DISTRESS BEHAVIOR OF FLEXIBLE PAVEMENTS THAT CONTAIN STABILIZED BASE COURSES

The distress behavior of full-scale experimental pavements is analyzed and discussed. The pavements contained five different base-course materials, namely, bituminous concrete, aggregate cement, aggregate-lime-pozzolan, aggregate bituminous, and crushed stone. Three types of aggregate--limestone, slag, and gravel--were used in the aggregate-cement base. Distress behavior discussed includes rutting, surface roughness, and cracking. Distress behavior observed is related to pavement response, which was analyzed by using the BISAR computer program. The critical responses analyzed are maximum tensile strain at the bottom of the base course and maximum compressive strain at the top of the subgrade. Various equations relating distress and response are established that permit prediction of the amount of rutting, roughness, and cracking, and allowable subgrade compressive strains to limit different distress modes within specified levels are also established. Field distress data are also related to the present-serviceability-index (PSI) values of each test pavement. From these relationships, various levels of each mode of distress manifestation are established for each level of PSI drop. Results obtained from this study may be useful in selecting allowable distress levels and allowable subgrade compressive strain for pavement design and can also be helpful in developing the relationship between distress and performance. (Author)