A 7-in. Overlay of polyethylene-modified asphalt concrete (usingthe novophalt process) was placed at the william hobby airport in houston, texas, in december 1988. The mixture was somewhat binder-rich according to traditional mixture design methodology (i.E., Marshall and hveem). The binder-rich mixture and the optimally designed polyethylene-modified mixture (optimum binder content according to marshall design) were evaluated. This evaluation included compressive uniaxial creep compliance testing, uniaxial repeated-load permanent deformation testing, tensile creep testing, tensile strength testing, and resilient modulus testing. Binder-rich polyethylene-modified asphalt concrete proved to be significantly less sensitive to permanentdeformation than the control mixture. The binder-rich mixture also demonstrated significantly greater resistance to fracture as verified by indirect tensile test data (toughness) over a range of temperature from 32 deg f to 104 deg f and by the slope of the steady-state region of indirect tensile creep plots. The response of the binder-rich mixtures also demonstrated a strong sensitivity to the initial level of compaction. Binder-rich mixtures compacted to air void contents between 5.0 And 6.5% Were not substantially more susceptible to permanent deformation than the optimally designed mixture at the 104deg f test temperature. Data from italy verify the hypothesis that binder-rich polyethylene-modified asphalt concrete mixtures can perform successfully in certain specialized applications with acceptableresistance to permanent deformation, potentially superior resistance to fracture (reflection cracking and thermal cracking), and potentially superior durability of the low-permeability, binder-rich mixture. This paper appears in transportation research record no. 1317, Asphalt mixtures: design, testing, and evaluation 1991.
Samenvatting