Study on Cold Recycled Asphalt Mixtures with Emulsified/Foamed Asphalt in the Laboratory and On-Site

Abstract

Millions of tons of reclaimed asphalt pavement (RAP) and reclaimed aggregate or reclaimed inorganic binder stabilized aggregate (RAI) is produced every year in China. The cold recycled mixture (CRM) technology reduces fuel consumption, emissions, and cost and utilizes the high content of RAP. In this paper, six types of CRM with varying RAP/RAI composition and asphalt binders were investigated. The laboratory tests included strength indicators, high temperature stability, low temperature crack resistance, water stability, and dynamic modulus. A full-scale trial section was constructed after the laboratory tests. Except for low temperature failure strain without secondary compaction in the mixture design, test results illustrated that the performances of different CRMs met the specifications. The cement addition limited the thermo-viscoelastic behavior of the CRM. The RAI contents had reduced the water sensitivity of CRM, and the emulsified asphalt CRM had better performance than the foamed asphalt CRM. The performances of samples cored from the test section in the field met the specifications and were lower than that in the laboratory. The curing conditions in the field were not as effective as in the laboratory. The curing conditions and compaction method should simulate the conditions in the field to guide the CRM selection and mixture design.

Effects of Anionic Emulsifiers and Emulsified Asphalt on Hydration and Microstructure of Cement

“…For example, in the spraying project, since the CEA needs to be rapidly solidified and hardened in a short time to form strong bonds, and the mixing of cement and emulsified asphalt is not involved in the spraying process, the emulsified asphalt with a poor retarding effect on cement should be selected at this time. In the application of cold recycled mixtures and asphalt pavement base materials, since cement and emulsified asphalt need to be mixed for a long time, emulsified asphalt with a good cement-retarding effect should be selected to increase the workability of the mixture [ 12 , 13 , 14 ]. Therefore, the selection of emulsifiers is the key step of CEA composite application in engineering [ 15 , 16 , 17 , 18 , 19 ].…”

Characterization of Cold Recycled Asphalt Mixtures including Reinforcing Fibers

“…In particular, they combine the advantage of mixing and laying the material at room temperature together with the reuse of high percentages of reclaimed asphalt pavement (RAP), up to 100% [1]. These advantages produce several benefits such as a reduction in the emissions, reduced contribution to landfills, virgin aggregate preservation and reductions in construction time and costs [2][3][4].…”

“…Even if profitable from economic and environmental points of view, cold mixtures do not guarantee the same performance as hot-mix asphalt (HMA), since they need 3-7 days of curing to develop a good early resistance, necessary for the reopening to road traffic [10,11]. Moreover, cold mixtures have a higher air-void content than HMA, which reflects in lower mechanical properties and, in particular, fatigue resistance [4,12]. All these reasons have led to the use of CRAM materials only in base or sub-base layers, typically overlaid with not less than 10 cm of asphalt concrete [13].…”

Optimum Fluid Content in Pavement Cold In-Place Recycling Containing Waste Materials

“…The use of Table 1. Mixtures and optimal water content and optimum asphalt content [37]. RAP with cement and bitumen emulsion was used for the construction of a rural road in Serbia [38].…”