physical and mechanical properties of CSG materials including characteristics of uniaxial compressive strength, microscopic structure and freezing and thawing resistance in accordance with the cement content and curing time of the cement, and size of specimen. In this study, specimens with cement content of 4, 6, 8 and 10% of the total weight were, and, in order to examine the characteristics of the sizes of specimen, specimens with ${\Phi}50{\times}100mm$, ${\Phi}100{\times}200mm$ and ${\Phi}150{\times}300mm$ were manufactured to assess the features including compressive strength, microscopic structure, freezing and thawing, and degree of wet-dry. As results, it was found that with greater size specimen or contents of cement in the specimen, compressive strength, freezing and thawing resistance, and wet-dry resistance increase. Moreover, reactive products for each size of specimen were examined and it was possible to verify that some typical needle structured ettringite was generated due to blending of cement through microscopic structure analysis such as SEM and EDS analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.29-32
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• 2004

An experimental investigation of the behavior of steel cords(SC) and SC and Polyethylene(PE) hybrid fiber reinforced cementitious material under compressive and tensile loading is presented. In this experimental research, the tensile and compressive strength and strain capacity of high performance fiber-reinforced cementitious composites(HPFRCC) were selected using the cylindrical specimens. Uniaxial compressive and tensile tests have also been carried out at varying strain rates to better understand the behavior of. HPFRCC and propose the standard loading rate for compressive and tensile tests of new HPFRCC materials. The results show that there is a substantial increase in the ultimate compressive and tensile strength with increasing strain rate.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.1
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• pp.15-22
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• 2020

Understanding the strength characteristics of model ice is an important issue for model testing in an ice model basin to estimate the ship performance in ice. In particular, the mechanical properties of the model ice including elastic modulus, flexural strength and compressive strength are key consideration factors. In order to understand the characteristics of the model ice during warm-up phase at KRISO's ice model basin, the strength properties are tested in this study. The infinite plate-bending method, in-situ cantilever beam test and ex-situ uniaxial compressive test are conducted to determine the strength properties of model ice. The strength characteristics of the model ice are then analyzed in terms of the warm-up phase and seasonality. These results could be valuable to quality control of the model ice characteristics in KRISO's ice model basin and to better understand the variations in strength properties during the ice model tests.

• Geomechanics and Engineering
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• v.13 no.3
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• pp.371-384
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• 2017

Physical and mechanical properties of rocks are of interest in many fields, including materials science, petrophysics, geophysics and geotechnical engineering. Uniaxial compressive strength UCS is one of the key mechanical properties, while density and porosity are important physical parameters for the characterization of rocks. The economic interest of carbonate rocks is very important in chemical or biological procedures and in the field of construction. Carbonate rocks exploitation depends on their quality and their physical, chemical and geotechnical characteristics. A fast, economic and reliable technique would be an evolutionary advance in the exploration of carbonate rocks. This paper discusses the ability of ultrasonic wave velocity to evaluate some mechanical and physical parameters within carbonate rocks (collected from different regions within Tunisia). The ultrasonic technique was used to establish empirical correlations allowing the estimation of UCS values, the density and the porosity of carbonate rocks. The results illustrated the behavior of ultrasonic pulse velocity as a function of the applied stress. The main output of the work is the confirmation that ultrasonic velocity can be effectively used as a simple and economical non-destructive method for a preliminary prediction of mechanical behavior and physical properties of rocks.

• Economic and Environmental Geology
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• v.21 no.4
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• pp.359-365
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• 1988

Extensive sets of data on the mechanical properties of more than 1000 granite specimens were analyzed to derive the relationships of the various properties: those are, (1) density, (2) porosity, (3) absorption ratio, (4) sonic wave velocity, (5) uniaxial compressive strength, (6) tensile strength, and (7) dynamic & static Young's moduli. The results will be of use to understand the mechanical characteristics of granites and some unknown properties can be estimated from the others. The various equations derived from the least square regression analysis and a brief description of the correlations are presented in this paper.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.273-285
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• 2004

The mechanical properties of the Cretaceous tuff distributed in the Goheung area were measured in the laboratory. Tuff (Goehung tuff and Palyeongsan welded tuff) in the study area is classified into vitric tuff with regard to its composition. The specific gravity, the dry density, the water content, the porosity and absorption ratio in tuffs of the study area are 2.51, $2.52(g/cm^2)$, 0.12($\%$), 4.51($\%$) and 1.91($\%$) in means, respectively. In the tuffs, dry densities are in inverse Proportion to Porosities, and absorption ratios are highly proportional with Porosities. The uniaxial compressive strengths(UCS) in the tuffs ranges from 80.4 to 208(MPa) and the average of the strength is 141.1(MPa). According to the engineering classification of intact rock (Deere & Miller, 1966), the tuffs are assigned to the high strength rocks. The point load strength index ($Is_a$) in axial test is 4.2(MPa) on the average, and the point load strength index ($Is_d$) in diametral test is 2.2(MPa) in mean, and the point load strength anisotrophic index($Ia_{(50)}$) by the ratio of $Is_a$ to $Is_d$ is 1.93. There is close linear correlation between the uniaxial compressive strength and point load strength index, and the equation representing the correlation is postulated as follows : UCS = 22 $Is_{(50)}$ +49 (MPa) (r=0.95). It is considered that this equation is a useful tool to estimate UCS for tuff in Goheung area.

• Steel and Composite Structures
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• v.49 no.6
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• pp.645-666
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• 2023

Due to the steadily declining supply of natural coarse aggregates, the concrete industry has shifted to substituting coarse aggregates generated from byproducts and industrial waste. Oil palm shell is a substantial waste product created during the production of palm oil (OPS). When considering the usage of OPSC, building engineers must consider its uniaxial compressive strength (UCS). Obtaining UCS is expensive and time-consuming, machine learning may help. This research established five innovative hybrid AI algorithms to predict UCS. Aquila optimizer (AO) is used with methods to discover optimum model parameters. Considered models are artificial neural network (AO - ANN), adaptive neuro-fuzzy inference system (AO - ANFIS), support vector regression (AO - SVR), random forest (AO - RF), and extreme gradient boosting (AO - XGB). To achieve this goal, a dataset of OPS-produced concrete specimens was compiled. The outputs depict that all five developed models have justifiable accuracy in UCS estimation process, showing the remarkable correlation between measured and estimated UCS and models' usefulness. All in all, findings depict that the proposed AO - XGB model performed more suitable than others in predicting UCS of OPSC (with R², RMSE, MAE, VAF and A_15-index at 0.9678, 1.4595, 1.1527, 97.6469, and 0.9077). The proposed model could be utilized in construction engineering to ensure enough mechanical workability of lightweight concrete and permit its safe usage for construction aims.

• Computers and Concrete
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• v.22 no.5
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• pp.469-479
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• 2018

The Brazilian tensile strength of concrete samples is a key parameter in fracture mechanics since it may significantly change the quality of concrete materials and their mechanical behaviors. It is well known that porosity is one of the most often used physical indices to predict concrete mechanical properties. In the present work the influence of porosity shape on concrete tensile strength characteristics is studied, using a bonded particle model. Firstly numerical model was calibrated by Brazilian experimental results and uniaxial test out puts. Secondly, Brazilian models consisting various pore shapes were simulated and numerically tested at a constant speed of 0.016 mm/s. The results show that pore shape has important effects on the failure pattern. It is shown that the pore shape may play an important role in the cracks initiation and propagation during the loading process which in turn influence on the tensile strength of the concrete samples. It has also been shown that the pore size mainly affects the ratio of uniaxial compressive strength to that of the tensile one in the simulated material samples.

• Geomechanics and Engineering
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• v.22 no.5
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• pp.461-473
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• 2020

Natural rock mass contains defects of different shapes, usually filled with inclusions such as clay or gravel. The presence of inclusions affects the failure characteristics and mechanical properties of rock mass. In this study, the strength and failure characteristics of rock with inclusions were studied using the particle flow code under uniaxial compression. The results show that the presence of inclusions not only improves the mechanical properties of rock with defects but also increases the bearing capacity of rock. Circular inclusion has the most obvious effect on improving model strength. The inclusions affect the stress distribution, development of initial crack, change in crack propagation characteristics, and failure mode of rock. In defect models, concentration area of the maximum tensile stress is generated at the top and bottom of defect, and the maximum compressive stress is distributed on the left and right sides of defect. In filled models, the tensile stress and compressive stress are uniformly distributed. Failing mode of defect models is mainly tensile failure, while that of filled models is mainly shear failure.

• Tunnel and Underground Space
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• v.28 no.2
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• pp.156-169
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• 2018

The relationship between the mechanical and textural properties of sedimentary rocks has been studied for decades. However, inconsistencies in the results have arisen from both the inhomogeneity of natural rocks and the difficulties encountered in controlling just one textural factor of interest in each experiment. This work produced artificial sedimentary rocks to enable control of every independent parameter at all times. Their homogeneity lowered the deviation of the results, and thus they produced clearer correlations than for natural rocks. The samples were made by mixing bassanite powder with water and silica sand, which produced rocks consisting of sand and gypsum cement. The effect of grain content and size on mechanical properties such as uniaxial compressive strength, Young's modulus, and seismic velocity was estimated. Increasing grain content lowered the compressive strength but raised Young's modulus and seismic velocity. Overall, grain size did not linearly affect the mechanical properties of the samples, but affected them in some way. In future, these results can be compared and integrated with similar experiments using different cement or grain types. This should allow comparison of the effects of the rock constituents themselves and their interactions, with applicability to all kinds of sedimentary rocks.