Research associate, N.W., Calgary, Alta
Professor, The University of Calgary, N.W., Calgary, Alta.
Three types of aggregates obtained by partial crushing of pebbles of different lithology and erosional history were investigated quantitatively with the modified Fourier technique. All the crushed particles were rougher, that is, more elongated and textured than the natural pebbles from which they were obtained. Surface texture increases more rapidly than the elongation. However, roughness, shape, and surface texture of the aggregates depend on the lithology of the raw material. There was also a difference in trend between changes of roughness within natural and crushed particles of different types when the size of the pebbles investigated decreased. Provided the number of profiles is representative, the modified Fourier method yields precise numerical values. These data could lead to improved control of the roughness, shape, and texture characteristics that have an important effect on the properties of aggregates in concrete. Studies with the scanning electron microscope showed conchoidal fractures on the surfaces of quartzite particles and finer textural features on limestone surfaces. These detailed features add to the surficial macrotexture of profiles investigated by the Fourier method.
Paper ID: CCA10182J