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Project Level Approach to Pavement Management
The project-level approach to pavement management uses a bottom-up methodology to combine methods, procedures, data, software, policies and decisions to produce network solutions. In essence, a project-level approach first uses individual section data (e.g., traffic, ESALs, safety, inventory, pavement condition) to determine the optimum section MR&R strategies and priority projects, and then, high-level network decisions … Read more
Marshall Mix Design
The basic concepts of the Marshall mix design method were originally developed by Bruce Marshall of the Mississippi Highway Department around 1939 and then refined by the U.S. Army. Currently, the Marshall method is used in some capacity by about 38 states. The Marshall method seeks to select the asphalt binder content at a desired … Read more
Pavement Response
How a pavement responds to applied stresses is the combined result of loading, environment, subgrade and pavement material characteristics. This section presents the typical stresses and deformations experienced by an HMA pavement structure under load. Stress The stresses that occur in a HMA pavement under load are quite complex; routine calculation of these stresses is … Read more
Recycled HMA
HMA is one of the most recycled products in the U.S. As much as 100 million tons of HMA are milled off roads during resurfacing and widening projects each year. Of this amount, 80 million tons (80 percent) are recycled as “reclaimed asphalt pavement” (RAP) (APA, 2001[1]). Additionally, in-place recycling techniques can also be used … Read more
Pavement Management
“Pavement management” refers to a systematic process of maintaining, upgrading and operating a network of pavements and involves three major components: the pavement life cycle, the costs associated with this life cycle and pavement management systems. Pavement Life Cycle All pavement will deteriorate over time. The pavement life cycle includes how pavements are built, how … Read more
Superpave Method
Like the Hveem and Marshall methods, the Superpave method has been proven to produce quality HMA from which long-lasting pavements can be constructed. This section briefly discusses the Superpave mix design method. The Superpave mix design method consists of three basic steps: Aggregate selection. Aggregate is specified in three ways. First, restrictions on aggregate gradation … Read more
Marshall Method
Most private laboratories use the Marshall method because it is a proven method and requires relatively light, portable and inexpensive equipment. Like the Hveem and Superpave methods, the Marshall method has been proven to produce quality HMA from which long-lasting pavements can be constructed. This section briefly discusses the Marshall mix design method. The basic … Read more
Rehabilitation
The combined effects of traffic loading and the environment will cause every pavement, no matter how well-designed/constructed to deteriorate over time. Maintenance and rehabilitation are what we use to slow down or reset this deterioration process. Maintenance actions help slow the rate of deterioration by identifying and addressing specific pavement deficiencies that contribute to overall … Read more
Drainage
Proper drainage is important to ensure a high quality long lived pavement; moisture accumulation in any pavement structural layer can cause problems. Moisture in the subgrade and aggregate base layer can weaken these materials by increasing pore pressure and reducing the materials’ resistance to shear. Additionally, some soils expand when moist, causing differential heaving (the … Read more
Segregation & Temperature Differentials
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
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