THE EFFECT OF AGGREGATE PARTICLE SHAPE ON THE WEAR RESISTANCE OF STONE MASTIC ASPHALT - A STUDY WITH FIELD TEST SLABS. FINAL REPORT1

The aim of this research was to determine the effect of particle shape on the wear resistance of stone mastic asphalt (SMA) by using test slab method. Four different kinds of mineral aggre-gates were sieved with bar sieves to produce 8 - 18 mm (two aggregates) or 8 - 20 mm (two aggregates) material of three particle shapes: good, normal and poor. Nordic abrasion values (studded tyre test) and fiakiness values of these aggregates were measured. The binder contents of different asphalt mixtures were determined based on the measurements of gyrator compactor. The difference between binder contents of aggregate mixtures with good and poor shape varied among 0,7 - 1,1 % units. 28 test slabs (50 x 70 cm) of asphalt concrete were rolled in the laboratory. Test slabs were placed in the road on main road 1 on the border of Espoo and Hel-sinki. Before placing test slabs four 50 cm wide and 7 cm deep grooves were milled in the right-hand wheel rut. Test slabs were placed on a special paste and rolled in the same level as the surrounding wearing course.