Warm Mix Asphalt (WMA) is a new technology that was introduced in Europe in 1995. WMA offers several advantages over conventional asphalt concrete mixtures, including: reduced energy consumption, reduced emissions, improved or more uniform binder coating of aggregate which should reduce mix surface aging, and extended construction season in temperate climates. Three WMA techniques, Aspha-min, Sasobit, and Evotherm, were used to reduce the viscosity of the asphalt binder at certain temperatures and to dry and fully coat the aggregates at a lower production temperature than conventional hot mix asphalt. The reduction in mixing and compaction temperatures of asphalt mixtures leads to a reduction in both fuel consumption and emissions. This research project had two major components, the outdoor field study on SR541 in Guernsey County and the indoor study in the Accelerated Pavement Load Facility (APLF). Each study included the application of four types of asphalt surface layer, including standard hot mix asphalt as a control and three warm mixes: Evotherm, Aspha-min, and Sasobit. The outdoor study began with testing of the preexisting pavement and subgrade, the results of which indicated that while the pavement and subgrade were not uniform, there were no significant problems or variations that would be expected to lead to differences in performance of the planned test sections. During construction, the outdoor study included collection of emissions samples at the plant and on the construction site as well as thermal readings from the site. Afterwards, the outdoor study included the periodic collection and laboratory analysis of core samples and visual inspections of the road. Roughness (IRI) measurements were made shortly after construction and after a year of service. The indoor study involved the construction of four lanes of perpetual pavement, each topped with one of the test mixes. The lanes were further divided into northern and southern halves, with the northern halves having a full 16 in (40 cm) perpetual pavement, and with the southern halves with thicknesses decreasing in one in (2.5 cm) increments by reducing the intermediate layer. The dense graded aggregate base was increased to compensate for the change in pavement thickness. The southern half of each lane was instrumented to measure temperature, subgrade pressure, deflection relative to top of subgrade and to a point 5 ft (1.5 m) down, and longitudinal and transverse strains at the base of the fatigue resistance layer (FRL). The APLF had the temperature set to 40°F (4.4°C), 70°F (21.1°C), and 104°F (40°C), in that order. At each temperature, rolling wheel loads of 6000 lb (26.7 kN), 9000 lb (40 kN), and 12,000 lb (53.4 kN) were applied at lateral shifts of 3 in (76 mm), 1 in (25 mm), -4 in ( -102 mm), and -9 in ( - 229 mm) and the response measured. Then each plane was subjected to 10,000 passes of the rolling wheel load of 9000 lb (40 kN) at about 5 mph (8 km/h). Profiles were measured after 100, 300, 1000, 3000, and 10,000 passes with a profilometer to assess consolidation of each surface. After the 10,000 passes of the rolling wheel load were completed, a second set of measurements was made under rolling wheel loads of 6000 lb (26.7 kN), 9000 lb (40 kN), and 12,000 lb (53.4 kN) at the same lateral shifts as before. Additionally, the response of the pavement instrumentation was recorded during drops of a Falling Weight Deflectometer (FWD).

TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.

The perpetual structural pavement design is currently being explored for usage in Canada and worldwide. This thick structural design can provide many potential benefits but it also has associated costs. Cold Canadian winters and warm summers impact pavement performance and make pavement design challenging. This is further complicated by a heavy dependence on trucks to transport imports and exports. Consequently, most Canadian roads are subjected to rapid deterioration due to high fatigue stresses and rapid growth of the traffic loads. The concept of a perpetual pavement design was raised to overcome the limitation of structural capacity of the conventional pavement designs. The concept of perpetual pavement was explained and introduced in this thesis and the benefits behind the perpetual pavement construction were studied.

This study provides guidance for future designs of perpetual pavements in New Mexico. The perpetual pavement in this study refers to only hot mix asphalt (HMA) pavement sections designed for a useful life of 50 years or more without having major distresses such as fatigue and rutting. This project conducts an in-depth literature search of state departments of transportation and foreign agencies pertaining to design and application of perpetual pavements. This report highlights the perpetual pavements designed by state highway agencies nationwide and summarizes their experience, as well as their conclusions on perpetual pavement performance. The Mechanistic Empirical Pavement Design Guide (MEPDG) is used as an analysis tool. This study evaluates the effects of moisture infiltration on perpetual pavements. A full literature review conducted on moisture damage testing indicates that dynamic modulus testing of wet and dry HMA samples is found to be an appropriate approach to account for moisture damage in perpetual pavements. This study determines the combination of layer, stiffness, and thickness to produce optimal perpetual pavements. This is achieved by creating a test matrix of varying MEPDG input parameters. Input parameters such as HMA layer thickness, HMA mix design, and performance grade (PG) binders are varied and analyzed using the MEPDG. From the trial designs, perpetual pavements have been found for moderate to high truck traffic using HMA thicknesses varying from 10 to 15 inches. Perpetual pavements have been found both with and without rich binder layers (RBLs). Results shown in this study indicate that fatigue cracking is not a major concern for designing perpetual pavements in New Mexico's conditions (using MEPDG), rather rutting is more of a concern.

This research was conducted to study more realistic explanations of how variables are created and dealt with during hot mix asphalt (HMA) paving construction.--P. ii.