• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.801-804
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• 2006

Polycarboxylate type superplasticizers(PC) have got widely used for making not only high performance concrete but low grade concrete as well. It is known that fluidity of cement with PC is affected by the characteristics of cement especially sulphate ion concentration and hydration activity. But the characteristics of PC also affect the fluidity. The fluidity of cement mortar with various types of PC was measured and critical dosage(CD) and dispersing ability(DA) was calculated. CD and DA is strongly dependent on the type of PC. And the variation of fluidity on time was affected by the type of PC also. So, it is advisable to investigate the property of PC before production of concrete and adjust it to meet the requirements of concrete depending on the materials, the time of transport and so on.

• 대한치과의사협회지
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• 제22권4호통권179호
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• pp.313-322
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• 1984

This study was designed to observe the marginal leakage of three permanent cements affected by three temporary cements. The temporary cements used in this study were Zinc oxide-eugenol, Non-eugenol, and Calcium hydroxide cements and the permanent cements were Zinc phosphate, Polycarboxylate and Alumina reinforced EBA cements. To measure the dye penetration into permanently cemented zone, the experimental specimens were treated with the temporary cements for a week. An analysis of the data obtained from 120 specimens resulted in the following conclusions: 1. Regardless of the types of the permanent cements used, using Calcium hydroxide cement as temporary cement showed higher marginal leakage than other temporary cements. 2. Using Polycarboxylate cement as permanent cement showed less marginal leakage than other permanent cements. 3. The marginal leakage in zinc phosphate cement was similar to Alumina reinforced EBA cement regardless of the types of the temporary cements.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.55-56
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• 2022

Recently, water leak is increasing due to poor compaction or segregation of concrete on external wall. In addition, the flatness quality of the slab is lowered due to the deterioration of the workability of concrete. In this study, the performance of high fluidity concrete of 21MPa using a polycarboxylate-based superplasticizer was evaluated to improve the compaction and quality of the concrete wall.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.81-82
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• 2020

Cement paste is the basic material constituting concrete and the most basic data of workability. This study quantitatively evaluated the measured data using a ring flow and a rotary viscometer to estimate the flow of cement paste, and also evaluated the flow and rheology over time. For this, the current work has studied admixtures that affect the fluidity of cement paste. As a result of the experiment, since fluidity and plastic viscosity are inversely proportional to each other, more experimental studies are needed to obtain high fluidity and high viscosity at the same time.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.61-62
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• 2022

Carbon nanotubes were used to secure high strength, high durability, and fracture toughness of cementitous composites.In this study, carbon nanotube dispersion solutions were prepared using commercial superplasticizers, such as polycarboxylate-ester and sodium naphthalene sulfonate with tip sonication. The solutions were used to prepare cement paste with MWCNT and The mechanical properties of the cement paste composite with MWCNT solutions were evaluated.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2004년도 춘계총회 및 연구발표회 초록집
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• pp.52.1-52.1
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• 2004

• 한국세라믹학회지
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• 제41권4호
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• pp.302-312
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• 2004

메톡시폴리에틸렌글리콜모노메타크릴레이트(MPEGMAA)와 메타크릴산(MAA)의 몰비와 MPEGMAA의 폴리에틸렌옥사이드(PEO)의 길이를 변화시켜 합성한 폴리카복실레이트계 고유동화제(PCA)를 시멘트 모르타르에 첨가한 경우. 그 물성에 미치는 영향에 대하여 조사하였다. PEO의 길이가 긴 경우 ［MPEGMAA］/［MAA］ 몰비가 낮을수록 모르타르의 유동성은 향상되었다. PCA를 첨가했을 때 응결시간은 지연되며, PEO의 길이가 짧고 ［MPEGMAA］/［MAA］ 몰비가 낮을수록 응결은 더 지연되었다. 특히 MPEGMAA의 분자량이 475인 경우(에틸렌옥사이드 반복단위는 10이다) 응결시간의 지연이 가장 컸다. PCA 분자내 존재하는 PEO의 영향으로 표면장력은 크게 낮아지며, 몰탈의 기공크기분포를 크게 변화시쳤다. PCA에 의해 생성되는 기공은 대부분 7∼370$\mu\textrm{m}$ 범위의 거대 기공이며, 이 기공들에 의해 몰탈의 밀도와 압축강도가 낮아지게 되었다.

• 대한치과보철학회지
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• 제20권1호
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• pp.25-32
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• 1982

An in vitro study was conducted to compare the bond strength of cements between Verabond coping and various cores. Fifty-four idential cores simulating maxillary central incisor prepared for PFM crowns were made. Eighteen samples were made with 20K cast gold, eighteen with Verabond, and eighteen with Adaptic. Samples were randomly divided into three groups, each consisting of six 20K cast gold, six verabond, and six Adaptic samples. The first group was cemented with zinc phosphate cement, the second group with poly-carboxylate cement, and the third group with glass ionomer cement. Constant finger pressure was applied for cementation. The sample were then stored at $37^{\circ}C$ in distilled water bath for 24 hours. The tensile strength test was performed on an Instron Universal test machine with crosshead speed of 0.05cm/min and the results compared statistically. Results of the study showed that: 1. A significant difference of bond strength was observed with different types of dental cements and core materials. 2. With gold core, zinc phosphate cement was stronger than both the polycarboxylate cement and glass ionomer cement, which did not differ in bond strength. 3. With base-metal core, zinc phosphate cement showed the highest bond strength and was followed by polycarboxylate cement and glass ionomer cement. 4. With composite resin core, zinc phosphate cement showed the highest bond strength and was followed by glass ionomer cement and polycarboxylate cement. 5. The base-metal core (Verabond core) privided the highest retention of all core materials.

• Restorative Dentistry and Endodontics
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• 제14권1호
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• pp.7-24
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• 1989

The purpose of the study was to evaluate the cytotoxic effects of polycarboxylate cements and zinc phosphate cements in vitro. Human fibroblasts were cultured in ${\alpha}$-MEM, and each cement was manually mixed and filled in glass ring cylinder (8${\times}$8mm in diameter, in height.) Cement filled cylinders were placed in the center of the dish (35mm in diameter) containing 3ml of ${\alpha}$-MEM. Millipore filters to simulate dentinal barrier were also placed between the cylinder and the dish, then stored in 5% $CO_2$ containing chamber for 1 and 2 weeks at the temperature of $36.6^{\circ}C$. The results of the experiments were analyzed by counting the cells in the period of one week and two weeks respectively, and were assessed by calculating the cell multiplication rate and the relative growth rate. The experimental groups and the control group were compared. The results of the study were summarized as follows. 1. Durelone brand of the polycarboxylate cements showed marked cytotoxicity after one week, but after two weeks the toxicity decreased remarkably. Poly-F brand exhibited moderate cytotoxicity after one week, but after two weeks the toxicity slightly decreased. HY-BOND brand was weakly cytotoxic after one week, but after two weeks the toxicity became significant. 2. The cytotoxicity of the zinc phosphate cements was negligible after one week, but after two weeks Lee Smith brand revealed considerable cytotoxicity. 3. In general, the zinc phosphate cements were less cytotoxic than the polycarboxylate cements.

• 콘크리트학회논문집
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• 제17권6호
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• pp.1019-1024
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• 2005

4종의 콘크리트용 화학 혼화제(리그노 술폰산, 나프탈렌 술폰산 축합물, 멜라민 술폰산 축합물, 폴리카복실레이트계)가 시멘트 수화 반응에 미치는 영향성을 평가하고자, 각각의 고유동화제들이 적용된 시멘트페이스트 경화 시편을 활용해 X-선 회절분석(XRD), 주사전자현미경(SEM), 그리고 열분석(DSC) 분석을 실시하였다. 고유동화제를 사용하지 않은 plain과 비교해 고유동화제를 첨가한 시편의 경우, 고유동화제의 종류 및 사용량에 관계없이 3일까지 수화 반응은 지연되었으나, 이후 재령에서는 고유동화제를 사용하지 않은 plain과 유사한 경향성을 보였다. 특히 고유동화제 사용량이 높아질 경우 수화 지연성은 커졌고, 리그노 술폰산, 폴리카복실레이트, 멜라민, 나프탈렌 술폰산 축합물 순으로 시멘트페이스트 초기 수화를 지연시켰다. 그러나, 이들 고유동화제를 사용할 경우, 시멘트의 분산성을 개선시켜 수화 생성물이 보다 치밀하고 균일했다.