Дисертації з теми "Bitumen emulsion cold mixtures"

With the current emphasis on sustainable development, recycling in the construction industry including highway planning, design, construction and maintenance has become a default option. Traditionally, recycled aggregate has been employed as filling or capping materials. However, the need to replace virgin materials in higher grade applications and reduce landfill has stimulated the need to enhance their performance. The requirements of using low energy and low environmental impact binders such as bituminous emulsion and industrial by-products as hydraulic binders whilst maintaining a long shelf life presented a further challenge. The primary aim of this research was to investigate methods by which a mixture of recycled aggregate composed of road planings, concrete demolitions and bricks with proprietary bitumen emulsion as binder could be enhanced to comply with the prevailing specifications and performance requirements for pavement materials, by using novel combinations of bituminous emulsions and latent hydraulic binders. The preliminary investigation focussed upon the establishment of an appropriate method of compaction of bitumen emulsion recycled aggregate mixtures to ensure results were consistent and representative of field performance. The main investigation evaluated the environmental conditions including freeze-thaw, low and high humidities and varying temperatures upon the behaviour and performance of loose pre-compacted and compacted recycled product using a range of novel latent hydraulic binders and bituminous emulsion combinations. Test methods included Indirect Tensile Stiffness Modulus test, Repeated Load Axial test, Indirect Tensile Fatigue test, Compressive Strength test and a novel modification of the Indirect Tensile Strength test was proposed and developed for enhance assessment of performance. The key findings were that whilst bitumen emulsion mixtures could perform adequately, the addition of a latent hydraulic binder enhanced the mixture's performance in terms of mechanical properties and withstanding extreme conditions exemplified by freeze-thaw and high humidity, whilst maintaining shelf life. However, it was deduced that the performance could be heavily influenced by the condition, consistency and composition of the recycled aggregate. It is recommended that further work should focus on rigorously investigating the influence of recycled components on mixture properties to optimise their performance for given applications, and extended to include tar bound material.

The increase of road infrastructure around the world involving the traditional hot mix asphalt (HMA) technology and its effects on the environment and health means that serious attention needs to be paid to building more sustainable flexible pavements. Cold bitumen emulsion mixture (CBEM) as an increasingly attractive cold asphalt mixture is therefore becoming an important subject area for study. Despite the efforts applied during the last few decades to enhance and develop CBEM application, certain issues still exist that make it inferior to HMA, resulting in limiting or minimizing its use. However, the enhancement of CBEM for flexible pavements construction, rehabilitation and maintenance is increasingly gaining interest in both pavement engineering industrial and research sectors. Therefore, the main aim of this study is to gain a deep insight and understanding into the impact response of using natural and synthetic fibres as reinforcing materials, on the mechanical properties and water susceptibility of CBEM including indirect tensile stiffness and resistance to rutting, cracking and moisture damage. Four different types of fibres were used: glass as a synthetic fibre, and hemp, jute and coir as natural fibres. Various samples of CBEM, with and without fibres, were fabricated and tested. Traditional hot mix asphalt mixture was also used for comparison. By achieving this aim it is expected that the use of CBEM would increase, allowing such mixtures to be used as structural pavement materials with some confidence. In spite of the quality of an asphalt mix being one of the most important and significant factors that affect the performance of both hot and cold mix flexible pavements, and the high quality mixes are often cost effective as these mixes require less maintenance and increase the service life of the pavements, it is also cost efficient to replace the semi-experimental flexible pavement design methods with fast and powerful software that includes finite element analysis. Several finite element models (FEM) have been developed to simulate the behaviour of hot mix asphalt, but none exists for cold mix asphalt reinforced by natural and synthetic fibres. This study also describes the development of a three-dimensional (3-D), finite element model of flexible pavements made with CBEMs, which has itself been reinforced with natural and synthetic fibres. The 3-D finite element model was employed to predict the viscoelastic and viscoplastic responses of flexible pavements based on CBEM when subjected to different multiple axle loads, bituminous material properties, tyre speeds and temperatures. The pavements were subject to moving and static loading conditions to test for permanent deformation (rutting). The results indicate a significant improvement in the indirect tensile stiffness modulus, for all fibre-reinforced CBEMs, over different curing times. The improved tensile behaviour represents a substantial contribution towards slowing crack propagation in bituminous mixtures, while scanning electron microscopy analysis confirmed the fibre shape and surface roughness characteristics. The improved performance of the reinforced mixtures with both natural and synthetic fibres facilitated a substantially lower permanent deformation than traditional hot and cold mixtures at two different temperatures (45 °C and 60 °C). When using glass and hemp fibres as reinforcing materials, there was a significant improvement in CBEM in terms of water sensitivity. These reinforcing materials can extend the service life of flexible pavements. Finally, the results show that the finite element model can successfully predict rutting of flexible pavements under different temperatures and wheel loading conditions.

Several benefits are gained from using cold mix asphalt (CMA) instead of hot mix asphalt (HMA). The benefits include conservation of materials and reducing energy consumption, preservation of the environment and reduction in cost. One of the common types of CMA is cold bitumen emulsion mixture (CBEM) which is the mixture produced by mixing mineral aggregate with bitumen emulsion. Despite the efforts applied in the last few decades in order to improve and develop CBEM utilization, certain deficiencies remain that make it inferior to HMA, resulting in restricting or minimizing of its use. However, the development of CBEM for road construction, rehabilitation and maintenance is steadily gaining interest in both pavement engineering industrial and research sectors. The present study was primarily aimed at evaluating the effect of using different cementitious materials on the performance of CBEM. The idea of the research is to provide a sustainable filler from supplementary cementitious materials (SCMs) to be used as fillers to provide enhanced properties of CBEMs. By achieving this aim it is expected that the utilization of CBEM would increase, allowing them to be used as structural pavement materials with some confidence. Research was first undertaken to optimize the mix design of CBEM using a statistical approach known as response surface methodology (RSM), as an alternative approach to achieve acceptable engineering properties. The optimization of CBEM was investigated, to determine optimum proportions to gain suitable levels of both mechanical and volumetric properties. This optimization focussed on the mix design parameters, namely bitumen emulsion content (BEC), pre-wetting water content (PWC) and curing temperature (CT). This work also aimed to investigate the effect of the interaction between these parameters on the mechanical and volumetric properties of CBEMs. The results indicate that the interaction of BEC, PWC and CT influences the mechanical properties of CBEM. However, PWC tends to influence the volumetric properties more significantly than BEC. The individual effects of BEC and PWC are important, rather than simply the TFC which is used in conventional mix design of CBEM. Furthermore, the experimental results for the optimum mix design corresponded well with model predictions. It was concluded that optimization using RSM is an effective approach for mix design of CBEMs. The study also investigated in-depth the performance characteristics of CBEMs using different filler treatments. The study was extended to understand the performance enhancement through mineralogical and microstructural investigations. The research was designed to use cement, binary and ternary blended fillers (BBF and TBF). Fly ash (FA) and ground granulated blast-furnace slag (GGBS) were used as BBF while silica fume (SF) was added to the BBF to obtain TBF. A significant improvement was achieved in mechanical and durability properties of CBEMs due to incorporation of both cement and blended fillers. Also, the results indicated that TBF was more suitable than BBF for the production of CBEMs. The microstructural assessment indicated that the effect of BBF on the internal microstructure of CBEMs was slightly negative and more noticeable in CBEMs containing FA. Mineralogical and microstructural assessments also suggested that the presence of bitumen emulsion might not affect the hydration of the silicates in treated CBEMs. The formation of additional CSH was observed due to the replacement of conventional limestone filler by cement, BBF and TBF. However, it seems that this can cause a delay in the formation of other hydration products (Ettringite) resulting from the hydration of aluminates in cement. Furthermore, it is proposed that the addition of SF to BBF mixtures can eliminate the delay in formation of hydration products caused by the bitumen emulsion. The present work was also aimed at better understanding the curing mechanism of CBEMs and to bridge the gap between laboratory curing and field evolution of these mixtures. This was achieved by evaluating the effect of the curing process on CBEM performance and developing a prediction model to assess in-situ CBEM performance using maturity relationships. Different contributory factors affecting the curing process were investigated such as curing temperature and relative humidity (RH) in addition to the impact of curing time and the presence of cement/active fillers. The results indicated that high curing temperature is responsible for additional stiffness gain by increasing the binder stiffness due to ageing and by increasing the moisture loss by evaporation during the curing process. However, at high curing temperature the moisture loss by evaporation may hinder the hydration of cement/active fillers. Moreover, the results also indicated that the high RH level influences the stiffness modulus of CBEMs negatively. The laboratory results were then used to develop a tool to assess in-situ curing of CBEMs using the maturity approach, which is widely used to estimate in-situ concrete properties. A strong correlation was found between maturity and the stiffness values obtained from the laboratory tests, which resulted in development of maturity-stiffness relationship. The application of this relationship to assess the in-situ stiffness of CBEMs is presented using three hypothetical pavement sections in the United Kingdom, Italy and Qatar; to simulate different curing regimes. A pavement analysis and design study was conducted to evaluate the incorporation of treated CBEMs into a pavement structure. CBEMs are suggested to be used in two scenarios: the first is as a surface course and the second is as a base course. The scope of the study is limited here to design based on the fatigue criterion only. Although, the structural design was based on practical hypothetical layer thicknesses, the results provided useful insight into the structural capabilities of CBEMs.

Dissertation (PhD)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: The use of foamed bitumen and bitumen emulsion as binders for use in road rehabilitation is gaining favour globally. High-level road facilities through to unpaved roads requiring attention are being treated with these binders due to environmental, economic and practical benefits in the use of cold bituminous mixes. In addition, static and mobile plant with the capability of performing stabilisation using bitumenemulsion and foamed bitumen has become commercially available and widely utilised, as a result of development in recycling technology and lapse in patent rights on foam nozzles. An understanding of the behaviour and failure mechanisms of these cold mixes, as well as sound guidelines for the mix design procedures of cold mixes, especially foamed bitumen, and design guidelines for pavements structures incorporating these materials, are lacking however. Mix designs are carried out primarily on the basis of experience and pavement designs are empirically based. The main objective of this dissertation is to address the need for a fundamental understanding of foamed bitumen and foamed bitumen mixes, and in so doing to develop techniques for adjudicating mixes, optimising their composition and rationalising their design both as mixes and as layers in road pavements. At the same time the exploration of new applications for foamed bitumen and the possibilities for progressive related technology, is a priority. To commence, this study includes an appraisal of most of the literature available on foamed bitumen. This is followed by a fundamental investigation of the colloidal mass of foam that is produced when small quantities of cold water are added to hot bitumen. Factors influencing the quality of the foam are identified and a Foam Index is developed for characterisation and optimisation of the foam. The spatial composition of a cold foamed bitumen mix, including Interaction of the foam with moist mineral aggregate, is also addressed in this dissertation. In particular, the stiffening of the filler mastic using foamed bitumen as binder is analysed. Techniques of optimising the sand type and content in the mix are also developed and guidelines for desired aggregate structures for foam treatment are established. The temperature of the mineral aggregate has been shown to have a profound influence on the behaviour and performance of a foamed bitumen mix. This has been selected as a focal area of further investigation and the research has lead to the development of a new process called "The half-warm foamed bitumen treatment process" that can produce mixes with almost the quality of hot mix asphalt with up to 40% less energy consumption. Other processes developed in this research include the use of cold mix asphaltic blocks for construction of road pavements in developing areas. This technology enhances the use of a high labour component in road construction in an economically competitive manner. The dissertation provides details for mix design and construction of the cold mix blocks. Finally, the study includes models for the performance prediction of foamed bitumen mixes. In particular, foamed mixes that exhibit stress-dependent behaviour have been investigated and models established on the basis of triaxial testing and accelerated pavement testing for the prediction of permanent deformation of such layers under repeated loading. Practical applications of the research findings are summarised in Appendix F. This includes: • methods for optimisation of the foamed bitumen properties, • guidelines for the selection of the ideal aggregate structure for cold foamed mixes, • procedures for carrying out cold mix design in the laboratory (including mixing, compaction and curing), • procedures for manufacturing half-warm foamed mixes in the laboratory, • methods for manufacturing cold mix blocks, and • pavement design methods for road structures incorporating foamed mix layers. Appendix G outlines statistical techniques that are relevant to the design of experiments in pavement engineering including examples of applications of these procedures. The techniques are applied selectively in the relevant chapters of the dissertation.
AFRIKAANSE OPSOMMING: Die gebruik van skuim bitumen en bitumen emulsie as bindmidel in pad rehabilitasie begin groter voorkeur wêreldwyd geniet. Van hoë vlak padfasiliteite tot ongeplaveide paaie wat aandag benodig, word met hierdie binders behandel vanweë die omgewings-, ekonomiese en praktiese voordele wat hierdie koue bitumen mengsels inhou. Voorts is statiese en mobiele masjinerie wat die vermoë het om stabilisasie in die gebruik van bitumenemulsie en skuimbitumen te bewerkstellig, in die handel verkrygbaar. Dit word algemeen gebruik as 'n uitvloeisel van ontwikkelings in herwinningstegnologie en die verslapping van patenteregte op skuim sproeikoppe. 'n Leemte bestaan in die begrip van die gedrags- en swigtingsmeganismes van hierdie koue mengsels, asook goeie riglyne vir die mengselontwerp van koue mengsels en in besonder skuimbitumen, en ontwerpriglyne vir plaveisel strukture waar hierdie materiaal geinkorporeer is. Mengselontwerpe word hoofsaaklik uitgevoer op grond van ondervinding, terwyl plaveiselontwerpe empiries gebaseer is. Die hoofdoel van die verhandeling is om die behoefte vir 'n fundamentele begrip van skuim bitumen en skuimbitumen mengsels aan te spreek, en daardeur tegnieke te ontwikkel vir die be-oordeling van mengsels, optimsering van hul samestelling en rasionalisering van hulontwerp vir beide mengsels en plaveisellae. Terselfdertyd is die ondersoek na nuwe toepassings van skuim bitumen en die moontlikhede van nuwe tegnologie 'n prioriteit. As beginpunt sluit hierdie studie 'n waardeskatting van die meeste literatuur beskikbaar op skuim bitumen in. Dit word gevolg deur 'n basiese ondersoek na die kolloidale massa van skuim wat geproduseer word wanneer klein hoeveelhede koue water by warm bitumen gevoeg word. Faktore wat die gehalte van die skuim beinvloed word uitgewys en 'n Skuim Indeks is ontwikkel vir die karakterisering en optimisering van die skuim. Die ruimtelike samestelling van 'n koue bitumen mengsel, wat die interaksie van die skuim met vogtige minerale samevoegings (aggregate) insluit, word ook aangespreek. Besondere aandag word gewy aan die verharding van die vuiler mastiekgom wat gebruik word as bitumen binder. Tegnieke om die sandtipe en inhoud van die mengsel te optimiseer is ontwikkel en riglyne vir die verlangde samevoegingstrukture (aggregate strukture) vir skuimbehandeling is opgestel. Daar is bevind dat die temperatuur van die minerale aggregaat 'n duidelike invloed op die gedrag en verrigting van 'n skuimbitumen mengsel het. Dit is gekies as In fokuspunt vir verdere studie en die navorsingswerk daarop het gelei tot die ontwikkeling van In nuwe proses wat "Die half-warm skuim bitumen behandelings proses" genoem word. Hierdie proses produseer mengsels wat byna gelykstaande is aan die gehalte van warm gemengde asfalt, maar met tot 40% minder energie verbruik. Ander prosesse wat met dié navorsing ontwikkel is, sluit koue gemengde asfaltiese blokke in, wat gebruik word in die konstruksie van padplaveisel in ontwikkelende gebiede. Hierdie tegnologie bevorder die ekonomiese gebruik van 'n hoë arbeidskomponent in padkonstruksie. Die studie stel besonderhede vir die mengselontwerp en konstruksie vir koue gemengde blokke voor. Laastens sluit die studie modelle in vir die werkverrigtingsvoorspelling van skuimbitumen mengsels. Op basis van drie-assige proewe in die laboratorium en versnelde belasting van paaie is modelle ontwikkel vir skuim bitumen mengsels wat spanningsafhanklike gedrag vertoon (die sogenaamde "granulêre" groep) om die permanente deformasie in die lae as gevolg van herhaalde verkeersbelasting te voorspel. 'n Opsomming van al die praktiese toepassings van die ontwikkelings van die navorsing word in Appendix F verskaf. Dit sluit in: • optimesering van die eienskappe van skuimbitumen, • riglyne vir gewenste samestelling van aggregaat in skuimbitumen mengsels, • ontwerp metodes vir koue skuimbitumen mengsels in die laboratorium (meng, verdigting en curing), • produksie metodes vir half-warme mensels in die laboratorium, • produksie metodes vir blokke wat met koue mengsels gemaak word, en • plaveiselontwerp metodes van strukture wat skuimbitumen lae inkorporeer. Appendix G gee 'n oorsig van statistiese tegnieke wat relevant is vir die ontwerp van eksperimente, insluitend voorbeelde van toepassings van die prosedures in plaveiselingenieurswese. Die tegnieke word selektief toegepas in die relevante hoofstukke van die verhandeling.

Cold mix asphalt (CMA) emulsion technology could become an attractive option for the road industry as it offers lower startup and equipment installation costs, energy consumption and environmental impact than traditional alternatives. The adhesion between bitumen and aggregates is influenced by diverse parameters, such as changes in surface free energies of the binder and aggregates or the presence of moisture or dust on the surface of aggregates, mixing temperatures, surface textures (including open porosity), nature of the minerals present and their surface chemical composition, as well as additives in the binder phase. The performance of cold asphalt mixtures is strongly influenced by the wetting of bitumen on surfaces of the aggregates, which is governed by breaking and coalescence processes in bitumen emulsions. Better understanding of these processes is required. Thus, in the work this thesis is based upon, the surface free energies of both minerals/aggregates and binders were characterized using two approaches, based on contact angles and vapor sorption methods. The precise specific surface areas of four kinds of aggregates and seven minerals were determined using an approach based on BET (Brunauer, Emmett and Teller) theory, by measuring the physical adsorption of selected gas vapors on their surfaces and calculating the amount of adsorbed vapors corresponding to monolayer occupancy on the surfaces. Interfacial bond strengths between bitumen and aggregates were calculated based on measured surface free energy components of minerals/aggregates and binders, in both dry and wet conditions. In addition, a new experimental method has been developed to study bitumen coalescence by monitoring the shape relaxation of bitumen droplets in an emulsion environment. Using this method, the coalescence of spherical droplets of different bitumen grades has been correlated with neck growth, densification and changes in surface area during the coalescence process. The test protocol was designed to study the coalescence process in varied environmental conditions provided by a climate-controlled chamber. Presented results show that temperature and other variables influence kinetics of the relaxation process. They also show that the developed test procedure is repeatable and suitable for studying larger-scale coalescence processes. However, possible differences in measured parametric relationships between the bitumen emulsion scale and larger scales require further investigation. There are several different research directions that can be explored for the continuation of the research presented in this thesis. For instance, the rationale of the developed method for analyzing coalescence processes in bitumen emulsions rests on the assumption that the results are applicable to large-scale processes, which requires validation. A linear relationship between the scales is not essential, but it is important to be able to determine the scaling function. Even more importantly, qualitative effects of the investigated parameters require further confirmation. To overcome the laboratory limitations and assist in the determination of appropriate scaling functions further research could focus on the development of a three-dimensional multiphase model to study coalescence processes in more detail, including effects of surfactants, pH and other additives such as mineral fillers and salts. Additionally, better understanding of the breaking process and water-push out could help significantly to optimize CMA mix design. Different methods, both numerical and experimental could be explored for this.
Cold mix asphalt (CMA) eller kall asfaltbetong med hjälp av emulsionsteknik kan vara ett attraktivt alternativ för vägbyggnadsindustrin då det möjliggör lägre uppstart- och investeringskostnader, lägre energiförbrukning och mindre miljöpåverkan än traditionella alternativ. Adhesionen mellan bindemedel och stenpartiklarna påverkas av ett flertal parametrar, så som förändring i fri ytenergi hos både bindemedel och partiklar i närvaro av fukt eller damm på stenytorna, blandningstemperatur, yttextur (inklusive ytporositet), mineralegenskaper och ytornas kemiska sammansättning lika väl som tillsatsmedel i bindemedlen. Beteendet hos kall asfaltbetong är starkt påverkad av vätningsegenskaperna hos bindemedlet när det kommer i kontakt med stenmaterialet och detta i sin tur är beroende på bitumenemulsionens brytegenskaper och förmåga att blandas. Bättre förståelse av dessa processer är av största vikt. I detta arbete är avhandlingen baserad på fri ytenergi hos både mineraler/aggregat och bindemedel, baserat på kontaktvinkel och på ångabsorptionsmetoder. Den exakta specifika ytan hos fyra typer av aggregat och sju mineraler undersöktes med en metod baserad på BET (Brunauer, Emmett och Teller):s teorier genom att mäta den fysiska adsorptionen av utvalda gaser på ytorna och beräkna mängden adsorberad ånga som korresponderade mot ytlagret. Styrkan hos kontaktytornas bindning mellan bindemedlet och stenaggregaten beräknades baserat på mätningar av den fria ytenergin hos bägge ingående komponenterna, dels i torrhet dels i våta omgivningar. Som tillägg har en ny experimentell metod utvecklats för att studera bitumens blandbarhet genom att studera bitumendroppars relaxation i en emulsionsmiljö. Genom att använda denna metod har korelationen mellan sväriska droppar av bitumen undersökts mot förändringen i ytans area under blandningsprocessen. Testprotokollet utformades för att studera blandningsprocessen i varierande miljöer i en klimatkammare. Presenterade resultat visar att temperatur och andra variabler påverkar de kinetiska förhållandena vid relaxationsprocessen. De visar även att den utvecklade testmetoden är repeterbar och passar för studier av storskaliga blandningsprocesser. Det bör dock påpekas att vidare studier krävs för att påvisa skillnaderna mellan bitumenemulsionsskalan och större skalor. Framtida forskning kommer att koncentreras på utveckling av tredimensionella multifas­modeller för att studera blandningsförlopp på en mer detaljerad nivå, inkluderande effekter på ytaktiva ämnen, pH-värden och andra additativ så som mineralfiller och salt. Som tillägg kommer nyttan av nya karaktäriseringsmetoder att utvärderas, så som lågvikelspridning av neutroner eller kombinationer av röntgen, neutronradiologi och datortomografi, för att studera brytmekanismer hos bitumenemulsioner vid kontakt med mineraler och aggregat.

QC 20160901

Bitumen emulsion mixtures, or cold mix, offers certain advantages over hot bituminous road mixtures in terms of potential cost savings, environmental factors, energy savings and easing of logistical difficulties inherent with hot mix. For these reasons, they are currently used in a number of regions including the United States of America, Continental Europe, Scandinavia, Southern Africa and Australia. However, cold mix has not been seriously evaluated or utilized in the UK until comparatively recently. This is due to the slow rate at which it builds strength or cures and its susceptibility to rainfall, particularly during this curing period. The overall aim of this research was, therefore, to study the behaviour of cold mix in terms of mechanical properties and the mechanisms involved in emulsion breaking and mixture curing to gain an insight into how performance may be improved. Mechanical properties were shown to be affected by a number of parameters, including binder grade, void content, curing time and additives such as cement. Fatigue tests showed that without cement, the performance in-situ of cold mix would be very poor. Pavement design calculations revealed that, with cement, emulsion mixtures could be expected to perform similarly to equivalent hot mix. Field trials have indicated that cold mix can be manufactured using conventional hot mix plant and laid using similar techniques. However, problems are still to be overcome in terms of the control of mixture composition and laying in adverse weather conditions. Fundamental tests have shown that emulsion droplet coalescence (which is an essential part of the curing process) was affected by pressure, bitumen type, emulsifier level, cement and temperature and that cement can cause emulsion charges to become more positive (or less negative) but other parameters had no effect on charge. It was also proved that cement can cause bitumen emulsion to set completely and that the residual binder has an increased viscosity compared with unmodified binder. This was shown to be due to the formation of a composite bitumen cement binder.

Les géopolymères sont des matériaux inorganiques fabriqués à partir de composés d’origine naturelle (kaolin, par exemple), ou issus de déchets industriels (cendres volantes, laitiers de hauts fourneaux…). Leurs excellentes propriétés physico-chimiques et mécaniques justifie l’intérêt grandissant qu’ils suscitent dans le domaine de la construction. Toutefois, leur potentiel d’utilisation reste limité en raison de l’emploi, lors de leur préparation, de solutions alcalines fortement concentrées présentant des risques sanitaires importants et d’une difficulté de stockage et transport ; d’où la nécessité d’implémenter des techniques de confection sans solvant. Cette thèse vise à proposer une nouvelle méthode d’élaboration de poudres pré-géopolymères (PGP) par « mécanosynthèse » faciles à transporter et à stocker. Plusieurs matières premières, de différentes natures et compositions chimiques, ont été testées comme précurseurs aluminosilicatés (cendres volantes, métakaolin, laitier de hauts fourneaux et argile) ; elles ont été activées par différents mélanges alcalins (NaOH, KOH, Na2SiO3 et CaO), à des ratios massiques fixés. L’effet de plusieurs paramètres de procédé a été considéré, notamment le temps et la vitesse de broyage. Les poudres pré-géopolymères produites ont été ensuite incorporées dans des formulations de pâtes, de mortiers et d’enrobés bitumineux. Les propriétés physico-chimiques et mécaniques des pâtes produites ont été étudiées. Les résultats obtenus ont été comparés à ceux des pâtes confectionnées par la méthode classique dans les mêmes conditions. La cinétique de la réaction de géopolymérisation des pâtes a été suivie par spectrométrie infrarouge in situ juste après l’hydratation des PGP. Par ailleurs, le procédé de mécanosynthèse indirecte a été utilisé pour améliorer la réactivité de l’argile.Les résultats ont mis en évidence l’efficacité du procédé de mécanosynthèse pour l’élaboration de poudres pré-géopolymères. Celles-ci donnent lieu après hydratation à des pâtes géopolymères avec une structure semblable à celle des géopolymères classiques. Ce procédé a également permis d’améliorer les performances mécaniques des produits géopolymères. Les poudres pré-géopolymères à base d’argile illitique produites par mécanosynthèse indirecte donnent lieu à des pâtes avec une résistance mécanique atteignant 72,5 MPa après 28 jours de cure à 20 °C et 50 % d’humidité relative, contre 12,5 MPa dans le cas classique. Les résultats obtenus sur les mortiers à base de PGP-laitier montrent des résistances mécaniques qui atteignent 38 MPa après 28 jours de cure.Enfin, les résultats préliminaires sur les enrobés bitumineux à base de PGP révèlent une meilleure tenue à l’eau et résistance à l’orniérage, même après 100.000 cycles, que celles des formules de référence sans PGP
Geopolymers are inorganic materials made from compounds of natural origin (kaolin, for example), or from industrial waste (fly ash, blast furnace slag, etc.). Their excellent physicochemical and mechanical properties justify the growing interest they arouse in the construction field. However, their potential of employment remains limited due to the use, during their preparation, of highly concentrated alkaline solutions causing significant health risks and transport storage difficulty; hence it is necessary to implement solvent-free manufacturing techniques.This thesis aims to propose a new producing pre-geopolymer powders (PGP) method by “mechanosynthesis” that are easy to transport and store. Several raw materials, of different types and chemical compositions, were tested as aluminosilicate precursors (fly ash, metakaolin, blast furnace slag and clay); they were activated by different alkaline mixtures (NaOH, KOH, Na2SiO3 and CaO), at fixed mass ratios. The effect of several process parameters was considered, including milling time and speed rotation. The produced pre-geopolymer powders were then incorporated into formulations of pastes, mortars and bituminous mixes. The pastes physicochemical and mechanical properties were studied. The obtained results were compared with those of pastes made by the conventional method under the same conditions. The kinetics of pastes geopolymerization reaction were followed by infrared spectrometry in situ just after the hydration of the PGP. In addition, the indirect mechanosynthesis process has been used to improve the reactivity of clay.The results demonstrated the mechanosynthesis process efficiency for producing the pre-geopolymer powders. These give rise after hydration to geopolymer pastes with a similar structure to that of conventional geopolymers. This process has also helped to improve the mechanical performances of geopolymer products. The pre-geopolymer powders based on illitic clay, produced by indirect mechanosynthesis, give rise to pastes with mechanical resistance reaching 72.5 MPa after 28 curing days at 20 ° C and 50% of relative humidity, against 12.5 MPa for the classic case. The results obtained on slag-based mortars show mechanical strengths reaching 38 MPa after 28 curing daysFinally, the preliminary results on slag PGP-based bituminous mixes reveal better water and rutting resistance, even after 100,000 cycles, than those of the reference formulas without PGP

Road structures are important to the survival of nations. As the cost for the rehabilitation and maintenance of highways soars, civil engineers and administrators face the ever present difficulty of meeting current resurfacing and rehabilitation needs. The deterioration of road structures under growing traffic weight and volume is occurring faster than agencies envisaged coupled with increasingly scarce and expensive new materials required. It is now apparent that for planning, design and construction for road structures, the most efficient and cost effective processes, materials and practices available must be appropriately considered. The use of recycled materials as a sustainable alternative is gaining significant worldwide attention. The overall purpose of this research was to conduct an in-depth investigation and analysis into the design and optimisation of Cold Asphalt Emulsion Mixtures (CAEMs) incorporating high contents of Reclaimed Asphalt Pavements (RAP). To achieve the objectives of the research, four proportions of RAP aggregate materials in addition to Virgin Aggregates (VA) were used as categorised below: - Category 1: 0% RAP (no RAP, 100% VA) - Category 2: 50% RAP (50% RAP, 50% VA) - Category 3: 85% RAP (85% RAP, 15% VA) - Category 4: 95% RAP (95% RAP, 5% VA) The effect of mixing and compaction temperatures at 5°C, 20°C and 32°C and how cement at 0%, 1% and 3% OPC influenced the CAEMs was also investigated. This study presents a practical mix design procedure to act as a guideline for CAEMs incorporating high RAP contents by identifying critical parameters for the various categories of CAEMs which stemmed from the fact that currently there is no universally accepted mix design. The proposed mix design guideline is presented in this thesis. The effect of accelerated curing was investigated to study the effects of temperature, curing duration, conditioning and the influence of cement on the CAEMs. The research showed that an increase in curing temperature results in an increase in the stiffness and strength of the CAEMs. The thesis presents results on the mechanical and performance properties which provided vital information on expected performance of CAEMs incorporating high contents of RAP for use as a road base material. The research was able to highlight the purported effects of residual binder in RAP which could contribute positively to the mechanical and performance properties of the CAEMs. This points to the fact that treating RAP as “black rock” is not the right approach. The RAP needs to be evaluated for its inherent properties and suitability for purpose. The stiffness and strength were investigated using the Indirect Tensile Stiffness Modulus (ITSM) and Indirect Tensile Strength (ITS) tests which proved useful in ranking them. The addition of 1% OPC improved the stiffness of Categories 1-3 mixtures by 32% with Category 4 having the highest increase at 89%. The inclusion of 3% OPC, more than doubled the stiffness values. The Indirect Tensile Fatigue Test (ITFT) was used to investigate the fatigue characteristics. Results showed that if the CAEMs with cement at 1% and 3% experienced strains in the region of 200µε, they tend to fail suddenly soon after crack initiation due to reduced flexibility of the CAEMs. This was more pronounced for the CAEMs at 3% OPC. Resistance to permanent deformation was investigated using the Vacuum Repeated Load Axial Test (VRLAT) which showed that the mixing and compaction temperature influenced the permanent deformation characteristics of the CAEMs. Increasing OPC content to 1% for Categories 2 and 3 resulted in a decrease in permanent strains of 47% and at 3% OPC, the decrease in permanent strains was 54%. Wheel Tracking Test (WTT) was conducted to ascertain the susceptibility of the CAEMs to deform under loading, investigate crack propagation and number of cycles to failure. The test showed that the performance of the specimens was affected by the test temperature. Increased test temperatures resulted in an increased rate of rutting and eventual failure of the specimens. The test further highlighted the positive benefits of adding cement to the mixtures which resulted in reduced strains and an increased number of cycles to failure for the CAEMs. Structural design and modelling was conducted using KENLAYER which was able to account for the non-linearity of the CAEMs. This was crucial in having a total overview of these mixture types. Although, the structural design was based on practical hypothetical layer thicknesses, the results provided useful insight into the structural capabilities of the CAEMs. The RAP CAEMs generally had lower horizontal tensile strain values in comparison to the VA CAEMs. The design charts showed that an increase in the thickness of the base course and surfacing layer resulted in an increase in the overall fatigue life of the pavement structure. Overall, evaluating the complete findings of this research, CAEMs produced with high RAP contents especially at 50% and 85% RAP had considerably enhanced mechanical and performance properties and are suitable for inclusion as a base material for reconstruction and rehabilitation.

Currently, there exists no universally accepted Cold Bituminous Emulsion Mixtures (CBEMs) design procedure. Three of the most popular design procedures, which in essence were based on AASHTO and the Asphalt Institute design guidelines were studied and tested in detail during the course of this investigation. In general, the design procedures investigated were found to be not user-friendly or simple to implement. The main obstacles that restrict the adoption of CBEMs as the first choice material as opposed to conventional hot asphalts, for all bound pavement layers are: the high compacted mixture porosity, low early life strength and long curing times. CBEMs are more widely accepted in low to medium trafficked pavements. The key aims of this investigation were to improve and simplify the design procedure of CBEMs, and to investigate ways of improving CBEMs volumetric and mechanical properties. The main aggregate materials used in this investigation were carboniferous limestone and quartzitic asphalt sand. But in response to environmental conservation campaigns, a range of selected waste materials were also tested as partial and full replacement to the virgin mineral aggregates, including: pulverized fuel ash (PFA), red porphyry sand, synthetic aggregates, steel slag, crumb rubber, and crushed glass. The aggregate gradations were designed using a modified Fuller's curve. The emulsion used in this investigation was a cationic bitumen emulsion with 60% and 62% binder content composed of 100 pen base bitumen. The mix design procedure initially developed in this investigation was found to be complicated from a practical application point of view, in particular the steps required to determine the optimum total liquid content at compaction, which were unlikely to be practicable for site applications. A more simplified CBEMs design procedure was therefore introduced in this thesis, where the coating test was found to play a very essential role. Improvements in all mixture properties were readily accomplished by increasing the compaction effort to reduce porosity and by incorporating cement. The porosity target of 5-10% and minimum indirect tensile strength (ITSM) value of 2000 MPa at a fully cured condition were more easily achievable. The main emphasis of this modified design procedure was on simplicity and practicality whilst maintaining the key volumetric and mechanical properties of the mixtures. In this investigation, the mechanical Performances of the CBEMs at full curing condition were more comprehensively evaluated in terms of fatigue and creep tests. Attempts to accelerate the curing times of cold asphalt mixtures were made by compacting the CBEM specimens in two layers (two lifts) thus allowing the moisture to escape faster from each layer and hence reducing the overall curing time. The results from these laboratory trials were very encouraging. Additionally, the incorporation of plastic cells was found to significantly reduce shear deformations of CBEMs under loading during their early lives. The inclusion of plastic grids in the upper layer of a two layered cold mixture system appeared to be very promising. It was concluded that the CBEMs design procedure proposed in this investigation was simpler than the initially adopted procedure. The main advantages of this modified design procedure were that whilst it maintained all the key volumetric and mechanical properties of the mixtures it was simpler and more practical than other existing procedures. Heavier compaction effort and the incorporation of I to 2% cementitious materials were found to be essential for improving the performance of CBEMs, and as is well known, CBEMs are most suitable in dry warmer climates. When CBEMs are carefully designed and are allowed to achieve a full curing condition, the performance of CBEMs can be comparable to hot asphalt mixtures with the same penetration grade binder.

Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The increased use of reclaimed asphalt (RA) in Bitumen Stabilised Materials (BSMs), shortcomings in the existing design guidelines and manuals and ongoing developments in the concepts and understanding of these materials require further research into the fundamental properties and behaviour of BSMs. The state-of-the-art of foamed bitumen techniques is reviewed in the literature study. Current best practices in the design of BSMs and pavements incorporating such materials are also included in this literature study. Shortcomings and areas for further improvement of the design practice have been identified. With new environmental legislation, the importance of BSM technology including RA as an environmentally-friendlier and more sustainable construction technique is set to increase in the coming years. Changes in the behaviour of materials and failure mechanisms of BSM mixes are long-term phenomena. This implies that the study of the physico-chemical and mechanical properties of the mixes with increasing amount of RA is vital. Therefore, fundamental understandings of moisture damage and thermo-physical characteristics, which are related to material properties, are required. The main objective of this study is to advance BSM technology by assessing the influence of the selected materials on durability behaviour, temperature distribution and long-term performance in all phases of application (i.e. mix design, construction, and in-service condition). This study begins with a comprehensive literature review of research dealing with the interactions between RA and mineral aggregates. The properties of RA and mineral aggregates were reviewed. This was followed by a review into the mechanical properties of BSM-foam mixes with high percentage of RA and its durability performance. Factors influencing the temperature gradient of BSMs were then identified. Achieving a better understanding of the fundamental performance properties and temperature influence on the behaviour of BSMs with high percentage of RA is one of the key factors of this research, with a view to using the extended knowledge for improvements to current mix design and structural design practices. Finally, the fundamental theories on thermo-conductivity and the mechanical properties of the BSM were used to create a relationship between temperature and mechanical properties in a pavement section. A laboratory testing programme was set up to study the properties and behaviour of BSMs and to establish links with the compositional factors, i.e. the type of binder used, the percentage of RA in the mix and the addition of a small amount of cement as active filler. BSMs were blended in three different proportions of RA and good quality crushed stone materials: 100% RA (with 2 % bitumen content), 50% RA and 50% G2 Hornfels crushed stone (with 2.1% bitumen content) and 100% G2 (with 2.3 % bitumen content). Tri-axial testing was carried out to determine shear parameters, resilient modulus and permanent deformation behaviour, while brushing testing was carried out to determine the possible durability performance of the BSMs. The mixture durability in terms of moisture damage was investigated. Temperature data were collected and a model to accurately simulate the temperature distribution in the BSMs was identified and proposed for further investigation and validation. It was found from the laboratory temperature data collected in this study that the temperature gradient varied according to the depth of the BSMs. A considerable part of the efforts of this study were dedicated to characterise and model the temperature distribution in a pavement section, taking into account the mechanical properties and performance of the BSMs at different temperature layers. The study provides an insight into fundamental mechanical performance, material durability properties, and the thermal capacity and conductivity of the BSM-foam mixes with high percentage of RA. This will assist in improving the current procedure for selection, combining and formulation of the mix matrices for BSMs. In addition, the study provides guidelines that will enable practitioners to confidently understand the relationship between temperature gradient and mechanical behaviours of BSM-foam pavement section. The specific durability-related issues addressed in this study are substance for future research.
AFRIKAANSE OPSOMMING: Die toenemende gebruik van herwonne asfalt (Engels: reclaimed asphalt (RA)) in bitumen gestabiliseerde materiaal (Engels: Bitumen Stabilised Materials (BSMs)), tekortkominge in die bestaande ontwerpriglyne- en handleidings en deurlopende verbeteringe in die konsepte en begrip van hierdie material vereis verdere navorsing oor die fundamentele eienskappe en gedrag van BSM. In die literatuurstudie word die huidige stand van kennis van die ontwerp van skuimbitumentegnieke ondersoek. Die literatuurstudie dek ook die huidige beste praktyke in die ontwerp van BSM en plaveisels wat hierdie materiale insluit. Tekortkominge en areas van verdere verbetering in die ontwerppraktyke is geïdentifiseer. Onlangse omgewingswetgewing verhoog die belangrikheid van BSM tegnologie, insluitend RA, as ‘n meer omgewingsvriendelike en volhoubare konstruksie-tegniek. Hierdie faktor sal in die toekoms al hoe belangriker word. Die verandering in die gedrag van materiaal en die falingsmeganismes van BSM mengsels is langtermynverskynsels. Dit impliseer dat die studie van die fisio-chemiese en meganiese eienskappe van mengsels met toenemende verhoudings van RA van kardinale belang is’n Fundamentele begrip van die vogskade en temo-fisiese eienskappe, wat verwant is aan die materiale se eienskappe, word vereis. Die primêre doelwit van die studie is die bevordering van BSM tegnologie deur die invloed van die geselekteerde materiale op duursaamheid, temperatuurverspreiding en langtermyn gedrag in al die fases van toepassing (mengselontwerp, konstruksie en in-dienstoestand) te bepaal. Die verhandeling begin met ‘n omvattende literatuuroorsig van navorsing oor die interaksie tussen RA en mineraalaggregate. Die eienskappe van RA en die mineraalaggregate word bespreek. Dit word gevolg deur ‘n oorsig van die meganiese eienskappe van die BSM-skuimbitumenmengsels met ‘n hoë persentasie RA en die duursaamheidgedrag daarvan. Faktore wat die temperatuurgradient van BSM beïnvloed word dan aangetoon. ‘n Beter begrip van die fundamentele gedragseienskappe en die invloed van temperatuur op die gedrag van BSM met ‘n hoë persentasie RA is een van die sleutelfaktore van hierdie navorsing. Dit het ten doel om die uitgebreide kennis te gebruik om huidige mengselontwerp en strukturele ontwerppraktyke te verbeter. Laastens is die fundamentele teorie van termogeleiding en die meganiese eienskappe van BSM gebruik om ‘n verhouding tussen temperature en meganiese eienskappe in ‘n plaveiselsnit te ontwikkel. ‘n Laboratoriumtoetsprogram is opgestel om die eienskappe en gedrag van BSM te bestudeer en om verwantskappe tussen samestellende faktore soos die tipe bindmiddel gebruik, die persentasie RA in die mengsel en die toediening van klein hoeveelhede sement as aktiewe vuller te bepaal. BSM is in drie verskillende verhoudings van RA en goeie gehalte gebreekte klipmateriaal vermeng: 100% RA met 2 % bitumen, 50% RA en 50 % G2 Hornfels gebreekte klip met 2.1 % bitumen en 100% G2 met 2.3 % bitumen. Drie-assige druktoetse is gebruik om skuifsterkteparameters, elastiese modulus en permanente vervormingsgedrag te bepaal. Borseltoetse is gebruik om die duursaamheidgedrag van BSM te bepaal. Die mengsels se duursaamheid is ook in terme van vogskade ondersoek.

Dans un contexte politique où les enjeux énergétiques et environnementaux sont de plus en plus importants, il faut favoriser les techniques économes en énergie et plus respectueuse de l'environnement. Parmi ces pratiques, l'utilisation d’enrobés à l’émulsion de bitume s'est révélée être prometteuse. La fabrication et la conception d’une chaussée comprenant une couche d’enrobé à l’émulsion sont très empiriques et reposent sur des compétences locales qui tendent à en limiter le développement. La première étape pour concevoir une chaussée consiste à connaître le comportement mécanique réversible engendrées par de lourd trafic de chaque matériau qui la compose. Lors d'une deuxième étape, ces valeurs doivent être comparées aux critères de durabilité mécanique des matériaux. Dans le cas de l'enrobé à l’émulsion, aucune loi de comportement mécanique n'a été établie pour tenir compte à la fois de son états frais et durcis. Ce travail de thèse vise donc à pallier à ce manque et à améliorer les connaissances acquises sur ce matériau. Pour cela, un modèle évolutif pour l’enrobé à l’émulsion intégrant l'évolution du matériau de son état frais à l'état durci a été développé. De plus, un nouvel essai de caractérisation a été développé et mis en place pour permettre de suivre l’évolution des performances mécaniques réversibles du matériau. Les résultats obtenus à partir des différentes campagnes d’essais ont permis de caler le modèle et de montrer la pertinence du modèle
Given a political context in which energy and environmental stakes have become increasingly dominant, road engineering practices have favoured saving energy and protecting the environment. Among these practices, the use of cold mixes treated with bitumen emulsion has proven to be a suitable technique. Cold mix design however, as well as the design of pavements including cold mix asphalt layers, is highly empirical and based on local skills. From prior experience, the transposition of established local rules from one site to another and their application to medium or heavy traffic pavements are not simple steps and tend to limit the development of this environmentally-friendly pavement technique. The first step in designing a pavement consists of knowing the stress-strain relationship of its constitutive materials in order to determine the stresses and strains generated by heavy lorry traffic. During a second step, these values must be compared with the mechanical durability of materials by reliance on damage tests comprising large numbers of load cycles. In the case of CMA, no mechanical behaviour law has been established to take into account both the fresh and cured states. This work aims to improve the knowledge acquired on this material. For this, an evolutiv model for the cold mix asphalt with bitumen emulsion incorporating the evolution of the material from its fresh state to its cured state has been developed. In addition, a new characterization test was developed and put in place to monitor the evolution of the reversible mechanical performance of the material. The results obtained from the test campaigns helped to calibrate the model and show the relevance of the model

Currently it is important to address the re-use of building materials from construction reconstructed or upgraded roads. Commonly used technologies cold and hot asphalt recycling are starting using to complement with technologies using cold asphalt mixtures with rejuvinators or softeners. This type of asphalt mixtures could be used in pavement constructions with lower traffic load. This thesis deals with the design and laboratory assessment of unbound and bound mixtures R-material and recycled concrete. This thesis is experimentally testing the possibility of using functional tests to optimize the design of asphalt mixture with 100% representation of R-material with a possible revival of asphalt emulsion with a rejuvenator.

碩士
國立中央大學
土木工程學系
107
The cold mix recycling method has been used widely in global. Road construction and renovation projects growth yearly in Taiwan. Causing the recycled asphalt pavement (RAP) accumulation and leads to excess and stockpiling problems. This study refers to the foreign cold mix recycling technology that aims to explore the feasibility of adding 100% RAP application to the base of Taiwan pavement along with laboratory evaluation and test road verification. Since relevant specifications regarding emulsified asphalt content of cold recycling mixture designs haven’t been issued in Taiwan. Laboratory test in this study uses AASHTO PP 86 specification in combination with Taiwan Specifications for Public Construction Chapter 02714“Bituminous treated base” E-class granule-grading curve for Marshall and indirect tensile stress mix design. After the mix design, AASHTO MP 31 and ARRA CR201 specifications are used to determine the optimum mixture, and then the road test is carried out using optimum mixture with 40% coarse RAP and 60% fine RAP. Marshall specimens with different emulsified asphalt and cement contents are prepared for further testing. The optimum mixture was found to contain 0.5% cement (Type I), 4% emulsified asphalt (CSS-1) as cementitious material and 1.5% of water. The laboratory result shows cold mix recycled emulsified asphalt concrete can quickly stabilize and the strength meets the relevant specifications' requirement. Moreover, according to the field road verification test results, the overall result maintained in good condition. In the feasibility assessment, the cold mix recycled emulsified asphalt concrete has better benefits in construction time, energy saving and carbon dioxide reduction when compared with conventional controlled low-strength concrete (CLSM), hot mix asphalt (HMA) and cold mix recycled foamed asphalt concrete (research by Wei Yuan Zeng. 2016). In summary, the cold mix emulsified asphalt concrete can be used in Taiwan pavement base while reducing the RAP stockpiling to reach the goal of eliminating the RAP.