Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This research investigates the flexibility and the performance properties of bitumen stabilised materials under the influence of mix variables. The laboratory testing consisted of two main phases. During the first phase (mix design), the strength and the flexibility of the mixes were assessed through ITS (Indirect Tensile Strength), UCS (Unconfined Compressive Strength), displacement at break, strain at break and fracture energy. The second phase consisted of a series of triaxial tests done to assess the performance properties (shear strength: cohesion and angle of internal friction; and stiffness: resilient modulus) of the mixes. The mineral aggregates used in this study were milled from different locations of the R35, near Bethal. This was a blend of granular material (dolerite, from various locations of the existing base and subbase layer of the R35) and Reclaimed Asphalt (RA) milled from the existing surfacing. During the mix design phase, two types of bituminous binders were used (bitumen emulsion and foamed bitumen) at bitumen content ranges of 2%, 2.4% and 2.8% each. Two types of active filler were used separately and in combination at a proportion of 1% and 2%. Finally, specimens were tested in wet and dry conditions for each mix combination. During the triaxial testing phase, only the optimum bitumen content of 2.4% was used, both for bitumen emulsion and foamed bitumen, with only cement as active filler in a proportion 1% and 2%. The specimens were tested at different ranges of densities and saturation levels. The flexibility of the mix was assessed through the fracture energy, the strain and the displacement at break parameters. An analysis of variance (ANOVA) was conducted on the data to assess the significance of experimental variables on this property. This property was found to be very sensitive to bitumen and cement content added to the mix. When assessing the combined effect and the significance of the variables on the flexibility of the mixes, it was found that fracture energy is mostly influenced by the cement content, followed by the bitumen content, then the type of treatment and finally the testing condition. However, the level of significance was not in the same order for the other two parameters (displacement and strain at break). It was also found that the combined effect of some independent variables (cement content + testing condition, type of treatment + cement content + bitumen content) had a significant effect on the fracture energy and the strain at break respectively. From the ITS and UCS tests, an increase in strength was noticed with the increase of cement content. On the other hand, the increase in bitumen content led to a decrease in strength of the material. The statistical analysis on the ITS and UCS values show that the independent variable with the most significant effect on the ITS is the cement content, followed by the testing conditions, then the bitumen content and finally the type of treatment. The combined effect of cement content + bitumen content was found to be significant both for ITS and UCS. In the second phase triaxial tests were performed in order to evaluate the performance properties of the mixes. It was found that the increase of the active filler content significantly improves the shear strength of the material. It was also found that at a fixed cement content, specimens tested at low density and/or high level of saturation show low shear strength. The Mr-θ model was used to model the resilient modulus of the mixes and the model coefficients used to evaluate the effect of experimental variables on the resilient modulus. It was found that the resilient modulus of the mixes increases as the bulk stress increases. This confirms the stress dependent behaviour of bitumen stabilised materials. The analysis show that increasing the percentage of active fillers content results in a significant increase in the resilient modulus values. An increase in relative density also resulted in an increase in the resilient modulus of the mixes, while the opposite effect was observed with the increased of the saturation level. Besides the engineering properties and the mechanical test parameters, other parameters such as the Tensile Strength Ratio (TSR) was calculated in order to evaluate the moisture sensitivity of the mixes. Weakening due to moisture was found to be more predominant in the mixes with less active filler. In addition, bitumen emulsion mixes were found to have a better resistance to moisture weakening effects compared to foamed bitumen. In addition, a comparison between the rapid curing and the accelerated curing was done. Higher ITS and UCS results were obtained for specimens cured using long term curing compared to specimens cured using the accelerated curing method. In conclusion, flexibility is an important property of bitumen road construction material (bitumen stabilised material include) however, it is not an easy property to measure. Although, displacement/strain at break and fracture energy from ITS and UCS were able to give us some indications on the main factors governing the flexibility of bitumen stabilised materials (the bitumen and active filler content), more accurate and adequate tests are required to evaluate the parameter. / AFRIKAANSE OPSOMMING: Die buigsaamheid en gedragseienskappe van bitumen gestabiliseerde materiale was getoets om sodoende die invloed van verskeie mengselveranderlikes te evalueer. Die ondersoek het uit twee fases bestaan. Tydens die eerste fase (mengfase) is die sterkte en buigsaamheid deur middel van indirekte treksterkte toetse (ITS), onbegrensde druksterkte toetse (UCS), verplasing – en vervorming by breekpunt sowel as breek-energie toetse gedoen en ondersoek. Die tweede fase het bestaan uit ʼn reeks drie-assige triaksiaal toetse. Triaksiaaltoetse is uitgevoer om die gedragseienskappe soos die skuifsterkte, kohesie, hoek van interne wrywing, styfheid en weerstand modulus te ondersoek. Die gemaalde mineraal-aggregaat wat in hierdie ondersoek gebruik is, was verkry op verskeie areas van die R35, geleë naby Bethal. Die materiaal is ʼn mengsel van granulêre materiaal (van die bestaande kroonlaag en stutlaag van die pad) en herwonne asfalt (RA). Tydens die mengontwerp fase is twee tipes bitumen gebruik naamlik bitumenemulsie en skuimbitumen in hoeveelhede van 2%, 2.4% en 2.8%. Twee tipes aktiewe vulstof (hoeveelhede van onderskeidelik 1% en 2%) was saam met elk van die verskeie bitumen-hoeveelhede gebruik. Proefstukke van elk van hierdie mengsel kombinasies is onder beide nat en droë kondisies getoets. Tydens die tweede fase, is slegs die optimum binder inhoud (2.4%) gebruik vir beide emulsie- en skuimbitumen, gekombineer met 1% en 2% aktiewe vulstof. Proefstukke was getoets by ʼn reeks van verskillende digthede en versadigingvlakke. Die buigsaamheid was ondersoek deur middel van breek-energie, vervorming en die verplasing by breekpunt. ʼn Analise van variasie (ANOVA) is uitgevoer op die toetsdata om sodoende die te evalueer of die veranderlikes beduidend is ten opsigte van buigsaamheid. Daar is gevind dat die buigsaamheideienskap sensitief is vir beide bitumen en sement inhoud. Met assessering van die gekombineerde effek en betekenis van die veranderlikes op die buigsaamheid van die mengsels, is daar gevind dat die hoogste beduidende veranderlike t.o.v breek-energie die sement inhoud is, gevolg deur die bitumeninhoud, tipe behandeling en laastens die toetskondisie. Die orde van belangrikheid verskil vir die ander twee parameters (verplasing en vervorming by breekpunt). Daar is ook gevind dat die gekombineerde effek van sommige veranderlikes (sement inhoud en toets kondisie, tipe behandeling en sement inhoud tesame met bitumen inhoud) ook beduidend was t.o.v breek-energie en vervorming by breekpunt. Vanuit die ITS en UCS toetse was daar ʼn toename in sterkte waargeneem soos die sementinhoud toeneem. Aan die anderkant, het ʼn toename in bitumeninhoud ‘n afname in sterkte veroorsaak. Die statistiese analise van ITS en UCS resultate, toon dat die grootste beduidende onafhanklike t.o.v ITS waardes ook die sement inhoud was, gevolg deur toets kondisies die grootste effek, bitumen inhoud en die tipe behandeling. Die gekombineerde effek van sementinhoud en bitumeninhoud, was betekenisvol vir beide ITS en UCS. Drie-assige triaksiaaltoetse was uitgevoer om die gedragseienskappe van die mengsels te evalueer. Daar is gevind dat die toename in sement inhoud, die skuif sterkte van die materiaal grootliks verbeter. By ʼn konstante sementinhoud, wys toetsresultate van proefstukke wat getoets is by lae digthede en hoë vlakke van versadiging, lae skuif sterkte. Die Mr – θ model was gebruik om die veerkragsmodulus van die mengsels te moduleer en die modelkoëffisiënte is gebruik om die effek van eksperimentele veranderlikes op die weerstand modulus te evalueer. Met toename in die omhullende spanning is ‘n toename in die veerkragsmodulus waargeneem, wat bevestig dat die gedrag van bitumen gestabiliseerde materiale spannings afhanklik is. ʼn Toename in die sement en relatiewe digtheid het ʼn merkwaardige toename in die veerkragsmodulus tot gevolg gehad, terwyl die teenoorgestelde waargeneem is met toename in versadigingsvlakke. Buiten die ingenieurseienskap en meganiese toetsfaktore, is ander faktore (soos die trekspanning verhouding) bereken om die vogsensitiwiteit van die mengsels te evalueer. Mengsels met laer sement inhoud het groter verswakking ervaar met blootstelling aan water. Bitumenemulsie proefstukke toon beter weerstand teen water as skuimbitumen. Vergelyking tussen versnelde en korttermyn nabehandelingsprosedure van proefstukke, toon hoër ITS en UCS waardes vir die versnelde nabehandelingsprosedure prosedure. Buigsaamheid is ‘n belangrike eienskap van bitumen in padkonstruksie materiale (insluitend bitumen gestabiliseerde materiale), maar word moeilik gemeet. Alhoewel verplasing/vervorming by breekpunt en breek energie, bepaal vanaf ITS en UCS, ‘n indikasie toon van die hooffaktore (binder en sement) wat buigsaamheid van bitumen gestabiliseerde materiaal beïnvloed, word meer akkurate toetse benodig om die eienskap te ondersoek.

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

by Chu Shun-wah, Sum Pun-wah, Jeremy. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 85-86). / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.iii / LIST OF ILLUSTRATIONS --- p.v / LIST OF TABLES --- p.vi / Chapter / Chapter I. --- INTRODUCTION --- p.1 / Background Information of the ILF --- p.2 / Paving Operations --- p.2 / Working Environment --- p.7 / Chapter II. --- PRELIMINARY UNDERSTANDING OF THE PROBLEMS --- p.9 / Interview with Staff Side od the ILF --- p.9 / Interview with the Management side of the ILF --- p.10 / Chapter III. --- STATISTICAL ANALYSIS --- p.12 / Explanatory Notes for the Cost Elements --- p.13 / Data Analysis --- p.16 / Sampling --- p.17 / Visual comparison of the cost data --- p.18 / Statistical Parameters Analysis --- p.19 / Test for the Equality of Variances for Both Samples --- p.20 / Test for the Equality of Means for Both Samples --- p.21 / Interpretation of Results --- p.23 / Paired T-test --- p.25 / Chapter IV. --- MAIN COST FACTORS ANALYSIS --- p.26 / Salary of Direct Labour --- p.26 / Material Cost --- p.28 / Hire of Services --- p.30 / Chapter V. --- SOLUTIONS TO PROBLEMS --- p.33 / Salary of Direct Labour --- p.33 / Material Cost --- p.36 / Hire of Services --- p.37 / Chapter VI. --- ALTERNATIVE ANALYSIS --- p.39 / Visual Comparison of Cost Data After Allocation of Fixed Cost --- p.41 / Statistical Analysis --- p.42 / Interpretation of Results of Alternative Analysis --- p.44 / Chapter VII. --- GENERAL RECOMMENDATIONS --- p.45 / Chapter VIII. --- CONCLUSION --- p.52 / APPENDIX --- p.64 / BIBLIOGRAPHY --- p.85

The main goal of this study consists of the development of new asphalt mixes, based on industrial waste materials as replacement of natural aggregates. To achieve this purpose, a new characterisation of these pavements was proposed so to verify that the new mix has good mechanical performance without any detrimental impact to the environment.<p>This characterisation was divided in three distinct steps:<p>• a physical and chemical characterisation of the different constituents of asphalt concrete, as well the natural materials as the industrial waste considered as potentially secondary aggregates,<p>• a study of the bitumen-aggregate interface by means of two techniques: a qualitative method (scanning electron microscope) and a quantitative one (nanoindentation)<p>• an evaluation of the mechanical performance of mixes containing industrial waste, before and after recycling, by means of four standard road-engineering tests.<p>The numerous results allowed to put in evidence the possibility to reuse some industrial waste materials in asphalt concrete. In addition, this characterisation containing both chemical and mechanical aspects, at the microscopic and macroscopic scales, would permit the transposition of this study to the whole of asphalt concrete./<p>Le principal objectif de ce travail consiste en le développement de nouveaux mélanges bitumineux utilisant des déchets industriels en tant que remplacement des matériaux naturels. Pour ce faire, une nouvelle caractérisation de ces revêtements a été proposée afin de vérifier que le nouveau revêtement obtenu présente de bonnes performances mécaniques tout en évitant un impact environnemental néfaste.<p>Cette caractérisation a été scindée en trois étapes distinctes :<p>•\ / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished