Thesis (PhD (Civil Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In both developing and developed countries, to ensure sustained economic growth the quest for optimal roads performance is an extremely high priority. A global increase in the use of foamed bitumen and bitumen emulsion materials (BSMs) as a solution to roads maintenance, rehabilitation, and upgrading has become evident. This is driven by environmental policies aimed at conserving energy and limiting the exploitation of new borrows pits. It has therefore become imperative that BSMs are used optimally, and, in order to achieve this, practitioners need to understand the mechanisms that influence durability and long-term performance. The changes in the behaviour of materials and the failure mechanisms of BSM mixes are long-term phenomena. This implies that the study of the physicochemical and mechanical properties of the mixes is vital. Therefore, a fundamental understanding of the moisture damage and age-hardening characteristics, which are related to materials’ properties, is required. The main objective of this study is to advance BSM technology by assessing the influence of the selected materials on durability behaviour 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 of binder and mineral aggregates. The properties of bitumen (foamed bitumen or bitumen emulsion) and mineral aggregates were reviewed. This was followed by review into the colloidal behaviour of foam and emulsion and physicochemical and mechanical interaction with mineral aggregates. Factors influencing the interaction of BSMs were then identified. Finally, the fundamental theories on thermodynamics, hydrodynamics, and electrokinetics were used to describe the step-by-step process by which adhesive bonding and cohesion occur in BSMs. The mixture durability in terms of moisture damage was investigated. To achieve this aim, the physical and mechanical moisture-induced damage process was analysed. The test control parameters were established and a laboratory device to quantify these parameters designed. New moisture conditioning procedures were developed and demonstrated in this study. From the moisture induction simulation test (MIST) procedure, it became evident that pulsing water pressures into compacted and cured BSM mixes simulates the hydrodynamic effect that occurs in the field due to dynamic traffic loading. The different mix matrices typically applicable to the recycling processes – such as Hornfels-RAP and Quartzite crushed stone, stabilised with either foamed bitumen or bitumen emulsion and the addition of active filler (cement or lime) – were investigated. It was found that a new moisture-conditioning procedure using the MIST device and monotonic triaxial testing can distinguish those BSM mixes that are resistant to moisture damage from those that are less resistant. The validation of the MIST and monotonic test results was done using the APT device, which is the MMLS3 wet trafficking test. The results on both tests showed good correlations in evaluating and screening BSMs in terms of moisture susceptibility. Field temperature data was collected and a model to accurately simulate the curing of BSMs was identified and proposed for further investigation and validation. It was found from the field temperature data collected in this study that the temperature gradient on the study site varied according to the depth of the BSMs (that is, 10oC-17oC during winter and 17oC– 47oC during summer). Understanding the influence of the temperature conductivity and rate of evaporation is important for inferring moisture damage and age-hardening behaviour and proper selection of BSMs. The age-hardening behaviour of BSMs is linked to the durability properties and longterm performance of these materials. The fundamental characteristics associated with shortand long-term age hardening were investigated in this study. The short-term dimension involved assessing the age-hardening characteristics of the binder (foamed bitumen colloids and bitumen emulsion droplets) prior to the production of BSMs. The long-term study involved extracting and recovering the binder from the briquettes (made from different mixes) compacted in the laboratory and cores extracted from different field pavement sections which were in service for 8-10 years. The study found that the length of time bitumen is kept in circulation in the laboratory plant at elevated temperature (170oC–180oC) before making BSM-foam contributes to the ageing of the binder, especially after eight hours. The foaming process in itself was found not to alter the bitumen properties. It is recommended that a temperature range between 160oC- 165oC be used for the production of foamed bitumen with softer bitumen. This will not compromise its quality. In addition, the time of circulation of bitumen in laboratory plant should not be longer than three (3) hours. The rheological properties of the bitumen recovered from laboratory briquettes and cores from field pavement show that age hardening on foamed bitumen and bitumen emulsion during in-service life occurred. The ageing also seemed to be dependent on the effect of traffic, with trafficked areas (i.e. on-wheel path and inner-wheel path) experiencing more ageing than untrafficked areas (i.e. between-wheel path). However, the extraction and recovery process was found to be complex, and produce uncertain results. Although the results show that binders in BSMs undergo age hardening, its distinct behaviour in BSM performance was not obvious from the extensive tests carried out in this study. The last part of the study contains its conclusions and recommendations. The study provides an insight into fundamental material durability properties, and 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 apply a mix that is durable and long-lasting. The specific durability-related issues addressed in this study are substance for future research. This novel solution to the application of BSMs will benefit all parties involved in the development of pavement recycling technology. / AFRIKAANSE OPSOMMING: Om volgehoue ekonomiese groei te verseker in beide ontwikkelende en ontwikkelde lande, geniet die soeke na die optimale werkverrigting van paaie ’n baie hoë prioriteit. ‘n Wêreldwye toename in die gebruik van skuimbitumen en bitumen-emulsiemateriale (BSMs) as ’n oplossing vir padonderhoud, rehabilitasie en opgradering is merkbaar. Dit word meegebring deur die omgewingsbeleide wat die ontginning van nuwe leengroewe beperk en besparing van energie bevorder. Die korrekte gebruik van hierdie materiale vereis dat die meganismes wat die duursaamheid en langtermyn-werkverrigting daarvan beïnvloed, deeglik verstaan word. Die verandering in materiaalgedrag en falingsmeganismes van BSM materiale is langtermynverskynsels. Dit impliseer dat bestudering van die fisiochemiese en meganiese eienskappe van die mengsels uiters belangrik is. Dis dus voor die hand liggend hoe belangrik vogbeskadiging en verharding met tyd, wat verwant is aan materiaaleienskappe, is. Die hoofdoelwit met hierdie studie is om die vooruitgang van BSM tegnologie te versnel deur dit moontlik te maak om gekose materiale te evalueer op grond van hulle invloed op duursaamheid en langtermyn-werkverrigting in alle toepassingsfases (naamlik mengontwerp, konstruksie en dienstoestand). Hierdie studie begin met ’n uitgebreide literatuuroorsig oor fundamentele begrippe van die karakterisering van interaksie van die bindstof en die minerale-aggregate. Inligting oor bitumen (skuimbitumen en bitumen emulsies) en eienskappe van minerale aggregate is bestudeer. Dit is gevolg deur ’n studie van die fundamentele begrip van die kolloïdale gedrag van skuim en emulsie, asook fisiochemiese en meganiese interaksie met minerale aggregate. Faktore wat die interaksie van BSM-materiale beïnvloed is geïdentifiseer. Die basiese teorie van termodinamika, hidrodinamika en elektrokinetika is daarna gebruik om stap vir stap die proses en formulering van adhesie-binding en kohesie in die BSMs, wat in hierdie studie aangebied word, te beskryf. Die kwantifisering van mengsel-duursaamheid in terme van vogbeskadiging is ontwikkel. Om hierdie doel te bereik, is die fisiese en meganiese proses van beskadiging deur vogindringing geïdentifiseer. Die gekontroleerde parameters is bepaal en ’n laboratoriumapparaat is ontwerp om hierdie parameters te kwantifiseer. Nuwe vogkondisioneringsprosedures is ontwikkel en in hierdie studie gedemonstreer. Van prosedures van voggeïnduseerde sensitiwiteitstoetsing (Engels: moisture induction simulation test (MIST)) was dit duidelik dat pulsering van waterdruk in BSM materiale die hidrodinamiese effek naboots wat in die veld bestaan as gevolg van dinamiese verkeerslaste. Verskillende mengselmatrikse wat tipies is van hergebruik, soos byvoorbeeld hoornfels-hersikleerde asfalt produk (Engels: recycled asphalt product (RAP)) en vergruisde granietklip, met skuimbitumen of bitumenemulsie gestabiliseer en met byvoeging van aktiewe vulmateriaal (sement of kalksteen), is ondersoek. Daar is bevind dat nuwe vogkondisioneringsprosedures (soos bepaal deur MIST apparaat en drie-assige toets) kan onderskei tussen BSM materiale wat weerstandig is teen vogbeskadiging en dié wat minder weerstandig (vatbaar) is. Die geldigheid van die MIST en monotone toetsresultate is bepaal deur gebruik van die APT apparaat wat ’n MMLS3 nat verkeerstoets is. Die resultate van beide toetse toon goeie korrelasie in die keuring van BM materiale in terme van vogvatbaarheid. In hierdie ondersoek is veldtemperatuurdata versamel en die toepaslike model om verouderende BM lae akkuraat te simuleer is geïdentifiseer en voorgelê vir verdere ondersoek en verifikasie. Daar is uit veldtemperatuurdata bevind dat temperatuurgradiënt op die betrokke terrein gewissel het met die dikte van die BSM, naamlik 10oC-17oC gedurende die winter en 17oC-47oC gedurende die somer. Begrip vir die invloed van temperatuuroordragkoëffisiënt en verdampingstempo is belangrik by die afleiding van vogbeskadiging en verharding met ouderdom en die korrekte keuse van BSM materiale.Verouderingsverhardinggedrag van BSMs is verwant aan die duursaamheidseienskappe en langtermynwerkverrigting van hierdie materiale. Die basiese karakteristieke wat met kort- en langtermyn verouderingsverharding geassosieer word, is in hierdie studie ondersoek. Die klem op die kort termyn is geplaas op die verouderingsverhardingsgedrag van die bindstof (skuimbitumen kolloïdes en bitumen-emulsiedruppels) voordat BSMs vervaardig word. In die lang termyn evaluasie het die studie ekstraksie en herwinning van bindstof uit brikette wat in die laboratorium gekompakteer is (van verskillende mengsels) en uit kerns verkry vanaf verskeie plaveiselgedeeltes na 8-10 jaar diens ingesluit. Die ondersoek het bevind dat die tydsverloop waarin bitumen in sirkulasie gehou is by verhoogde temperatuur (170oC-180oC) in die laboratorium-aanleg voordat BSMs vervaardig is, veral indien na 8 uur, bydra tot die veroudering van die bindstof. Die skuimproses op sigself verander nie die bitumeneienskappe nie. Daar word aanbeveel dat temperature tussen die grense 160oC-165oC gehandhaaf word vir produksie van skuimbitumen met sagter bitumen sonder dat die kwaliteit benadeel word en dat die sirkulasietyd nie 2 tot 3 ure behoort te oorskry nie. Die reologiese eienskappe van die herwinde bitumen vanuit laboratoriumbrikette en kerns van plaveisels toon dat ouderdomsverharding van skuimbitumen en bitumen-emulsie tydens die diensleeftyd plaasvind. Die veroudering is skynbaar ook afhanklik van verkeerseffekte, met belaste areas (in wielspoor of binne wielspoor) wat ’n hoër mate van veroudering toon as onbelaste areas (tussen wielspore). Die ekstraksie- en herwinningsproses op sigself was egter bevind as baie kompleks met uiters onseker resultate. Dit het gelei tot onsekere gedrag in terme van ouderdomsverharding van die BSM bindmiddel (skuim of emulsie). Alhoewel resultate toon dat die bindmiddels ouderdomsverharding ondergaan het, is die BSM werkverrigting nie duidelik uit die uitgebreide toetse wat in hierdie studie uitgevoer is nie. Die laaste deel van die studie bevat gevolgtrekkings en aanbevelings. Die studie lewer insig in die fundamentele duursaamheidseienskappe van die materiaal, wat bydra tot verbetering van die huidige prosedure van seleksie, saamstelling en formulering van die mengmatriks vir BSMs. Verder voorsien dit ’n metode wat in die praktyk gebruik kan word om met vertroue duursame mengsels met lang diensbaarheidsleeftye te vervaardig. ’n Nuwe oplossing en vooruitgang in die toepassing van BSMs is daargestel tot voordeel van alle partye betrokke by die ontwikkeling van herwinningstegnologie.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: With the depletion of high quality conventional materials for road pavements, the consideration of cement stabilisation for sub-base and base layer materials often provide a feasible solution to the road industry. Like all pavement material types, the design inputs should be determined using reliable test methods, which provide a good indication of the property of materials. Any evaluation should provide a better understanding of the engineering and behavioural properties of the materials. This should form the basis for ascertaining their suitability for use in the pavement structure. However, the road industry is dependent on strength testing of cement-stabilised materials as a means to ascertain material suitability for use. Strength alone does not offer reliable insight regarding the performance and durability of the stabilised layer. This is because a cement-stabilised layer may be very stiff but not strong enough to withstand the loading and endure adverse environmental conditions. Similarly, the stabilised layer may be prone to cracking emanating from shrinkage, which leads to performance and durability related distresses. A stabilised sub-base and base of the pavement structure experiences tensile stresses and strains under traffic loading. At laboratory level, the flexural beam test simulates to an acceptable degree the mode of stress to strain to which the pavement layer experiences. However, the test lacks a standard test protocol. This leads to inconsistencies while evaluating the same material type. Due to this fact, the formulation of a standard laboratory test procedure is necessary. Shrinkage cracking is one of the major causes of pavement failure. The manifestation of wide cracks leads to performance related distresses. Cracks provide zones for the infiltration of water into the underlying layers, an aspect that results in further deterioration of the pavement structure. However, the evaluation of shrinkage at laboratory level is not usually undertaken. Disregarding shrinkage evaluation stems from the fact that a number of guidelines consider it as a natural material characteristic. The road industry frequently depends on the use of low cement contents among other techniques as a means to mitigate shrinkage cracking in cement-stabilised layers. The selection of a mitigation measure usually lacks reliable data concerning the material’s shrinkage potential. Because of this, the requirement to evaluate shrinkage at laboratory level as part of a material property measure provides a good indication regarding the quality of material. Nanotechnology products such as the Nanotterra Soil® a polymer cement additive are purported to mitigate shrinkage cracking in cement-stabilised layers. However, their suitability for use remains unspecified and dependent on the stakeholders. With the development of a shrinkage method, the evaluation of shrinkage reducing products can be undertaken. This research proposes a flexural beam test protocol for cement-stabilised materials, comprising of a span-depth ratio of nine or greater as fitting to provide a reliable measure of the material’s flexural strength and elastic modulus. The developed shrinkage test method provides a good repeatability and is user friendly. The test provides a good indication of the shrinkage criteria of ferricrete and hornfels with and without the polymer. The efficacy of the polymer is dependent on the cement content in the mix and the type and quality of the material. The research provides insight pertaining to the characterisation of shrinkage, behavioural properties, and durability of cement-stabilised materials. Analysis of the shrinkage crack pattern reveals that use of the polymer lessens the development of tensile stress in a cement-stabilised layer. Equally, the application of the low cement contents for stabilisation may not result in cracking of the stabilised layer. This research contributes to a better understanding of cement-stabilised materials. / AFRIKAANSE OPSOMMING: Namate hoë kwaliteit konvensionele materiale uitgeput raak, word sementstabilisasie van stutlaag en kroonlaag materiale al hoe meer oorweeg en is dit ʼn geskikte oplossing vir die padbou-nywerheid. Soos vir alle padboumateriale moet die ontwerpeienskappe bepaal word deur middel van betroubare toetsmetodes wat ʼn goeie aanduiding van die materiaal se eienskappe sal gee. Enige evaluering moet ʼn beter insae in die materiaal se ingenieurseienskappe en gedrag oplewer. Dit moet dan die basis vorm om die materiaal se gebruik in ʼn padstruktuur te evalueer. Die padbou-nywerheidmaak grootliks staat op die toetsing van skuifsterkte van sementgestabiliseerde materiaal om die geskiktheid daarvan vir gebruik te bepaal. Sterkte op sigself lewer egter nie ʼn betroubare maatstaf van die materiaal se gedrag en duursaamheid nie. Dit is aangesien ʼn sementgestabiliseerde laag baie solied mag wees maar nogtans nie sterk genoeg om belasting te weerstaan en bestand teen omgewingstoestande te wees nie. Net so mag ʼn gestabiliseerde laag vatbaar vir kraakvorming as gevolg van krimping wees en dit kan lei tot duursaamheid-verwante en werkverwante skade. ʼn Gestabiliseerde stutlaag en kroonlaag in die plaveiselstruktuur is onderhewig aan trekspannings en vervormings as gevolg van verkeerslaste. Op laboratoriumvlak boots die balkbuigtoets die spanning en vervorming wat ʼn plaveisellaag ondervind tot ʼn aanvaarbaar hoë mate na. Die toets beskik nie oor ʼn standaard-toetsprosedure nie. Dit lei tot afwykings terwyl dieselfde materiaal evalueer word. Om hierdie rede is die ontwikkeling van ʼn standaard-laboratoriumprosedure nodig. Krimpkraking is een van die grootste oorsake van plaveiselswigting. Die onwikkeling van wye krake lei tot werksverwante skade. Krake veroorsaak areas vir die infiltrasie van water in die onderliggende plaveisellae wat verdere agteruitgang van die plaveiselstruktuur veroorsaak. Desnieteenstaande word ʼn evaluering van kraking op laboratoriumvlak selde gedoen. Dit spruit uit die feit dat ʼn aantal ontwerp-riglyne kraking as ʼn natuurlike materiaaleienskap beskou. Die padbounywerheid moet dikwels staatmaak, op onder andere, ʼn lae sementinhoud om krimpkraking te minimeer. Hierdie tipe benadering gaan dikwels mank aan betroubare inligting oor die materiaal se krimpingspotensiaal. Om hierdie rede is die ondersoek van krimping op laboratoriumvlak nodig as deel van die ondersoek van die materiaaleienskappe om die kwaliteit van materiale te bepaal. Minimeringstegnieke verander deurlopend. Die toepassing van nanotegnologieprodukte, soos Nanotterra Soil®, ‘n polimeersement bymiddel, wat na bewering krimpkraking in sementgestabiliseerde lae kan minimeer, kom voortdurend op die mark. Nogtans bly hulle geskiktheid ongespesifiseerd en afhanklik van die leweransiers. Indien ʼn krimptoetsmetode ontwikkel word, sal die effektiwiteit van krimpverminderingsmiddels getoets kan word. Hierdie navorsing stel die ontwikkeling van ʼn toetsprosedure vir ʼn balkbuigtoets voor met ʼn spanlengte tot diepteverhouding van minstens nege as betroubare maatstaf van ʼn materiaal se buigsterkte en modulus van elastisiteit. Die ontwikkelde krimptoetsmetode lewer ʼn goeie herhaalbaarheid en is gebruikersvriendelik. Die toets verskaf ʼn goeie aanduiding van krimpingskriteria van ferrikreet en horingfels met en sonder polimeer. Die effektiwiteit van die polimeer hang af van die sementinhoud in die mengsel asook die tipe en kwaliteit van die materiaal. Die navorsing verskaf insig aangaande die karakterisering van krimping, gedragseienskappe en duursaamheid van sementgestabiliseerde materiale. Die navorsing help mee om sementgestabiliseerde materiale beter te verstaan.

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: A major challenge for our society is the protection of the environment. Some of the important issues are the reduction in the consumption of energy and natural raw materials, as well as the increase in consumption of waste materials. At present these topics are getting considerable attention as part of sustainable development programs. The use of recycled concrete aggregates (RCA) from construction and demolition waste (C&DW) in construction, as alternative to virgin (natural) aggregates, has strong potential. The use of RCA preserves natural resources and reduces the space required for the disposal of RCA in landfill. It is estimated that 16 thousand million (billion) tons of concrete (and 25 billion tons of aggregate) were used in 2010. Of the 2-3 billion tons of C&DW which are produced worldwide every year, South Africa contributes 5-8 million tons. This amount is increasing rapidly every year. Significant amounts of demolished concrete find their way to landfill sites. A solution for excess waste production would be the utilization of RCA together with an improvement in the final quality of RCA. It might be an important breakthrough for our society in our attempt towards sustainable development. Worldwide, infrastructure has developed a great deal since the beginning of the twentieth century. Much of the core infrastructure, including roads, bridges, water systems, and sewers, was put in place during the first half of that century. Aggregates used as construction materials, as for instance in road pavements, or as an ingredient of concrete, are important components of infrastructure. Urbanization involves reduction of natural aggregate (NA) resources, but environmental concern and the rising cost of NA is the reason that recycled materials from different sources (like roads, buildings) are being used more and more with NA in new construction work. Environmental awareness is increasing in every country for many reasons and sustainable development is demanded of all industries, including the building and construction industries. By nature, construction is not environmentally friendly, and sometimes it also changes the behavior of nature in many ways. Recycling is one of the most important ways to minimize the waste that comes from different sources, thereby avoiding repetition of, and additional environmentally hazardous practices. It may create new wealth by diminished transport and production costs and sparing of landfill site space and cost. It has the potential to extend the life of natural resources by adding a source of material, thereby reducing environmental interference and impacting on nearby construction sites, all of which improve sustainability of our natural resources. Much research on the uses of RCA has been performed during the last few decades. In fact, most of them showed that the strength class of recycled aggregate concrete (RAC) is adequate for use as structural concrete although volume changes in and durability performance of RAC in comparison with natural aggregate concrete (NAC) are still being debated and researched. Some researchers found that the durability of concrete produced with RCA is inferior, but others have found it to be sufficient for use in structural concrete. The fact that an insufficient number of studies have been carried out on the durability aspects, has limited the use of RCA as material for road construction. The aim of this study is to determine the suitability of using the RCA in structural concrete based on its strength, stiffness, dimensional stability and durability. Three types of RCA designated RCA1, RCA2 and RCA3 in this study, were taken from three different sources. These materials were tested to establish their mechanical characteristics for use as aggregates in concrete. In the experimental program RCA was used at replacement percentages of 0%, 30% and 100% to (partially) replace NA in order to study its suitability as aggregate in concrete, and to what level of NA replacement its behavior is satisfactory for structural application. A single compressive strength class was studied, due to the limited time. By performing tests of compressive strength, Young’s modulus, creep, shrinkage, and durability performance, it has been found that selected types of RCA show a real possibility for use as aggregate in concrete. When concrete with a RCA replacement of 100% was compared with NAC100% there was a small decline in strength, but when concrete with a RCA replacement of 30% was compared with NAC100% the results showed almost equal strength. A slight reduction in durability performance was found for RAC30% compared with NAC100%, but similar dimensional stability performance in terms of specific creep and drying shrinkage was measured for RAC30% and NAC100%. Based on detailed experimental results obtained from this thesis project, a number of recommendations have therefore been made for RCA characteristics that will be used in concrete mixes also taking into account the quality of RCA. Some suggestions are proposed based on the mechanical properties and durability of the concrete. In the final conclusions, future studies on RCA properties are suggested, which would help us in increasing our knowledge in the application of RCA, and which may lead to the optimal production of structural concrete in a sustainable way. In general the use of RCA in concrete is feasible and good quality RCA at 30% replacement of NA may be suitable for any kind of structural concrete. / AFRIKAANSE OPSOMMING: ‘n Groot uitdaging vir ons samelewing is die beskerming van die omgewing. Van die belangrike sake is die vermindering in die verbruik van energie en van natuurlike, onverwerkte materiale asook die groter verbruik van afvalmateriaal. Hierdie onderwerpe kry tans aanienlike aandag as deel van volhoubare ontwikkelingsprogramme. Die gebruik van betonaggregate, herwin vanaf konstruksie-en slopingsafval, en gebruik in konstruksie as alternatief vir ongebruikte natuurlike aggregate, het goeie potensiaal. Die gebruik van herwonne aggregaat beskerm natuurlike hulpbronne en verminder die oppervlakte en volume wat nodig is vir die weggooi daarvan op stortingsterreine. Dit is beraam dat 16 duisend miljoen (biljoen) ton beton (en ongeveer 25 biljoen ton aggregaat) gedurende 2010 gebruik is. Van die 2-3 biljoen ton konstruksie-en slopingsafval wat jaarliks wêreldwyd gegenereer word, dra Suid Afrika 5-8 miljoen ton by. Hierdie hoeveelheid word elke jaar vinnig meer. Beduidende hoeveelhede gesloopte beton beland elke jaar op stortingsterreine. ‘n Oplossing vir die probleem van te veel atval generering sou wees die gebruik daarvan as herwonne beton-aggregaat, sou saamval met ‘n verbetering in die uiteindelike kwaliteit van herwonne aggregaat beton. Dit kan dalk ‘n belangrike deurbraak wees vir ons samelewing in ons strewe na volhoubare ontwikkeling. Infrastruktuur het wêreldwyd baie ontwikkel sedert die begin van die twintigste eeu. Baie van die kerninfrastruktuur insluitende paaie, brue, waterstelsels en riole is gebou tydens die eerste helfte van daardie eeu. Aggregaat gebruik as konstruksiemateriaal, byvoorbeeld in padplaveisels of as’n bestanddeel van beton, is ‘n belangrike deel van infrastruktuur. Verstedeliking veroorsaak vermindering van natuurlike aggregaat hulpbronne maar besorgdheid oor die omgewing en die stygende koste van nataurlike aggregaat veroorsaak dat herwonne materiale vanaf verskillende bronne (soos paaie en geboue) meer en meer aanvullend tot natuurlike aggregaat in nuwe konstruksiewerke gebruik word. Omgewingsbewustheid is om baie redes aan die toeneem in elke land en volhoubare ontwikkeling word vereis van alle industrieë. Herwinning is een van die hoofmaniere om afval vanaf verskillende bronne tot ‘n minimum te beperk. Dit skep nuwe rykdom, verminder vervoeren vervaardigingskoste en benut afval wat anders op stortingsterreine verlore sou gegaan het. Dit het die potensiaal om die lewensduur van natuurlike hulpbronne te verleng deur ‘n materiaalbron by te voeg, deur inmenging in die omgewing te verminder, wat almal bevorderlik is om volhoubare benutting van ons hulpbronne te verbeter. Baie navorsing is gedurende die laaste paar dekades gedoen aangaande die gebruik van herwonne aggregaat. Die meeste van die navorsing het inderdaad getoon dat die sterkte van beton met herwonne aggregaat genoegsaam is vir gebruik as struktuurbeton alhoewel daar wel debatte gevoer word oor die volumeveranderings en duursaamheid prestasie van herwonne aggregaat beton vergeleke met dié van natuurlike aggregaat beton. Sommige navorsers het bevind dat die duursaamheid van beton wat met herwonne aggregaat gemaak is, minderwaardig is maar andere het bevind dat dit voldoen aan die vereistes van struktuurbeton. Slegs die feit dat daar onvoldoende toetse rakende duursaamheid gedoen is, het die gebruik van herwonne beton aggregaat beperk tot padboumateriaal. Die doel van hierdie navorsing is om te bepaal wat die geskiktheid van herwonne betonaggregaat is vir gebruik in struktuurbeton, gegrond op sterkte en duursaamheid. Drie soorte herwonne betonaggregaat wat in hierdie studie as RCA1, RCA2 and RCA3 aangedui word, is elk vanaf ‘n ander bron geneem. Hierdie materiale is getoets om hulle meganiese kenmerke vas te stel vir gebruik as aggregaat in beton. In die eksperimentele program is 0%, 30% en 100% herwonne betonaggregaat gebruik om natuurlike aggregaat gedeeltelik be vervang om sodoende die geskiktheid as betonaggregaat te bestudeer. Deur toetse uit te voer op ‘n beperkte sterkte-klas beton, soos toetse vir die bepaling van druksterkte, Young’s modulus, kruip, krimp en duursaamheid, is daar bevind dat sekere soorte herwonne betonaggregaat heel moontlik gebruik kan word in struktuurbeton. Toe beton met 100% herwonne betonaggregaat vergelyk is met beton met 100% natuurlike aggregaat, is bevind dat daar ‘n klein vermindering in sterkte was, maar waar beton met 30% herwonne betonaggregaat vergelyk is met beton met 100% natuurlike aggregaat, het die resultate byna dieselfde sterkte getoon. Dus op grond van gedetaileerde eksperimentele resultate is ‘n aantal aanbevelings gemaak vir kenmerke van herwonne betonaggregaat wat in betonmengsels gebruik sal word met inagneming van die gehalte van herwonne betonaggregaat. Die resultate vir beton met 30% en 100% herwonne betonaggregaat word vergelyk met beton wat slegs natuurlike aggregaat bevat. Sekere voorstelle gegrond op meganiese eienskappe en duursaamheid van die beton word gemaak, asook aanbevelings vir toekomstige studies van herwonne betonaggregaat wat ons sal help om ons kennis vir die toepassing van herwonne betonaggregaat uit te brei.

In the process of engine design, it is important for the engine designer to predict the accurate component temperatures. Controlling the temperature of engine components requires a better understanding of the coolant behaviour in the coolant jacket of an engine which is critical to internal combustion engine design, The studies reported in the literature emphasize the influence of the cooling system on other engine operation such as exhaust emission, fuel consumption and engine wear. In this context, much work has been done with the purpose of improving the coolant jacket design and components of the cooling system to achieve higher performance. (Some of these studies) Previous researches have shown the possibility of achieving higher engine efficiency and performance with higher coolant temperature. This project aims at understanding the coolant flow behaviour in the coolant jackets of a diesel engine and investigating the possibility of running the engine at higher coolant temperatures by predicting the temperature distribution of the structure which is required for the assessment of the durability ofthe engine components. In this thesis, CFD (Computational Fluid Dynamics) and FE (Finite Element) techniques are used to study coolant flow in the coolant jackets and to predict the temperature distribution within the engine structure respectively. The objectives are to develop an FE model of the engine structure for thermal analyses and a CFD model of the fluid domain for the coolant flow CFD analyses. A number of case studies are carried out with the purpose of determining the most suitable technique for accurate temperature prediction. The methodology of manual coupling approach between CFD and FE analyses, which is more widely used in industry, and conjugate approach are demonstrated. Using these approaches, thermal analysis of the engine is conducted with the purpose of identifying the thermally critical locations throughout the engine. Furthermore, the influences of higher coolant temperature on these thermally critical regions of the engine are highlighted by carrying out four case studies with coolant inlet temperatures of 110°C, !ISOC, 117.5"C and !20°C. The temperature rise at the particular points around thermally critical regions is found to be in the range of 3-9 degrees at the higher coolant temperatures. This slight increase in temperature of critical locations may affect the durability of the structure. However, without carrying out the structural analyses it is not possible to comment on the durability of the engine structure. The effects of surface roughness and viscosity on heat transfer rate are also investigated and shown to be insignificant.

La conservation des monuments implique fréquemment une étape de substitution des parties dégradées par des pierres de tailles neuves. Cependant, la pierre d’origine est souvent indisponible, ce qui soulève la question du choix d’une pierre de remplacement compatible. La question de la compatibilité de la pierre est abordée à travers une démarche transversale considérant à la fois des critères physicochimiques et des critères d’aspect visuels. Les objectifs principaux ont été d’une part l’identification les mécanismes d’altération les plus impactants en termes de changement de couleur et d’autre part, la prise en compte du contexte visuel sur la compatibilité esthétique des matériaux de remplacement. L’étude porte sur un calcaire oolitique échantillonnée en carrière et sur des monuments bâtis à différentes époques. Il résulte que les lichens endolithiques ont un effet déterminant sur la durabilité et l’aspect à long terme de la pierre via un mécanisme protecteur d’imperméabilisation de la surface. Concernant l’aspect visuel, une méthode est proposée pour mesurer la gamme de couleur acceptable dans un monument à l’aide d’un test psychovisuel. Pour cela, une chaine de traitement d’image depuis l’acquisition jusqu'à l’affichage a été mise au point pour simuler des remplacements virtuels à partir d’images colorimetriquement calibrées. A partir d’un panel d’observateurs, un protocole de test a été conçu pour identifier la gamme de couleur indiscernable au sein d’une façade de monument. La discussion s’appuie sur des résultats préliminaires concernant la muraille de la cité médiévale d’Aigues-Mortes. / The preservation of monuments frequently involves the replacement of deteriorated stones by new ones. However, the original stone is often unavailable, which raises the question of the selection of a compatible replacement stone. In this study, the compatibility of the stone is addressed through a transverse approach considering both physicochemical and aesthetic criteria. The main aims were firstly to identify the weathering mechanisms with the greatest impact in terms of colour change and secondly to study the effect of visual context on aesthetic compatibility of replacement materials. Regarding the weathering mechanisms, the study focuses on an oolitic limestone sampled on quarry and on monuments built at different periods. It results that endolithic biological colonization determines the long-lasting durability of the stone through a waterproofing protective effect. In a second step, a methodology is proposed in order to measure the acceptable colour range in a monument using psychovisual experimentation. An image processing chain from the acquisition to the display was developed to simulate realistic virtual replacements from colorimetrically calibrated images. Based on a panel of observers, a test protocol was designed to locate color thresholds that separate a perceptible from an imperceptible replaced stone. The discussion is based on preliminary results from the Aigues-Mortes medieval city walls.

Dans le cadre du concept français de stockage géologique profond des déchets radioactifs, ilest envisagé de stocker les colis vitrifiés de déchets de Moyenne Activité à Vie Longue au sein de surconteneurs en béton. La chimie de l'eau interstitielle étant susceptible de modifier la durabilité chimique des matrices vitreuses, cette étude a été menée afin d'appréhender la phénoménologie d'altération du verre au contact d'eaux cimentaires. Des solutions représentatives des deux premiers stades de dégradation d'un ciment Portland et d'un ciment bas pH ont été étudiées. Les conditions dans lesquelles le rapport S/V (surface de verre sur volume de solution) et la chimie de la solution pilotent les mécanismes d'altération du verre sont clairement établies.Si le flux d'éléments relâchés par le verre est suffisant pour atteindre et maintenir un état de sursaturation qui permette la nucléation de phases secondaires (C-S-H et zéolithes), alors la précipitation de ces phases pilote la dissolution du verre. Les rôles antagonistes du calcium ont été mis en évidence en fonction du régime d'altération du verre. A faible rapport S/V, l'incorporationdu calcium au sein de la pellicule d'altération augmente ses propriétés passivantes. A l'inverse, àfort rapport S/V, le calcium précipite sous forme de phases cimentaires consommatrices d'élémentsréticulants de la pellicule d'altération, ce qui engendre le maintien d'une vitesse d'altération élevée.Le rôle bénéfique d'un ciment bas pH vis-à-vis de l'altération du verre est expliqué à partir de cesrésultats. Ce travail constitue une première étape visant à la compréhension fine des mécanismesd'altération du verre en milieu cimentaire. / In the French deep geological repository concept, intermediate-level vitrified wastepackages could be disposed of concrete medium. Chemical composition and pH of the interstitialleaching water are expected to influence the chemical durability of glass. Investigations have thusbeen carried out to study glass dissolution mechanisms and kinetics in contact with cement waters.Three cement pore waters were studied: the first two correspond to two stages of the Portlandcement aging and the third corresponds to equilibrium with a low pH concrete. The S/V ratio(glass-surface-area-to-solution-volume ratio) and the chemistry of cement waters are the two mainparameters that control glass alteration mechanisms.If the leaching flow from the glass allows a degree of supersaturation to be reached and maintainedwhich leads to nucleation of secondary phases, then precipitation of these phases drives glassdissolution. At a very low S/V ratio, the calcium uptake into the alteration layer increases itspassivating properties. Conversely, at a high S/V ratio, the calcium precipitates as cementitiousphases consuming elements which form the alteration layer. The glass dissolution is maintained ata high rate.This study contributes to highlighting the beneficial role of low pH cement in glass alteration, andis a first step towards understanding the mechanisms between the glass and the cement medium.

L'enjeu de la thèse est de proposer une stratégie de gestion durable de la résistance génétique à la rouille brune du blé, basée sur des sources de résistance quantitative. Nous proposons d'identifier des résistances se traduisant par une diminution des performances du pathogène sur les différentes phases du cycle infectieux. Ainsi, l'exercice de contraintes diversifiées sur le pathogène devraient ralentir son adaptation et augmenter la durabilité de la résistance. La confrontation d'un ensemble de génotypes de blé à trois isolats de rouille brune a permis de mesurer le niveau de résistance pour cinq composantes en serre (efficacité d'infection, période de latence, taille de lésion, sporulation par lésion, sporulation par unité de surface sporulante), et à différentes étapes de l'épidémie au champ. Nous avons mis en évidence une grande diversité des composantes affectées, et une variabilité importante pour toutes les composantes. Le développement d'un modèle statistique a permis d'établir que l'ensemble des composantes intervient dans la détermination du niveau de résistance à l'échelle épidémique, mais l'efficacité d'infection et la latence sont les composantes qui jouent le rôle le plus important pour déterminer le niveau de résistance au champ. L'impact d'une composante sur le niveau global de résistance change selon les étapes de l'épidémie. Les trois isolats utilisés ont exprimé un profil d'agressivité contrasté vis-à-vis des différentes composantes. La cartographie des QTLs associés aux différentes composantes de résistance a permis d'établir que la diversité phénotypique observée est liée à une diversité génotypique. / The issue of this thesis is to propose a durable management of genetic resistance to wheat leaf rust, based on quantitative resistance. We propose to identify resistance factors reducing pathogen development across the different stages of the infectious cycle. Diversifying constraints exerted by host resistance on the pathogen development should slow down the pathogen adaptation, and increase resistance durability. A set of wheat genotypes was confronted to three leaf rust isolates, and resistance level was measured for five components in the greenhouse (infection efficiency, latent period, lesion size, spore production per lesion, spore production per unit of sporulating tissue), as well as at different stages of field epidemics. Across the germplasm investigated, the resistance components involved were diversified, and their resistance level varied. Developing a statistical model, we established that all the components are involved in the resistance level observed in field epidemics, the most important components being infection efficiency and latent period. The incidence of a component on the field resistance level varied across epidemic stages. The three pathogen isolates used displayed contrasted aggressiveness profiles, according to the different resistance components. QTL mapping of resistance associated to the different components showed that phenotypic diversity corresponded to genotypic diversity.

Les matériaux cimentaires peuvent se détériorer grandement lorsqu'ils sont soumis à des cycles de gel/dégel avec ou sans sels de déverglaçage. Ceci peut porter atteinte à la durabilité à long terme des bétons/mortiers dans les régions aux hivers froids. Laissant de côté les processus d'endommagement et de rupture mécanique à l'oeuvre dans de tels problèmes, ce mémoire de thèse est consacré aux phénomènes physiques et thermo-mécaniques accompagnant la solidification de l'eau dans des solides poreux cohésifs, avec une attention particulière aux «propriétés matériau» issues de l'hydratation du ciment et de l'évolution de la microstructure. Ce travail reprend la poromécanique des milieux poreux partiellement gelés telle que développée par Olivier Coussy, tout en lui adjoignant une analyse de l'effet de la fin de la surfusion (en volume, hors contribution capillaire) et de la présence de sels dans le liquide saturant l'espace poreux. Nous avons mesuré la température de fin de surfusion en fonction de la concentration en sel. Ceci nous permet ensuite de calculer l'angle de contact entre la glace et les parois des pores dans le cadre classique de la nucléation hétérogène : on trouve que cet angle diminue avec la concentration en sel. Nous montrons que la dilatation instantanée consécutive à la fin de la surfusion dépend de la structure poreuse puisque cette dernière détermine la teneur en glace dans l'espace poreux. À l'aide de la distribution de tailles de pores estimée par porosimétrie par intrusion de mercure, nous estimons le degré de saturation en glace en fonction de la température et de la concentration initiale en sel via la relation de Gibbs-Thomson. Nous avons mesuré la déformation d'échantilllons de pâte de ciment saturées. L'analyse poromécanique montre que la déformation dépend de la concentration initiale en sel et de la structure poreuse des pâtes de ciment. En utilisant la même approche expérimentale sur des pâtes de ciment sèches, nous trouvons que la porosité (avec ou sans vide d'air entraîné) influence significativement le coefficient d'expansion thermique du matériau. En ce qui concerne les pâtes de ciment saturées, les mesures expérimentales et l'approche poromécanique en condition drainée ou non-drainée montrent que le degré de saturation initiale en liquide des vides d'air entraîné a un impact important sur la déformation de l'échantillon avec la température / When subject to freezing/thawing cycles with or without deicing salt, cement-based materials can suffer severe damage, which raises the long term sustainability problem of concrete/mortar in cold regions. Leaving aside the precise fracture mechanics and damage processes in this kind of problem, this PhD deals with the physical and thermomechanical phenomena undergone by cohesive porous solids under freezing, with particular attention to the material properties arising from cement hydration and microstructure development. The present work revisits the poromechanics of freezing porous materials developed by Olivier Coussy. This gives the opportunity to add the effect of the bulk supercooling and of salt in the liquid saturating the porous space.We measured the relation between depressed temperature at the end of bulk supercooling and salt concentration. We then obtained that the contact angle between ice and pore wall by heterogeneous nucleation decreases as salt concentration increases. We showed that the instantaneous dilation at the end of bulk supercooling is related to the pore structure because the latter determines the in-pore ice content. Using the pore size distribution measured by mercury intrusion porosimetry, we estimated the ice saturation degree with temperature and NaCl solution at different concentration through the Gibbs-Thomson equation. We measured the deformation of saturated cement pastes. The poromechanical analyses show that the strains depend on the initial salt concentration and pore structure of our cement pastes. By the same experimental approach on dried cement pastes, we concluded that the porosity (with or without air voids) has significant influence on the thermal expansion coefficient of our cement pastes. We also performed measurements on the deformation of saturated air entrained cement pastes. The results obtained by both experiments and poromechanical analyses under drained and undrained conditions showed that the initial saturation degree in air-voids has significant influence on the deformation curves with temperature

Die für die Untersuchung des Ermüdungswiderstandes von Elastomerbauteilen verwendeten Formulierungen basieren häufig auf Modellen, die für Anwendungen in der Metalltechnik entwickelt wurden. Die damit verbundenen Eigenschaften wie Isotropie oder Elastizität stehen hingegen im Konflikt mit den Anforderungen, die zu der Wahl eines gefüllten Polymers als Werkstoff geführt haben. Gleichzeitig weisen technische Gummiwerkstoffe ein hochgradig nichtlineares Materialverhalten auf und zeigen vom Polymer und Füllstoffgrad abhängig eine unterschiedlich ausgeprägte belastungsinduzierte Anisotropie. Diese Umstände führen zu dem Bedarf, das Ermüdungsverhalten technischer Gummiwerkstoffe in Abhängigkeit der für Gummi typischen Eigenschaften intensiver zu untersuchen und neue Ansätze für die Auslegung der Lebensdauer von elastomeren Werkstoffen bereitzustellen. Im Rahmen der Arbeit wird eine Auswahl an unterschiedlichen Modellwerkstoffen auf polymerer Basis auf ihre Lebensdauereigenschaften hin analysiert. Den Schwerpunkt bilden hierbei modulierte Belastungsrichtungen, die über eine einfache Scherung mit rotierenden Achsen versuchstechnisch abgebildet werden. Anhand der Versuchsergebnisse werden neue Ansätze zur Vorhersage der Lebensdauer technischer Gummiwerkstoffe formuliert und mit bisherigen Ansätzen verglichen. Neben der Formulierung neuer Berechnungsvorschriften zur Bestimmung des Ermüdungswiderstandes polymerer Werkstoffe werden zudem die einfache Scherung mit rotierenden Achsen sowie das Versuchsprinzip zu deren Umsetzung eingehend untersucht. Dies umfasst auch eine Analyse einer mechanischen Charakterisierung technischer Gummiwerkstoffe anhand einer einfachen Scherung mit rotierenden Achsen.

Accelerated durability testing of automotive components has become a major interest as it may predict the life characteristics of the vehicle by testing fatigue failure at higher stress level within a shorter period of time. In this work, a specially designed sub-scaled experimental testing bed with the rigid and elastic supports of a simply supported beam was designed and built to compare the effects of the elastic foundation on the change of modal parameters of the tested structure which was later used to tune the FE model. Afterwards, the accelerated loading profiles of both sine sweep and random vibration were applied on the FE model to compare the deviation of the cumulative fatigue damage between the elastic and rigid supports. This work reveals a significant amount of inaccuracy in the current laboratory testing system where the dynamic properties of the tested structure are not maintained close to the real situation. / October 2016