The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.ukThe International Journal of Pavement Engineering and Asphalt Technology (PEAT) ISSN 1464-8164. Volume: 16, Issue: 2, December 2015, pp.39 ABSTRACTAggregate gradation plays an important role in the behaviour of asphalt mixtures. Packing of aggregate is a very important factor that will be affected by changing the aggregate gradation. Many researchers have investigated different ways of describing packing both theoretically and practically. Bailey ratios have recently been used to understand the volumetric properties of mixtures. In this paper, the Bailey ratios have been used, and two further ratios have also been introduced to allow the asphalt mixture gradation to be fully understood. Thirteen different aggregate gradations have been chosen within the 14 mm asphalt concrete specification to investigate the effect of particle size distribution on the stiffness of the mixture. It was found that variation in aggregate gradation has a significant effect on asphalt stiffness, even within specification limits, and a reasonable correlation between the set of ratios investigated and the Indirect Tensile Stiffness.

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Rapid worldwide urbanization and drastic population growth have increased the demand for new road construction, which will cause a substantial amount of natural resources such as aggregates to be consumed. The use of recycled concrete aggregate could be one of the possible ways to offset the aggregate shortage problem and reduce environmental pollution. This paper reports an experimental study of unbound granular material using recycled concrete aggregate for pavement subbase construction. Five percentages of recycled concrete aggregate obtained from two different sources with an originally designed compressive strength of 20–30 MPa as well as 31–40 MPa at three particle size levels, i.e., coarse, fine, and extra fine, were tested for their properties, i.e., the optimum moisture content density, Californian bearing ratio, and resilient modulus. A characterization of the resilient modulus of the mixes under complex stress conditions was performed. The characterized modulus model was used in the nonlinear analysis of the pavement structure under traffic loading using KENALYER software. Consequently, the two critical responses, i.e., the tensile strain at the bottom of the asphalt layer and the vertical compressive strain at the top of the subgrade, were computed and compared for the pavement structures with varying types and percentages of recycled concrete aggregate used in the subbase layer.

This paper studies the problem of noise pollution on the roads of the campus of University of Baghdad in Baghdad, Iraq. Due to the continuous redevelopment process conducted on the masterplan of the university, the noise levels have significantly impacted the education environment. The purpose of this paper was thus to study the sources caused and maximized the noise levels at the campus and also formulate a prediction model, identified the guidelines used for designing or developing future campus masterplans. Then, the noise levels were measured based on three variables: skid number, vehicle speed, and distance from the classrooms at seven selected points of the main ring road surrounding the university campus. Finally, the finding has shown that the classrooms' locations of the new urban additions, built in the last two decades, were laid out in the prohibited distance of road-traffic noise. In addition to that, it has confirmed that students studying in these classrooms are exposed to noise levels beyond the legislative norms and codes. Further, studying the alternatives used to improve the performance of the education environment in the existing campus of University of Baghdad can be considered in the future research directions.

Warm Mix Asphalt (WMA) is a good pavement option due to its environmental benefits. Short-term aging is one of the critical factors that the WMA should carefully study. This research aims to study the effect of short-term aging on the warm mix asphalt that has different percentages of rubber. In this study, three percentages of rubber (1, 1.5, and 2%) by weight of aggregate are considered to be added to the WMA. By use of the Indirect Tensile Strength test for HMA, WMA unmodified and modified with CR that is exposed to an aging protocol to assess the sensitivity of asphalt mixture to moisture damage. The results show that HMA is less sensitive to moisture than WMA, and the addition of crumb rubber to WMA generally improves the resistance to moisture compared with WMA with 0% of rubber. However, as the rubber content increases to 2%, the resistance starts to decrease. Finally, SEM images were taken of rubber particles, WMA with and without rubber to investigate the changes occurring to the mixtures. Doi: 10.28991/CEJ-2022-08-12-09 Full Text: PDF