• Journal of the Korean Institute of Educational Facilities
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• v.19 no.5
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• pp.29-36
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• 2012

The goals of this study are to develop a sprayable strain-hardening cement composite (SHCC) and to investigate the potential of the sprayable SHCC for packing the joint between existing R/C building and seismic retrofit elements. This paper provides the procedure for the development of a sprayable SHCC, test results of fresh properties required to a sprayable SHCC, and mock-up test results of developed sprayable SHCC. Control mixture of polyvinyl alcohol (PVA) fiber-reinforced SHCC (PVA-SHCC) was predetermined based on available research results. The pumpability and sprayability of the SHCC mixture were depended on the fluid property of fresh SHCC mixture. In this study, the effects of admixtures such as AE agent and fly ash on the rheological and rebound properties of control SHCC mixture were investigated to determine a sprayable SHCC mixture. Flow values and air content during shotcreting procedure of sprayable SHCC were also evaluated. The results show that flow or flowability and amount of air of three SHCC mixtures decreased almost linearly according to shotcreting procedure from mixer to nozzle. And the pumpability and sprayability of mixture with AE agent and low amounts of fly ash were superior to the those of SHCC. Mock-up test result show that developed sprayable SHCC indicates much improved workability and shotcrete construction period than conventional method(nonshrinkage mortar).

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.189-197
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• 2018

A sprayable waterproofing membrane which has relatively high adhesive property onto concrete enables faster construction with better waterproof performance compared with a conventional sheet membrane. However, the sprayable waterproofing membrane is a recently developed material and its performance and behavior with structures are not sufficiently reported. Therefore, in this study, the shear behavior of sprayable waterproofing membrane was numerically analyzed using the results of previous studies of composite shotcrete with sprayable waterproofing membrane. From the previous study, shear behavior of shotcrete with sprayable waterproofing membrane was different from shotcrete case and there was a limitation to express the behavior of the interface in general shear strength method. Therefore, in this study, the direct shear test was numerically simulated using two contact models, and then the best suitable method to express the shear behavior of the sprayable waterproofing membrane was suggested.

• Tunnel and Underground Space
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• v.26 no.3
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• pp.212-219
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• 2016

The sprayable waterproofing membrane is installed between shotcrete to provide crack bridging and hence prevent flow of liquid water as a waterproofing system. Because of its material characteristics, the sprayable membrane can be constructed at more complex structure than sheet membrane. The main component of the sprayable waterproofing membrane is a polymer-based material, therefore, moisture can migrate through sprayable waterproofing membrane materials by capillary and vapor diffusion mechanisms. The moisture transport mechanisms can have an influence on the degree of saturation and may influence the pore pressure and risk of freeze-thaw damage on concrete linings and membrane. In this study, long-term hygrothermal behavior was simulated with considering moisture transport and long-term effects on saturation of tunnel linings. From the simulation, due to water absorption and vapor transport properties of sprayable membrane, change of relative humidity and water content in tunnel lining can be evaluated.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.93-102
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• 2018

A sprayable waterproofing membrane which is composed of polymer-based material is relatively easy to install due to its construction method comparing with sheet-type membranes. And a sprayable waterproofing membrane has very similar material composition to the TSL which is for a permanent support. In this study, material composition of the sprayable waterproofing membrane was changed to enhance structural properties of membrane while maintaining waterproofing performance. In order to compare with a previous research for the TSL, series of tests were performed according to the performance criteria used for permanent support material (TSL) by EFNARC (2008). From the test result, the structural performance of the sprayable waterproofing membrane considered in this study showed a performance that could be used as a permanent support material.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.557-565
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• 2003

• Tunnel and Underground Space
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• v.26 no.3
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• pp.220-234
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• 2016

Sprayable waterproofing membrane has been considered as a substitute for a sheet waterproofing membrane in a variety of underground excavation works. However, fundamental properties of sprayble waterproofing membrane have not been fully given yet. In this study, a new two-component sprayable waterproofing membrane prototype was developed. In addition, its physico-mechanical properties were measured and compared with those of two kinds of thin spray-on liners where constitutive materials and construction methods are very close to each other. From direct tensile tests, the sprayable waterproofing membrane with elongations at break between 250% and 300% showed much higher ductility than TSLs. However, the sprayable waterproofing membrane had a limitation as a support member since its bond strength and loading capacity was lower than those of TSLs. From three-dimensional X-ray CT images, the porosity of the sprayable waterproofing membrane was estimated to be 26.13%. However, most of pores which might have been generated during membrane curing were not observed to be interconnected but isolated.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.207-211
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• 2006

This paper presents an experimental study on the repair performance of sprayed engineered cementitious composites(ECC) serving as a repair material. Sprayable ECC, which exhibit tensile strain-hardening behavior in the hardened state and maintain sprayable properties in the fresh state, have been developed by using a parallel control of micromechanical design and rheological process design. The effectiveness of sprayable ECC in providing durable repaired structures was assessed by spraying the ECC and testing them for the assessment. The experimental results revealed that, when sprayed ECC were used as a repair material, both load carrying capacity and ductility represented by the deformation capacity at peak load of the repaired flexural beams were obviously increased compared to those of commercial prepackaged mortar(PM) repaired beams. The significant enhancement in the energy absorption capacity and tight crack width control of the ECC repair system treated with wet-mix spraying process suggests that sprayed ECC can be effective in extending the service life of rehabilitated infrastructures.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.581-584
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• 2004

High ductile fiber reinforced mortar suitable for wet-mix shotcreting (sprayable ductile mortar) 10 the fresh state, while maintaining tensile strain-hardening behavior in the hardened state, has been developed based on micromechanics and workability control. In the development concept of sprayable ductile mortar, micromechanics is adopted to properly select the matrix, fiber, and interface properties to exhibit strain hardening and multiple cracking behaviors in the composites. Within the pre-determined micromechanical constraints, the workability is controlled by optimizing mix proportions. A series of spray tests show the excellent pumpability and sprayability of the sprayable ductile mortar. Subsequent direct tensile tests demonstrate that the tensile performance of sprayed mortar is comparable to that of cast mortar, for the same mix design.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.279-283
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• 2013

This work was carried out to evaluate the effect of preharvest sprayable 1-methylcyclopropene (1-MCP: $Harvista^{TM}$) treatment on the fruit quality attributes in cold stored 'Gamhong' (Malus domestica Borkh) apples. Preharvest sprayable 1-MCP treatment did not affect fruit qualities at harvest but titratable acidity (TA) was higher in fruit treated 10 days before harvest (DBH) than in control. During cold storage, fruit firmness and TA were higher in 1-MCP treated fruit than in control fruit as storage duration progressed, while SSC was not affected. Internal ethylene concentration (IEC) levels were not different among treatments at harvest. While the IEC level in control fruit reached to $58.3{\mu}L{\cdot}L^{-1}$ after 6 month cold storage, the IEC levels in 1-MCP treated fruit ranged from 18.2 to $25.0{\mu}L{\cdot}L^{-1}$. Therefore, this result indicates that preharvest sprayable 1-MCP treatment should be another promising approach to retain fruit quality attributes in long-term cold stored 'Gamhong' apples.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.15-23
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• 2019

The sprayable waterproofing membrane is a recently introduced material in the civil engineering field, and is a material that sprays and attaches a single phase or two phase powder or liquid material to a surface to be covered using a pump and nozzle. Although the material properties are gradually reported through researches, there is a lack of studies on long-term performance compared to concrete materials used with the membranes. In this study, the long-term performance of materials was estimated using the Arrhenius equation. The temperature conditions used in this study were 65℃, 80℃ and 95℃, and the temperature was maintained with the membrane attached to the concrete block for long-term behavior. Then the membranes were tested for tensile strength and adhesion strength in the order of 30, 90, 150, 200, and 300 days. The long-term performance of the material was determined from a long-term perspective by estimating the activation energy by the Arrhenius equation. Consequently, the time to reach 50% of the performance standard could be estimated by long-term test.