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

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

Clear asphalt concrete for energy saving in road tunnels

Nowadays the interest in clear pavements for road tunnel applications is rapidly increasing, as their high photometric properties assure an important reduction of power consumption for electric lighting and an improvement of safety conditions. One of the solutions for manufacturing clear pavements consists in mixing light-colored mineral aggregates with particular transparent asphalt binders. This production technique was used in 2012 to manufacture the clear asphalt concrete for wearing courses of two road tunnels in the north of Italy. The present paper deals with the mix design and the evaluation of mechanical and photometric properties of the clear asphalt concrete used for paving these tunnels. In particular, tests were carried out on the raw materials and on both lab-manufactured and plant-manufactured mixes. At the end of the tests clear mixtures showed good mechanical properties, similar to a traditional “black” asphalt concrete in terms of indirect tensile strength and indirect tensile stiffness modulus. In addition clear mixtures showed very high photometric properties after five months from the opening to traffic