Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The Berg River is one of the largest rivers in the winter rainfall area of the Western Cape and is one of the most important water supply sources of the area. The Riviersonderend-Berg system needs to be expanded in order to meet increasing water demands of the Greater Cape Town (GCT) region. The implementation of future schemes will remove additional fresh water from the Berg River main stem, which will give rise to increased nutrient levels and higher salinity in the water. A water quality information system (WQIS) has been proposed to benefit the management of water resources, the flow quantity and the quality of the water. A part of this WQIS will be a water-quality simulation model that characterizes the water quality situation and is able to predict water quality responses to future implementations, as well as simulate different scenarios that can be used for management purposes. The objective of this study is to represent the water quality situation of the Berg River in a simulation model by implementing, testing and verifying a water quality simulation model, and assembling a hydraulic and water quality database suitable to meet foregoing objectives. This study firstly examined the water quality variables of concern: pH, Total Dissolved Salts (TDS) and phosphates to develop an understanding of the water quality responses and causes of the main stem of the Berg River system. A thorough review of the available models has been undertaken in the light of certain selection criteria, before determining that DUFLOW would be an acceptable model for this study. The water quality variables that have been modelled are TDS, Phosphates as P04, Oxygen and Temperature. As no predefined module simulating temperature, TDS and COD was included; these algorithms, describing the processes of these water quality variables have been additionally coded. The coding was possible, as DUFLOW' s water quality module consists of an open structure. The predefined water quality module was simplified to only include the water quality process algorithms, for water quality variables where data was available. Unfortunately, phosphates were mainly simulated on advection, and the influence of all the additional processes could not be assessed. All data gathering and preparation for the model had to be completed before commencing the model configuration. This included information on cross-sections, historical flow records, bridges and weirs for the hydraulic component ofDUFLOW. For the water quality module, information on historical grab samples has been obtained and 'infilled' to provide daily time series. To simulate the water quality in a river as accurately as possible, the flow simulation needs to be accurate. Ungauged subcatchment runoff was added to the simulation model to improve the correspondence between the simulated and the measured flow. Calibration of the water quality part of DUFLOW was completed by adjusting the different parameters after a sensitivity analysis. The model was verified by using a different time period than for the configuration, to ensure that an independent data set has been used. After configuring, calibrating and verifying the model, the applicability of the model could be tested for different scenario runs. Three scenarios were chosen according to real situations: • a short term effluent spill, with and without water releases from an upstream source (either Skuifraam Dam or Voëlvlei Dam); • the impact on the flow and water quality situation of the river when an upstream dam is built; • a long term management control scenario, that analyses load or concentration releases into the river according to limitations upstream and downstream of the discharge location. The scenario analysis provides an opportunity to assess the applicability of DUFLOW to simulate real time management and operational issues in a river and to aid in management decisions. / AFRIKAANSE OPSOMMING: Die Bergrivier is een van die grootste riviere in die winterreënvalgebied van die Weskaap en is een van die mees belangrike waterverskaffingsbronne in die area. Die Riviersonderend-Bergrivier-stelsel moet uitgebrei word om aan die groeiende waterbehoefte van die groter Kaapse Metropolitaanse Area te voldoen. Die implementering van toekomstige skemas sal addisionele vars water uit die hoof-loop van die Bergrivier onttrek, wat tot hoër voedingstof-vlakke en soutgehalte in die water sal lei. 'n Waterkwaliteitsinformasiestelsel (WQIS) sal van nut wees om die vloei-omvang en waterkwaliteit van waterbronne te bestuur. 'n Deel van die WQIS sal 'n waterkwaliteit-simulasiemodel wees, wat die waterkwaliteitsituasie sal kan ontleed, waterkwaliteit-reaksies op toekomstige implementerings kan voorspel, asook verskeie scenarios vir bestuursdoeleindes kan simuleer. Hierdie studie behandel spesifiek die waterkwaliteitsveranderlikes pH, totale opgeloste soute, fosfate, temperatuur en suurstof om 'n begrip te ontwikkel van die waterkwaliteitsreaksies en oorsake van die hoofloop van die Bergriviersisteem. Die doelwit van hierdie studie is om die waterkwaliteitsituasie van die Bergrivier uit te beeld deur die implementering, toets en kalibrasie van 'n waterkwaliteit-simulasie model, asook die insameling van hidrouliese- en waterkwaliteitsdata om aan bogenoemde doelwitte te voldoen. 'n Reeks beskikbare modelle is deeglik ondersoek voordat besluit is dat die DUFLOW model 'n gepaste model vir hierdie spesifieke studie is. Die keuse was gebaseer op spesifieke vereistes wat as belangrik beskou is deur potensiële bestuursgeorienteerde gebruiksgroepe. Die waterkwaliteitsveranderlikes wat gemodelleer is, is totale opgeloste soute, fosfate as P04, suurstof en temperatuur. Omdat geen voorgegewe temperatuur-, TDS- en COD modules in die model ingesluit is nie, is die algoritmes wat die prosesse van hierdie waterkwaliteitsveranderlikes beskryf, addisioneel gekodeer. Die kodering is moontlik gemaak deur die oop struktuur van DUFLOW se waterkwaliteitsmodule. Die voorgegewe waterkwaliteitsmodule is vereenvoudig om alleenlik die waterkwaliteit proses-algoritmes in ag te neem wanneer data vir waterkwaliteitsveranderlikes beskikbaar was. Ongelukkig is die fosfate hoofsaaklik op beweging gesimuleer, en die invloed van alle addisionele prosesse kon nie getoets word nie. Alle data-insameling en -voorbereidings vir die model moes voltooi word, voordat begin kon word met die opstel van die simulasie-model. Dit het inligting oor dwarssnitte, historiese vloeirekords, brik en keerwalle vir die hidrouliese komponent van DUFLOW ingesluit. Vir die waterkwaliteitsmodule is inligting van historiese bemonstering verkry en ingevulom 'n daaglikse tydreeks te verkry. Om die water-kwaliteit van 'n rivier so akkuraat as moontlik te simuleer, moet die vloei-simulasie redelik akkuraat wees. Ongemete sub-opvanggebied afloop is bygetel om die korrelasie tussen die gesimuleerde en gemete vloei te verbeter. Kalibrasie van die waterkwaliteitmodule van DUFLOW is voltooi deur die verskillende parameters te verstel na 'n sensitiwiteits-analise. Die model is geverifieer deur 'n ander tydperiode as die vir die opstel te gebruik, om sodoende te verseker dat Inonafhanklike data stel gebruik word. Na die opstel, kalibrasie en verifiering van die model, kon dit toegepass word vir verskillende bestuursscenanos. Drie scenarios is na aanleiding van werklike situasies gekies: 'n korttermyn uitvloeisel storting-situasie met en sonder loslatings van 'n stroomop bron (Of Skuifraamdam Of Voëlvleidam), die impak op die vloei- en waterkwaliteitsituasie van die rivier sou 'n dam stroomop gebou word. 'n langtermyn bestuurs-scenario waarin die lading en konsentrasies, veroorsaak deur die loslatings vanuit die dam na die rivier, ontleed word na aanleiding van beperkings stroomop en -af van die loslatingsplek. Die analise van die scenarios verskaf 'n geleentheid om die toepaslikheid van DUFLOW te ondersoek om werklike operasionele aangeleenthede te simuleer en om sodoende bestuursbesluite te vergemaklik.

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: In an attempt to improve the efficiency of the transport system, the national government has instituted a new tender system for public transport contracts. Small bus and taxi operators are unfamiliar with operating in the formal sector. This study focuses on the extent of their disadvantage in the current tender system and recommends measures to counterbalance this. A questionnaire was devised to determine how much assistance these operators would require to prepare them for the tender, using the model bus tender document as a basis for this. The response rate was 20% with 14 taxi and 17 bus questionnaires being retrieved for analysis. The results showed that 10% of operators had no know ledge of the tender and many needed training in basic accounting and business procedures as well as public transport operation skills. Recommendations included institutional changes in public transport funding, management and allocation of resources as well as the type of education and training required. These changes should be implemented soon enough to ensure that small, medium and micro enterprises (SMME) operators are well prepared for the new tender system. / AFRIKAANSE OPSOMMING: In 'n poging om die effektiwiteit van die vervoersisteem te verbeter, het die nasionale regering 'n tendersisteem vir openbare vervoerkontrakte ingestel. Klein bus en taxioperateurs is nie bekend met die bedryf van 'n besigheid in die formele sektor nie. Hierdie studie konsentreer op hul agterstand in die huidige tendersisteem en maak aanbevelings oor hoe dit oorkom kan word. 'n Vraelys is opgestel om te bepaal hoeveel bystand hierdie operateurs sal benodig om hu1le voor te berei vir die tender. Die model bus tenderdokument is as basis gebruik. 20% van die operateurs het op die vraelys gereageer - 14 taxi- en 17 busvraelyste is ontvang vir verder verwerking. Die resultate van die opname het getoon dat 10% van die operateurs geen kennis van die tender gehad het nie en dat baie van hulle opleiding benodig in basiese rekeninkundige en besigheidsprosedures sowel as openbare vervoer bedryfsmetodes. Aanbevelings van die studie sluit lil institusionele veranderinge lil openbare vervoerbefondsing, bestuur en die toewysing van hulpbronne asook die tipe onderrig en opleiding wat benodig word. Hierdie veranderinge behoort so gou as moontlik geïmplementeer te word sodat klein, medium en mikro operateurs goed voorberei kan word vir die nuwe tendersisteem.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: End stop impact forces are horizontal longitudinal forces imposed by the crane on the end stops. Both the previous South African loading code SABS 0160:1989 and the current South African loading code SANS 10160 , classify end stop impact force as an accidental load case , hence they are not expected to occur within the expected lifetime when the guide lines for crane operation are strictly adhered to. In the estimation of end stop impact force, the previous South African loading code SABS 0160:1989 gives two guidelines for estimating the end stop impact force. The first guideline is simplistic in its approach and it’s based on the assumption that the crane and its supporting structure act as rigid bodies; hence calculation is based on rigid body mechanics. Literature reviewed reveals that this is not correct. The second guideline is more explicit in its approach as it takes into account the crane speed, resilience of the buffers and resilience of the end stops. The current South African loading code, SANS 10160 gives a better representation of the dynamics of the crane movement. However, the dynamic factor recommended for the estimation of end stop impact force is empirical in nature and thus lacks adequate scientific backing. One of the purposes of this research was to investigate the influence of the stiffness of the crane bridge on the end stop impact force. This was achieved by conducting a series of FEA simulations on the double bridge EOHTC fitted with elastomeric buffers. For this set of simulations, the effect of each influencing parameter on the end stop impact force was investigated, and the maximum end stop impact force was obtained using a constraint optimization technique. From the results obtained, comparison was then made with the existing maximum end stop impact force for a single bridge EOHTC fitted with elastomeric buffers. Another purpose of this research was to investigate the end stop impact force for an electric overhead travelling cranes (EOHTC) fitted with hydraulic buffers taking into account the dynamics involved in the movement of the EOHTC. This was achieved by a series of experimental and numerical investigation. The numerical investigation was conducted using an existing numerical model of an EOHTC which captures the crane and its supporting structure as a coupled system. Finite element analysis (FEA) impact force histories obtained were calibrated to the base experimental impact force histories. Thereafter, a series of FEA simulations were conducted by changing the parameters which have a substantial effect on the end stop impact forces. This yielded various maximum impact peaks for various parameters. The maximum impact force was then mathematical obtained from the FEA impact force histories for a given level of reliability using a constraint optimization technique. Also, codified end stop impact forces were calculated for the SABS 0160:1989 and SANS 10160-6:2010. From the results obtained, comparison was made between the codified end stop impact force and the maximum impact force obtained from the constraint optimization technique. / AFRIKAANSE OPSOMMING: Ent buffer impak kragte is horisontale kragte wat deur die kraan op die entbuffers aangewend word. Beide die Suid Afrikaanse las kode SABS 0160:1989 en die voorgestelde Suid Afrikaanse las kode SANS 10160, klasifisseer die entbuffer impak kragte as ‘n ongeluks las geval, dus word die kragte nie verwag tydens die verwagte leeftyd van die kraan wanneer die riglyne van die kraan prosedures streng gevolg word nie. Volgens die Suid-Afrikaanse las kode SABS 0160:1989 word daar twee riglyne voorgestel om die entbuffer kragte te bepaal. Die eerste riglyn is ‘n eenvoudige riglyn en word gebaseer op die aaname dat die kraan en die ondersteunende struktuur as ‘n starre ligame reageer en dus word die kragte bereken deur star ligaam meganika, alhoewel, uit die literatuur word dit bewys as inkorrek. Die tweede riglyn is ‘n meer implisiete benadering aangesien dit die kraan snelheid, elastisiteit van die buffers sowel as die elastisiteit van die end stoppe in ag neem. SANS 10160-6:2019 gee ‘n beter benadering van die dinamiese beweging van die kraan. Die voorgestelde dinamiese faktor waarmee die ent_buffer_kragte bereken word, is empiries van natuur . Een van die doelstellings vir die navorsings projek was om te bepaal wat die invloed van die kraan brug se styfheid op die entbuffer kragte is. ‘n Aantal Eindige Element Analise (FEA) simulasies is uitgevoer op ‘n dubbel brug elektriese aangedrewe oorhoofse kraan met elastomeriese buffers. Van die stel FEA simulasies kan die invloed van elke parameter op die entbuffer impak_kragte bepaal word. Die maksimum entbuffer impak_kragte is bepaal met behulp van ‘n beperking optimiserings tegniek. Vanaf hierdie resultate is ‘n vergelyking gemaak met die bestaande maksimum ent_buffer impak_kragte vir ‘n enkel brug elektriese oorhoofse aangdrewe kraan met elastomeriese buffers. ‘n Tweede doel rede vir die navorsing was om te bepaal wat die ent buffer impak_kragte op ‘n elektriese aangedrewe oorhoofse kraan met hidrouliese buffers is. Dit is bepaal deur ‘n aantal eksperimentele en numeriese toetse uit te voer. Die numeriese toetse is uitgevoer deur gebruik te maak van ‘n huidige numeriese model van ‘n elektriese aangedrewe oorhoofse kraan wat die kraan en die ondersteunende struktuur as ‘n. Die Eindige Element Analise impak_kragte is gekalibreer teen die eksperimenteel bepaalde impak- kragte. Daarna is ‘n reeks Eindige Element Analise simulasies uitgevoer en sodoende die parameters te verander wat die mees beduidende invloed op die end stop impak_kragte het. Dit het verskeie impak_krag pieke vir verskillende parameters meegebring. Die maksimum impak kragte is bepaal van die impak kragte van die Eindige Element Analise vir ‘n gegewe vlak van betroubaarheid deur gebruik te maak van die beperking optimiserings tegniek. Daarmee saam is die gekodifiseerde ent buffer impak kragte bereken volgen SABS 0160:1989 en die SANS 10160- 6:2010. Vanaf hierdie resultate is ‘n vergelyking gemaak tussen die gekodifiseerde entbuffer impak_kragte en die maksimum impak_kragte wat bepaal is deur die (beperking optimiserings tegniek).

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In this research a Real-Time hydrodynamic optimisation model of the Orange-Fish-Sundays River (OFS) system which uses real-time data in order to forecast release hydrographs, is evaluated. The OFS system stretches over three catchment areas in the Eastern Cape namely Great Fish, Little Fish and Sundays Rivers. The OFS supplies water from the Orange River through a 800 km system of canals, tunnels, dams and rivers to registered water users in this area. In order to cope with increasing pressures on water saving, water demand, water quality and dam safety, the Department of Water Affairs implemented this Orange Fish Sundays-Real Time (OFS-RT) system to calculate the optimal water flow, by running customised Danish Hydraulic Institute (DHI) MIKE11 software. The system utilizes an optimisation module that evaluates the simulated outcome at seven water release structures (dams, weirs and tunnels). Then during the optimisation process performs more adjustments to reach the objectives of the system to obtain the forecast release hydrographs. This OFS-RT model aims at target based objectives, using: (i) Hydras real-time field data of dam water levels, river flows and water quality from the area sent to the control office main computer at four hourly intervals via SMS and (ii) abstractors weekly water requests. This system takes irrigation and domestic demand into account as well as water quality, evaporation, rainfall, dam levels, dam safety, instream flow requirements and tributary flow. In order to manage the water flows through the OFS system the OFS-RT model forecasts the release hydrographs and uploads the predictions to a website to smooth operational procedures. The target outcomes were tested and evaluated during this research and it was found that the OFS- RT model succeeded in delivering release forecasts for the seven control structures to manage the OFS system. This research proved that management of river systems by using a real-time hydrodynamic model with optimisation is a useful tool for the optimal utilisation of water resources. / AFRIKAANSE OPSOMMING: Die doel van hierdie navoring is die evaluering van „n intydse hidrodinamiese optimiseringsmodel van die Oranje-Vis-Sondagsrivier (OVS) stelsel wat intydse data ontvang en loslatings hidrograwe verskaf. Die OVS stelsel strek oor drie opvangsgebiede in die Oos-Kaap: naamlik die Groot Vis-, Klein Vis- en Sondagsriviere en voorsien water vanuit die Oranjerivier deur „n 800 km stelsel van kanale, tonnels, damme en riviere, aan geregistreerde waterverbruikers in die gebied. Ten einde te voldoen aan die eise van waterbesparings, stygende vraag na water, die verskaffing van goeie water gehalte en damveiligheid, het die Departement van Waterwese „n intydse rekenaar model (OVS-IT) geïmplimenteer om die optimale watervloei deur middel van die aangepaste MIKE11 sagteware van die Danish Hydraulic Institute (DHI) te bereken. Hierdie stelsel maak gebruik van „n optimisering module wat die gesimuleerde uitkomste van verstellings aan sewe waterloslatingstrukture evalueer. Met optimisering word die verlangde hidrograaf deur verder aanpassings verkry. Data wat nodig is om die OVS-IT model se doel te bereik is: (i) Hydras intydse velddata van damwatervlakke, riviervloeie en water gehalte van die gebied ontvang deur die beheerkantoor se hoofrekenaar via SMS elke vier ure, en (ii) water verbruikers se weeklikse wateraanvrae Die stelsel neem die besproeiing en huishoudelike aanvraag in ag, sowel as soutgehalte, verdamping, reënval, damvlakke, dam veiligheid, stroom vloei vereistes en sytak byvloei. Die OVS se watervloei word beheer deur voorspelde loslatings hidrograwe, opgesom op „n webwerf wat die uitvoer prosedures aandui. Die intydse hidrodinamiese model met optimisering het volgens hierdie navorsing daarin geslaag om vir die beheer van die OVS stelsel, die loslatings van sewe beheerstrukture akkuraat te voorspel en bevind dat die model „n waardevolle instrument is vir die optimale bestuur van waterhulpbronne.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The hypothesis postulated in this research, namely that the effectiveness of natural and constructed buffer dune systems can be assessed by a set of indicators that defines the integrity of the dune system and triggers informed management decisions, was evaluated and proved to be essentially true. Two key objectives, namely (1) the identification of key indicators that define the buffer dune integrity; and (2) the development of a scientifically defendable and practical checklist-based method of gathering qualitative information on the identified key indicators so as to guide decision-making at municipal level formed the core of the study. The six dune integrity indicators that collectively define the risk profile of a particular site along the Southern Cape coastline are (1) the degree of protection from prevailing wave energy, (2) the characteristics of the dominant winds and sand supply during the dry season, (3) the relative height of the foredune, (4) the degree of pressure on the buffer dune due to humans, (5) the vulnerability of the type of coastline to erosion, and (6) the coastline stability considering the prevailing coastal processes. The first two indicators relate to the natural (permanent) characteristics of the site and can be defined by experts and presented in the form of a risk and vulnerability atlas layer for direct use by non-experts. The third and fourth indicators relate directly to the implementation of proactive assessment and appropriate management actions to ensure a high level of buffer dune integrity. The last two indicators allow for management intervention to reduce the vulnerability but may entail costly engineering solutions and require expert input. A conceptual risk profile assessment procedure and a decision support guideline incorporating these indicators were developed and evaluated for relevance and practicality through a series of workshops with municipal officials along the south coast of South Africa. It was seen that although some initial basic training may be required, carrying out rapid assessments of the environmental status of key components of an identified human–nature system, such as a buffer dune, is practical and achievable by non-experts. / AFRIKAANSE OPSOMMING: Die hipotese wat in hierdie navorsing gepostuleer is, naamlik dat die doeltreffendheid van natuurlike en geboude bufferduinstelsels geassesseer kan word deur ’n stel aanwysers wat die integriteit van die duinstelsel bepaal en ingeligte bestuursbesluite tot gevolg het, is getoets en bewys hoofsaaklik waar te wees. Twee sleuteldoelwitte, naamlik (1) die identifisering van sleutelaanwysers wat die bufferduinintegriteit bepaal; en (2) die ontwikkeling van ’n praktiese kontrolelys-gebaseerde metode wat wetenskaplik verdedigbaar is om kwalitatiewe inligting oor die geïdentifiseerde sleutelaanwysers in te samel ten einde besluitneming op munisipale vlak te bevorder, vorm die kern van die studie. Die ses duin-integriteitsaanwysers wat gesamentlik die risikoprofiel van ’n bepaalde terrein langs die kuslyn bepaal, is (1) die graad van beskerming teen die heersende golfenergie, (2) die kenmerke van die dominante winde en sandbron gedurende die droë seisoen, (3) die relatiewe hoogte van die voorduin, (4) die graad van druk op die bufferduin as gevolg van mense, (5) die eroderingskwesbaarheid van die soort kuslyn, en (6) die kuslynstabiliteit met inagname van die kusprosesse. Die eerste twee aanwysers het betrekking op die natuurlike (permanente) eienskappe van die terrein en kan deur kundiges bepaal word en in die vorm van ’n kaart in ’n risiko-enkwesbaarheidsatlas aangebied word vir direkte gebruik deur niedeskundiges. Aanwysers 3 en 4 hou direk verband met die implementering van tydige en deurlopende proaktiewe assessering en gepaste bestuursaksies om ’n hoë vlak van bufferduinintegriteit te verseker. Aanwysers 5 en 6 bevorder bestuursaksies om kwesbaarheid te verminder, maar kan moontlik duur ingenieursoplossings inhou en kundige insette benodig. ’n Konseptuele risikoprofielassesseringsprosedure en ’n besluitondersteuningsriglyn wat die aanwysers insluit, is ontwikkel en geëvalueer vir toepaslikheid en uitvoerbaarheid deur ’n reeks werkswinkels met munisipale amptenare aan die suidkus van Suid-Afrika. Hoewel aanvanklike basiese opleiding nodig kan wees, bly dit dat vinnige assessering van die omgewingstatus van sleutelkomponente van ’n geïdentifiseerde mens–natuurstelsel, soos ‘n bufferduin, prakties en haalbaar deur niedeskundiges is.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Electric driven overhead travelling bridge cranes (EOHTC) form a vital part of industrial plants where heavy objects require moving. Overhead travelling cranes aid in production by allowing an uninterrupted work process on the ground while heavy loads are moved to their required locations. Various factors need consideration in determining the loads induced by an EOHTC on its support structure. In order to design such a support structure, the designer must understand and take into account the various loads that the support structure will be subject to during its lifetime. The procedure for determining the loads induced by the EOHTC on its support structure is laid out in the SANS 10160-6:2010 code of practice. This document was published in June 2010 and as a result very few worked examples exist to test the coherence of the procedure. This thesis presents an investigation into the procedure for determining the actions induced by overhead travelling bridge cranes adopted in the SANS 10160-6:2010 code of practice. The investigation was conducted by developing a software application to automatically determine the necessary crane actions needed for the design of the crane support structure, given certain input parameters. The motivation behind this was to have a tool that can calculate the crane induced loads automatically. And by developing such a tool the procedure given in the code of practice is better understood. The Java programming language was used to code the calculations with an object oriented programming approach (OOP). NetBeans, the integrated development environment for developing with Java was used to generate the required graphical user interface of the application. In addition, a Microsoft Excel calculation sheet was also developed for the purpose of comparison and verification. Whilst developing the software application, it was found that the model for the acceleration or deceleration of the crane was specific for four wheel cranes only. This model was then extended to accommodate eight and sixteen wheel cranes and incorporated into the algorithm architecture of the application. The application was successfully completed and verified using benchmarked examples. / AFRIKAANSE OPSOMMING: Elektriese oorhoofse brugkrane vorm ‘n belangrike deel van baie nywerheidsprosesse, waar dit gebruik word om swaar laste in die nywerheidsaanleg te verskuif. Oorhoofse brugkrane voeg waarde by die produksie lyn deur te sorg dat die werksproses op die grond onversteurd voortgaan terwyl swaar laste na hul vereiste posisies verskuif word. Verskillende faktore moet in ag geneem word om die nodige kraanlaste te bepaal. Hierdie laste word benodig om die kraan se ondersteuningstruktuur te ontwerp. Die ontwerper moet die nodige kundigheid hê en moet ook die verskeie laste in ag neem wat die ondersteuningstruktuur gedurende sy leeftyd sal dra. SANS 10160-6:2010 verskaf riglyne vir die bepaling van die laste wat deur oorhoofse brugkrane uitgeoefen word. Hierdie dokument is in Junie 2010 gepubliseer dus bestaan daar min uitgewerkte voorbeelde om die korrektheid van die riglyne te toets en toepassing te demonstreer. Hierdie proefskrif ondersoek die riglyne vir die bepaling van oorhoofse brugkraan aksies soos uiteengesit in die SANS 10160-6:2010. Die navorsing is uitgevoer deur middel van die ontwikkeling van ‘n sagteware toepassing wat die nodige oorhoofse brugkraanlaste automaties bepaal, gegee sekere invoer waardes. Die rede hiervoor was om ‘n hulpmiddel te ontwikkel vir die outomatiese bepaling van oorhoofse brugkraan. Deur die bogenoemde hulpmiddel te ontwikkel word die riglyne, soos gegee in die kode beter verstaan. Java is gebruik as programmeringstaal waar die objek geörienteerde programeringstyl toegepas was. Die geintegreerde ontwikkelingsomgewing vir ontwikkeling met Java, naamlik NetBeans is gebruik om die nodige gebruikers koppelvlak op te bou. ‘n Microsoft Excel sigblad is ook ontwikkel vir kontrolerings doeleindes. Gedurende die ontwikkeling van die sagtewarepakket is dit bevind dat die lasmodel vir die versnelling of vertraging van die oorhoofse brugkraan slegs op vierwiel krane van toepasing is. Hierdie lasmodel is dus uitgebrei om agt- en sestienwiel krane ook te bevat. Die lasmodel aanpassing is dan ook in die program se algoritme-argitektuur ingebou. Die sagteware toepassing is suksesvol ontwikkel en gekontroleer met ‘n maatstaf voorbeeld.

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.

Thesis (MScEng (Civil Engineering))- -University of Stellenbosch, 2011 / ENGLISH ABSTRACT: The limited water supply and an increasing water demand means that the effective management of water resources becomes much more important than in the past. The implementation of water demand management / water conservation (WDM/WC) projects are usually used as a crisis management tool to reduce immediate water shortage and to allow time for the planning and construction of infrastructure to increase water supply. It is however possible to incorporate WDM/WC into integrated water resource management and to use WDM/WC as an economic viable option for the upgrade of infrastructure to balance supply and demand. Existing economic evaluation methods to compare different options with each other were used to evaluate WDM/WC measures. Literature showed that to perform an economic evaluation of WDM/WC measures, the costs associated with the implementation of the WDM/WC measures, as well as the expected water saving from the implementation of the WDM/WC measure, must be known. Models were developed to estimate the expected water savings from different WDM/WC measures. The economic impacts of specific WDM/WC measures were investigated by using these models. Different economic models were developed to perform an economic evaluation of WDM/WC measures. WDM/WC measures were evaluated in terms of its economic feasibility. Economical evaluations of WDM/WC measures were also done as an alternative to the upgrading of infrastructure. In the last evaluation, the financing of WDM/WC measures through the deferral of capital cost, was investigated. Case studies from literature, where costs as well as water savings were available, were used to evaluate these WDM/WC measures by using the developed economic models. Cost estimates for the upgrading of infrastructure, to supply an equal amount of water as the water saving achieved in each case study, were done. These estimates were used to compare WDM/WC measure with the upgrading of infrastructure. / AFRIKAANSE OPSOMMING: Daar word al hoe meer druk op bestaande hulpbronne geplaas om voldoende water te lewer. Die fokus skuif na effektiewe bestuur van hierdie hulpbronne. Wateraanvraagbestuur/ Waterbewaring (WAB/WB) projekte word geïmplementeer om krisisse van water tekorte aan te spreek en tyd te wen om nuwe hulpbronne te ontwikkel. Dit is wel moontlik om WAB/WB in geïntegreerde waterbron bestuur in te sluit en WAB/WB as ʼn ekonomiese alternatief tot kapitale investering aan te wend. Om die ekonomiese aspekte van WAB/WB te ondersoek, is daar op bestaande ekonomiese evaluerings metodes gefokus om verskillende opsies met mekaar te vergelyk. Uit die literatuur is gevind dat die belangrikste aspekte vir die ontleding van WAB/WB alternatiewe i.t.v. hul ekonomiese waarde, die koste van implementering van die WAB/WB alternatief is en die waterbesparing wat deur die implementering van die WAB/WB alternatief verkry word. WAB/WB modelle is ontwikkel om die verwagte water besparing van bepaalde WAB/WB alternatiewe te beraam. Die moontlike ekonomiese impak van bepaalde WAB/WB alternatiewe is deur die gebruik van hierdie modelle ondersoek. Ekonomiese evaluerings modelle is opgestel om WAB/WB alternatiewe te ontleed. WAB/WB alternatiewe kan as ʼn ekonomiese haalbare projek geïmplementeer word waar die kostes van die waterbesparings meer as die kapitale koste van die projek is. WAB/WB alternatiewe kan ook meer ekonomies as die ontwikkeling van nuwe bronne of opgradering van ʼn bestaande netwerk wees. Laastens is die moontlikheid om WAB/WB as ʼn alternatief te finansier deur die besparing wat bereik kan word deur ʼn kapitale projek uit te stel, ondersoek. Gevalle studies uit die literatuur, waar die kostes en waterbesparings bekend is, is ontleed deur van hierdie ekonomiese evaluerings modelle gebruik te maak. Vir elk van die gevalle studies is ʼn koste vir die opgradering van die infrastruktuur beraam om die ekwivalente hoeveelheid water te voorsien as wat deur die WAB/WB alternatief bespaar is.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: South African municipalities are under pressure to improve the current state of the water andwastewater service delivery industry. Knowing that there exists a need for improvement within the municipal water and wastewater industry, the Department of Water Affairs (DWA) launched a municipal strategic self-assessment (MuSSA) initiative to evaluate the business health of the industry. MuSSA asks high level technical management staff five key questions about sixteen key business attribute areas. This study seeks to determine if theMuSSA data can be used to aid municipal decision making, by way of drawing correlations between key performance indicators contained in the MuSSA questions. The correlations are to bring forth areas thatmust be focussed on to improve selected attribute areas requiring attention within municipalities. Three areas have been chosen from theMuSSA data to be investigated in this research project namely; (i)staff skill levels and capacity, (ii)non-revenue water and (iii)the execution of planned water services activities. In the MuSSA questionnaire there are questions addressing each of (i), (ii) and (iii) to determine the municipality’s performance in each of the three areas. Non-parametric statistics are used to determine with which of the MuSSA questions’ answers the relevant questions’ answers significantly correlate for (i), (ii) and (iii). Engineering judgement and expert opinion are used to determine if the questions correlating with the relevant questions for (i), (ii) and (iii) either affect, are affected by or have no relation with the question. These results are then organized using a flow diagram and are discussed in detail by way of a bivariate histogramof each correlation. The investigation revealed that municipalities not having sufficient technical management capacity are not performing well on at least one of the five questions asked on eleven of the sixteen MuSSA business attributes. The skill level of water and wastewater treatment works staff were found to be strongly affected by technical management capacity and skill, water services planning and financial sustainability of the organization. Municipalities training technical management and operational staff showed a high percentage of skilled operational staff employed at treatment works. Water and wastewater treatment works staff capacity are very dependent of the level of skill and capacity of technical management employed by the municipality. Municipalities having appropriate budgets and funding to appoint and train staff showed a tendency to be better at operational staff capacity building than those lacking funding. The reduction of non-revenue water (NRW) showed strong correlations with technical management and network operational repair staff skills and development. Municipalities employing staff with correct skills and experience combined, with commitment from management to reduce NRW by way of monitoring and practicing of pressuremanagement programs, significantly reduced NRW percentages. Equally crucial to the reduction of NRW, as revealed from the investigation, is the practicing of infrastructure asset management within the municipality. It was concluded that municipalities should strive to reach a NRW percentage of 30% or less to become financially stable, due to correlation between funding of routine operations and building up of cash reserve versus NRW percentages. Municipalities wanting to improve the execution rate of planned water services activities are recommended to address, among other factors, technical management skill levels and capacity. Municipalities lacking technical management skill and capacity reported a low percentages of planned activities being executed. Also of high significance, is the technical operational staff skill levels and capacity, due to their involvement in the execution of planned activates. The involvement of council members in water and wastewater planning and the reporting of data and issues to council greatly enhancesmunicipalities’ abilities to execute planned activities. This can mainly be contributed to increased funding in situations where council members support planned projects. The lack of funding was found to be a major inhibitor of the execution of planned activities. Even though a great deal of municipalities indicated that they are effectively spending allocated budgets, this positive indication is not seen in the percentage municipalities executing planned activities and leads to the conclusion that there is a lack of funding. Municipalities taking actions in other areas of their business such as infrastructure assetmanagement and planning were more effective at executing planned activities. In all, it was concluded that technicalmanagement and operational staff skill levels and capacity need to be present for amunicipality to function properly. Municipalities also are in need of funding to execute planned activities and need to become financially self sustainable. One way of working towards the goal of financial self sustainability is the reduction of NRW percentages. The data from this investigation shows great similarity with the literature consulted on the current state and functioning of South African municipalities. The statistical analysis of the MuSSA data accurately revealed correlations among key performance indicators in municipalities. The conclusion can be drawn that investigation of correlations amongMuSSA questions can be used to help aid municipal decision making. / AFRIKAANSE OPSOMMING: Suid-Afrikaanse munisipaliteite is onder druk om die huidige toestand van die water en afvalwater dienslewering te verbeter. Met die wete dat daar ’n behoefte vir verbetering in die munisipale water en afvalwater bedryf is het dieDepartement vanWaterwese ’n munisipale strategiese self-assessering (MuSSA) projekte geïnisieer omdie welstand van die bedryf te evalueer. MuSSA vra hoë vlak tegniese bestuurs personeel vyf kern vrae oor sestien sleutel besigheids aspekte. Hierdie studie poogomvas te stel of dieMuSSA data gebruik kan word om munisipale besluitneming te help verbeter, deur middel van die evaluering van korrelasies tussen die sleutel prestasie aanwysers soos vervat in MuSSA vrae. Die korrelasies bring na vore gebiede waar op gefokus moet word om geselekteerde kenmerk areas binne munisipaliteite, wat aandag vereis, te verbeter. Drie areas uit die MuSSA-data is ondersoek in hierdie navorsings projek naamlik; (i) personeel vaardigheidsvlakke en kapasiteit, (ii) nie-inkomste water en (iii) die uitvoering van die beplande waterdienste aktiwiteite. In die MuSSA vraelys is daar vrae wat elk van (i), (ii) en (iii) aanspreek om die munisipaliteit se prestasie op die drie gebiede te monitor. Nie-parametriese statistiek word gebruik om die oorblywendeMuSSA vrae wat se antwoorde met die relevante vrae se antwoorde korreleer vir (i), (ii) en (iii) vas te stel. Kundigheid en oordeel van ingenieurs word gebruik om te bepaal of die vrae wat korreleer met die relevante vrae vir (i), (ii) en (iii) die relevante vraag beïnvloed, beïnvloed word deur die relevante vraag of geen verhouding het met die relevante vraag nie. Hierdie resultate word dan georganiseer met behulp van ’n vloeidiagram en word in detail bespreek deur middel van ’n tweeveranderlike histogram van elke korrelasie. Die ondersoek het aan die lig gebring dat munisipaliteite wat nie genoegsame tegniese bestuurs kapasiteit het nie swak presteer op ten minste een van die vyf vrae van elf van die sestienMuSSA besigheid eienskappe. Die personeel vaardigheidsvlakke van water en afvalwater behandelings werke word sterk beïnvloed deur die tegniese bestuurskapasiteit en -vaardigheid, waterdienste beplanning en die finansiële volhoubaarheid van die organisasie. Munisipaliteite wat opleiding van tegniese bestuur en operasionele personeel uitvoer het ’n hoë persentasie van opgeleide operasionele personeel werksaam by suiweringswerke. Water en afvalwater behandelingswerke se personeelkapasiteit is baie afhanklik van die vlak van vaardigheid en kapasiteit van tegniese bestuur in diens van die munisipaliteit. Munisipaliteite met toepaslike begrotings en befondsing om personeel aan te stel en op te lei het ’n neiging om beter te presteer met kapasiteitsbou van operasionele personeel as die wat aan ’n gebrek ly van befondsing. Die vermindering van nie-inkomste water (NRW) het sterk korrelasies met tegniese bestuur en netwerkherstel personeelvaardighede en ontwikkeling. Munisipaliteite wat personeel met die korrekte vaardighede en ervaring in diens het, gekombineer met bestuur wat dit nastreef om NRW te verminder by wyse van monitering en uitvoering van druk beheer in water netwerke het aansienlik kleiner NRWpersentasies. Ewe noodsaaklik vir die vermindering van NRW, soos geopenbaar deur die ondersoek is die beoefening van interne infrastruktuur batebestuur deur diemunisipaliteit. Daar is tot die gevolgtrekking gekom dat munisipaliteite daarna moet streef om ’n NRW persentasie van 30% of minder te bereik om finansieel stabiel te word, as gevolg van die korrelasie tussen befondsing van roetine bedrywighede en die opbou van kontant reserwe teenoor NRWpersentasies. Munisipaliteitewat die uitvoeringskoers van beplande waterdienste aktiwiteitewil verbeter, word aanbeveel om onder andere, tegniese bestuurs vaardigheids vlakke en kapasiteit aan te spreek. Munisipaliteite wat nie tegniese bestuursvaardigheid en -kapasiteit het nie, berig dat ’n lae persentasie van beplande aktiwiteite uitgevoer word. Die tegniese operasionele personeel vaardigheidsvlakke en kapasiteit, as gevolg van hul betrokkenheid in die uitvoering van beplande aktiwiteite is ook van groot belang. Die betrokkenheid van lede van die raad by water en afvalwater beplanning en die rapportering van data en kwessies aan die raad verhoog baiemunisipaliteite se vermoëns om beplande aktiwiteite uit te voer. Dit kan hoofsaaklik toegeskryf word aan verhoogde befondsing in situasies waar raadslede beplande projekte ondersteun. Dit is gevind dat die gebrek aan befondsing ’n groot inhibeerder van die uitvoering van beplande aktiwiteite is. Alhoewel ’n meerderheid van die munisipaliteite aangedui het dat hulle begrotings effektief spandeer, word dit egter nie weerspieël in die persentasie munisipaliteite wat beplande aktiwiteite uivoer nie en lei dit tot die gevolgtrekking dat daar n gebrek aan befondsing is. Munisipaliteite wat klem lê op ander gebiede van hul besigheid soos, infrastruktuur batebestuur en beplanning was meer effektief met die uitvoering van die beplande aktiwiteite. Daar is tot die gevolgtrekking gekom dat tegniese bestuur en operasionele personeel vaardigheidsvlakke en kapasiteit noodsaaklik is vir ’n munisipaliteit om behoorlik te funksioneer. Daar is ook ’n behoefte aan befondsing by munisipaliteite om beplande aktiwiteite uit te voer en munisipaliteite moet finansieel onafhanklik en lewensvatbaar word. Een manier om te werk te gaan om finansiële self volhoubaarheid te bereik, is die vermindering van NRW persentasies. Die data van hierdie ondersoek toon groot ooreenkomste met die literatuur wat geraadpleeg is oor die huidige stand en funksionering van Suid-Afrikaanse munisipaliteite. Die statistiese analise van die MuSSA data het akkurate korrelasies geopenbaar tussen die sleutel prestasie-aanwysers inmunisipaliteite. Die gevolgtrekking kan gemaak word dat die ondersoek in terme van die korrelasie tussen MuSSA vrae gebruik kan word om munisipale besluitneming te help verbeter.

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