M. Tech. Engineering: Civil. / Discusses the objective of this study was to develop an equation to determine the penetrometer penetration rate (DN) of a pavement consisting of Bitumen Stabilised Material layers are constructed. The aim is to use laboratory results of Bitumen Stabilised Material and study the relations between the Indirect Tensile Strength and the Unconfined Compressive Strength. With the relations a penetrometer penetration rate (DN value in millimetre per blow) can be determined. This will enable the designer to apply the strength-balance concept on a pavement consisting of Bitumen Stabilised Materials. As indicated previously it was found during the design stages that only the Indirect Tensile Strength data on the Bitumen Stabilised Material was available. Developing an equation to convert the Indirect Tensile Strength data to a DN value will allow the designer to apply the strength-balance concept and adjust the design for improved performance life of a pavement.

Prime coats have been in use for many decades to help protect the base before the subsequent application of bituminous surface treatments. Prime coat is an application of a low viscosity binder onto the base to help protect the base from moisture, to provide an adequate bond between the bituminous surface coating and the base, to strengthen the base near the surface by binding the fines, and to protect the base from detrimental effects of weather and light traffic until the surface can be constructed. For a prime coat to function efficiently it should penetrate sufficiently into the base and should be cured before the application of subsequent layers. Evaluation of the time required for curing of prime coats and how the curing time depends on various weather parameters has received a lack of attention. In view of this, the time taken for curing of different prime coats and the dependence of curing time on weather parameters was studied. The prime coats most commonly used in Texas were selected for this study, namely; MC-30, EC-30, CSS-1H, SS-1H and AEP. All testing was done in real conditions, that is, samples were prepared and exposed to actual weather conditions. Since each prime coat is chemically very different, they were analyzed separately to determine the minimum curing time. Curing time was calculated in three different weather conditions to understand how the weather affects curing time. Further, two different application methods were used to determine the effect of application method on the curing time. In addition to determining curing times, other important engineering properties of prime coats that determine the performance of prime coats such as strength, permeability and penetration were also studied. Strength and permeability tests were done on cured specimens and the effect of application method on these values was also determined. Strength values were measured using a pocket penetrometer and penetration was determined by using sand penetration tests. A unique ranking system list was developed using curing time, strength, penetration and permeability as the key factors to determine the prime coat which would serve all the intended functions effectively and efficiently. / text

Unresolved Complex Mixtures (UCMs) of hydrocarbons are found in crude and refined oils and in water, sediments and biota polluted with oils. The concentrations of UCMs in oils are significant (e.g. >65% of the aliphatic hydrocarbons in fresh Kuwait crude) and it is perhaps surprising that virtually nothing is known about UCM composition. The present study sought to redress this paucity of information in three main ways: First, following two recent studies of aliphatic UCMs, an investigation of the composition of the "aromatic" UCM of Venezuelan Tia Juana Pesado crude oil was made by spectroscopic (IR, NMR, MS) and oxidative (CrO3, Ru04) methods. These showed that the UCM was, in fact, highly aliphatic. The major compounds identified were alkyl substituted naphthenoaromatics with one and two aromatic rings. Chemical oxidation indicated that the alkyl branched side chains extended to at least twenty three carbon atoms. Second, an investigation into the origins of UCMs was made. The products of hydrous pyrolysis of man-made (polythene) and biogenic (cutan) polymers under conditions proposed previously to simulate catagenesis, included, in the hydrocarbons, high proportions of UCMs (50% - >70%). Hydrous pyrolysis of polythene produced a mixture of saturated (56%) and olefinic (44%) hydrocarbons, whilst pyrolysis of cutan produced hydrocarbon (aliphatic and aromatic; 30-75%) and nonhydrocarbon (70-25%) fractions, both with >60% unresolved components. Oxidative characterisation of these UCMs produced mainly n-acids with somewhat similar results to those found when oil UCMs were oxidised. However, the laboratory generated UCMs are not perfect oil UCM models since some oil UCM oxidation products were not observed in the laboratory models. Finally, an attempt was made to release the geochemical information contained within UCMs. Replicate oxidations of milligram quantities of oil UCMs followed by quantitative GCMS characterisation and multivariate statistical analysis of the resolved oxidation products gave reproducible distributions with >80% similarity. Application of this method to two oil spill incidents where the source oil was known (Milford Haven and the Humber Estuary) gave good correlations between sediment and source. In contrast analysis of Mersey Estuary sediments contaminated with heavy asphaltic oil and of Sullom Voe sediments contaminated with UCMs failed to show any correlation between the sediments and the source oils. However, subsequent re-analysis of the data excluding the major UCM oxidation products (n-carboxylic acids) produced better correlations which indicated that the greatest correlation potential for these UCMs was contained within the minor oxidation products. A similar study of UCMs from two oil seeps from the Siljan Ring region of Sweden failed to show any correlation with potential source rocks, in agreement with biomarker data. This study has extended present knowledge of UCM composition and suggested a mechanism for UCM formation. Furthermore, quantitative and statistical analysis of UCM oxidation products has been shown to be useful for oil identification. There is still much to be learned about UCMs and the subject should provide a fruitful area for further research. Some possible approaches are suggested. Parts of this work have been published (Revill et al. 1991), Organic Geochemistry: Advances and Applications in Energy and the Natural Environment, Manchester University Press

Thesis (M.Eng.(Civil and Biosystems Engineering))--University of Pretoria, 1985. / Summaries in Afrikaans and English. Includes bibliographical references.

The purpose of this investigation was to study the factors affecting the low-temperature carbonization of seam number one, Penn-Lee coal from southwestern Virginia, by determining the effect of pretreatment of the charge, temperature of the retorting gas, and time of retorting on the yields and properties of the products of carbonization. After an examination of the literature pertinent to the investigation, a pilot-scale carbonization unit was constructed. The construction of the unit consisted partly of the modification of an existing fluidization unit. Various auxiliary apparatus were also added to the modified unit for more satisfactory operation. A series of bench-scale tests were performed to study the effect of pretreatment conditions on the free-swelling index, the weight loss, and the volatile matter in Penn-Lee coal. Time and temperature had a significant effect upon the free-swelling index. Temperature of pretreatment had a significant effect on the weight loss during pretreatment. Time and the time by temperature effect were found to be significant with regard to the volatile matter remaining in the coal after pretreatment. Also, the decomposition point of Penn-Lee coal was found to lie between 427 and 454 °C (800 and 850 °F). Twelve pilot-scale tests were performed to study the effect of carbonizing conditions on the products of carbonization. The pretreatment time had a significant effect upon the dry tar yield, the tar viscosity, the tar specific gravity, and the twenty per cent tar distillation temperature. The time of carbonization had a significant effect upon the gas yield. None of the variables studied showed a significant effect within the range studied, upon the volatile matter in the char product, the bulk density of the char, or the calorific value of the char. / Ph. D.

The surface properties of coal greatly affect its use in industrial processes such as gasification, liquefaction and the use of coal slurries. In addition, such processes also involve reagent penetration into coal pores and the oxidative state of the coal surface. Reagent penetration into coal was examined by determining the heat and kinetics of immersion of Pocahontas No. 3 coal in water, methanol, a series of n-alkanes, and several cyclic and heterocyclic hydrocarbons. Results indicate that the heat of immersion is sensitive to the carbon chain length of the wetting liquid and its ability to hydrogen bond to coal. The time of immersion is insensitive to carbon chain length but is increased by the presence of nitrogen in a cyclic hydrocarbon. The oxidation of both unextracted and extracted coal at 3200C was followed by immersional measurements in water. The heat of immersion increased rapidly with oxidation time, leveling off after 3 hours of oxidation. Extraction with methanol or pyridine prior to oxidation and immersion lowered the time of immersion in water compared to the unextracted case. The oxidation of coal was also followed by x-ray photoelectron spectroscopy (XPS). The XPS oxygen/carbon ratios correlated linearly with the heats of immersion for the extracted, oxidized coals. Thus, XPS was shown to be a useful ancillary technique to heat of immersion for the study of coal surfaces. / Master of Science

Thesis (MEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: Two common methods of road pavement, granular material stabilisation used in road construction throughout South Africa today include Cold in Place Recycling (CIPR) and stabilisation with cement or bitumen and an active filler to create Bitumen Stabilised Materials (BSM). As part of the updating of the South African Pavement Design Method (SAPDM) an experimental section, investigating the structural capacity of cement and lime stabilised and BSM pavement layers, was constructed and will be monitored over a two year period. As part of this study Falling Weight Deflectometer (FWD) measurements were taken on the various experimental stabilised pavement layers constructed. The FWD deflection data, measured at various time intervals over a 360 day period, forms the basis of the study presented here. The objective of this thesis was to identify typical back-calculated layer stiffnesses and their variability over time for the various in-situ recycled and stabilised base layers constructed within the experimental section. Stabiliser type, content and layer thicknesses were varied across experimental sub-sections. Trends in back-calculated stiffness of cement stabilised base layers consistently showed significant reductions in layer stiffness subsequent to construction traffic loading. Subsequent to the initial reduction in stiffness little change in stiffness was noted under normal traffic loads. Observations on the trends in back-calculated stabilised layer stiffness per material type over time indicated that seasonal moisture and temperature fluctuations have an effect on the stiffness of the pavement structure as a whole. BSM materials showed significant variability over time in-line with seasonal variability in the supporting subgrade stiffness in the southbound lane. BSM materials with 1% cement added in the northbound lane show initial stiffness reductions due to direct rainfall application however a significant increase in layer stiffness occurs up to 360 days after construction. BSMs with 2% cement in the northbound lane show significant increases in layer stiffness over the 360 day observation period. No significant difference in stiffness trend was observed between BSM emulsion a BSM foam materials. The BSM emulsion with 0.9% residual bitumen and 1% cement was observed to show rapid reduction in stiffness upon opening to traffic and reverting to stiffness values similar to an unbound material of approximately 350 MPa. Cement and lime stabilised materials showed typical post 28 –day average stiffnesses per sub-section ranging between 600 MPa and 1800 MPa. BSM foam with 1% cement added were observed to have average stiffnesses per sub-section in the range of 400MPa to 2200 MPa and BSM emulsion with 1% cement with stiffnesses between 400 MPa to 1700 MPa over the 360 day period. BSMs with 2% cement added showed stiffness ranges between 900 MPa to 4300 MPa for BSM foam and 900 MPa to 3900 MPa for BSM emulsions over the 360 day period. The spatial variability of back-calculated stiffness per sub-section of a particular stabilisation design was significant and was observed, through the Co-efficient of Variation (COV), to increase over time. The effect of the observed variability when incorporated into a pavement design scenario, requiring a design reliability of 90%, showed 50% of the pavement structure would be overdesigned by a factor of 4. With respect to the current philosophies on the development of stiffness over time of cement and lime stabilised and BSM pavement layers some useful observations were made. Cement stabilised materials correlate well with stiffness development theories predicted by previous studies. Theories relating to the stiffness development of BSMs however did not predict the levels of variability in base layer stiffness observed on the experimental section. The continued observation of the experimental section for another year will give greater insight to the stiffness trends of the stabilised materials discussed above.

With the introduction of high-speed trains over the past few years, as well as withan increase in traffic loads and volumes, the attractiveness and competitiveness ofthe railway transport system have increased. This leads to the need to develop newcost-effective ways in railway construction, providing an increase in the life cycle ofthe railway track and reducing the need for maintenance.In several European countries, Japan, and the USA, asphalt mixtures, also called“bituminous mixtures”, are used as such an alternative solution in both traditionalballasted and ballastless railway designs. International experience has shown thatbituminous mixtures have good technical characteristics and can meet many of therequirements of modern railway construction, especially when it comes to the useof asphalt materials in ballasted tracks. However, there is a lack of knowledge andexperience in using bituminous mixtures in railway construction in the northernregions and harsh winter conditions.In this thesis, the development of two- and three-dimensional models of ballastedrailway track with an asphalt sub-ballast layer is presented. The analysis of thestatic and dynamic characteristics of the whole model and the asphalt layer exposedto different temperatures is carried out using the finite element method (FEM) inthe COMSOL software. Simulation for all conditions is carried out with a trainspeed of 200 km/h. The relationship between various temperatures from 􀀀30 °Cto +30 °C and the stress-strain behaviour of the asphalt sub-ballast layer is alsodetermined. The results of the study show that both under the influence of lowand high temperatures, the stresses and strains in the asphalt layer are quite small.Besides, the use of asphalt sub-ballast in the track structure reduces deformationsand stresses acting on the subgrade surface.

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

The subject of this diploma thesis is a research of bituminous binder modification by fast react-ing polymer SBS. The theoretical part covers an introduction to bituminous binders, their pro-duction, chemical and physical-mechanical properties. The identification of bituminous binders and their use in bituminous mixtures is briefly described. To conclude, current modification methods are described in detail and important modifiers are introduced. In the practical part, three applied tests (softening point, elastic recovery and penetration) are described in detail. The bituminous binders tested (20/30, 30/45, 70/100, PMB 25/55-55 and PMB 45/80-50) and the fast-reacting polymer SBS are introduced. Samples with two weight percentages of SBS, 7,5% and 10%, are produced. Two mixing times, 60 seconds and 600 seconds were used to mix the bituminous binder and SBS. In conclusion, the results are evaluated and commented. Further research suggestions regarding this field are recommended.