Asphalt mixtures with construction and demolition debris

Abstract

This paper reports on research into the technical viability of the use of construction and demolition debris in hot mix asphalt. A semi-dense and a coarse asphalt mixture were studied, both containing 50% recycled aggregate from construction and demolition debris. Two control mixtures were also studied, similar in grading but not containing recycled aggregates.It was proven that the mixtures containing recycled aggregates were more open graded and had considerable potential for stripping, a characteristic that can be related to the high water absorption level of the mortar adhered to the recycled aggregates. It was also proven that the dynamic modulus is higher in the mixtures made with recycled aggregates, particularly in the semi-dense asphalts. Whereas a deterioration of the fatigue law was observed in the semi-dense mixtures, this property did not appear to worsen in the coarse mixtures. This meant it was possible to design structural sections for flexible pavements bearing medium or low volumes of traffic with a service life comparable to that of conventional materials.Nevertheless, further research is required as, for the time being, the lack of resistance to water action casts doubt on the use of asphalt mixtures incorporating these types of recycled aggregate.

Overview of bituminous mixtures made with recycled concrete aggregates

“…1a, a common RCA particle consists primarily of an original natural aggregate partially covered by a mortar layer. This attached mortar is more porous and less dense than the original natural aggregate [20,[29][30][31][32][33] and has relatively weak bonding with the original natural aggregate [34], which negatively affects the RCA properties. Moreover, the attached mortar has a variable content or thickness, age, composition, porosity and texture.…”

“…1b shows that besides these common particles, the RCA also includes other materials: mortar fragments, stones and aggregates without mortar, ceramics, asphalt and other impurities such as gypsum, wood, glass, paper or metals; these impurities should be removed to improve the RCA heterogeneity [29][30][31]35].…”

“…The majority of studies have stated that HMA using RCA have higher optimum asphalt contents (OAC) than conventional mixtures [28,[30][31][32][33][36][37][38][39][40][41][42][43] mainly because of the high porosity of the attached mortar [28,43]. Several typical findings, shown in Fig.…”

“…HMA using RCA have higher air-voids contents (Va) than conventional mixtures [29][30][31][32][33]37,38,42,46]; the Va could exceed 30% for RCA [35]. Several authors stated that, generally, the percentage of air voids grow as the RCA percentage grows [29][30][31][32][33]35,42,46].…”

Editorial

“…There are two materials-related papers. The first looks at asphalt mixtures made with construction and demolition debris (Pérez et al, 2010) and the second investigates the rheological and electrical properties of modified bitumen (Rodgers et al, 2010). Runoff infiltration through permeable block pavements is investigated (Hassani et al, 2010) and the measurement and modelling of proximal safety measures is presented (Archer and Young, 2010).…”