Asphalt binder adsorption by aggregates: a microscopic study

Asphalt adsorption by aggregates is an important parameter in hot mix asphalt mix design. In the present study, a comparison is made between asphalt binder adsorption obtained from volumetric calculations with that of from microscopic observations. Four different types of aggregates (of sieve size 50–80 mm) are used in the study. Volumetric measurements are carried out on individual aggregates to calculate the percentage of adsorbed asphalt binder. On the other hand, the depth of asphalt binder penetration (obtained from microscopic observation) is used to quantify the amount of adsorbed asphalt binder. From the results, it appears that microscopic studies consistently over-estimate the percentage of asphalt binder adsorbed. Scanning electron microscope with energy dispersive X-ray spectroscopy is used to further investigate some possible reasons for such a discrepancy.