Abstract
The need for road (re)construction materials is constantly growing. At the same time, there is a limited quantity of new, high-quality materials available and a buildup of secondary/recycled construction materials. One possible solution may be the use of recycled concrete aggregate (RCA) in asphalt mixtures instead of natural aggregate (NA), which also promotes economic and environmental sustainability. The potential use of fine and coarse RCA in road asphalt mixtures is analyzed in this work. Nine asphalt mixtures were tested for base course layers, where RCA was used as a NA substitute. The impact of the quantity of RCA (up to 45% by mass) on the resulting physical and mechanical properties of asphalt mixtures was investigated, and consequently compared with the properties of a reference control mixture produced with NA only. Results reveal that the addition of RCA requires higher bitumen in comparison to the control mixture (up to 1%). Consequently, mixtures with RCA had 15−20% lower stiffness and up to 26% higher critical fatigue strain value (ε6). Although RCA mixtures contained more bitumen, their low-temperature resistance was slightly inferior compared with the control mixture (failure temperatures were up to 4.3 °C higher). In conclusion, asphalt mixtures with up to 45% RCA can be used without substantially reducing performance.
Highlights
Each year, more than 26 billion tons of natural aggregate are consumed by the construction industry worldwide [1]
Nine asphalt mixtures were tested for base course layers, where recycled concrete aggregate (RCA) was used as a natural aggregate (NA) substitute
A conventional asphalt mixture used for base course layers of the type AC 22 base 50/70 was selected for this study, enabling lower bitumen content and higher possible RCA content compared with conventional asphalt wearing course mixtures
Summary
More than 26 billion tons of natural aggregate are consumed by the construction industry worldwide [1]. The substitution of coarse natural aggregate (particle diameter > 4.75 mm) with RCA decreased the stiffness of the asphalt mixtures [20,21], in contrast to the results obtained by Alvarez et al [15]. There is limited research available on testing the fatigue and low-temperature cracking resistance of asphalt mixtures containing RCA. The main research objective of this study was to evaluate the application of RCA in road asphalt mixtures In this regard, the impact of RCA quantity and particle size distribution (i.e., the replacement of conventional aggregate with coarse RCA, with fine RCA, and with both coarse and fine RCA) on the physical and mechanical properties of road asphalt mixtures is investigated, in particular RCA effects on stiffness, fatigue, and low-temperature cracking resistance
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