• Proceedings of the KSME Conference
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• 2004.11a
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• pp.319-324
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• 2004

In this study, the high strength and superior toughness spring steels as the suspension material, used for automobile and railroad industries were utilized to carry out the following investigations. Corrosion times were controlled in 7, 14, 30 and 60days to examine the relation between corrosion pit and compressive residual stress in the static corrosion environment after shot peened. And then corrosion current and corrosion potential were measured for every 24 hours to investigate the corrosion mechanism. Shot peened material shows the low or rate of corrosion current as compared with unpeened material. In case of peened material which has the highest residual stress, it has a low corrosion current density.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.665-670
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• 2000

In this study mechanical properties of various fiber reinforced permeability concrete mixtures are investigated. Several mixes with fiber kinds(steel fiber, polyprophylen fiber, carbon fiber) and different fiber content(steel fiber : 0.3~0.9vol.%, polyprophylen fiber : 0.1~0.5vol.%, carbon fiber : 0.2~0.7vol.%) were studied. Test results are presented in terms of compressive strength, tensile-flexural strength and load-deflection behavior. The effect of fiber reinforcement does not increase the compressive strength of permeability concrete without fiber. Also, the tensile-flexural strength using various fibers are appeared good strength increase as conventional fiber reinforced concrete. Therefore, use of fiber for permeability concrete is necessary to improve of tensile-flexural properties and deformation performance(toughness).

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.192-197
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• 1996

An experimental study was performed to examine the feasibility of using silicic wastes as construction materials for civil structures, and investigate its utility as a replacement for the favored nature resource to prevent the economic loss. In order to achieve this objective, mechnical properties of concrete containing silicic wastes is tested by investigating the strength development through parameters of water-binder ratios replacement 10 percent ratio with respect to curting conditions. The effect of stringth development is investigated for curing conditions when silicic wastes of 10 percent of cement-binder ratios is containde. Comparision on compressive strength of normal concrete and concrete containing silicic wastes at 28 day is conducted. The concrete with silicic wastes have larger compressive strength than of normal concrete by about 20 percent, when cured at 80 degree. The wastes concrete using silica sand shows increased strength, fracture toughness, elastic modulus and strain than the normal concrete, although the silicic wastes concrete could be able to satisfy the generally required strength for conventional concrete structures.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.30-35
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• 1996

Accumulations of worn-out automobile tires creat fire and health hazards. As a possible solution to the problem of scrap-tire disposal, an experimental study was conducted to examine the potential of using tire chips as aggregate in rubber mortar. This paper examines strength and toughness properties of rubber mortar in which different amounts of rubber-tire particles of several sizes were used as aggregate. The rubber mortar mixtures exhibited lower compressive, bending, tensile than did normal mortar. However, these mixtures did not demonstrate brittle failure, but rather a ductile, plastic failure, and had the ability to absorb a large amount of plastic energy under compressive loads.

• Advances in materials Research
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• v.5 no.3
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• pp.171-179
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• 2016

Fusion and characterization of bisphenol-A diglycidyl ether based thermosetting polymer mortars containing an epoxy resin, Fly ash and Rock sand are presented here for the Experimental study. The specimens have been prepared by means of an innovative process, in mild conditions, of commercial epoxy resin, Fly ash and Rock sand based paste. In this way, thermosetting based hybrid mortars characterized by a different content of normalized Fly ash and Rock sand by a homogeneous dispersion of the resin have been obtained. Once hardened, these new composite materials show improved compressive strength and toughness in respect to both the Fly ash and the Rock sand pastes since the Resin provides a more cohesive microstructure, with a reduced amount of micro cracks. The micro structural characterization allows pointing out the presence of an Interfacial Transition Zone similar to that observed in cement based mortars. A correlation between micro-structural features and mechanical properties of the mortar has also been studied.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.115-127
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• 2014

Addition of fibers in cement or cement concrete may be of current interest, but this is not a new idea or concept. Fibers of any material and shape play an important role in improving the strength and deformation characteristics of the cement matrix in which they are incorporated. The new concept and technology reveal that the engineering advantages of adding fibers in concrete may improve the fracture toughness, fatigue resistance, impact resistance, flexural strength, compressive strength, thermal crack resistance, rebound loss, and so on. The magnitude of the improvement depends upon both the amount and the type of fibers used. In this paper, locally available waste fibers such as coir fibers, sisal fibers and polypropylene fibers have incorporated in concrete with varying percentages and l/d ratio and their effect on compressive, split, flexural, bond and impact resistance have been reported.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.44-50
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• 1996

Accumulation of worn-out automobile tires creat fire and health hazards. As a possible solution to the problem of scrap-tire disposal, an experimental study was conducted to examine the potential of using tire chips as aggregate in Railroad block. This paper examines strength and toughness properties of Railroad block in which different amounts of rubber-tire particles of several sizes were used as aggregate. The Railroad block mixtures exhibited lower compressive, bending than did normal block. However, these mixtures did not demonstrate brittle failure, but rather a ductile, plastic failure, and had the ability to absorb a large amount of plastic energy under compressive loads.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.308-314
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• 1997

Shrinkage and creep are the fundamental properties of concrete. These long term deformations can be seen as bothersome(increased deflection) or can be seen as reduction of compressive stress of prestressed concrete. Steel fibers advance the mechanical properties of concrete:tensile strength, ductility, flexural strength, fracture toughness, and post-cracking resistance, etc...Silica fume is pozzolanic material which combines with hydrated lime to generate silicate materials which increase the compressive strength and reduce somewhat the creep of concrete. This paper is the result of the long-term deformation by silica fume and steel fibers with varying percentages.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.657-660
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• 2006

HPFRCCs(High performance fiber reinforced cementitious composites) exhibit characteristics of strain harding and multiple crack. These lead to improvement in ductility, toughness, and deformation capacity under compressive and tensile stress. These properties of HPFRCCs are affected by type of fiber, size of sand. Furthermore these influence compress strength and flexural strength. Therefore experimental study on the mechanical properties of HPFRCCs using PVA fiber was carried out. In this paper, HPFRCCs made of PVA fiber were tested with size of sand, strength of concrete to evaluate characteristics of compressive strength and flexural strength.

• Computers and Concrete
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• v.32 no.6
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• pp.577-594
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• 2023

Engineered cementitious composites with calcined clay limestone cement (LC³-ECC) as a kind of green, low-carbon and high toughness concrete, has recently received significant investigation. However, the complicated relationship between potential influential factors and LC³-ECC compressive strength makes the prediction of LC³-ECC compressive strength difficult. Regarding this, the machine learning-based prediction models for the compressive strength of LC³-ECC concrete is firstly proposed and developed. Models combine three novel meta-heuristic algorithms (golden jackal optimization algorithm, butterfly optimization algorithm and whale optimization algorithm) with support vector regression (SVR) to improve the accuracy of prediction. A new dataset about LC³-ECC compressive strength was integrated based on 156 data from previous studies and used to develop the SVR-based models. Thirteen potential factors affecting the compressive strength of LC³-ECC were comprehensively considered in the model. The results show all hybrid SVR prediction models can reach the Coefficient of determination (R²) above 0.95 for the testing set and 0.97 for the training set. Radar and Taylor plots also show better overall prediction performance of the hybrid SVR models than several traditional machine learning techniques, which confirms the superiority of the three proposed methods. The successful development of this predictive model can provide scientific guidance for LC³-ECC materials and further apply to such low-carbon, sustainable cement-based materials.