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No abstract available. / Thesis (Ph.D.)--University of Natal, Durban, 1984.

Call number: LD2668 .T4 1950 Z54 / Master of Science

M. Tech. Civil Engineering. / The purpose of this study is to evaluate the effect of an increase in stone size and volume on asphalt. This will be limited to asphalt surfacing with a viewpoint to the coal haulage industry.

Warm mix asphalt (WMA) is an environmental friendly technology that contributes to the workers safety, reduction of energy consumption and emissions. In this study, the rheological properties of a PG 64-22 asphalt binder blended with Cecabase RT, Rediset, Evotherm, and Sasobit WMA additives are investigated as a function of laboratory aging. Binders modified with WMA additives and the control samples were both aged in the rolling thin film oven (RTFO) at 143°C and at 163°C, respectively. All samples were then long-term aged in an environmental chamber kept at 60°C. The longterm aged samples were collected at different intervals during a six-month period. Rheological data were collected on each aged sample by performing dynamic shear rheometer (DSR) frequency sweep from 25 to 0.1 Hz. at three different temperatures, i.e. 45°C, 60°C, and 76°C. Samples were also evaluated with the Bending Beam Rheometer (BBR) and Fourier-Transform Infrared (FTIR) Spectroscopy. Gauss-Newton method was vii used for non-linear parameter estimation for modeling the relationship of complex modulus (G*) with temperature, frequency, and aging. Regression analysis was also used for modeling BBR creep stiffness and BBR m-value. Although FTIR results show higher oxidation levels for control than all WMA samples, DSR and BBR results show that Sasobit tends to behave closely to control while Cecabase, Evotherm, and Rediset exhibit lower stiffness than both. / text

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M. Tech. Civil Engineering / Asphalt mixes are commonly used for paving roads around the world. They consist of mainly bitumen and aggregate materials, which may differ depending on the type of asphalt mix. The shape properties of aggregate particles relevant for the performance of asphalt mixes include the form, angularity and surface texture. There are concerns about the standard test methods used to quantify the shape properties (i.e. angularity, surface roughness, flatness, elongation and sphericity) of aggregates used for road pavement design and construction. These test methods have been reported as time and labour intensive, and have several limitations including human error, lack of accuracy, and repeatability of test results. Although results obtained from these tests have been linked to performance, however these links are questionable. Recently, various researchers and practitioners have indicated that advanced and automated approaches such as imaging and laser scanning techniques would better quantify the shape and surface properties of aggregates. For instance, researchers at the Council for Scientific and Industrial Research (CSIR) found that a portable three-dimensional (3-D) laser scanning system can be used to accurately quantify the shape properties of aggregate particles that are relevant to the performance of asphalt mixes. The overall objective of this study was to use a 3-D laser scanning technique to quantify the shape properties of aggregate materials and relate them to performance of laboratory compacted asphalt mixes.