Construction quality is crucial to the long-term pavement performance. Construction factors such as surface preparation, placement, joint construction and compaction/consolidation have an overwhelming effect on pavement performance, which cannot be ignored or compensated for in mix or structural design.
Compaction is the process by which the volume of air in an HMA mixture is reduced by using external forces to reorient the constituent aggregate particles into a more closely spaced arrangement. This reduction of air volume produces a corresponding increase in HMA density (Roberts et al., 1996). Compaction is the greatest determining factor in … Read more
Stabilizers/Reclaimers A stabilizer/reclaimer is a vehicle with a dual purpose. These machines have a large rotor blade which may be used to cut and pulverize damaged or old pavement, but which also may be used to mix lime, fly ash, or cement into the subbase in order to stabilize poor soils. Milling Machines A top … Read more
Mix laydown involves everything used to place the delivered HMA on the desired surface at the desired thickness. The asphalt paver is the principal machine involved in mix laydown and is assisted by the material transfer vehicle (MTV) in some instances. Placement Considerations There are, of course, many considerations to take into account when placing … Read more
Segregation and temperature differentials are construction-related HMA pavement problems that can lead to early pavement failure. Aggregate Segregation Aggregate segregation is the non-uniform distribution of coarse and fine aggregate components within the HMA mixture. There are two basic types of aggregate segregation: Coarse segregation. Occurs when gradation is shifted to include too much coarse aggregate … Read more
Quality has become one of the most important consumer decision factors in the selecting among competing products and services. This is true not only for individual consumers but also for large corporations, government organizations and the taxpaying public as a group. In its broadest sense, quality is a degree of excellence: the extent to which … Read more
Mix transport involves everything required to convey HMA from a production facility to a paving site including truck loading, weighing and ticketing, hauling to the paving site, dumping of the mix into the paver or material transfer vehicle hopper, and truck return to the HMA production facility (Roberts et al., 1996). Ideally, the goal of … Read more
Specifications are used (1) to convey information concerning desired products from a buyer to a seller or potential seller, (2) as a basis for competitive bidding for the delivery of products, and (3) to measure compliance to contracts. Typically, four types of specifications; proprietary product, method, end-result and performance specifications; are generally recognized in the … Read more