Abstract
This article presents research on recycled cold mix with foamed bitumen (MCAS) containing recycled concrete aggregate. The primary concept driving this research was to determine if recycled concrete aggregate (RC) could be used as a substitute for reclaimed asphalt pavement (RAP). Recycled concrete aggregate was used in the MCAS mix in amounts ranging from 20%, 60% and 80%. The reference mix was the MCAS mix containing 50% reclaimed asphalt pavement (RAP) and virgin aggregate. Identical 0/31.5-mm continuously graded dolomite virgin aggregate was used in all mixes. 2.5% foamed bitumen (FB) and 2.0% CEM I 42.5R Portland cement (PC) were used to increase the cohesion of the mineral mix. Foamed bitumen was produced from 50/70 penetration paving bitumen. The behaviour of the recycled base course was tested in the range of cyclic sinusoidal strain with amplitude εo = 25–50 με. The tests were carried out in the (-7°C, 5°C, 13°C, 25°C, 40°C) temperature and (0.1 Hz, 0.3 Hz, 1 Hz, 3 Hz, 10 Hz, 20 Hz) loading time range. The complex modulus was tested in a direct tension-compression test on cylindrical samples (DTC-CY) in accordance with EN 12697-26. The results of the tests were used to assess the complex modulus (E*), phase angle (φ) and complex modulus components (E1) and (E2).Tests of the mixes indicate that recycled concrete aggregate can be used in recycled cold mixes in amounts of up to 80%. Increasing the amount of recycled concrete aggregate does not cause excessive stiffness of the recycled mix in comparison with the reference mix. The tests did not demonstrate a significant difference in terms of the phase angle (φ), which indicates a similar content of the viscous part and elastic part in the obtained complex modulus for the reference mix (RAP + MCAS) and the mix containing recycled concrete aggregate (RC + MCAS).
Highlights
The expansion of road infrastructure and availability of a wide range of construction methods [1,2,3,4,5] give more opportunities when designing flexible [6, 7], semi-rigid [6, 7] and rigid pavements [8]
The use of waste materials in the form of recycled aggregate, reclaimed asphalt pavement and mineral dust in recycled cold mix with foamed bitumen was discussed in papers presented by authors [12, 13]
In the available studies, using reclaimed asphalt pavement is limited to adding recycled concrete aggregate (RCA) to cement concrete as a substitute for new aggregate
Summary
The expansion of road infrastructure and availability of a wide range of construction methods [1,2,3,4,5] give more opportunities when designing flexible [6, 7], semi-rigid [6, 7] and rigid pavements [8]. The use of waste materials in the form of recycled aggregate, reclaimed asphalt pavement and mineral dust in recycled cold mix with foamed bitumen was discussed in papers presented by authors [12, 13]. In the available studies, using reclaimed asphalt pavement is limited to adding recycled concrete aggregate (RCA) to cement concrete as a substitute for new aggregate. Research in this regard was carried out by many researchers [15,16,17,18]. This article presents studies of recycled cold mix with foamed bitumen containing recycled concrete aggregate as a substitute for the conventionally used reclaimed asphalt pavement. The first step of this testing plan was to design the recycled cold mix with foamed bitumen in terms of its RCA content
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