• 폴리머
• /
• 제28권4호
• /
• pp.321-327
• /
• 2004

2,2 bis 〔4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl〕propane을 기본 단량체, triethylene glycol dimethacrylate를 희석제로 포함하고 있는 고분자계 치아 수복재는 중합 수축률에서의 문제점으로 인하여 사용에 제약을 받아오고 있다. 본 연구에서는 기존 고분자계 치아 수복제의 문제점인 중합 수축률을 감소시키기 위해 중합시 부피 팽창이 기대되는 비대칭 스파이로 오쏘카보네이트를 합성하고, 이를 포함하는 새로운 치아 수복재를 제조하여 이의 특성을 시험하였다. 스파이로 오쏘카보네이트를 포함하는 새로운 치아 수복재의 중합 수축율은 약45% 감소하여 우수한 체적 안정성을 나타내었다. 그러나 새로운 치아 수복재의 중합특성, 기계적 물성 등은 기존 치아 수복재에 비해 다소 저하되었다.

• 콘크리트학회논문집
• /
• 제13권1호
• /
• pp.30-37
• /
• 2001

본 연구에서는 열경화성인 UP 수지에 열가소성 스티렌 수지를 혼합하여 사용함으로써 UP 수지의 경화기구 중 스티렌 수지가 수축보완 효과를 일으켜 UP 모르타르의 경화수축을 저감시킬 수 있다는 가능성을 확인하고자 실시하였으며 그에 따른 역학적 성질의 변화를 함께 검토하였다. 본 연구결과, 폐 스티로폴 용해액을 첨가한 불포화 폴리에스테르 수지의 점도는 EPS/PS비가 30% 미만일 경우는 PS/UP비가 증가함에 따라 감소하여 시공성 면에서 EPS/PS비가 30%이내에서 적절하였다. 또한 휨 및 압축강도는 EPS/PS비보다는 PS/UP비에 따른 영향이 크게 나타났으며 PS/UP비 30%이하에서 감소 정도가 작았으며, EPS/PS비와 PS/UP비가 증가함에 따라서 경화수축은 전체적으로 감소되는 경향을 보였다. 적절한 시공성과 휨 및 압축강도 특성 그리고 경화수축 시험의 종합적인 결과, EPS/PS비 30%, PS/UP비 30%일 때 최적의 배합 조건으로 나타났다. 이로서 폐 스티로폴을 UP 모르타르이 수축저감제로서 사용함에 있어 역학적 성질의 큰 변화 없이 경화수축을 제어할 수 있다는 결과를 얻어 실제현장에서의 사용성이 기대되며, 또한 본 연구에서 사용한 스티렌 수지는 폐 발포 폴리스티렌을 스티렌 모노머에 액화시킨 것으로서 폐기물로 발생되는 폐 스티로폴의 자원재활용의 측면에도 그 의미가 있다고 할 수 있다.

• International Journal of Concrete Structures and Materials
• /
• 제8권3호
• /
• pp.229-238
• /
• 2014

Typical high-performance concrete (HPC) mixtures are characterized by low water-cementitious material ratios, high cement contents, and the incorporation of admixtures. In spite of its superior properties in the hardened state, HPC suffers from many practical difficulties such as its sensitivity to early-age cracking (which is associated with self-desiccation and autogenous shrinkage). In this context, conventional curing procedures are not sufficiently effective to address these limitations. In order to overcome this issue, two strategies,which are based on the use of internal reservoirs of water, have been recently developed.One of these strategies is based on the use of lightweight aggregates (LWA), while the other is based on the use of superabsorbent polymers (SAP). This paper studies and compares the efficiency of the LWA and SAP approaches.Moreover, some of the theoretical aspects that should be taken into account to optimize their application for internal curing of HPC are also discussed. Two fine LWA's and one SAP are studied in terms of autogenous deformation and compressive strength. Increasing the amounts of LWAor SAP can lead to a reduction of the autogenous deformation and compressive strength (especially when adding large amounts). By selecting appropriate materials and controlling their amount, size, and porosity, highly efficient internal water curing can be ensured.

• 한국염색가공학회지
• /
• 제14권1호
• /
• pp.43-50
• /
• 2002

Silk/Cotton fabrics were treated with butanetetracarboxylic acid(BTCA) to improve crease recovery and anti-shrinking properties at various curing temperatures and pH values. We investigated the effects of finishing conditions on add-on of BTCA, bending property(E, 2HB), wrinkle recovery angle, shrinkage, and dyeing properties. The Add-on of BTCA increased with increasing curing temperature and concentration. Crease recovery was improved with decreasing shrinkage. Maximum add-on of BTCA was showed at pH 2.5. In case of dyeing and mercerization, silk side treated with BTCA was more flexible than untreated, whereas cotton side was more stiff. In dyeing after mercerization, B and 2HB values were higher and K/S values were doubled nearly. The hand of fabric improved with decreasing B and 2HB by the BTCA treatment. BTCA treatment after reactive dyeing improved crease recovery, and caused no change of color difference. However, BTCA treatment after reactive dyeing didn't improve crease recovery, whereas B and 2HB were decreased considerably by the treatment.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
• /
• pp.343-348
• /
• 1999

The purpose of this study is to evaluated the effects of added expanded polystyrene on the basic properties of UP mortar. Polyester resin mortars are prepared with expanded polystyrene ratio in styrene monomer (EPS/PS), and the ratio of total polystyrene resin to UP resin (PS/UP). And it is tested for viscosity of UP resin added PS resin, slump-flow test, working life, flexural and compressive strengths, and curing shrinkage test. From the test result, Viscosity of resin for polymer mortar increases with increasing PS content. Curing shrinkage of UP mortar is considerably smaller than that of plain UP mortar, nevertheless, reduction in the strengths is not recognized according to adding PS resin. In this study, we can obtain the optimum mix proportions of polymer mortar using PS resin.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
• /
• pp.925-928
• /
• 2000

In this paper, physical properties of cement mortar for floor using expansion agent are discussed varied with mixing time and curing temperature, delivery time and content of added water for preventing fluidity loss. According to experimental results, slump loss shows high with elapse of time And as curing temperature goes up, it also show high when curing temperature goes up and time lag between mixing and casting increases. As curing temperature goes down, drying shrinkage shows to be decreased. But it shows decline tendency with increase of added water content.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.825-828
• /
• 2006

In this paper, experimental studies are performed to find out properties of crack according to the change of curing conditions of flyash concrete. To study the effect of curing conditions on flyash concrete, slump, bleeding, air content and hydration temperature of fresh concrete are measured according to various curing conditions. In addition, the effect of caring conditions on compressive strength, tensile strength and Plastic drying shrinkage cracking of hardened concrete is also considered.

• 콘크리트학회논문집
• /
• 제11권3호
• /
• pp.23-34
• /
• 1999

In designing PSC box girder bridge, the dead load, prestressing force, creep and shrinkage of concrete are the main factors which influence the camber and deflection of segmental concrete structure under construction. Among these factors the creep and shrinkage are the functions of the time-dependent property which, therefore, must considered with time. The prediction model for estimating creep and shrinkage of concrete has been suggested by ACI, CEB/FIP, JSCE and KSCE design code. In this study the creep and shrinkage test were carried out for four curing ages of concrete which was applied to the pretressed concrete box-girder bridge at a construction site, and the results of test were compared to the values of prediction by the design code. Shrinkage test shows that the test results are similar to KSCE-96 and JSCE-96 but very higher than other prediction model and creep test results are generally similar to ACI-209 and DSCE-96 but lower than other prediction models in contrast to shrinkage test.

• 한국해양공학회지
• /
• 제23권4호
• /
• pp.1-5
• /
• 2009

A dilatometer was used to investigate the effect of cure conditions, mold types and the presence of filler in an epoxy system. These studies showed shrinkage in the cured epoxy when heating it through the glass transition temperature region. The magnitude of the shrinkage, related to stress build up in the epoxy during curing, was influenced by the processing conditions, filler presence and the nature of the mold used to contain the resin. Cure and cyclic cure at a lower temperature, prior to a post cure, decreased the magnitude of observed shrinkage. Cure shrinkage decreased with the number of cyclic cures. Post cured samples outside the mold led to less shrinkage compared with samples in the mold. Sample cured in a silicon mold represented less shrinkage than sample cured in an aluminum mold. Sample containing kaolin filler showed less shrinkage than unfilled sample.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
• /
• pp.181-186
• /
• 1999

When the expansive additives are used in concrete to reduce the shrinkage cracking, it shows variable properties with the curing method and curing temperature. Therefore, in this study, the experiments are perfomed to present the expansion of cement mortar by varying the unit additions of expansive additives and the curing method. According to the test results, the order of expansion by curing method, which is caused by hydration heat of cement, is follows ; curing at water > curing at air after curing at water for 7 days > curing at air. Cement mortar using expansive additives shows that high expansion is place with rise of temperature.