• International Journal of Highway Engineering
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• v.19 no.5
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• pp.33-42
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• 2017

PURPOSES : The purpose of this study is to suggest the construction and quality control method for the re-repair of a deteriorated partial depth repair for sections of Portland cement concrete pavement. METHODS : An experimental construction was conducted to extend the repair width for removing an existing repair section. A removal method was used to ensure early performance for a deteriorated partial depth repair section. Bond strength and split tensile strength were measured at the near vertical interface layer between the existing pavement and repair material. The area was analyzed for various conditions such as the extended repair area and the removing method of the existing repair section. RESULTS : As a result of analysis of bond strength and split tensile strength, the bonding performance of a milling removed section was improved over a cutting and hand breaker removed section. The bond strength was analyzed to increase slightly as the extended repair width for removing the existing repair section increased. The split tensile strength did not show a clear relationship to an increased extended repair width of an existing removed repair section. CONCLUSIONS : The milling removal method should be applied in the removal of existing deteriorated partial depth repair sections. The extended repair width for a re-repair section should be wider than the existing partial depth repair with at least a 75-mm length and width for the bond strength and the split tensile strength.

• International Journal of Highway Engineering
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• v.4 no.3 s.13
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• pp.15-23
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• 2002

The waterproofing system's performance is known to show a determing by complex interaction of material factors, design details, and the quality of construction, and the waterproofing integrity of waterproofing membranes is determined by the bond to the deck and the amount of damage to the waterproofing membrane. In this research, the basic properties of waterproofing membranes on market and the tensile adhesive chracteristics of waterproofing systems of concrete bridge deck have also been investigated in the view of the damages frequently reported from job site. For the tensile adhesive strength of sheet waterproofing membranes, the results after asphalt concrete paving tends to increase more than before those. The results of the liquid waterproofing membranes are upside-down, and the more concrete has strength, the more strength of tensile adhesive increase. The ambient temperature of asphalt concrete when application of the waterproofing membrane has considerable influence on the performance of waterproofing system. As described above, waterproofing system can be influenced by several factors. If they are not considered under construction, the overlooking will cause the damages of pavement and waterproofing system after traffic opening.

• Polymer(Korea)
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• v.33 no.6
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• pp.520-524
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• 2009

The effects of oxidative degradation on the performance of crosslinked polyethylene pipes were analyzed by the investigation of tensile properties and chemical structure change of the pipes during oxidative degradation. Annealing at high temperatures or UV irradiation method was used to induce the oxidative degradation of the crosslinked polyethylene pipes and the effects of the die temperature on the oxidative degradation of the pipes were also investigated. The tensile properties and chemical structure change of the pipes were investigated by universal testing machine and FT-IR, respectively. With the progress of thermo-oxidative degradation the tensile strength of the pipes slowly decreased but the elongation at break rapidly decreased, and the chemical structure of the pipes also changed considerably because of the introduced oxygen molecules. These results would be useful in estimating the performance deterioration of the crosslinked polyethylene pipes due to the oxidative degradation during production and storage.

• Journal of the Korean Society of Clothing and Textiles
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• v.47 no.2
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• pp.311-322
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• 2023

In this study, the properties of various material combinations were evaluated and an ideal material for fabricating protection pads for women's army combat uniforms was determined. Eight specimens were used for the evaluation: two types of materials, namely thermoplastic polyurethane for 3D printing, T and ethylene-vinyl acetate, E; two infill densities, namely 10%, 10 and 30%, 30; two types of pad designs, i.e., without holes, A and with holes, B; 2×2×2=8 and control E. The tensile strength, flexural strength, impact absorption, and weight of these specimens were evaluated. Results revealed that E was the most flexible material; however, its tensile strength and impact absorption were very low. Protection pads made from T (T-10A, T-10B, T-30A, and T-30B) had excellent tensile strength and impact absorption; however, they had low performance in ease of movement. Alternatively, protection pad with holes and an infill density of 30% produced using a combination of T and E had a high initial tensile modulus and exhibited excellent impact absorption. Moreover, it was flexible and light, which satisfies the standards and conditions required by protection pads. However, if T-E-10A and T-E-30B exhibited low impact absorption, as required, they can be regarded as appropriate materials for protection pads.

• Computers and Concrete
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• v.19 no.6
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• pp.667-675
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• 2017

One of the main disadvantages of Ultra High Performance Concrete exists in the large suggested value of UHPC ingredients. The purpose of this study was to find the models mechanical properties which included a 7, 14 and 28-day compressive strength test, a 28-day splitting tensile and modulus of rupture test for Ultra High Performance Concrete, as well as, a study on the interaction and correlation of five variables that includes silica fume amount (SF), cement 42.5 amount, steel fiber amount, superplasticizer amount (SP), and w/c mechanical properties of UHPC. The response surface methodology was analyzed between the variables and responses. The relationships and mathematical models in terms of coded variables were established by ANOVA. The validity of models were checked by experimental values. The offered models are valid for mixes with the fraction proportion of fine aggregate as; 0.70-1.30 cement amount, 0.15-0.30 silica fume, 0.04-0.08 superplasticizer, 0.10-0.20 steel fiber, and 0.18-0.32 water binder ratio.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.162-165
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• 2006

I-section prestressed concrete(I-PC) beam crack due to low tensile strength, may decrease rigidity and structural performance by excessive deflection. In an effort to this problem, in this research, I-section prestressed dual concrete(I-PDC) beam has been proposed, consisting of normal strength concrete in compression zone, and high performance steel fiber reinforced concrete(HPSFRC) with a bottom flange depth in tensile zone. Crack formation and its propagation are controlled by the HPSFRC in I-PDC beam. The initial cracking and service limit loads are increased along with the load carrying capacity and flexural stiffness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.127-131
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• 2008

This paper deals with the performance evaluation of piezoelectric unimorph actuator. In the unimorph design, the thickness ratio of substrate to piezoelectric material and the elastic modulus ratio of substrate to piezoelectric material are important parameters. There exists only one structural configuration that satisfies the optimal condition among them, and actuators using that configuration exhibit better actuating displacements. Another design parameter is the piezoelectric coefficient which can be improved due to the induced tensile stress and voltages. The application of the tensile stress to the piezoelectric material makes it get higher piezoelectric coefficient and the total displacement performance of the unimorph actuator is improved. Finally, the piezoelectric actuator system with spring elements is fabricated and it shows higher actuating displacement capability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.28-29
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• 2016

Recently, the attention on high tensile, and high performance cementitious composite (HPFRCC) which can minimize the damage from explosion of inflammable gas and chemicals has been increased. In spite of outstanding tensile performance, HPFRCC has the drawbacks of fiber ball, undesirable cost, and high autogenous shrinkage. therefore, in this research, to develop the optimum HPFRCC, the fundamental properties and autogenous shrinkage of HPFRCC was analyzed depending on various combination and content of organic and inorganic fibers.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.147-148
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• 2018

Seat waterproofing materials applied to the roof of a building concrete structure inevitably produce joints and are applied with opposite dam joints or overlapping joints depending on the waterproof material applied to the top of the sheet. In this case, the joint performance is determined by the material at the top, rather than by the superimposed joint. In order to solve this problem, various reinforcements have been used to apply to the connecting parts of the opposite dam, but the problem of attachment between different materials or the lack of reinforcement of the joint tape has not been solved. Therefore, for the purpose of securing tensile performance to the joints, this study is used as a reinforcement for the joints of PP materials with high tensile performance and as a reinforcement for nylon materials.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.63-64
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• 2014

In this study, we has a purpose to estimate the joint movement responsiveness performance for the domestic products of one-component structural silicon sealants. For this purpose, we make a comparative study for the four domestic products focused on tensile properties after allowed the cyclic-movements for three days at initial step of curing phase. A joint movement range ±10% and the rate of compression and extension 3.2mm/h were assumed in those tests. As a result, the large space were induced inside the sealant by rupture, and then adhesion and cohesion failures were caused by stress concentration. The tensile properties were reduced by 15~60% in comparison with physical properties. In this case, the generating defect was caused and the service-life was decreased. Thus, further researches as relationship of test condition and products properties on this behavior would be studied.