The mechanical properties of asphalt-mineral filler mastics have long been known to significantly influence the overall performance of paving mixtures. However, reinforcement mechanisms associated with the presence of fillers in asphalt mastics are not well understood. Particulate composite micromechanical models are shown to be a powerful tool for separating various reinforcing mechanisms in asphalt mastics, including volume filling, physiochemical, and particle-interaction reinforcement. The generalized self-consistent scheme model is shown to predict very reasonable baseline reinforcement levels for asphalt mastics, and simplified prediction tools are presented as an alternative to the cumbersome micromechanical solution. An experimental program was conducted to evaluate micromechanical predictions of mastic properties over a broad range of temperatures and filler concentrations. A new equivalent rigid layer modeling technique was developed, which suggests that stiffening effects observed in mastics beyond those due to volume filling may be largely explained by an effective increase in volume concentration of rigid inclusions due to a rigidly adsorbed asphalt layer just 0.02 to 0.10 µm thick. Particle-interaction reinforcement appears to play a smaller role, possibly as a result of the interaction of partially altered asphalt layers, and was observed to be significant only at very high filler contents. More work is needed to better understand the nature of physiochemical reinforcing and to study other possible stiffening mechanisms in mastics such as agglomeration, state of dispersion, and particle-size distribution.The asphalt mastic, or the combination of the asphalt binder (cement) and mineral filler in an asphalt paving mixture, has long been known to influence the overall performance of asphalt paving mixtures (1,2). The behavior of the asphalt mastic influences nearly every aspect of asphalt mixture design, construction, and performance. In the design of asphaltic paving mixtures, the mastic influences the lubrication of the larger aggregate particles and thus affects voids in the mineral aggregate, compaction characteristics, and optimum asphalt content. During construction of hot-mix asphalt (HMA) pavements, the mastic must have enough stiffness to prevent drain-down, or the downward migration of the mastic mainly due to gravitational forces during storage and handling. This is particularly important in open-or gapgraded mixtures, such as stone mastic asphalt (SMA) mixtures. Finally, the stiffness of the mastic in the field affects the ability of the mixture to resist permanent deformation at higher temperatures, influences stress development and fatigue resistance at intermediate temperatures, and influences stress development and fracture resistance at low temperatures.Although considerable work has been conducted to measure and even predict empirical and fundamental properties of asphalt mastics, very little work has been reported in which rigorous mechanicsbased models have been used to study the c...

The Illinois Department of Transportation (IDOT) spends $2 million annually on reflective crack control treatments; however, the costeffectiveness of these treatments had not been reliably determined. A recent study evaluated the cost-effectiveness of IDOT reflective crack control System A, which consists of a nonwoven polypropylene paving fabric, placed either in strips longitudinally over lane-widening joints or over the entire pavement (area treatment). The study was limited to projects constructed originally as rigid pavements and subsequently rehabilitated with one or more bituminous overlays. Performance of 52 projects across Illinois was assessed through crack mapping and from distress and serviceability data in IDOT's condition rating survey database. Comparisons of measured reflective cracking in treated and control sections revealed that System A retarded longitudinal reflective widening crack development, but it did not significantly retard transverse reflective cracking, which agrees with earlier studies. However, both strip and area applications of these fabric treatments appeared to improve overall pavement serviceability, and they were estimated to increase rehabilitation life spans by 1.1 and 3.6 years, respectively. Reduction in life-cycle costs was estimated to be 4.4 and 6.2 percent when placed in medium and large quantities, respectively, and to be at a break-even level for small quantities. However, life-cycle benefits were found to be statistically insignificant. Limited permeability testing of field cores taken on severely distressed transverse joints suggested that waterproofing benefits could exist even after crack reflection. This was consistent with the observation that, although serviceability was generally improved with area treatment, crack reflection was not retarded relative to untreated areas.

The purpose of this paper is to compare the value of predicting capacity using dynamic formulas, wave equation analysis, and dynamic monitoring without load tests. A database of pile load test results is used to quantify the precision associated with predictive methods. These methods are quantified and ranked using a “wasted capacity index” (WCI) to quantify the effect of precision. The WCI is a measure of how inefficiently a method predicts capacity. A precise method will be very efficient and accordingly have a low WCI. On the other hand, a less precise method requires a more conservative design and thus a greater WCI. The value of the wasted capacity index is calculated from the precision of the method and the reliability required for the pile foundation. The WCI is presented for the following methods: Engineering News (EN) formula, Gates formula, wave equation analysis program (WEAP), measured energy (ME) approach, pile driving analyzer (PDA), and CASE Pile Wave Analysis Program (CAPWAP).

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