New developments with cold asphalt concrete binder course mixtures containing binary blended cementitious filler (BBCF)

A weakness in early strength and the need for longer curing times in the case of cold bituminous emulsion mixtures (CBEMs) compared to hot mix asphalt have been cited as barriers to the wider utilization of these mixtures. A binary blended filler material produced from high calcium fly ash (HCFA) and a fluid catalytic cracking catalyst (FC3R) was found to be very effective in providing microstructural integrity with a novel fast-curing cold asphalt concrete for the binder course (CACB) mixture. Balanced oxide compositions within the novel filler were identified as responsible for an enhanced hydration reaction, resulting in a very high early strength and a significant improvement in permanent deformation and fatigue resistance. Improved water sensitivity for progressive hydration with the new binary filler was also established while SEM analysis confirmed the formation of hydration products after various curing ages. © 2016 Elsevier Lt

New laboratory procedure using a modal approach to obtain vibration attenuation properties of unaged and aged asphalt mixtures

[EN] During asphalt mixture service life, its structural and physical capabilities deteriorate progressively. A modal analysis using impact hammer excitation technique is put forward to measure the damping factor instead of the commonly destructive test described in the standards. Concerning to this modal approach, an aging procedure is presented to obtain and compare the vibration attenuation capacity variation of the mixtures considering aging deterioration. In this research, this new procedure has been applied to asphalt concrete and stone mastic asphalt mixtures with different amounts of polyethylene terephthalete. It has been validated using results from four-point bending test. Finally, the results confirmed that asphalt mixtures with 0 2% of polyethylene terephthalete present better vibration attenuation capacity than mixtures without it, even when aging appeared.Real Herraiz, TP.; Montalbán Domingo, ML.; Masanet Sendra, C.; Real Herráiz, JI. (2016). New laboratory procedure using a modal approach to obtain vibration attenuation properties of unaged and aged asphalt mixtures. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications. 230(2):627-639. doi:10.1177/1464420715584095S627639230

Design considerations of high RAP-content asphalt produced at reduced temperatures

In many countries recycling of reclaimed asphalt pavement (RAP) for road surface layers is limited to a maximum of 10–30%. This is due to technical limitation of common asphalt plant but also to specifications that are still restrictive when it comes to increasing RAP in surface courses. The mistrust in this practice is mainly related to uncertainty in performance of these mixes as well as to existing fundamental issues with the mix design, especially when production temperatures are lowered. This paper analyses some of the factors affecting the design of warm asphalt mixtures for surface course layers containing 50% RAP, and suggests a framework to justify the common assumption of full blending by optimising production conditions. A control hot mix asphalt which was manufactured with 49 dmm penetration binder and asphalt mixtures containing 50% RAP produced at temperatures between 95 and 135 °C and at different mixing times were investigated in terms of volumetric properties, indirect tensile stiffness modulus, and indirect tensile strength. The high-content RAP mixtures were produced within the warm mix region by using only a very soft binder as a rejuvenator, which reduces production costs. Statistical analysis was deployed, and different models were developed to estimate degree of blending between RAP binder and rejuvenator binder, and to predict the equivalent penetration of the blend without binder extraction and recovery. The analysis results showed that the selected performance indicators correlate significantly with mixing time and temperature, and provide evidence that only in certain circumstances and if the production conditions are accurately controlled, the practical full blending approach is acceptable

Overview of Pavement Life Cycle Assessment Use Phase Research at the MIT Concrete Sustainability Hub

© 2019 American Society of Civil Engineers. In 2009, the U.S. cement and concrete industries established the Concrete Sustainability Hub at the Massachusetts Institute of Technology. A primary thrust of MIT's activities has been improving the life cycle assessment practices to better quantify the environmental impacts over the life of a pavement. In their research, the MIT CSHub determined that the "use phase" can dominate the materials, construction, and maintenance phases of a pavement LCA and that two of the important factors in the use phase are pavement vehicle interaction (PVI) and Albedo. PVI describes the excess fuel emissions/energy from vehicles due to excess rolling resistance between the pavement and the vehicle. Albedo is the fraction of solar energy reflected by the Earth's surface, with lighter color, higher albedo surfaces reflecting more energy than lower albedo, darker surfaces. This paper will summarize the CSHub use phase research findings to date