• 한국도로학회논문집
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• 제3권1호
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• pp.177-184
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• 2001

본 연구는 노후된 폐아스콘으로부터 폐아스팔트를 추출하여 ASTM방법을 이용해서 폐아스팔트의 화학적 조성을 성분별로 분리하고, 이들을 신제아스팔트의 구성성분과 비교하여 노후시 변화하는 성분들을 파악하였다. 이러한 분석결과를 토대로 폐아스팔트의 성상복원을 위한 재생첨가제를 제조하여 재생첨가제를 10%, 20% 첨가했을 때 폐아스팔트의 복원정도를 침입도$(25^{\circ}C)$, 신도, 연화점, 점도의 네 가지 시험을 수행하여 폐아스팔트의 물성 변화 특성을 고찰하였다. 연구결과에 의하면 아스팔트의 노화시 아스팔텐의 함량이 하고, 방향족성분의 함량이 감소함을 알 수 있었고, 증가한 아스팔텐의 함량을 줄여주기 위해 아스팔트의 방향족 성분자 화학적으로 비슷한 아로마틱기유를 사용하여 재생첨가제를 제조했다. 그리고 제조된 재생첨가제를 노화가 진행된 폐아스팔트에 무게 비로 20% 첨가했을 때, 신제아스팔트 (AP-3)와 유사한 정도로 성상이 복원됨을 확인할 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제26권4호
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• pp.92-97
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• 1998

Four urea-formaldehyde (UF) resins were synthesized as a particleboard (PB) binder with the four different initial formaldehyde/urea mole ratio and the final mole ratio of 1.15. The UF resins were characterized according to the standard method of resin adhesive analysis. PBs were manufactured using liquid UF resins at 5 minutes press time and 6% resin solids levels on an ovendry particle weight basis. A total of 20 PBs was fabricated for 5 panel replication per UF resin types. The panels were tested for physical strength properties per the procedure ASTM D 1037. The formaldehyde emission levels from the PBs bonded with the UF resins were tested according to 2-hour desiccator test method ASTM D 5582. There were no significant differences among UF resin types for internal bond strength of PBs. But there were significant differences among UF resin types for formaldehyde emission level of PBs. The results showed that the formaldehyde emission level was influenced by the UF resin types without reducing the adhesive performance.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술.기술논문발표회
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• pp.67-76
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• 2002

Self-leveling material(SLM) is one of the floor finishing materials which make flat surface like as water level by itself in a short time. So it is possible to increase construction speed and enhance economical efficiency. In this study, author intended to develop SLM for the industrial warehouse and factory loading heavy weight machinery and vehicles. The demanded properties for this type of SLM are above 20mm of flow value and above 300kgf/cm2 of 28-days compressive strength. To possess demended strength and fluidity, SLM have to be composed of many types of binders and chemical additives. So it is difficult to decide suitable mixing proportion of composition materials. In this study, author investigated the weight percentage effect of main composition materials for high-strength self-leveling material, by experimental design such as tables of orthogonal arrays and simplex design, and by statistical analysis such as analysis of variance and analysis of response surface. Variables of experiments were ordinary portland cement(OPC), alumina cement(AC), anhydrous gypsum(AG), lime stone(LS) and sand, and properties of tests were fluidity of fresh state and strength of hardened state. Results of this study are showed that suitable mix proportions of binders for the high strength self-leveling materials are two groups. One is 78~85.5% OPC, 7.5~9.5% AC, 9~12.5% AG and the other is 72.5~78% OPC, 9~12.5% AC, 13~l5% AG.

• 펄프종이기술
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• 제44권5호
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• pp.14-20
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• 2012

In this paper, the flame-retardant wall paper was successfully prepared with recycled polyethylene terephthalate (PET) short cut fiber with flame-retardant property and wood pulp using polyvinyl alcohol (PVA) as binder followed by treatment of non-halogen flame retardant. Physical properties such as formation index, tensile strength, elongation, and burst strength increased as defibrillation increased except tear strength. Bulk increased but formation index, tensile strength, elongation and burst strength decreased along with addition of PET short cut fiber. It was also found that tear strength rose significantly up to 30% of PET short cut fiber and then declined (fell) rapidly. As addition level of PVA increased tensile strength, elongation and burst strength increased, but tear strength decreased slightly. Addition of 20% of PET short cut fiber and 13% of PVA provided the flame-retardant wall paper with both improved flameproofing and physical properties.

• 한국임상약학회지
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• 제24권3호
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• pp.199-205
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• 2014

Objectives: Current studies are debating on the association of vascular calcification and the benefit of treatment to lower serum phosphorus level in patients with chronic kidney disease. The aim of this study was to evaluate the association of mortality and risk of vascular calcification in patients with CKD who were taking phosphate binders. Methods: This study was conducted through retrospective medical chart review for 420 patients aged 18 years and older who were admitted for chronic kidney disease. Results: Vascular calcification was not statistically significantly associated with increased mortality in patients with CKD [16.7% vs. 19.2%; 95% CI; 0.388 to 1.818 (p=0.656)]. Intervention of calcium-based phosphate binders was not significantly associated with vascular calcification in patients with CKD [9.1% vs. 12.5%; 95% CI; 0.364 to 1.358 (p=0.292)]. Ca x P product ${\geq}55mg^2/dL^2$ was not significantly associated with increased 1 year mortality in patients with CKD [25.4% vs. 17.5%; 95% CI; 0.851 to 3.013 (p=0.142)]. Intervention of sevelamer was significantly associated with reduced 1 year mortality in patients with CKD than that of patients who did not take sevelamer [6.3% vs. 25.3%; 95% CI; 0.044 to 0.880 (p=0.020)]. Conclusion: There was not a statistically significant association between vascular calcification and phosphate binder's use. But phosphate binder use was significantly associated with decreased mortality in patients with CKD.

• 한국디지털건축인테리어학회논문집
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• 제12권3호
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• pp.59-66
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• 2012

Autoclaved Lightweight Concrete(ALC) features such as a high performance insulation, the fire resistance, the advantage of easy handing construction, and lightweight panels applied the curtain wall system. ALC materials are certified as non-toxic environmental and eco-friendly productions. But ALC external panels mixed with blast furnace slag pounder and silica fume have to be coated with a stucco compound or plaster because of resisting the ambient environment. This study is that mixing tests to evaluate a performance analysis of exterior paints to be make-up pigments(organic or inorganic) coated with panel surface. Testing compared by KS F 2476; flow test, KS F 2426; compression strength test, KS F 2762; bond strength test. In results, the case of the inorganic binder, ratio of alumina cement : anhydrite is 90:10 to 80:20 at the highest level of intensity. In the case of the organic binder, adhesive strength rating at surface of ALC, the pullout strength is below 0.5 $N/mm^2$ but the normal concrete is over 2.0$N/mm^2$. A contents ratio of EVA resin is more than 3% and then bond strength is effectively.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.577-580
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• 2006

This paper presents the experimental results of frost durability characteristics including freezing-thawing and de-icing salt scaling of the concrete used for gutter of the road. Mixtures were proportioned with the three level of water-binder ratio (W/B), 0.58, 0.53, and 0.48, and two binder compositions corresponding to Type I cement without any supplementary cementitious materials (OPC) and Type I cement with 30% blast-furnace slag replacement (Slag30). Also, two different solutions of calcium chloride and water that contains 0 and 8g of anhydrous calcium chloride in each 100 mL of solution, respectively, were used to evaluate their effect on the frost durability resistance. Test results showed that the Slag30 mixture exhibited higher durability factor and lower mass loss values than those made with OPC. Among the mixture tested in this work, the mixtures (OPC and Slag30) made with a relatively higher W/B of 0.58 exhibited large amount of the de-icing salt scaling regardless of calcium chloride concentration. Finally, the use of slag can be used effectively in terms of economy and frost durability of the concrete designated for gutter.

• Computers and Concrete
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• 제32권2호
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• pp.185-206
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• 2023

This article aimed to explore the optimization of mineral admixtures and retarding admixture for high-performance concrete. In essence, fresh concrete can be regarded as a mixture in which both coarse and fine aggregates are suspended in a cement-based matrix paste. Based on this view, the test procedure was divided into three progressive stages of binder paste, mortar, and concrete to explore their rheological behavior and mechanical properties respectively. At each stage, there were four experimental control factors, and each factor had three levels. In order to reduce the workload of the experiment, the Taguchi method with an L9(3⁴) orthogonal array and four controllable three-level factors was adopted. The test results show that the use of the Taguchi method effectively optimized the composition of high-performance concrete. The slump of the prepared concrete was above 18 cm, and the slump flow was above 50 cm, indicating that it had good workability. On the other hand, the 28-day compressive strength of the hardened concretes was between 31.3-59.8 MPa. Furthermore, the analysis of variance (ANOVA) results showed that the most significant factor affecting the initial setting time of the fresh concretes was the retarder dosage, and its contribution percentage was 62.66%. On the other hand, the ANOVA results show that the most significant factor affecting the 28-day compressive strength of the hardened concretes was the water to binder ratio, and its contribution percentage was 79.05%.

• 한국건축시공학회지
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• 제14권6호
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• pp.515-522
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• 2014

혼화재로서 플라이애시가 콘크리트의 전과정 환경영향에 미치는 효과를 정량적으로 평가하기 위하여, 4023개의 실내배합 및 2120개의 레미콘 배합을 분석하였다. 전과정 환경 평가에서 환경부하는 분류화, 특성화, 정규화 및 가중치 단계를 거쳐 정량적인 환경영향 지표로 환산되었다. 콘크리트 전과정 환경영향은 주로 지구 온난화, 광화학 산화 생성물 및 무생물 자원고갈의 세 범주로 분류될 수 있었다. 또한, 콘크리트의 환경영향 지표들은 플라이애시 치환율의 증가와 함께 감소하였으며, 대부분 보통 포틀랜드 시멘트의 양에 의해 결정되었다. 이를 고려하여, 콘크리트의 환경영향 지표들은 단위 결합재 양 및 플라이애시 치환율의 함수로 간단하게 모델링 될 수 있었다.

• 한국구조물진단유지관리공학회 논문집
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• 제14권5호
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• pp.87-92
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• 2010

본 연구에서는 실리카흄 대체재로 활용 가능한 실리카 흄 무혼입 결합재(SFFB)의 치환율에 따른 고강도 콘크리트의 품질특성을 비교 분석하기 위하여, 실리카흄, SFFB의 2수준과 물-결합재비는 25, 35% 치환율은 실리카 흄 10%, SFFB 5, 10, 15(%)의 4수준으로 설정하였다. 실험을 실시한 결과, 목표 유동성을 확보하기 위한 고성능감수제의 첨가율은 물-결합재비가 낮을수록 증가하였으며, SFFB가 실리카 흄 보다 저흡수성을 갖는 재료적 특성으로 인해 고성능감수제의 첨가율이 감소하는 경향을 나타내었다. 압축강도에서는 SFFB 치환율이 10%일 경우 인장강도에서는 치환율이 15%일 경우 가장 우수한 강도를 나타내었으며, 자기수축에서는 W/B와 SFFB의 치환율과 상관없이 Plain(SF)에 비해 수축이 저감하는 것으로 나타났다.