Composition Design and Performance Evaluation of Emulsified Asphalt Cold Recycled Mixtures

Abstract

Based on an analysis of the cold regeneration mechanism of emulsified asphalt, the emulsified asphalt binders and cement were applied to prepare the cold recycled mixtures, and the main technical performances of the designed mixtures were evaluated, including high-temperature stability, water stability, and fatigue characteristics. A high content of 65% recycled asphalt pavement (RAP) material was used with some new aggregates and mineral powders, and the optimal emulsified asphalt binder and cement dosages were determined as 2.9% and 1.5% respectively. The technical performance test results show that: (1) The well-designed emulsified asphalt cold recycled mixtures have good high-temperature stability and water stability, and can meet the requirements of the road base layer and the lower layer. (2) When the stress level is lower, the fatigue performance of mixtures with lower emulsified asphalt binder dosage and lower cement content is better, but when the stress level is higher, the high dosage of emulsified asphalt binder is more favorable, while the cement content has little effect on the fatigue property. (3) The emulsified asphalt cold recycled mixtures have relatively poor fatigue resistance, and their fatigue life is significantly lower than that of the hot mixed asphalt mixtures.

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

“…The TSR Freeze-thaw values of emulsified and foamed asphalt CRM with RAP under different asphalt contents were higher than the limit (70%) imposed by the recycling specification (JTG/T 5521 2019) [57]. The strength of asphalt cement and the bond between the asphalt and RAP material could be reinforced by the increase in asphalt, which can prevent water damage under freeze-thaw conditions [42,66,87,88].…”

“…The emulsified asphalt needs enough working time after being mixed with aggregates and filler. Considering the alkaline environment of cement hydration and the initial setting time requirement, as well as ensuring that emulsified asphalt can participate in the formation of cement paste structure after demulsification [66], a commercial cationic slowcracking emulsified asphalt was used in this paper. The compatibility experiment between emulsified asphalt and aggregates was performed for assuring that the demulsification speed of the recycled mixture was about 2 to 3 h and compatible with aggregates.…”

Research on Design and Performance of Self-Compacting Cement Emulsified Bitumen Mixture (CEBM)

“…However, the cement/emulsified asphalt mixture requires a certain amount of time to demulsify and hydrate. It also needs time for curing, which will prolong the construction period and affect traffic [ 21 ]; moreover, the fatigue and water damage resistance of cement/emulsified asphalt mixture is not good [ 22 , 23 ], which also limits the wide application of cement/emulsified asphalt mixture [ 24 ]. Furthermore, the above mixtures are not self-compacting, and all of them are required to be compacted after the paving [ 25 ], which virtually makes the operation and construction harder.…”

Fiber-Reinforcing Effect in the Mechanical and Road Performance of Cement-Emulsified Asphalt Mixtures

“…Specifically, mechanical properties, including indirect tensile strength (ITS), indirect tensile stiffness modulus, creep stiffness, and durability in term of water sensitivity of cement-emulsified asphalt mixture have been investigated [ 7 , 8 , 9 , 10 ]. Meanwhile, road performance, such as wheel-tracking and fatigue performance, have also been studied [ 11 , 12 , 13 ]. In addition, the microstructures of cement-emulsified asphalt binders or mixtures have been studied for enhancing adhesion between aggregate and mastic [ 14 , 15 ].…”