• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.3
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• pp.41-49
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• 2015

The repair of manhole raise has been caused much construction times and disruption of traffic flow, serious environmental pollution from crushed construction wastes, and budget waste due to the repeated repair construction works. In order to overcome such problems, we have developed the new manhole repairing composite structures by using a glass fiber-reinforced polymer (GFRP) pipe, which can raise manhole to the regular height of the overlayed road pavement with rapid construction and minimum traffic jams. This environmental-friendly technology is method completed by the methyl methacrylate monomer (MMA) double wide flanged GFRP pipe composite structures in order to raise manhole to the regular height. In this paper, two kinds of the compressive strength tests of MMA mortar composites were conducted and evaluated by a general compressive strength test, and compressive strength test after freezing-thawing resistance test. It was found that this MMA mortar composites will be used for the application of the double wide flanged GFRP pipe composite structures.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.653-660
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• 2008

The purpose of this study is to analyze the optimal mix design of the sound absorption material that is made from perlite and various binder systems for noise barrier wall. The polymer cement slurry which is made from two types of polymer dispersions, and silicone type inorganic material are used as binder. The test specimens are prepared with various polymer cement ratios, binder ratios, and tested for strengths, freezing and thawing and sound absorption performance by the tube and the reverberation room methods. From the test results, the difference of sound absorption coefficient by the tube method is a little recognized, however, noise reduction coefficient (NRC) of test specimens bound by the polymer cement slurry is in the ranges of 0.48 to 0.51. They are a little higher than those bound by cement only, and are lower values than recommended value of 0.7 by the Ministry of Environment. However, the sound absorption coefficient of test specimens at low frequency range of 250 to 500 Hz by reverberation room method shows very high values as 0.84 to 1.00, and 0.57 to 0.77 at the high frequency. The test specimens with polymer cement slurry binder have a good balance between performance and cost, and have proper properties in strengths, freezing and thawing resistance as sound absorption material for noise barrier wall. It is apparent that the good sound absorption material can be produced according to the optimum mix design that is recommended from this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.22-29
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• 2015

In this study, we tested to develop and apply structural insulation performance improvement concrete to field, which had compressive strength in 24 MPa and thermal conductivity twice as much as normal concrete. After experiment about slump and air contents, combination product of Plain and calcined diatomite powder showed reduction of slump and air contents and combination product with micro foam cell admixture, we cannot find result of slump and air contents reduction. Unit weight of combination product with insulation performance improvement materials decreased more than that of Plain. In the test of compressive strength, compressive strength of insulation performance improvement concrete decreased more than that of Plain but was content with 24 MPa. thermal conductivity of insulation performance improvement concrete tended to decrease. Freezing and thawing resistance of insulation performance improvement concrete was similar to that of Plain. In carbonation resistance test, combination product with calcined diatomite powder showed the result which was similar to that of Plain. In carbonation resistance test, combination product with micro foam cell admixture showed a increase compared to that of Plain and length variation of combination product generally increased.

• Geomechanics and Engineering
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• v.34 no.1
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• pp.51-67
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• 2023

In this research, the degradation rate of physical properties of the Angouran pit bedrock (calc-schist) is first investigated under the specific numbers of freeze-thaw (F-T) cycles. Then, the durability of calc-schist specimens against the F-T cycle number (N) is examined considering the mechanical parameters, and using the decay function and half-time techniques. For this purpose, point load strength (I_S(50)), second durability index (I_d2), Brazilian tensile strength (BTS), and compressive (V_P) and shear (V_S) wave velocities of calc-schist specimens are measured after 0, 7, 15, 40, and 75 N. For comparing the degradation rate of mechanical properties of available rock types on the Angouran mine walls, these tests are also carried out on the limestone and amphibolite schist specimens beside the calc-schist. According to test results, the exponential regression models are developed between the mechanical parameters of rock specimen's and N variable. Also, the long-term durability of each rock type versus N is studied using the decay function and half-time techniques. Results indicated that the degradation rate differs for the above rock types in which amphibolite schist and calc-schist specimens have the highest and least resistance against the N, respectively. The obtained results from this study can play a key role in the optimal design of the mine's final walls.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.5
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• pp.23-30
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• 2007

This research was to evaluate the shrinkage and durability performance of latex modified repair mortar and to improve the service lift of the agricultural concrete structures. The shrinkage characteristics of the repair material creates the delamination of repair materials and existing concrete. It may reduce the service life of structures. Also the reduction of durability performance of the repair materials induces the destruction of the repaired concrete structures at early stage. In this research, plastic and drying shrinkage, thermal expansion coefficient for shrinkage properties, durability performance, permeability, repeated freezing and thawing, and resistance of chemical solution test were performed. Test results showed that the latex modified repair mortar indicated the shrinkage amount which the delamination does not happen, and the latex modified repair mortar appeared excellent long-term durability performance which can increase the service life.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.227-232
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• 2002

To evaluate the practical application of oyster shells as construction materials, an experimental study was performed. More specifically, the long-term mechanical properties and durability of concrete blended with oyster shells were investigated. Test results indicate that long-term strength of concrete blended with 10% oyster shells is almost identical to that of normal concrete. However, the long-term strength of concrete blended with 20% oyster shells Is appreciably lower than that of normal concrete. 1'hereby, concrete with higher oyster shell has the possibility giving a bad influence on the concrete long-term strength. Elastic modulus of concrete blended with crushed oyster shells decreases as the blending mixture ratio increases. Namely, the modulus is reduced by approximately 10∼15% when oyster shells are blended up to 20% replacing the fine aggregate. The drying shrinkage strain increases as the blending ratio increases. In addition, the existing model code of drying shrinkage does not coincide with the test results of this study. An adequate prediction equation needs to be developed. The utilization of oyster shells as the fine aggregate in concrete has an insignificant effect on freezing and thawing resistance, carbonation and sulfuric acid attack of concrete recycling. However, water permeability is considerably improved.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.87-92
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• 2010

This study evaluates the laboratory properties of asphalt binder and mixture modified with R-EPDM(Recycling Ethylene Propylene Dien Monometer), which consists of R-EPDM as a main ingredient that is an industrial by-product made by manufacturing waste EPDM below 50 mesh as an additive. Superpave system was used to determine the PG(Performane Grade) and evaluate the property of R-EPDM modified binder. OACs(Optimum Asphalt Contents) of R-EPDM modified asphalt mixtures were determined by Superpave mix design using gyratory compactor and wheel tracking test and moisture susceptibility test were carried out with R-EPDM modified asphalt mixtures at OACs. The results from these tests, rutting-resistance and freezing and thawing resistance by moisture susceptibility of R-EPDM modified asphalt mixtures were superior to one of general asphalt mixtures(AP-5).

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.77-87
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• 2015

PURPOSES: It is theoretically well known all over the world, that porous hot mixed asphalt (HMA) with hydrated Lime improves moisture and rutting resistance, and reduces pothole occurrence frequency, as well as the life cycle cost (LCC). METHODS : Addictive in the two different formations of the liquid anti-stripping Agent and powder Hydrated-Lime was applied in this investigation in order to obtain relatively clear results according to their types and conditions. Firstly, the moisture conditions were set, and applied to the porous HMA mixtures with hydrated lime (anti-stripping agent). Next, it was followed by a non-destructive test with the application of three freeze-thaw cycles, which were individually carried out thrice to compare the results of the dynamic moduli. Lastly, the hydrated lime effect related to moisture sensibility to porous HMA has been verified through the analysis of the modulus results regarding the change rate of dynamic modulus per n-cycle. RESULTS: It is clear from this investigation, that the dynamic modulus is inversely proportional to the change in temperature, as the graph representing the rigidity of the thermorheologically simple (TRS) material showed gradual decline of the dynamic modulus with the increase in temperature. CONCLUSIONS: The porous HMA mixture with the anti-stripping agent (hydrated Lime) has been found to be more moisture resistant to freezing and thawing than the normal porous HMA mixture. It is clear that the hydrated lime helps the HMA mixture to improve its fatigue resistance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.489-495
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• 2016

In this study, the Warm-Mix Asphalt was prepared using a modified Sulfur Binder mixed with an additive of a polymer component in sulfur, which is an industrial by-product generated in the crude oil refining process. The dynamic stability and durability characteristics of the prepared Warm-Mix Asphalt was evaluated by the indirect tensile strength, the tensile strength ratio before and after water immersion and freezing-thawing, and the dynamic stability by wheel tracking test. The Warm-Mix Asphalt Mixtures using Modified Sulfur Binder has a tensile strength ratio before and after water immersion of 0.88, which is about 1.13 times that of the Warm-Mix formed modified Asphalt, and the tensile strength ration before and after freezing-thawing is also 0.82, thus, all tensile strength ratios satisfied the KS quality standard value of 0.75 or more. The indirect tensile strength was 1.6MPa which was twice the KS quality standard value of 0.8MPa, and about 1.24 times higher than that of normal heated asphalt 1.29MPa. In addition, the dynamic stability by the wheel tracking test was 14,075 times/mm, which was about 15 times higher than that of normal heated asphalt and about 3 times higher than that of the Warm-Mix formed modified Asphalt, showing excellent resistance to plastic deformation such as fatigue cracks.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1273-1278
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• 2007

The cement-asphalt mortar is a mixture of cement and asphalt emulsion, and is utilized as a underpouring materials for the railway track which is used to fill under slab panel space so as to provide a stabilized track support and a tool for reduction of noise and vibration. To increase the workability of grouting, this study investigates the effect of temperature on cement-asphalt mortar by analyzing its physical and mechanical properties before/after hardening according to the temperature (10, 15, 20, 25, $30^{\circ}C$). According to the test results, it is found that as for the physical property of fresh cement-asphalt mortar the more mixture temperature become higher or lower, the more fluidity become worse. But by increasing reducing agent amount and its unit quantity, the required fluidity is met. The compressive strength as physical property of hardened cement-asphalt mortar become lower when temperature is lower but taking it by and large the physical properties of cement-asphalt mortar before/after hardening aren't so affected by temperature and well satisfy the requirement. And it has proved that rate of expansion and freezing and thawing resistance aren't affected by temperature.