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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

The effect of thermal-cycling on the bond strength of a two step and single-step dentin bonding agent

Omer, Amir Isam January 2010 (has links)
Magister Scientiae Dentium - MSc(Dent) / The aim and objective of this study was to determine the bond strength of a twostep and a single-step dentin bonding agent and to determine the effect of repeated thermal-cycling from 50C and 550C on the bond strength values of these dentin bonding agents. / South Africa
262

Influência de diferentes tratamentos de superfície sobre a adaptação marginal e resistência de união entre coroas Y-TZP e um material análogo à dentina

Antunes, Monize Carelli Felipe 09 March 2015 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2015-12-04T17:19:33Z No. of bitstreams: 1 monizecarellifelipeantunes.pdf: 3029600 bytes, checksum: 8f67d08272a23a5ae00bcc9865b95fc8 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2015-12-07T03:23:14Z (GMT) No. of bitstreams: 1 monizecarellifelipeantunes.pdf: 3029600 bytes, checksum: 8f67d08272a23a5ae00bcc9865b95fc8 (MD5) / Made available in DSpace on 2015-12-07T03:23:14Z (GMT). No. of bitstreams: 1 monizecarellifelipeantunes.pdf: 3029600 bytes, checksum: 8f67d08272a23a5ae00bcc9865b95fc8 (MD5) Previous issue date: 2015-03-09 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este estudo avaliou o efeito de diferentes tratamentos de superfície na resistência de união e adaptação marginal entre uma coroa de cerâmica Y-TZP e um material análogo à dentina. Foram confeccionadas 40 bases de um material resinoso análogo à dentina (NEMA grade G-10) para originar preparos padronizados. Estes foram usinados para simular um dente preparado para coroa total com término em chanfro, paredes de 6 graus de convergência e anatomia radicular. A porção radicular foi coberta com poliéter (Impregum - 3M ESPE) e incluída em poliuretano (F16 - Axson). Quarenta coroas cerâmicas IPS emax ZirCAD (Ivoclar - Vivadent) foram fabricadas pelo sistema CAD/CAM. Para o tratamento de superfície foram realizadas a silicatização, aplição de primer para zircônia e duas técnicas de vitrificação, sendo que estas representaram os grupos teste. As coroas foram aleatoriamente divididas em 4 grupos (n=10), conforme o tratamento de superfície: GS (Glaze Spray VITA AKZENT), condicionamento com ácido fluorídrico a 10% (HF) (1 min) + silanização (RelyX Ceramic Primer - 3M ESPE); GP (Glaze Pó/Líquido VITA AKZENT), condicionamento com HF a 10% (1 min) + silanização (RelyX Ceramic Primer - 3M ESPE); P: aplicação do primer (Signum Zirconia Bond - Heraeus Kulzer) e RS: jateamento com partículas de óxido de alumínio revestidas por sílica 30 μm (Rocatec Soft® 3M ESPE ) (silicatização) + silanização (RelyX Ceramic Primer - 3M ESPE). Em seguida, realizou-se a cimentação das coroas com o cimento autoadesivo Rely X U200 (3M ESPE), seguindo as recomendações do fabricante. Todas as amostras de cada grupo foram submetidas à ciclagem termomecânica (TC) (2.000.000 ciclos – 100 N, 4 Hz, 5 ºC – 55 ºC, tempo de permanência 60 s), com um pistão de aço inoxidável (Ø=4mm) no centro da superfície oclusal. Para avaliação da desadaptação marginal entre a coroa cimentada e o G-10, realizou-se a análise por estereomicroscópio (EM) (40x), fazendo-se 8 aferições para cada amostra e, por microscópio eletrônico de varredura (MEV). Para determinação da resistência a tração, foi realizado o ensaio mecânico numa máquina de ensaio universal (célula de carga de 1000 Kgf, v= 1mm/min) até o descolamento da coroa. Os dados de desadaptação marginal obtidos foram analisados estatisticamente (Teste Kruskal Wallis e de Dunn: p ˂ 0,05) e os dados de resistência de união foram analisados pelo teste Anova (um fator) e de Tukey (p ˂ 0,05). Os resultados de desadaptação marginal (média e desvio padrão) foram os seguintes GS (48,69±19,90ª μm); GP (65,48±42,57ª μm); P (156,0±113,3c μm) e RS (96,05±62,98b μm). Os resultados de resistência de união foram: GP (470,5±104,1ª μm); GS (416,8±170,2ª μm); P (342,1±109,7ab μm) e RS (208,9±110,0b μm). Através do estudo realizado concluiu-se que os grupos que tiveram menor desadaptação marginal foram GS e GP; os valores de resistência de união dos grupos GP e GS foram estatisticamente superiores aos valores de resistência de união do grupo RS e semelhante aos valores encontrados para grupo P. / This study evaluated the effect of different surface treatments on the bond strength and marginal adaptation from a Y-TZP ceramic crown and a material similar to dentin. Were made 40 bases in a similar resinous material to dentin (NEMA G-10 grade) to give standardized preparations. These were machined to simulate a tooth prepared for full crown in bevel, walls of 6 degrees of convergence and root anatomy. The root portion was covered with polyether (Impregum - 3M ESPE) and included in polyurethane (F16 - Axson). Forty crowns IPS emax ZirCAD (Ivoclar - Vivadent) were fabricated by CAD / CAM system. For the surface treatment were carried out silica coating, application of primer to zirconia and two glazing techniques, and these test groups represented. The crowns were randomly divided into 4 groups (n = 10), as the surface treatment: GS (VITA Akzent Glaze Spray), etching with hydrofluoric acid 10% (HF) (1 min) + silanization (RelyX Ceramic Primer - 3M ESPE ); GP (Glaze Powder / Liquid VITA Akzent), etching with HF 10% (1 min) + silanization (RelyX Ceramic Primer - 3M ESPE); P: primer (Signum Zirconia Bond - Heraeus Kulzer) and RS: sandblasting with aluminum oxide particles coated with silica 30 microns (Rocatec SOFT® 3M ESPE) (silica coating) + silanization (RelyX Ceramic Primer - 3M ESPE). Then was held the cementation of crowns with the self-adhesive cement Rely XU200 (3M ESPE), following the manufacturer's recommendations. All samples from each group were submitted to thermomechanical cycling (TC) (2,000,000 cycles - 100 N, 4 Hz, 5° C - 55° C, residence time 60 sec) with a stainless steel piston (= Ø 4mm) the center of the occlusal surface. Then the analysis by stereomicroscope (MS) (40x) and scanning electron microscope (SEM) to evaluate the marginal leakage between the cemented crown and the G-10 was held. To determine the tensile strength, the mechanical test was performed in a universal testing machine (load cell of 1000 kgf, v = 1 mm / min) until the detachment of the crown. Data marginal misfit obtained were analyzed statistically (Kruskal Wallis and Dunn: p ˂ 0.05) and bond strength data were analyzed by ANOVA (one factor) and Tukey (p ˂ 0.05). The results of marginal leakage (mean and standard deviation) were as follows GS (48.69 ± 19,90ª μm); GP (65.48 ± 42,57ª μm); P (156.0 ± 113,3c μm) and RS (96.05 ± 62,98b μm). The results of bond strength were: GP (470.5 ± 104,1ª μm); GS (416.8 ± 170,2ª μm); P (342.1 ± 109,7ab μm) and RS (208.9 ± 110,0b μm). Through the conducted study showed that the groups that had less marginal discrepancy were GS and GP; values of bond strength of GP and GS groups were statistically superior to the values of bond strength of the RS group and similar to values found for group P.
263

Antibacterial activity and shear bond strength of a composite resin containing selenium in vitro

Nguyen, James 01 December 2011 (has links)
Introduction: Orthodontic treatment may cause an increased accumulation of cariogenic bacteria. An orthodontic resin with antibacterial properties may inhibit bacterial growth around the brackets. The aims of this in-vitro study were to compare the antibacterial and mechanical properties of the newly introduced orthodontic resin containing selenium with a standard resin and a resin modified glass ionomer (RMGI). Methods: Three orthodontic materials were tested (SeLECTDefense; TransbondXT, Fuji Ortho-LC). The antibacterial properties of these materials were evaluated by studying the bacterial growth in liquid media (BG) and agar diffusion (AD) tests. In the BG testing, 100 adhesive discs (3mmx2mm) were created of each material. Five discs were then placed into each vial containing 0.5ml of brain-heart-infusion broth and 2.5µl of streptococcus mutans (MS)(n=20). Following incubation (37°C, 24hours), the vials were placed in a Spectrophotomoter (Genesys 20) at 600 nm to determine bacterial growth by measuring the optical density (OD). In the AG testing, agar plates were inoculated with 100µl of MS in brain heart infusion agar. Fifteen adhesive discs (6mmx2mm) of each material were prepared and placed into groups of five on 3 agar plates. Following incubation (37°C, 48 hours), the agar plates were visually inspected for zones of bacterial inhibition. The mechanical properties were evaluated using shear bond strength testing (SBS) and an adhesive remnant index scoring (ARI). Sixty human premolars were randomly assorted into groups of 20 for each material (n=20). The brackets were bonded following the manufacturers' instructions. Debonding was performed using a universal testing device (Instron)(crossheadspeed 5mm/min). The mode of failure was evaluated using a stereomicroscope (OlympusSZX7) and scored 0-to-3 for remaining adhesive on enamel. Results were statistically analyzed using Welsch's ANOVA, One way ANOVA, Tukey's Kramer and Tukey's HSD tests. Results: In BG, the resin containing selenium (SD) promoted more bacterial growth (OD=0.427) compared to the standard resin (XT) (OD= 0.222) and RMGI (OD=0.275). In AD, no zones of inhibition were observed which means that no antibacterial agent was released from any of the orthodontic adhesives. In SBS, SD (11.63±2.07MPa) showed statistically lower bond strength than XT (15.16±4.68MPa) but both resins were in the clinically acceptable range. RMGI (6.03±3.95MPa) showed a statistically lower bond strength at a clinically unacceptable degree. Debonding was mostly at the bracket-adhesive interface for SD (ARI=2&3) meaning that most of the adhesive remained on the enamel. In XT and RMGI groups, debonding occurred mostly at the adhesive-enamel interfaces (ARI=0&1). Conclusion: Within the limitations of this in vitro study, the resin containing selenium did not show any favorable antibacterial properties in comparison to the other materials. None of the materials, including fluoride-releasing RMGI, caused bacterial inhibition in their surroundings. The resin containing selenium showed clinically acceptable but statistically lower bond strength as compared to standard resin but its mode of failure was more favorable because most of the adhesive remained on enamel.
264

Shear bond strength of metallic brackets using a 6 and 12 second curing time with high power monowave and polywave LED units

McCarthy, Shannon 01 January 2013 (has links)
A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Objectives: To date, the literature has shown that a 10 second curing time is necessary to consistently achieve effective shear bond strengths (SBS) of greater than 10 MPa. Recently, several manufacturers have developed high power curing lights that claim only a 6 second cure time is needed. The purpose of this study was to evaluate the shear bond strength of orthodontic brackets when using two new high power LED curing lights after a 6 and 12 second light curing time. Methods: 120 extracted premolars were divided into 6 groups (n=20). Metallic brackets were bonded using Transbond XT (3M-Unitek) and cured for 6 or 12 seconds using two high power LED curing lights (Ortholux Luminous LED, 3M-Unitek; OrthoValo, Ultradent) and one control LED unit (Ortholux LED, 3M-Unitek). The samples were stored in distilled water for 24 hours at 37°C, thermocycled and then debonded using an Instron Universal Testing Machine at a crosshead speed of 5mm/min. Bond failure was evaluated under optical microscopy using a modified adhesive remnant index (ARI). Results: All sample groups produced mean SBS higher than 10MPa. Significant reductions in SBS were observed with the Ortholux LED when the curing time was reduced from 12 to 6 seconds. The OrthoValo had significantly higher SBS than the Ortholux LED and the Ortholux Luminous LED at 6 seconds. At 12 seconds, OrthoValo SBS were significantly higher than Ortholux LED only. A higher frequency of enamel damage occurred in the OrthoValo group (28.2%) compared to the Ortholux LED (12.5%) and Ortholux Luminous LED (7.5%). No significant correlation was found between ARI score and SBS. Conclusions: Higher SBS were obtained in the OrthoValo group. This coincided with a higher frequency of enamel damage.
265

Opravy kompozitních rekonstrukcí v prevenci ztrát zubních tkání. Dlouhodobá odolnost vazby kompozit-kompozit v různých prostředích. / Prevention of dental tissue loss by composite restoration repairs. Long-term durabillity of composite to composite bond in various environments.

Comba, Lukáš January 2020 (has links)
in english Introduction: Composite restorations in the oral cavity are exposed to an aggressive environment and mechanical challenge that gradually impairs their physical and mechanical properties. This may result in an enhanced wear rate, loss of esthetic properties and an increased risk of a restoration fracture or its marginal failure with a negative impact on the restoration's durability. Worn or failed restorations are usually completely replaced, which increases the irreversible loss of dental hard tissues. Repair of composite restorations by their partial replacement is therefore a minimally invasive, preventive and less time-consuming alternative to their complete replacement and increases their longevity. In the oral cavity, the adhesive bond between the existing composite restoration and the repair composite resin is exposed to various chemical substances and mechanical stress, e.g. surfactants in toothpastes, which can initiate its degradation. By decreasing the surface tension, the penetration of water into the adhesive joint can be enhanced, accelerating the hydrolysis of the adhesive and reducing the composite repair strength. The major and not yet fully resolved issue of composite repairs is how to achieve a strong and durable bond between the existing and repair composite materials....
266

The Effect of Surface Treatment on The Adhesive Strength of Chairside Hard Liners to Dental Polymers Used for The Conventional, Additive, and Subtractive Fabrication of Complete Dentures.

Aldosari, Abdullah Mohammed January 2022 (has links)
No description available.
267

Bindningsstyrkan mellan CoCr och porslin utifrån olika förbehandlingar

Byman, Marie, Kelemen, Evalotta January 2018 (has links)
SammanfattningSyfteSyftet med föreliggande studie var att undersöka om olika förbehandlingar av metallens yta påverkar bindningsstyrkan mellan CoCr och porslin.Material och metodSexton metallbasar med totalt 64 porslinscylindrar tillverkades genom gjutning av CoCr och porslinsuppläggning (de olika skikten; bondingagent, opak och dentin). Metallbasarna delades slumpmässigt in i 4 grupper; SB 50 sandblästrade med 50 m Al2O3, SB 250 sandblästrade med 250 m Al2O3, OASB oxiderade med atmosfäriskt tryck och sandblästrade med 250 m Al2O3, samt kontrollgrupp OVSB oxiderade i vakuumtryck och sandblästrade med 250 m Al2O3, samtliga grupper blästrades med 3 bars tryck. Efter glansbränning termocyklades provkropparna i 5000 cykler, förvarades fuktigt i 36o C och testades enligt ISO/TS11405:2016. Resultaten analyserades med one-way ANOVA, Tukey´s test. Signifikansnivån sattes till  = 0,05. Brottytorna analyserades visuellt och fotograferades i mikroskop. ResultatMedelvärdet för samtliga grupper var likvärdiga men med stor skillnad i spridning inom grupperna. Brotten delades in i tre grupper, adhesiv-, kohesiv- och blandfraktur.Slutsats Med reservation för de begränsningar som finns inom föreliggande studie kan följande slutsatser dras:•De olika förbehandlingsmetoderna, oxidering med vakuum eller atmosfäriskt tryck följt av sandblästring eller enbart sandblästring med olika kornstorlekar, ger ingen specifik skillnad vad gäller bindningsstyrkan mellan metall och porslin.•Oxidering med vakuum har ingen negativ inverkan på bindningsstyrkan mellan metall och porslin. De-gasing av metallen kan utföras.•Sandblästring med 50 μm hade större spridning inom gruppen än de övriga tre grupperna. •Studiens nollhypotes kan bekräftas. / Abstract PurposeThe purpose of the present study was to investigate whether various pretreatments affect the bond strength between CoCr and porcelain.Material and method64 porcelain cylinders were manufactured (bonding agent, opaque, dentin) divided on sixteen metal bases. The metal bases were randomly divided into 4 groups; SB 50 sandblasted with 50 m Al2O3, SB 250 sandblasted with 250 m Al2O3, OASB oxidized with atmospheric pressure and then sandblasted with 250 m Al2O3 and control group OVSB oxidized in vacuum and then sandblasted with 250 m Al2O3. All groups were sandblasted with 3 bars pressure. After glazefiring, the specimens were thermocycled 5000 cycles, stored in moist at 36o C and tested according to ISO / TS11405: 2016. The results were analyzed with one-way ANOVA, Tukey's test with significance level  = 0.05. The fracture surfaces were analyzed visually and photographed in microscope.ResultsThe mean values in all groups were equivalent but with large difference in standard deviation within the groups. The fractures were divided into three groups, adhesive-, cohesive and mixed fractures.ConclusionWithin the limitations of the study, the following conclusions can be drawn: •The different pretreatment methods, vacuum or atmospheric pressure, oxidation with or without sandblasting do not affect the bond strength between metal and porcelain.•Oxidation with vacuum does not adversely affect the bonding strength between metal and porcelain. De-gasing of the metal can be performed.•Sandblasting with 50 μm had a greater deviation within the group than the other groups•The study's null-hypothesis can be confirmed
268

Study on flexural behavior of steel-concrete composite deck with DFT connectors / DFT形鋼ジベルを用いた鋼-コンクリート合成床版の曲げ挙動に関する研究

Hu, Yiming 24 July 2023 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第24847号 / 工博第5164号 / 新制||工||1986(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 杉浦, 邦征, 教授 高橋, 良和, 教授 山本, 貴士, 教授 北根, 安雄 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
269

Development of a standard test method for determining the Bitumen bond strength of emulsions : a South African perspective

Greyling, Andries Hendrik 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Chip and spray surfacing seals has been widely used in South Africa as the preferred surface treatment for rural roads. The design of these seals has also experienced renewed interest and continuous development in several other countries over the past two decades. In South Africa seals are continually used as increasing attention is given to the periodic maintenance of existing surfaced roads. There is also a significant increase in the use of surfacing seals in North America as the need to develop more energy and resource efficient surfacing options becomes a priority. Despite this growing use of surface seals, the seal design and especially the selection of binder type and grade does not always follow scientific processes. Seals are often designed based on client preference, previous experience, material availability and industry trends. With an ageing road network and limited funding to ensure timeous maintenance, the focus in South Africa is moving towards more stringent and scientific design processes. The USA and Europe, forced by increasing traffic volumes and heightened performance demands, are moving towards performance- based specification to account for deficiencies in their current surface seal design methods. One of the major failure mechanisms of surface seals is ravelling which takes place when the binder and the aggregate bond becomes weak and are broken by the forces generated by traffic. This leads to loose aggregate on the road which in turns leads to bare surface patches and broken windscreens. To prevent and address this as part of the development of performance-based specifications, the need for a simple and inexpensive technique for evaluating bitumen and bitumen emulsion bond strength development over time, as well as binder-aggregate compatibility, was identified. Although various tests exist for investigating adhesion between bituminous emulsions and aggregate chips most of the tests does not deliver the level of information required by the performance-based specifications. The Bitumen Bond Strength (BBS) test method was therefore developed with the aim to address some of the limitations encountered in evaluating bond strength between binders and aggregates. The BBS test (AASHTO TP-91, 2011) was developed by the University of Wisconsin – Madison (UWM) in partnership with the University of Ancona – Italy (UAI) and the University of Stellenbosch – South Africa (US) specifically for evaluating bond strength between aggregates and hot applied binders and emulsions, respectively. US became involved in BBS test efforts in 2008 to assist in the development and practical evaluation of the BBS test method. UAI contributed significantly to the development of the test apparatus through their work in conjunction with UWM. Due to time and resources available, the involvement of the US was limited to various discussion sessions, a study tour, the evaluation of the BBS test, and conducting a series of control tests. By using the Bitumen Bond Strength test it was possible to evaluate the practicality and repeatability of the developed procedure and the results measured was successfully used to evaluate the bond strength development of modified and unmodified bitumen emulsions on tillite and granite aggregates. It was also possible to correlate the results achieved at the University of Stellenbosch with results from the University of Wisconsin-Madison due to the fact that testing took place at both institutions. The development of the test and the inter-laboratory test results in essence reinforced the hypothesis that the BBS test protocol can be used to effectively evaluate bond strength of different emulsion types and aggregate types. Except for the loading rate which is a known critical influence, the emulsion type and curing intervals are both identified as the most significant other factors contributing to bond strength development. Aggregate type is also identified as a significant factor that will influence the bond strength development. Interactions between emulsion type and curing interval are identified as the most significant interaction. A lot of further validation test on the BBS test method is still required for the test to be integrated into a performance-based specification system for surface seals. / AFRIKAANSE OPSOMMING: “Chip and Spray” oppervlak seëls is die verkose seël tipe vir gebruik op Suid Afrikaanse plattelandse paaie. Die ontwerp van hierdie tipe seëls is ook tans besig om hernude aandag te trek in heelwat lande. In Suid Afrika word die tipe seël al meer gebruik soos die behoefte na herseël projeke op die verouderde pad netwerk groei . Daar is ook heelwat groei in die gebruik van “Chip en Spray” seëls in Noord Amerika aangesien daar n behoefte is om n meer energie en materiaal effektiewe seëls te gebruik. Ten spyte van die groeiende gebruik van hierdie seëls het daar min wetenskaplike ontwikkeling plaasgevind in the ontwerp daarvan. Seëls word meestal ontwerp gebaseer op klient voorkeur , ondervinding, materiaal beskikbaarheid en ook industrie norms. ‘n Verouderde pad netwerk dwing die Suid Afrikaanse industrie om meer deeglike en wetenskaplike ontwerp prosedures te volg. Die VSA en Europa word deur vinnig groeiende verkeersvolumes en verhoogte kwaliteits behoeftes gedwing om prestasie gebaseerde spesifikasies te ontwikkel. Een van die hoof defekte op seëls is klipverlies wat plaasvind as die verbinding tussen die bitumen en aggregaat verswak en gebreek word deur die kragte wat deur verkeer oorgedra word. Dit lei tot los klip op die pad wat weer tot skade aan voertuie lei. Om dit te voorkom en aan te spreek het die behoefte laat ontwikkel vir n maklike en goedkoop tegniek om te meet hoe sterk die verbinding is wat ontwikkel tussen verskillende bitumen, bitumen emulsies en aggregaat monsters. Alhoewel daar alreeds toetse bestaan wat kan toets hoe sterk die verbinding is , gee die meeste van die toetse nie die informasie wat benodig word deur die voorgestelde prestasie gedrewe spesfikasies nie. Die “Bitumen Bond Strength” (BBS) toets metode is daarom ontwikkel om die tekortkoming in die toets van die bitumen en aggregaat verdindinge aan te spreek. Die BBS toets (AASHTO TP-91, 2011) is ontwikkel by die Universiteit van Wisconsin – Madison (UWM) in vennootskap met die Universiteit van Ancona – Italy (UAI) en die Universiteit van Stellenbosch (US) , spesifiek om die die sterkte van die verbinding wat vorm tussen aggregaat en bitumen te meet. Die US het in 2008 betrokke geraak by die BBS toets studie om hulp te verleen met die ontwikkeling en praktiese evalueering van die BBS toets metode. As gevolg van tyd en personeel tekorte is die betrokkendheid by die US beperk tot verskeie besprekings sessies, n studie toer, die evalueering van die BBS toets sowel as die voltooing van n uitgebreide stel toetse. Deur die voltooing van eksperimente met die BBS toets was dit moontlik om die uitvoerbaarheid en herhaalbaarheid van die ontwikkelde prosedure te toets. Die resultate van die toetse is suksesvol gebruik om die ontwikkeling van die verbinding sterkte tussen gemodifiseerde en ongemodifiseerde bitumen emulsies en tilliet en graniet te definïeer en te evalueer. Dit was ook moontlik om die resultate van die Universiteit Stellenbosch en die Universiteit of Wisconsin-Madison suksesvol met mekaar te vergelyk aangesien toetse by beide die instansies voltooi is. Die ontwikkeling van die toets en die inter laboratorium toets resultate het dit moontlik gemaak om die hipotese te bevestig dat die BBS toets prosedure effektief gebruik kan word om die bitumen en aggregaat verdindinge te toets en te evalueer. Behalwe vir die tempo van die lading waarteen die aftrek sterkte getoets word , is die emulsie tipe en die nabehandeling tydperk beide geidentifiseer as die mees beduidende invloede wat bydrae tot die ontwikkeling van die verbinding sterkte. Die aggregaat tipe is ook geidentifiseer as n belangrike faktor wat die verbinding sterkte ontwikkeling sal beïnvloed. Die interaksie tussen die emulsie tipe en nabehandeling tydperk was geïdentifiseer as die mees beduidende interaksie. Daar sal wel nog heelwat eksperimente voltooi moet word met die BBS toets prosedure voordat dit volkome geïntegreer kan word as deel van n prestasie gebaseerde spesifikasie stelsel vir die ontwerp van seëls.
270

Influence of surface seal variables on bitumen bond strength properties

Lombard, Le Riche 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Surface seals are widely used in South Africa. There are a number of reasons which include affordability, versatility and durability. There are, however, in some cases problems with stone loss that can lead to a shortened lifespan of the pavement. The loss of aggregate chippings in surface seals poses a major problem in the seal pavement industry. This study aims to identify the influencing factors that lead to these adhesive failures as well as to find optimum combinations of binders and aggregates at various conditions. Various binders commonly used in South African surface seal construction will be tested using the Bitumen Bond Strength (BBS) test method. The binders used in the study include 80/100 penetration grade bitumen, elastomer modified bitumen, bitumen rubber, elastomer modified emulsion and cationic rapid setting emulsion. Aggregates used in the study include dolerite, granite and quartzite. The test samples were cured and tested at two temperatures, 15 °C and 35 °C. The samples were also cured for 2, 6 and 24 hours respectively. The study tackles a wide range of variables in order to obtain a good understanding of adhesion properties of surface seals used in South Africa. Tests were repeated at least once to ensure repeatability and in some cases up to four repeats were performed. The loading rate at which the tests were performed had a significant influence on the BBS results. This rate varied which complicated the process of comparing the results. It was therefore decided to unify the loading rates. The BBS results exposed the difference between hot applied binders and emulsions. The former having significant stronger adhesion properties. It was also confirmed by the results that temperature plays a key role in the BBS results due to the visco-elastic properties of bitumen. These influences will be discussed along with others such as aggregate types and curing times. The type of failure is also discussed. Failure can either be adhesive or cohesive, the former being a failure between the aggregate and the binder while the later refers to a failure in the binder itself. The results of other students will also be discussed and compared to the results of this study. These include results of predecessors that tested emulsions as well as results from tests done on fractured aggregate surfaces and precoated aggregates. This study showed very similar results as these from other students, except for tests done with emulsions. It was discovered that the method of curing of the emulsions must be adapted to ensure proper curing of the emulsions. It was found that aggregates did not influence the BBS properties to the same extent as temperature and binder application type. The BBS results of hot applied binders also did not significantly increase as the curing time increased, but the results of emulsions showed some increase. However, the emulsions needed more time to cure properly. / AFRIKAANSE OPSOMMING: Oppervlak seëls word algemeen gebruik in Suid-Afrika. Daar is verskeie redes hiervoor waaronder bekostigbaarheid,veelsydigheid en duursaamheid. Daar is egter in sommige gevalle probleme met klipverlies wat kan lei tot n verkorte leeftyd. Hierdie klipverlies ontstaan as gevolg van verskeie redes of kombinasies daarvan. Die studie beoog om hierdie faktore wat die adhesie eienskappe beïnvloed te identifiseer sowel as om optimum kobinasies van bindmiddels en klipsoorte te bewerkstellig by verkeie kondisies. ‘n Verskeidenheid van bindmiddels wat algemeen in Suid-Afrika gebruik word, word in die studie getoets met die Bitumen Bond Sterkte (BBS) toets metode. Die bindmiddels wat in die studie gebruik word sluit 80/100 penetrasie graad bitumen, elastomeer gemodifiseerde bitumen, bitumen rubber, elastomeer gemodifiseerde emulsie en kationiese snel settende emulsie. Die klipsoorte wat vir die studie gebruikword is doleriet, graniet en kwartsiet. Hierdie gesteentes word algemeen in die praktyk gebruik. Die toets monsters word ook by twee temperature gekuur en getoets. Hierdie temperature is 15 °C en 35 °C. Die toets monsters word ook onderskeidelik vir 2, 6 en 24 uur gekuur. Die studie ondersoek 'n wye verskeidenheid van veranderlikes om sodoende 'n goeie begrip van adhesie eienskappe van die oppervlak seëls wat in Suid-Afrika gebruik word te verkry. Elke toets was ten minste een maal herhaal om herhaalbaarheid te verseker. Sommige toetse was tot 4 keer herhaal. Die belasting tempo van die toetse het ‘n beduidende uitwerking op die BBS resultate as gevolg van die visko-elastiese eienskappe van bitumen. Hierdie tempo het gewissel en dit moeilik gemaak om die resultate te vergelyk. Daarom was daar besluit om die tempo van die toetse te verander na ‘n gelykvormige tempo. Daar was ‘n duidelike verskil in BBS resultate van die warm toegepaste bindmiddels en die emulsies. Die warm bindmiddels het baie hoër BBS resultate gelwer. Dit was ook bevestig in die resultate dat temperatuur ‘n beduidende rol speel in die BBS. Hierdie invloede sal bespreek word tesame met ander, soos klipsoorte en kuring tye. Die tipe versaking word ook bespreek. Versaking kan plaasvind as gevolg van adhesie of cohesie, waar adhesie versaking 'n versaking is tussen die klip en die bindmiddel terwyl cohesie versaking verwys na 'n versaking in die bindmiddel self. Die uitslae van die ander studente sal ook bespreek word en vergelyking word met die resultate van hierdie studie. Dit sluit die resultate van voorgangers in wat emulsies getoets het sowel as die resultate van toetse wat gedoen is op gebreekte klipoppervlaktes en bitumen behandelde klippe. Hierdie studie het baie soortgelyke resultate getoon as dié van ander studente, behalwe vir die toetse wat gedoen was met emulsies. Daar is vasgestel dat die metode van kuring van die emulsies moet aangepas word om behoorlike kuring van die emulsies te verseker. Daar is ook gevind dat klipsoorte nie die BBS eienskappe in dieselfde mate as temperatuur en bindmiddel toepassingstipe beïnvloed het nie. Die BBS resultate van warm aangewende bindmiddels het ook nie aansienlik verhoog soos die kuringstyd toegeneem het nie, maar die resultate van emulsies het wel 'n toename getoon. Die emulsies het wel meer tyd nodig gehad om behoorlik te kuur.

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