Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Strain Hardening Cement Based Composite (SHCC) is a type of High Performance Fibre Reinforced Cement-based Composite (HPFRCC). SHCC contains randomly distributed short fibres which improve the ductility of the material and can resist the full tensile load at strains up to 5 %. When SHCC is subjected to tensile loading, fine multiple cracking occurs that portrays a pseudo strain hardening effect as a result. The multiple cracking is what sets SHCC aside from conventional Reinforced Concrete (RC). Conventional RC forms one large crack that results in durability problems. The multiple cracks of SHCC typically have an average crack width of less than 80 μm (Adendorff, 2009), resulting in an improved durability compared to conventional RC. The aim of this research project is to quantify the cracking behaviour of SHCC which can be used to quantify the durability of SHCC. The cracking behaviour is described using a statistical distribution model, which represents the crack widths distribution and a mathematical expression that describes the crack pattern. The cracking behaviour was determined by measuring the cracks during quasi-static uni-axial tensile tests. The cracking data was collected with the aid of a non-contact surface strain measuring system, namely the ARAMIS system. An investigation was performed on the crack measuring setup (ARAMIS) to define a crack definition that was used during the determination of the cracking behaviour of SHCC. Several different statistical distributions were considered to describe the distribution of the crack widths of SHCC. A mathematical expression named the Crack Proximity Index (CPI) which represents the distances of the cracks to each other was used to describe the crack pattern of SHCC. The Gamma distribution was found to best represent the crack widths of SHCC. It was observed that different crack patterns can be found at the same tensile strain and that the CPI would differ even though the same crack width distribution was found. A statistical distribution model was therefore found to describe the CPI distribution of SHCC at different tensile strains and it was established that the Log-normal distribution best describes the CPI distribution of SHCC. After the cracking behaviour of SHCC was determined for quasi-static tensile loading, an investigation was performed to compare it to the cracking behaviour under flexural loading. A difference in the crack widths, number of cracks and crack pattern was found between bending and tension. Therefore it was concluded that the cracking behaviour for SHCC is different under flexural loading than in tension. / AFRIKAANSE OPSOMMING: “Strain Hardening Cement-based Composite” (SHCC) is ‘n tipe “High Performance Fibre Reinforced Cement-based Composite” (HPFRCC). SHCC bevat kort vesels wat ewekansig verspreid is, wat die duktiliteit van die material verbeter en dit kan die maksimum trekkrag weerstaan tot en met ‘n vervorming van 5 %. Wanneer SHCC belas word met ‘n trekkrag, vorm verskeie fyn krake wat ‘n sogenaamde vervormingsverharding voorstel. Die verskeie krake onderskei SHCC van normale bewapende beton. Normale bewapende beton vorm een groot kraak met die gevolg dat duursaamheidsprobleme ontstaan. Die gemiddelde kraakwydte van SHCC is minder as 80 μm (Adendorff, 2009) en het dus ‘n beter duursaamheid as normale bewapende beton. Die doel van die navorsingsprojek is om die kraak gedrag van SHCC te kwantifiseer en wat dan gebruik kan word om die duursaamheid van SHCC te kwantifiseer. Die kraak gedrag is beskryf deur ‘n statistiese verspreiding model wat die kraak wydtes se verspreiding voorstel en ‘n wiskundige uitdrukking wat die kraak patroon beskryf. Die kraak gedrag was bepaal deur die krake te meet tydens die semi-statiese een-asige trek toetse. Die kraak data was met behulp van ‘n optiese vervormings toestel, naamlik die ARAMIS, versamel. ‘n Ondersoek is gedoen op die kraak meetings opstelling (ARAMIS), om ‘n kraak definisie te definieer wat gebruik is om die kraak gedrag te bepaal. Daar is gekyk na verskeie statistiese verdelings om die kraak wydtes van SHCC te beskryf. Die kraak patroon van SHCC is beskryf met ‘n wiskundige uitdrukking genoem die “Crack Proximity Index” (CPI) wat die krake se afstande van mekaar voorstel. Dit is bevind dat die Gamma verdeling die kraak wydtes van SHCC die beste beskryf. Daar is waargeneem dat verskillende kraak patrone by dieselfde vervorming verkry kan word en dat die CPI kan verskil al is die kraak wydte verdeling dieselfde. ‘n Statistiese verdelingsmodel is dus gevind om die CPI verdeling van SHCC te beskryf by verskillende vervormings, en daar is vasgestel dat die Log-normaal verdeling die CPI verdeling van SHCC die beste beskryf. Nadat die kraak gedrag van SHCC bepaal is vir semi-statiese trek-belasting, is ‘n ondersoek gedoen waar die trek-kraak gedrag vergelyk is met buig-kraak gedrag. ‘n Verskil in die kraak wydtes, aantal krake en kraak patroon is gevind tussen buiging en trek. Dus is die gevolgtrekking gemaak dat die kraak gedrag van SHCC verskillend is in buiging as in trek.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The southbound screener lane of the Heidelberg Traffic Control Centre received structural improvements by means of an ultra thin continuously reinforced concrete pavement (UTCRCP) overlay. This experimental overlay forms part of the South African National Roads Agency Limited’s innovative highway repair strategy on existing pavements that have exceeded design life. The primary objective of this study was to characterize the UTCRCP overlay with regard to crack spacing formation under accelerated pavement testing (APT). Characterization comprised of empirical modelling techniques, statistical analysis, non destructive testing and software simulations. Pavement deflection responses were empirically and linear elastically converted to input parameters. These parameters were used in the mean crack spacing prediction model of the Mechanistic-Empirical Pavement Design Guide (M-E PDG). Observed cracking under APT was recorded and analyzed by means of descriptive statistics. The outcome of the M-E PDG’s mean crack spacing and the statistics of the observed cracking were evaluated against cncPave simulations. Initial shrinkage crack formations ranged from 500 mm to 900 mm, with a mean spacing of 695 mm. Subsequent secondary cracking reduced the segments, delineated by initial cracking, to intervals consisting of 100 mm to 350 mm. A statistical analysis of the observed cracking indicated that traffic had little effect on the transverse crack spacing formation. The observed cracks yielded a mean spacing of 296 mm, compared to the 186 mm of the M-E PDG mean crack spacing calculation. cncPave simulations indicated that the expected range of cracking would fall between 237 mm and 350 mm with a probability of 50% that crack spacing would exceed 265 mm. The 50th percentile of the observed cracks resulted in a spacing of 233 mm. The APT project was limited to a single test section. No pavement failures occurred during the APT project. A total of 2.8 million 80 kN load repetitions were applied to the UTCRCP. However circular crack formations regarded as a punchout development have formed on the UTCRCP test section. Circular cracks formed around weaknesses in the pavement system. The prediction of these punchout formations incorporates the mean crack spacing result. Occurrence of mean crack spacing forms part of a crack spacing distribution defined by a range. Therefore designing a punchout prediction model for UTCRCP should include the characteristics and range of the crack pattern and not merely the mean crack spacing value. Key Words: UTCRCP, APT, Mean Crack Spacing, Punchout, Descriptive Statistics, cncPave, M-E PDG, Transverse Cracks, Dense Liquid Foundation, Elastic Solid Foundation. / AFRIKAANSE OPSOMMING: Die suidwaartse moniteerings laan van die Heidelberg Verkeersbeheer Sentrum, het strukturele verbetering ondergaan deur die konstruksie van ‘n ultradun aaneen-gewapende betonplaveisel (UDAGBP) wat dien as ‘n deklaag. Hierdie eksperimentele deklaag is deel van die Suid-Afrikaanse Nasionale Paaie Aggentskap Beperk (SANRAL) se vernuftige deurpadherstelstrategie vir bestaande deurpaaie waarvan die ontwerplewe verstryk het. Die primêre doel van hierdie studie is om die UDAGBP te karakteriseer, met betrekking tot kraakspasiëring, deur middel van Versnelde Plaveisel Toetsing (VPT). Die karakteriseringsproses het bestaan uit empiriese moduleringstegnieke, statistiese ontleding, nie-destruktiewe toetsmetodologieë en sagtewaresimulasies. Die plaveiseldefleksiegedrag is empiries en linieêr elasties ontleed en omgeskakel na invoerparameters. Hierdie parameters is gebruik in die peilingsmodel vir gemiddelde kraakspasiëring van die Meganisties-Empiries Plaveisel Ontwerpsgids (M-E POG). Waargenome kraakspasiëring na die afloop van VPT is opgeteken en deur middel van beskrywende statistiek ontleed. Die resultate van die M-E POG se gemiddelde kraakspasiëring en die statistiese ontleding van die waargenome krake is geëvalueer teenoor cncPave simulasies. Aanvanklike krimpingskrake het gevorm met wisselende kraakspasiëring tussen 500 mm en 900 mm met ‘n gemiddelde spasiëring van 695 mm. Daaropvolgende krake het die aanvanklike segmente, wat gevorm het tydens die aanvanklike krimpingskrake, verkort na intervalle van 100 mm tot 350 mm. ‘n Statistiese ontleding van die waargeneemde krake het aangedui dat verkeer weinig ‘n aandeel het in die dwarskraak-vormingsproses. Die waargenome krake het ‘n gemiddelde spasiëring van 296 mm in vergelyking met 186 mm van die M-E POG se gemiddelde kraakspasiëring berekening. cncPave simulasies het aangedui dat die verwagte kraakspasiëringsgrense tussen 237 mm en 350 mm is en ‘n 50% waarskynlikheid dat die kraakspasiëring meer as 265 mm is. Die VPT projek is beperk tot ‘n enkele toetsseksie. Geen plaveiselfalings is waargeneem gedurende die VPT projek nie. In totaal was 2.8 miljoen as-lasherhalings aangewend op die UDAGBP. Daar het egeter sirkelvormige kraakformasies, wat beskou word as ponsswigting, ontwikkel op die UDAGBP toetsseksie. Sirkelvormige kraakpatrone het gevorm rondom swak plekke in die plaveisel. Die peilingsmodelle van hierdie ponsswigting maak gebruik van die gimiddelde kraakspasiëringsresultaat. Die verskynsel van gemiddelde kraakspasiëring in hierdie studie is deel van ‘n kraakspasiëringsverdeling, gedefinieerd deur ‘n spasiëringsgrens. Daarom moet die kraakspasiëringskarakteristieke en spasiëringsgrense in ag geneem word in die ontwerpsproses van ‘n UDAGBP ponsswigting-peilings-model, nie slegs die waarde van die gemiddelde kraakspasiëring nie. Sleutel woorde: UDAGBP, VPT, Gemiddelde Kraakspasiëring, Ponsswigting, Beskrywende Statistiek, cncPave, M-E POG, Transversale Krake, Digte Vloeistof Fondasie, Elasties- Soliede Fondasie.

Currently, the maintenance and repair of civil engineering infrastructures (especially bridges and highways) have become increasingly important, as these structures age and deteriorate. Interface between two different mixes or strengths of concrete also appear in large concrete structures involving mass concreting such as dams, nuclear containment vessels, cooling towers etc., since joints between successive lifts are inevitable. These joints and interfaces are potential sites for crack formation, leading to weakening of mechanical strength and subsequent failure. In case of a bi-material interface, the stress singularities are oscillatory in nature and the fracture behavior of a concrete-concrete bi-material interface is much more complicated. A comprehensive experimental work has been undertaken for characterization of the behavior of different concrete-concrete interfaces under static and fatigue loading. The effect of specimen size on the concrete-concrete interfaces is studied and the non-linear fracture parameters such as fracture energy, mode I fracture toughness, critical crack tip opening displacement, critical crack length, length of process zone, brittleness number, size of process zone, crack growth resistance curve and tension softening diagram. These parameters are required for modeling the concrete-concrete interfaces in non-linear finite element analysis. Presently, the advanced non-destructive techniques namely acoustic emission, digital image correlation and micro-indentation have great capabilities to characterize the fracture behavior. The damage in plain concrete and concrete interface specimens is characterized both qualitatively and quantitatively using acoustic emission technique by measuring the width of fracture process zone and width of damage zones. The DIC technique is used to obtain the fracture parameters such as mode I and mode II fracture toughness and critical energy release rate. The micro-mechanical properties are obtained by performing depth-sensing micro-indentation tests on the concrete-concrete interfaces. Civil engineering structures such as long-span bridges, offshore structures, airport pavements and gravity dams are frequently subjected to variable-amplitude cyclic loadings in actual conditions. Hence, in order to understand the fracture behaviour under fatigue loading, the fatigue crack growth in plain concrete and concrete-concrete interface is also studied using the acoustic emission technique. An attempt is made to apply the Paris’ law, which is applicable to mechanical behaviour of metals, for acoustic emission count data. All these studies show that, as the difference in the compressive strength of concrete on either side of the interface increases, the load carrying capacity decreases and the fracture parameters indicate the increase in the brittleness of the specimens. It is concluded that the repair concrete should be selected in such a way that its elastic properties are as those of the parent concrete.

M. Tech. Civil Engineering. / Evaluates various laboratory test methods to assess rutting potential in the hot-mix asphalt (HMA) and the effects of compaction methods. To achieve this objective, rutting potential of HMA samples prepared and compacted in the laboratory, and in the field was evaluated using different laboratory test methods under a range of temperatures and loads.

Les structures en béton et béton armé de grandes dimensions, en particulier les enceintes de confinement, peuvent être sujettes à de la fissuration localisée suite à leur vieillissement ou dans le cas d’une forte sollicitation (APRP, par exemple). Afin d’optimiser les actions de maintenance, il est nécessaire de disposer d’un modèle prédictif de l’endommagement du béton. Ce phénomène se produit à une échelle matériau relativement petite et un modèle prédictif nécessite un maillage fin et une loi de comportement non linéaire. Hors ce type de modélisation ne peut être directement appliquée sur une structure de génie civil de grande échelle, le calcul étant trop lourd pour les machines actuelles.Une méthode de calcul est proposée, qui concentre l’effort de calcul sur les zones d’intérêt (parties endommagées) de la structure en éliminant les zones non endommagées. L’objectif est ainsi d’utiliser la puissance de calcul disponible pour la caractérisation des propriétés des fissures notamment. Cette approche utilise la méthode de condensation statique de Guyan pour ramener les zones élastiques à un ensemble de conditions aux limites appliquées aux bornes des zones d’intérêt. Lorsque le système évolue, un système de critères permet de promouvoir à la volée des zones élastiques en zones d’intérêt si de l’endommagement y apparaît. Cette méthode de condensation adaptative permet de réduire la dimension du problème non linéaire sans altérer la qualité des résultats par rapport à un calcul complet de référence. Cependant, une modélisation classique ne permet pas de prendre en compte les divers aléas impactant le comportement de la structure : propriétés mécaniques, géométrie, chargement… Afin de mieux caractériser ce comportement en tenant compte des incertitudes, la méthode de condensation adaptative proposée est couplée avec une approche de collocation stochastique. Chaque calcul déterministe nécessaire pour caractériser les incertitudes sur les grandeurs d’intérêt de la structure est ainsi réduit et les étapes de prétraitement nécessaires à la condensation sont elles-mêmes mutualisées via une deuxième collocation. L’approche proposée permet ainsi de produire pour un coût de calcul limité des densités de probabilités des grandeurs d’intérêt d’une grande structure. Les stratégies de résolution proposées rendent accessibles à l’échelle locale une modélisation plus fine que celle qui pourrait s’appliquer sur l’ensemble de la structure. Afin de bénéficier d’une meilleure représentativité à cette échelle, il est nécessaire de représenter les effets tridimensionnels des hétérogénéités. Dans le domaine du génie civil et nucléaire, cela concerne au premier chef les câbles de précontrainte, traditionnellement représentés en unidimensionnel. Une approche est donc proposée, qui s’appuie sur un maillage et une modélisation 1D pour reconstruire un volume équivalent au câble et retransmettre les efforts et rigidités dans le volume de béton. Elle combine la représentativité d’un modèle 3D complet et conforme des câbles lorsque le maillage s’affine et la facilité d’utilisation et paramétrage d’un modèle 1D. L’applicabilité des méthodes proposées à une structure de génie civil de grande échelle est évaluée sur un modèle numérique d’une maquette à l’échelle 1/3 de l’enceinte de confinement interne d’un réacteur de type REP 1300 MWe à double paroi. / Large-scale concrete and reinforced concrete structures, and in particular containment buildings, may undergo localized cracking when they age or endure strong loadings (LOCA for instance). In order to optimize the maintenance actions, a predictive model of concrete damage is required. This phenomenon takes place at a rather small material scale and a predictive model requires a refined mesh and a nonlinear constitutive law. This type of modelling cannot be applied directly on a large-scale civil engineering structure, as the computational load would be too heavy for the existing machines.A simulation method is proposed to focus the computational effort on the areas of interest (damaged parts) of the structure while eliminating the undamaged areas. It aims at using the available computing power for the characterization of crack properties in particular. This approach uses Guyan’s static condensation technique to reduce the elastic areas to a set of boundary conditions applied to the areas of interest. When the system evolves, a set of criteria allows to promote on the fly the elastic areas to areas of interest if damage appears. This adaptive condensation technique allows to reduce the dimension of a nonlinear problem without degrading the quality of the results when compared to a full reference simulation.However, a classical modelling does not allow to take into account the various unknowns which will impact the structural behaviour: mechanical properties, geometry, loading… In order to better characterize this behaviour while taking into account the various uncertainties, the proposed adaptive condensation method is coupled with a stochastic collocation approach. Each deterministic simulation required for the characterization of the uncertainties on the structural quantities of interest is therefore reduced and the pre-processing steps necessary to the condensation technique are also reduced using a second collocation. The proposed approach allows to produce for a reduced computational cost the probability density functions of the quantities of interest of a large structure.The proposed calculation strategies give access at the local scale to a modelling finer than what would be applicable to the full structure. In order to improve the representativeness at this scale, the tridimensional effects of the heterogeneities must be taken into account. In the civil and nuclear engineering field, one of the main issues is the modelling of prestressing tendons, usually modelled in one dimension. A new approach is proposed, which uses a 1D mesh and model to build a volume equivalent to the tendon and redistribute the forces and stiffnesses in the concrete. It combines the representativeness of a full conform 3D modelling of the tendon when the mesh is refined and the ease of use of the 1D approaches.The applicability of the proposed methodologies to a large-scale civil engineering structure is evaluated using a numerical model of a 1/3 mock-up of a double-wall containment building of a PWR 1300 MWe nuclear reactor.

Structural concrete is the most widely used material in the construction of bridges, pave-ments, runways, dams and other infrastructures which are subjected to uctuating loads during its service period. Concrete contains internal aws in the form of micro-cracks as an inherent property. When subjected to fatigue loading, distributed micro-cracks are formed at the sites of pre-existing aws, which subsequently, localize to form a major crack and propagates. The crack growth curve of a structural component when subjected to fatigue loading depicts a sigmoidal pattern. This curve is divided into three distinct regions namely sub-threshold crack propagation (short crack), stable crack propagation (long crack) and unstable crack propagation depending on the crack propagation rate. Most of the fatigue life is spent in the sub-critical stage (small crack) before the for-mation of long cracks. Hence, from the view of estimating the fatigue life, the crack initiation and early crack propagation (short crack stage) phase are the most important and correct concepts need to be developed. Hence, in this work, the behavior of propa-gation and non-propagationof short cracks in concrete when subjected to fatigue loading is addressed. Small non-propagating cracks are usually found at notch roots when the nominal stress range is below certain limits that depend on the notch sensitivity. Analysis is performed on geometrically similar three-point bend beams of three di erent sizes and subjected to fatigue loading in order to determine the important factors that a ect the notch sensitivity and to determine the minimum stress range required for the initiation and propagation of short cracks. A criterion for crack initiation and propagation is proposed based on linear elastic fracture mechanics. Using this criterion, the maximum length of non-propagating crack that can be formed from fatigue loading alone and the minimum stress range required to propagate a crack without arrest are computed. It is observed that the notch sensitivity increases with increase in beam size, decrease in notch-tip aspect ratio and increase in the fatigue limit of the material. Since the probability of formation of a non-propagating crack at a notch tip decreases with increase in notch sensitivity, and since it is desirable not to have a non-propagating crack in experimental investigations, it is essential to design a specimen with higher notch sensitivity. A crack spends a considerable amount of time in the short crack regime. The short cracks are found to propagate at higher rates than the long cracks at the same nominal stress intensity factor which is known as the short crack anomaly. It is important to consider this anomaly in the prediction of the residual life of damaged concrete structures. Hence, in the present work, an analytical model is developed using the principles of dimensional analysis and self-similarity in order to estimate the rate of short crack growth in concrete. The important parameters such as load range, threshold value of stress intensity factor range, modulus of elasticity, tensile strength, fracture energy, stress ratio, crack size and the maximum aggregate size are considered in the development of the short crack growth model. The model is calibrated and validated using the experimental results that are available in the literature. A probabilistic analysis is carried out to determine the sensitivity of each of the di erent parameters that has been considered on the crack growth rate using the coe cient of variation method. It is found that the crack length is the most sensitive parameter to short crack growth rate followed by the load range. A term called `characteristic fatigue life of short crack' is de ned as the number of fatigue cycles that can be applied such that not more than ve percent of the short cracks is expected to proceed to the long crack regime. Furthermore, the fatigue life of a crack spent in the short crack regime is determined through a reliability based study using the Monte Carlo technique. It is found that the smaller sized specimens have larger fatigue life in the short crack regime than the larger specimens.

Ces travaux ont pour but d'étudier le comportement mécanique de structures précontraintes et d'évaluer l'influence de la technologie de précontrainte utilisée : précontrainte par torons adhérents, précontrainte par torons non-adhérents TGG. Le champ d'application final porte sur l'analyse de la sûreté et de la durabilité des enceintes de confinement de centrales nucléaires. L'attention est alors portée principalement sur le comportement à la fissuration du béton et au rôle de la liaison mécanique torons de précontrainte-structure.La démarche proposée se décompose en trois étapes successives. Elle débute par la caractérisation expérimentale des mécanismes de dégradation à l'échelle de la structure (essais de flexion 4 points sur poutres précontraintes) et à l'échelle locale du matériau (fissuration, déformations différées du béton, liaisons armatures passives-béton et torons-structure par des essais d'arrachement et de traction sur tirants). Une instrumentation multiple (CIN, fibres optiques) favorise la robustesse de la démarche. Des modèles numériques sont ensuite développés pour décrire les mécanismes caractérisés expérimentalement. Un intérêt particulier est porté à la modélisation mésoscopique de l'interface armatures-béton et macroscopique de l'interface torons-coulis d'injection. L'utilisation des différents modèles, couplée à la prise en compte de l'évolution temporelle des déformations différées du béton, favorise une analyse prédictive du comportement des structures étudiées.L'application à une tranche d'enceinte de confinement permet de prédire l'influence de la technologie de précontrainte utilisée sur le comportement à la fissuration de la structure. / This work aims to study the mechanical behavior of partially prestressed structures and to evaluate the influence of the post-tensioning system: bonded tendons, individual unbonded greased and sheathed strands. Under the scope of the safety and durability of nuclear containments, specific attention is devoted to the concrete cracking behavior and to the role of the mechanical tendons-structure bond. The proposed approach is divided into three successive parts. It starts with an experimental study of damage mechanisms at the structural level (4-point bending tests on prestressed concrete beams) and at the local scale (cracking, delayed strains of concrete, reinforcement-concrete bond, tendons-structure bond with pull-out tests and tension tests on reinforced concrete ties). The used instrumentation (DIC, optical fibers) allows for the robustness of the approach. Numerical models are then developed, based on the previous characterized mechanisms. A particular interest is focused on the meso-modeling of the reinforcement-concrete interface and on the macro-modeling of the tendons-injected grout bond. The use of the developed models, considering in parallel the influence of the evolutive delayed strains of concrete, provides a predictive analysis of the mechanical behavior of the studied prestressed structures. A final application to a part of a nuclear containment offers an accurate prediction of the influence of the post-tensioning system on the cracking behavior of the structure.

No description available.

No description available.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Flexible pavement designers have a choice of two wearing course: either asphalt concrete or surfacing seals. The latter have been widely used by several countries as their preferred wearing course over other methods, especially countries with a limited number of average inhabitants per square kilometre. Moreover, the surfacing seals were identified as an efficient cost effective road preventive maintenance technique. Surfacing seals in New Zealand, South Africa and Australia cover about 65%, 80% and 90% of their surfaced road networks respectively. The preference of surfacing seals is due to their competitive initial cost and ease of construction. In South Africa, the life expectancy of surfacing seals varies between 8 and 12 years with an average of 10 years. This has not been the case in a number of surfacing seals constructed in winter, especially when the night recorded temperature is below 10oC. The dominant failure mechanism is ravelling (chip loss) soon after construction due to traffic loading. This chip loss is linked to the poor adhesion bond development rate in the bitumen-aggregate system during winter adverse conditions. In order to address the issue of premature chip loss the need for the development of a robust adhesion test method was identified. For that purpose, recently, researchers in the bitumen industry developed the Bitumen Bond Strength test method. This method was used in this study. This study intends to contribute to the understanding of binder-aggregate adhesion bond development for winter surfacing seals using the BBS test. Binder type, precoat type and conditioning, aggregate type and curing time are amongst the factors influencing winter seals adhesion bond performance. An experimental matrix involving three types of binder, two types of aggregate, four different precoating fluids, two precoat conditionings and two binder-curing times were then developed and investigated. Winter weather parameters affecting adhesion properties were also taken into consideration during the course of the investigation. Throughout the test, the procedure described in AASHTO TP 91-11 was followed. However, in order to enhance the control of the binder application temperature, a new method for hot applied binder sample preparation was developed as part of this study. The findings show that there is a significant difference between adhesion properties of the hot applied binders (70/100 and S-E1) and the emulsion (SC-E1). In most of the cases, the hot applied binders performed better than the emulsion. The failure mode observed was found to be linked to the condition of the precoating. The influence of the precoat type and conditioning, and effect of binder curing time were significantly highlighted. The use of a dry precoat benefited the adhesion bond strength up to around 50% relatively to the corresponding non-precoated combination. However, a decrement in the bond strength due to precoating of up to 28.7% was also observed. A statistical analysis using ANOVA did not illustrate any statistical significant effect of the aggregate type. The interaction effects analysis using ANOVA revealed the aggregate type interacting with precoat type to be the most influential interaction at level two. The precoat conditioning implication to the adhesion development rate, which influences the time for opening to traffic after construction, was illustrated. Insightful aspects on the compatibility between the binder type and precoat type and conditioning during the aggregate precoating practices and on the time for opening to traffic are highlighted. Finally, the repeatability analysis proved the BBS test to be a repeatable testing method with caution. Recommendations for further studies that could support the conclusions drawn in this study were provided. / AFRIKAANSE OPSOMMING: Buigbare plaveiselontwerpers het 'n keuse van twee deklae: óf Asfalt of oppervlak seëls. Laasgenoemde word algemeen gebruik deur verskeie lande as hul voorkeur deklaag, veral die lande met beperkte aantal gemiddelde inwoners per vierkante kilometer. Verder, is die seëls geïdentifiseer as 'n doeltreffende koste-effektiewe deklaag tegniek. Oppervlakseëls in Nieu-Seeland, Suid-Afrika en Australië dek ongeveer 65%, 80% en 90% van hul padnetwerke onderskeidelik. Die seëls se voorkeur is te danke aan hul mededingende aanvanklike koste en eenvoudige vorm van die konstruksie. In Suid-Afrika wissel die seël se lewensverwagting tussen 8 en 12 jaar met 'n gemiddeld van 10 jaar. Dit is egter nie die geval van 'n aantal seëls wat in die winter gebou word nie, veral wanneer die aangetekende nagtemperatuur onder 10o C daal nie. Die dominante swigtingsmeganisme is stroping (klipverlies) kort na konstruksie. Hierdie klipverlies is gekoppel aan die power kleef-ontwikkeling van bitumen gedurende die winter. Ten einde die probleem van voortydige klipverlies aan te spreek het die behoefte vir die ontwikkeling van 'n robuuste toetsmetode ontstaan. Om hierdie rede het navorsers onlangs in die bitumenbedryf die “BBS toetsmetode” ontwikkel en is dié toetsmetode in hierdie studie gebruik. Hierdie studie beoog om by te dra tot die begrip van bindmiddel-klip kleefontwikkeling vir die winter seëls dmv die BBS toets. Die faktore, insluitend maar nie beperk tot bindmiddeltipe, voorafdekking (“PRECOAT”) -tipe en kondisionering, aggregaattipe en kuurtyd beïnvloed winter seëls se kleefeienskappe. 'n Eksperimentele matriks met drie tipes bindmiddels, twee tipes aggregate, vier verskillende voorafdekking-vloeistowwe, twee voorafdekking kondisionering en twee bindmiddel kuurtye is toe ontwikkel en ondersoek. Winter weer parameters wat kleefeienskappe beïnvloed is ook in ag geneem tydens die verloop van die ondersoek. Regdeur die studie is die prosedure AASHTO TP 91-11 gevolg, maar ten einde die beheer van die bindmiddel spuittemperatuur te verbeter, is ‘n nuwe metode vir warmspuit-bindmonsters voorbereiding ontwikkel as deel van hierdie studie. Die bevindinge toon dat daar 'n beduidende verskil tussen die kleefeienskappe van die warm aangewende bindmiddels (70/100 en S-E1) en die emulsie (SC-E1) is. In die meeste van die gevalle het die warmspuit-bindmiddels beter as emulsie gevaar. Daar is gevind dat die swigtingsmeganisme verbind word met die toestand van die voorafdekking. Die invloed van voorafdekkingtipe, kondisionering, en die effek van bindmiddelkuurtyd is duidelik uitgelig. Die gebruik van droë voorafdekking het die kleefkrag tot sowat 50% verhoog relatief tot die ooreenstemmende onbedekte klipkombinasie. Daar is egter ook ‘n verlaging van die kleefkrag weens voorafdekking gevind van tot so hoog soos 28,7 persent. Die statistiese ontleding met behulp van ANOVA het geen statisties beduidende effek van die verksillende aggregaattipe te vore gebring nie. Die interaksie-effek analise, met behulp van ANOVA, het wel die interaksie met voorafdekkingtipe met aggregaat die mees invloedryke bevestig. Die voorafdekking kondisioneering het ver rykende kleefkrag implikasies bloot gelê, wat die tyd vir die opening van die verkeer na konstruksie beïnvloed. Insigwekkende aspekte oor die versoenbaarheid tussen die bindmiddeltipe, voorafdekkingtipe, kondisionering, voorafdekkingpraktyk en tyd tot opening vir verkeer word uitgelig. Ten slotte, die herhaalbaarheidsanalise het die BBS toets as 'n herhaalbare toetsmetode met omsigtigheid bewys. Daar is aanbevelings tot verdere studies, wat uit die gevolgtrekking gekom het, gemaak.