The occurrence of higher air and surface temperatures in urban areas is known as the urban heat island (UHI) effect. Reducing the UHI effect may decrease summer energy use and improve human and ecological health. The Leadership in Energy and Environmental Design certification system has awarded up to three points for construction projects that provide any combination of the following cool pavement strategies for up to 75% of the site landscape: ( a) shading hard surfaces on the site with landscape features, ( b) using high-reflectance materials with a minimum solar reflectance index (SRI) of 29, and ( c) utilizing an open-graded pavement or porous pavement system. Although a guide to the design and construction of porous asphalt pavements has existed for some time, such a guide is not readily available for high-reflective asphalt pavements. The objective of this study is to identify and validate high-reflectance asphalt materials and pavement surface treatments that are suitable for use in parking lots and other large paved surfaces, have a minimum SRI of 29, and are economical. In this study, six technologies exhibited SRI values of 29 or greater: E-Krete microsurfacing, Street-Bond coating, synthetic binder, Densiphalt, and chip and sand seals using light-colored aggregates. Another technology, surface gritting using light-colored aggregate, most likely would have exhibited SRI values of at least 29 if the aggregate had adhered properly to the asphalt mat.

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This paper describes the performance of test sections containing moderate and high levels of reclaimed asphalt pavement (RAP) at the National Center for Asphalt Technology test track. The test sections included two with 20% RAP, four with 45% RAP, and a control with no RAP. Each mixture contained the same component aggregates and RAP. One of the 20% RAP mixes contained PG 67-22 binder, and the other contained PG 76-22 binder. Different binders in the 45% RAP mixes included PG 52-28, PG 67-22, PG 76-22, and PG 76-22 plus 1.5% Sasobit. All sections performed well for rutting and raveling. Low-severity longitudinal wheelpath cracking was documented in two sections. The 45% RAP section with PG 76-22 plus Sasobit had moderate cracking, which appears to reflect cracking from the underlying pavement. The 20% RAP section with PG 76-22 had less cracking. Other sections had no cracking. Laboratory tests included asphalt pavement analyzer (APA) rutting tests, dynamic modulus, bending beam fatigue, and energy ratio. The APA results corresponded to the effective stiffness of the binder in the mixes. Master curves of dynamic moduli showed the effects of the virgin binder grade on the stiffness of the mixtures. Beam fatigue tests indicated that the 45% RAP mixes have lower fatigue lives compared with those of the other mixes, but this is because of a lower effective volume of asphalt in these mixes.

Under static loading, crack formation in titanium carbide is shown to obey Auerbach's law for hemispherical indenters. From the results, using the Frank and Lawn theory of 1967, an estimate of the surface energy of TiC is obtained. In the case of sliding contact the load to fracture varies markedly with the coefficient of friction. A reasonable estimate of the sliding load to fracture is obtained by assuming that the fracture stress, as calculated using the analysis of Hamilton and Goodman in 1966, is the same as in the case of static loading for the same indenter. This is at some variance with the Lawn's 1967 predictions.

One-third-scale model mobile load simulator (MMLS3) testing was conducted at the National Center for Asphalt Technology test track. Dry and wet-heated MMLS3 tests were done on five sections. The rutting performances of the sections under MMLS3 trafficking were compared with that under full-scale truck trafficking (truck test sections). A synthesis of the research included evaluation of results from laboratory tests done on cores taken from the MMLS3 test sections within and outside trafficked wheelpaths. Tests on the cores included wet and dry Hamburg wheel tracking, Superpave® shear tester frequency sweep, and semicircular bending (SCB) strength testing. Investigations included the evaluation of full-scale rutting data, laboratory wheel-tracking test results, and climatic data monitored on the track during full-scale truck trafficking. The project validated the rut prediction approach developed to compare MMLS3 and full-scale rutting performance and indicated that the MMLS3 may be used to estimate full-scale rutting at the track under specific conditions. Distress due to wet trafficking was also quantified as reduction in tensile strength as measured by the SCB. Conclusions were drawn and recommendations made for MMLS3 as well as continued full-scale testing at the track. Comparative full-scale rutting performance of the track sections evaluated may be quantified and ranked by the MMLS3 performance of these sections.