An investigation of cement coating for aggregates in bituminous material
This research was designed to investigate the properties of aggregate with a new cement coating applied, and to test the effect of including this aggregate in a bituminous road mixture. The investigation was divided into three main areas of study. They were, chemical and physical testing of the aggregate, and testing of a bituminous road mixture containing the modified aggregate, namely porous asphalt wearing course. Chemical testing involved a regime to show the affinity between coated and uncoated aggregates, and bitumen, in terms of adsorption, and desorption in the presence of water. Physical testing included all the common tests for demonstrating the advantageous properties of an aggregate. These tests included, the shear box test, the polished stone value test, the aggregate crushing value test and tests for surface roughness. Porous asphalt was chosen as a suitable road material for testing the effects of the modified aggregate on a bituminous material, as it is a stone matrix dependant mixture and is currently enjoying increased acceptance Europe wide as a driver friendly, high quality surfacing material. Tests applied included the repeat load axial, and the repeat load indirect tensile tests. In order to undertake large parts of the testing program, much of the equipment was constructed by the researcher at Liverpool John Moores University (LJMU). This included the shear box apparatus and the repeat load axial test apparatus. These were both designed to the relevant British standards and verified as being so. Observations made during the testing programme showed the coated aggregates displayed a useful improvement in their chemical and physical properties over uncoated aggregates in almost all the areas tested. Future recommendations include mass production prototyping so that the coated aggregate mixtures can be placed in road trial sections.
TE Highway engineering. Roads and pavements, TP Chemical technology
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