Abstract
The thesis presents details of tests carried out to assess the correlation between the major mechanical properties of selected bituminous mixes using the Marshall, the unconfined compressive strength, and the triaxial compressive strength tests. The influence of the type of aggregate on the Marshall test parameters has been investigated using five combinations of aggregates with continuous and gap grading for tests at 60°C and 45°C. The role of filler has been examined by preparing limestone aggregate mixes with a wide range of filler contents for test by the normal Marshall procedure. Tests have also been carried out to investigate the effect of density on the unconfined compressive strength of continuously graded gravel aggregate mixes, the tests being carried out at 2 in/min rate of strain and at 60°C. The effect of testing rate of strain and of testing temperature was noted for the three types of aggregate. The Marshall stability test and the unconfined compressive strength test results were obtained using a trace recorder and the continuous results of lead/deformation thus obtained have been analysed in detail. Values of cohesion and angle of internal friction have been determined for two types of aggregate using an "open-system" triaxial compressive strength test at different values of lateral pressure. The tests in this part of the study were limited in number of lateral pressure undertaken at 45°C and 2 in/min rate of strain. The review of previous work covers mix design methods and observations on the three mechanical tests used in the investigations carried out. Reference is also made to some other aspects that affect the value of the tests. The experimental results obtained are discussed in detail and a number of conclusions are drawn regarding the significance of the tests carried out. In particular, the type of aggregate used is shown to have a dominant effect on the properties measured. Recommendations are given for further work with emphasis on the need to correlate laboratory results with practical pavement mixes.