Effect of Asphalt Mixture Surface Preparation Methodology on Determining Luminance Level in Laboratory Conditions:...

This paper verifies a method for determining the luminance of a pavement surface made of SMA mixtures at the design stage under laboratory conditions. Tests were conducted on surfaces made of six types of SMA mixtures with varying grain sizes (between 8 and 11 mm) and coarse aggregate types like trachybasalt with a luminance coefficient in diffused light of Q_d-53 mcd/m²/lx, gabbro with Q_d-83 mcd/m²/lx, and granite with Q_d-115 mcd/m²/lx. The effect of the glassblasting process on the changes in the luminance coefficient in diffused light (Q_d) was analyzed while simultaneously monitoring parameters describing skid resistance and macrotexture. Additionally, it was decided that tests would be performed on two sets of specimens differing in their conditioning temperatures. It was found that conditioning at -15 °C significantly improved the binder film removal process from asphalt mixture surfaces compared to those conditioned at 22 °C. Differences were recorded between individual specimens conditioned at -15 °C at the end of the glassblasting. The lowest Q_d values were found for specimens with the darkest trachybasalt aggregate (SMA 8-53.0; SMA 11-51.7 mcd/m²/lx) and the highest for specimens with the lightest granite aggregate (SMA 8-63.9; SMA 11-59.8 mcd/m²/lx). However, considering the differences in Q_d between individual coarse aggregates, the differences between specimens with these aggregates are insignificant. Glassblasting is a cheap and quick procedure for removing a binder from the surface of specimens, preparing them for luminance determination in the laboratory. It should be noted that glassblasted surfaces should not be used to determine the skid resistance and macrotexture changes at the design stage of an asphalt mixture.