No description available.

M. Tech. Civil Engineering / Climatic data is one of the most important inputs required in any road design. The historical information being currently relied upon for pavement design may soon lose its significance due to the expected global climate change. The broad objective of the study was to determine and simulate future climate change for road sub-grades in the southern African region, with a view to developing new pavement design parameters in order to protect the pavement infrastructure.

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.

M. Tech. Civil Engineering. / Aims to assess the influence of the type of binder on the evolution of the macro texture in asphalt at an early age. The objective are to : 1. To assess the approach and methodology of French asphalt design method. 2. To establish the contributors to the reduction of skid resistance of asphalt. 3. Identify effective methods and develop guidelines for improving the surface drainage of asphalt with the use of tests from the laboratory. Asphaltic materials and factors under investigation include: pervious asphalt, continuously grade asphalt and various asphalt surface characteristics and correlation with the Tri-dim laser.

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

No description available.

The primary objective of this study is to investigate the suitability of utilizing dune sand as a paving construction material in hot desert-like areas of the world, where regions of sand dunes exist. The high availability, low cost, and excellent physical properties of the current surplus of elemental sulfur and the benefits given to asphaltic binders by sulfur raises the possibility of using sulfur in asphalt mixes to produce stable mixtures with locally obtainable dune sand. Characterization of various sulfur-asphalt-dune sand mixtures for highway construction were made. The materials used in this investigation were elemental sulfur, AR-4000 (60-70 pen.) asphalt, and dune sand from Yuma, Arizona. The main variables include (a)proportion of sulfur and asphalt in the binder, (b)amount of binder in the mixture, (c)curing temperature, (d)test temperature, and (e)mixing techniques. The various mixtures were prepared by the one-wet mixing cycle technique. Similar dune sand mixtures with asphalt only were evaluated for comparison purposes. The different mixes were evaluated by the Marshall method, tensile strength tests (double punch), compression tests (standard and immersion), flexural tests (standard), dynamic modulus tests (double punch), and microscopic examinations of sulfur-asphalt binders and sulfur-asphalt-dune sand mixtures (thin sections). Preliminary characterizations of the various mixes were made on the basis of their Marshall stability, flow, density, and air void contents. Other engineering properties such as tensile strength, compressive strength, modulus of rupture, dynamic modulus, and microscopic studies were determined for selected mixes. The results consistently indicated that the sulfur-asphalt-dune sand mixes exhibited superior engineering characteristics and performance as compared to similar mixes without sulfur. The overall conclusion drawn from this study is that the dune sand which is not normally accepted for use as aggregate in asphaltic mixtures, can be used with the utilization of sulfur-asphalt binder systems to produce paving mixtures with compatible or better engineering properties in comparison to conventional asphaltic concretes.

The research presented in this thesis studies the effects of foamed bitumen on the deformational behaviour and performance of pavement materials. The research was conducted in the laboratory and the field, using specific New Zealand materials. The aggregate used is a blend of a coarse aggregate imported from the Auckland region with a crushed dust from the Canterbury region. The bitumen selected for the study is an 80/100 bitumen grade, and the active filler was a Portland Cement, both commonly used for foamed bitumen stabilization in New Zealand. In the laboratory, samples of mixes with different foamed bitumen content were tested under various loading and stress conditions to investigate the effects of foamed bitumen on the deformational behaviour of the mix. The tests performed were: Indirect Tensile Strength (ITS), Indirect Tensile Resilient Modulus (ITM), Repeat Load Triaxial compression (RLT) and Monotonic Load Triaxial compression (MLT). Preliminary ITS and RLT tests conducted on mixes with 1% and 0% cement, at different foamed bitumen contents, indicated that mixes without cement performed poorly compared to the mixes with 1% cement. Therefore, the rest of the laboratory study was on mixes with 1% cement. ITS tests were conducted on 150 mm specimens prepared with 0% 1%, 2%, 3% and 4% bitumen content, with a common 1% cement. Results indicated that foamed bitumen increases the ITS values of the mix, up to an estimated optimum of 2.8% bitumen content. Similar trends were obtained with ITM tests, in which a diametrical load pulse was applied on 150 mm specimens, showing an estimated resilient modulus peak near to 2.8% bitumen content. RLT specimens were prepared at 0%, 2% and 4% bitumen content, at two compaction efforts, creating specimens at low and high bulk density. Permanent deformation RLT tests involved the application of seven stages of 50,000 load cycles each (4 Hz), with increasing deviator stress (from 75 kPa in the first stage, up to 525 kPa in the seventh stage) and at constant confining pressure of 50 kPa. Results of RLT permanent deformation tests indicated that the increase in the foamed bitumen content resulted in an increase in the permanent deformation of the material. MLT tests were conducted on specimens at 0%, 2% and 4% bitumen contents, at two compaction efforts, creating specimens of low and high bulk density, at confining pressures ranging from 50 kPa to 300 kPa, with a deformation rate of 2.1% per minute. Results indicated that the effect of foamed bitumen was a reduction of the peak vertical stress, or a reduction in the peak strength. The peak stresses obtained in MLT tests were plotted in stress diagrams, and the failure was approximated as linear function of the confining stress. The fundamental shear parameters (angle of internal friction and apparent cohesion) were estimated, and results indicated that foamed bitumen has no apparent effect in cohesion but does reduce the angle of internal friction. The reduction of the angle of internal friction explains the general trends observed in the laboratory, that on one hand the compressive strength decreases with increasing bitumen content, but on the other hand, the tensile strength increases up to an optimum. A full-scale experiment was carried out using an accelerated testing of foamed bitumen pavements at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF). In the full-scale experiments, the same materials that were tested in the laboratory (aggregates, bitumen, cement) were used to construct six different pavement sections, each with different contents of bitumen and cement. Three were constructed using foamed bitumen contents of 1.2%, 1.4% and 2.8% respectively, plus a common active filler content of 1.0% cement. Two more pavements were constructed adding cement only (1.0%), and foamed bitumen only (2.2%). In addition, one control section with the untreated unbound material was tested. Strains were collected using a 3D Emu soil strain system installed in each pavement section. The curing time between construction and pavement loading was approximately three months. The pavement response, such as surface deformation (rutting), surface deflections and strains were periodically recorded during the execution of the test. The strains were collected at different depths by using an array of Emu strain gauges. Deflections were recorded using both a Falling Weight Deflectometer (FWD) and CAPTIF Beam deflectometer, which is a modified Benkelmann beam. A total number of approximately 5.6 million equivalent standard axles were applied on the pavement sections. The rutting measured in the sections stabilised with foamed bitumen and cement was the lowest, showing that the addition of foamed bitumen significantly improved the performance of materials with 1% cement. The sections stabilised with cement only, foamed bitumen only, and the control untreated section showed large amounts of rutting and heaving by the end of the test. Deflection measurements showed that the effect of foamed bitumen content is a reduction of pavement deflections, with the lowest deflection measured in the section stabilised with 2.8% bitumen and 1% cement. The elastic pavement strains showed that foamed bitumen reduced the tensile strains in the basecourse but did not have a significant effect on vertical compressive strains. During the construction of pavements, material samples were taken for ITS and RLT testing. Results indicated that the highest ITS was measured in the section with 2.8% foamed bitumen content and 1% cement, and the ITS in the section without cement and foamed bitumen only was about 4-5 times lower than the ITS measured in specimens with cement. RLT specimens without cement performed poorly in comparison with the specimens with 1% cement. The specimens with 1% cement showed higher permanent deformation with increase in the foamed bitumen content, supporting the results from the previous laboratory study. To interpret and relate the results observed in the laboratory and the field, stress path analysis was used, in which the stress ratio of the foamed bitumen layers was calculated at different depths. The analysis showed that foamed bitumen content decreases the maximum stress ratio, hence reducing the proximity to failure and relative damage of the layer. Three-dimensional and two-dimensional finite element modelling of the CAPTIF pavements, were used to further investigate the stress and strain fields induced by the loading and to explain the pavement performance observed in the full-scale experiment.

A practical and reliable alternative or supplement to injury accident data is necessary to diagnose dangerous sites and evaluate remedial measures because available accident data is scarce, is lacking in detail about the events preceding the accident and it takes a long time to accumulate statistically reliable data. The most favoured alternative is the Traffic Conflicts Technique which satisfies most of the requirements of a supplementary measure, but has so far only been successfully validated for rural dual carriageway intersections (Spicer, 1973). To establish the technique it is necessary a) to ensure that the subjective judgements on which it is based are reliable, b) to develop the best methods of recording conflicts, and of training and selecting observers, and then c) to test the validity of the best available technique. The main part of this thesis reports three studies aimed at each one of these issues. In the first study intra observer reliability tested on filmed material varied between rs = 0.30 and 0.91 (0.65 overall for N = 42), but poor observers could be identified. By selecting the best observers an overall reliability figure of up to 0.88 could be obtained. Reliable observers remained reliable or even improved slightly on the second testing. These reliable observers also showed good agreement with expert judges who had viewed the film many times, and by selection a correlation with the criterion value of up to 0.83 could be obtained. In the second study a new recording method was developed, incorporating factors that experienced observers used to differentiate the grades of severity currently in use. This helped observers by defining the criteria for detection and grading of a conflict more objectively. This increased the overall intra observer reliability from 0.73 to 0.80, and agreement with the criterion values from 0.66 to 0.76. Transfer from laboratory to field led to a drop in the numbers of conflicts reported. From these studies and a survey of the requirements of local authority accident investigation units, a manual and training package was developed giving guidance on training and selecting observers for the purpose of obtaining reliable conflict data, such as that required for validating the technique. In the third study this package was validated in a study of a sample of eight urban T-junctions. Again the best observers were selected and found to have an overall reliability of 0.88. It was found that, when rear end conflicts were excluded (on the grounds that they led to so few reported injury accidents while occurring in large numbers), there was a high correlation between accidents per vehicle and conflicts per vehicle (rs = 0.79, p<0.025), accounting for 62% of the variance. This compares very favourably with the maximum possible percentage (77%) which could be expected given the relaibility (rs = 0.88) of the observers. Although a validity correlation of 0.79 is very satisfactory and the method of obtaining the data is reasonably economical, an attempt was made to find a still more economical alternative to accident statistics. The most obvious of these are subjective judgements or a combination of these with traffic flow. Traffic flow data for different manoeuvres at each of the eight T-junction sites were obtained and various groups of people were asked to judge the subjective risk of these sites from scale maps and photographs or directly on-site. Judgements from maps and photographs tended to be negatively correlated with accidents. The best subjective estimate (driving instructors judging on-site) correlated 0.44. An attempt to improve on these by combining the traffic flows and judged risk of the different manoeuvres at each site failed to produce a higher correlation. None of these correlations were significant, but the failure of any one of several different corrrelations to be higher than 0.46 suggests very strongly that these simpler methods are very unlikely to have the validity of the full conflicts technique. However, the present study has validated the Traffic Conflicts Technique only for urban T-junctions (the commonest of all accident sites). It could, therefore, only be used for evaluating the effects of small changes in the layout of such junctions. It could be used to evaluate more radical changes eg. T-junction converted to a mini roundabout, provided the conflict to accident ratios of the different layouts were known. In this study the conflict to accident ratio was 125:1 for vehicles turning right out of the minor road. For the T-junctions as a whole it was 275:1 while Older and Spicer(1976) found a ratio of 2000:1 for rural dual carriageway intersections. By obtaining more information of this kind, the utility of the Traffic Conflicts Technique could be greatly extended.

The present thesis analyzes the Byzantine mosaic pavements of Phoenicia and Northern Palcatine from a socio-economic perspective, primarily by examining the laying of pavements including technical aspects and bedding, the quality of decoration, the distribution of pavements in time and space, as well as inscriptions which provide names of donors and artists as well as dates. The approach adopted represents a novel alternative and complement to typical interpretations of mosaic floor decoration which overwhelmingly focus on the development and diffusion of style, or provide an exegesis of figurative iconography. Key aspects discussed include the extent to which chronological patterns of mosaic floor laying may be used to gauge economic conditions; the factors which determined the quality and distribution of technique and decoration in different building types; as well as the social mechanisms of patronage. Close scrutiny of the regional mosaic Corpus (which includes the total number of pavements) suggests that mosaic pavements provide a reasonable indication of economic conditions, especially in association with other media (coins, pottery, inscriptions). Together these media paint a historical picture of the economy of the period. Having graded according to four Levels of Complexity all the geometric designs in the Corpus after their codification following the rules devised by the Association Internationale pour l'Etude de la Mosaïque Antique (AIEMA), and with the support of the written ancient sources, it is demonstrated that quality and distribution of technique and style were governed by a combination of factors, notably function, financial expenditure, social use and various socio-economic categories of patrons, liturgy and liturgical level of participation. By building on the methodologies followed and the conclusions reached by other mosaic scholars, this innovative approach has attempted to reintroduce the human element into a discipline focused since the late 1960s on codification and descriptive precision. Revealing the hidden costs underlying the laying of mosaic pavements has presented a new insight into mosaic pavements as tri-dimensional products of team work. Likewise, stripping the literary language of dedicatory formulas down to essential information has challenged the misinterpreting of epigraphic evidence regarding donations and donors. In-depth analysis of Christian mosaic inscriptions has strengthened the pattern of changes plotted by historians of the Early Byzantine period and suggested that Christian patronage of mosaic art is to be equated with the local initiatives of the Church, ecclesiatics and wealthy laymen (or women) as private donors, and more rarely entire village communities. By contrast, scrutiny of the Jewish and Samaritan mosaic inscriptions has highlighted the fact that benefaction emanated from rich and poor alike, and was far more family and community oriented.