• The Korean Journal of Ceramics
• /
• 제1권3호
• /
• pp.160-164
• /
• 1995

Mechanical and chemical tests were performed on $Zro_2 \cdot SiO_2$ glass fibers manufactured by the sol-gel method and E-glass fibers-reinforced cement composites in order to investigate the interactions between glass fibers and cement matrices. Chemical attack leads to corrosion of the glass fiber surfaces. In the corrosion reactions, the surface of $30ZrO_2 \cdot 70 SiO_2$ glass fibers developed a densified concentric layer, which consists of glass corrosion products with much higher Zr and lower Si than the fresh glass fiber. The layer of reaction product is regarded to stiffen the cement matrices and provide a useful improvement to the mechanical properties. The addition of $ZrO_2$ content increases the corrosion resistance of glass fibers in cement by forming a passivating layer on the surface of glass fibers.

• The Korean Journal of Ceramics
• /
• 제4권3호
• /
• pp.189-192
• /
• 1998

The mechanical properties of alkali resistance (AR) glass fiber reinforced cement(GFRC) under different curing conditions were investigated in this study. The specimens were formed by extrusion process, and then steam cured and autoclaved. An autoclaved specimen showed the elastic-brittle behavior up to 4% of fiber volume fraction. However, it was found that the fracture behavior for cured specimen was changed to the elastic-plastic with crack branches fracture at greater than 3 vol.% of fiber.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
• /
• pp.93-98
• /
• 1993

In order to discuss the mechanical properties of fiber reinforced composites with fly ash, lime, gypsum and polymer emulsion-Stylene Butadiene Rubber Latex (SBR) , experimental studies on FRC were carried out. The kinds of fiber used in FRC are PAN-dervied and Pitch-derived carbon fiver, alkali-resistance glass fiber. As a test results, the flexural strength and tougthness of fiber reinforced fly ash. lime.gypsum cement composites are remarkably increased by fiber contents ,but compressive strength of the composites are influenced by kinds of fiber more than by fiber contents. Also, addition of a polymer emulsion (SBR) to the composites decreased the bulk specific gravity, but compressive and flexural strengths, toughness of the composites are not influenced by it, are considerably improved by increasing fiber contents.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1990년도 봄 학술발표회 논문집
• /
• pp.5-10
• /
• 1990

There are two main methods in reinforcing cements with glass fibers : spray-suction and premixing method. But GRC have been mostly studied by spray technique. In order to develop GRC made by premixing method, in this paper, the influence of glass fiber length, volume content and curing conditions upon the compressive, direct tensile and bending strengths of composites fabricated by a premixing method, were investigated. According to the test results, although it was difficult to obtain perfectly uniform distribution of fibers in GRC Pannel, it was found that tensile strength of cements with glass fiber was improved 2~5 times and flexural strength 4 times compared to conventional cement mortar upto fiber length 35 mm, volume content 4%.

• 대한치과보철학회지
• /
• 제38권5호
• /
• pp.618-630
• /
• 2000

As Fiber-reinforced composite restorations cannot be made without leaving a marginal gap, luting cements play a pivotal role in sealing the margins as a prevention against margnal leakage. A recently introduced adhesive resin cement system is claimed to adhere chemically, as well as mechanically, to tooth substances, dental alloys and porcelain. But when considering the clinical variation conventional cementation using Zinc Phosphate and Glass-Ionomer can be requested. A vitro study was undertaken to compare microleakage and marginal fitness of Fiber-reinforced composite crowns(Targis/Vectris) depending upon luting cements. Fifty non-carious human premolar teeth were randomly divided into five experimental groups of 10 teeth each and luted with five luting cements. ($Bistite\;II^(R),\;Super-bond^(R),\;Variolink\;II^(R)$), Zinc phosphate and Glass-Ionomer cement) After 24 hours of being luted, all specimens were thermocycled 300 times through water bath of $5^{\circ}C\;and\;55^{\circ}C$ in each bath, then the quality of the marginal fitness was measured by the Digital Microscope and marginal leakage was characterized using Dye Penetration technique and the Digital Microscope The results were as follows : 1. The mean values of marginal fit were Bistite II($46.78{\mu}m$), Variolink II($56.25{\mu}m$), Super-Bond($56.78{\mu}m$), Glass-Ionomer($99.21{\mu}m$), Zinc Phosphate($109.49{\mu}m$) indicated a statistically significant difference at p<0.001. 2. The mean microleakage values of tooth-cement interface, restoration-cement interface were increased in the order of Variolink II, Bistite II, Super-Bond, Glass-Ionomer, Zinc Phosphate 3. Crowns luted with resin cement (Bistite II, Super-Bond, Variolink II, etc) exhibited less marginal gap and marginal leakage than those luted with conventional Glass-Ionomer and Zinc Phosphate cement. 4. The results indicated that all five luting systems yielded comparable and acceptable marginal fit.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
• /
• pp.49-54
• /
• 2001

Using waste glass in concrete can cause crack and strength loss by the expansion of alkali-silica reaction(ASR). In this study, ASR expansion and properties of strength were analyzed in terms of brown waste glass content, and fibers(steel fiber, polypropylene fiber) and fiber content for reduction ASR expansion due to waste glass. In this accelerated ASTM C 1260 test of waste glass, pessimum content can not be found. Also, when used the fibers with waste g1ass, there is an effect on reduction of expansion and strength loss due to ASR between the alkali in the cement paste and the silica in the waste glass. Specially, adding 1.5 vol.% of steel fiber to 20% of waste glass the expansion ratio was reduced by 40% and flexural strength was developed by up to 110% comparing with only Waste glass ( $80^{\circ}C$ $H_{2}$ O curing).

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
• /
• pp.903-908
• /
• 2002

The production of waste glasses has been increased with the development of industry. The utilization of waste glass for concrete can cause the concrete to be cracked and to be weakened due to an expansion by alkali-silica reaction(ASR). When used the fibers with waste glass, there is an effect on reduction of expansion and strength loss due to ASR between the alkali in the cement paste and the silica in the waste glass. In this study, we conducted basic experimental research to analyze the possibilities of recycling of amber waste glass as fine aggregates for steel fiber reinforced concrete. Test results of fresh concrete. slump is decreased because grain shape is angular and air content is increased due to involving small size particles so much in waste glasses. Also. tensile and flexural strengths increased as the content of steel fibers increased. In conclusion, the content of waste glass below 40% is reasonable and usage of pertinent admixture is necessary to obtain workability or air content.

• 한국해양환경ㆍ에너지학회지
• /
• 제11권1호
• /
• pp.46-49
• /
• 2008

폐FRP의 로빙층을 매트층과 수지로부터 분리하여 섬유 형태의 'F섬유'를 얻었으며, 이것의 용도로 콘크리트 제품 또는 구조물을 고려하였다. 골재는 시멘트의 2.45 배(무게비)로 하고 F섬유(밀도 1.45)는 시멘트와 골재의 부피비로 계산하여 만든 공시체에 대한 휨강도를 실험하였다. 1%의 F섬유를 갖는 것이 양생한 지 28일째 되었을 때 넣지 않은 것에 비해 23%의 강도 증가를 보였다. 그러나 0.5%를 포함한 공시체의 경우는 강도의 변화를 보이지 않음으로써 강도 보강용으로 쓰일 수 있는 최소 혼입량이 0.5% 보다는 크다는 것을 알았다. 철근 콘크리트 시제품인 벤치 플룸의 경우 1% F섬유를 포함할 때 포함하지 않은 것에 비해 휨강도가 21%증가하였다.

• Structural Engineering and Mechanics
• /
• 제87권6호
• /
• pp.585-599
• /
• 2023

Geopolymer concrete (GC) can be competently utilized as a practical replacement for cement to prevent a high carbon footprint and to give a direction toward sustainable concrete construction. Moreover, previous studies mostly focused on the axial response of glass fiber reinforced polymer (glass-FRP) concrete compressive elements without determining the effectiveness of repairing them after their partial damage. The goal of this study is to assess the structural effectiveness of partially damaged GC columns that have been restored using carbon fiber reinforced polymer (carbon-FRP). Bars made of glass-FRP and helix made of glass-FRP are used to reinforce these columns. For comparative study, six of the twelve circular specimens-each measuring 300 mm×1200 mm-are reinforced with steel bars, while the other four are axially strengthened using glass-FRP bars (referred to as GSG columns). The broken columns are repaired and strengthened using carbon-FRP sheets after the specimens have been subjected to concentric and eccentric compression until a 30% loss in axial strength is attained in the post-peak phase. The study investigates the effects of various variables on important response metrics like axial strength, axial deflection, load-deflection response, stiffness index, strength index, ductility index, and damage response. These variables include concentric and eccentric compression, helix pitch, steel bars, carbon-FRP wrapping, and glass-FRP bars. Both before and after the quick repair process, these metrics are evaluated. The results of the investigation show that the axial strengths of the reconstructed SSG and GSG columns are, respectively, 15.3% and 20.9% higher than those of their original counterparts. In addition, compared to their SSG counterparts, the repaired GSG samples exhibit an improvement in average ductility indices of 2.92% and a drop in average stiffness indices of 3.2%.

• The Journal of Advanced Prosthodontics
• /
• 제5권2호
• /
• pp.126-132
• /
• 2013

PURPOSE. Post surface conditioning is necessary to expose the glass fibers to enable bonding between fiber post and resin cement. The purpose of the present study was to evaluate the effect of different surface conditioning on tensile bond strength (TBS) of a glass fiber reinforced post to resin cement. MATERIALS AND METHODS. In this in vitro study, 40 extracted single canal central incisors were endodontically treated and post spaces were prepared. The teeth were divided into four groups according to the methods of post surface treatment (n=10): 1) Silanization after etching with 20% $H_2O_2$, 2) Silanization after airborne-particle abrasion, 3) Silanization, and 4) No conditioning (Control). Adhesive resin cement (Panavia F 2.0) was used for cementation of the fiber posts to the root canal dentin. Three slices of 3 mm thick were obtained from each root. A universal testing machine was used with a cross-head speed of 1 mm/minute for performing the push-out tests. Two-way ANOVA and Tukey post hoc tests were used for analyzing data (${\alpha}$=0.05). RESULTS. It is revealed that different surface treatments and root dentin regions had significant effects on TBS, but the interaction between surface treatments and root canal regions had no significant effect on TBS. There was significant difference among $H_2O_2$ + Silane Group and other three groups. CONCLUSION. There were significant differences among the mean TBS values of different surface treatments. Application of hydrogen peroxide before silanization increased the bond strength between resin cements and fiber posts. The mean TBS mean values was significantly greater in the coronal region of root canal than the middle and apical thirds.