Abstract
Cement emulsified asphalt composite binder (CEACB) plays a determining role in the construction of cold recycled asphalt pavements. Understanding the interaction behaviors of cement-emulsified asphalt is very essential to promote the serviceability of CEACB. The objective of this study was to explore the interaction behaviors and mechanism of cement-emulsified asphalt associated with microstructural characteristics and to assess the interaction ability of cement-emulsified asphalt by performing macro-rheological measurements. Firstly, the physico-chemical interaction of cement-emulsified asphalt was qualitatively discussed by analyzing the difference of characteristic peaks based on Fourier transform infrared (FTIR) spectrometer. Secondly, the micro-morphological evolution behaviors of CEACB attributing to the cement-emulsified asphalt interaction were investigated by using a fluorescence microscope (FM) and laser particle size analyzer (LPSA). Thirdly, the microstructural characteristics of CEACB were studied by observing the spatial network structure through the scanning electron microscopy (SEM). Finally, the macro-rheological index based on dynamic rheological shear (DSR) test was proposed to evaluate the interaction ability of cement-emulsified asphalt. The results show that the cement-emulsified asphalt interaction is merely a physical blending process due to the occurrence of no new characteristic peaks in the FTIR spectrum except for cement hydration products. The cement-emulsified asphalt interaction in early-age CEACB could be reflected by the aggregation process among asphalt droplets and the adsorption action of cement particles to asphalt droplets. A reasonable ratio of cement to emulsified asphalt could promote the formation of the denser spatial network structure of CEACB along with cement hydration products growing and interweaving with asphalt films. The K-B- index based on macro-rheological properties of CEACB with full consideration of cement hydration process is very suitable for evaluating the interaction ability of cement-emulsified asphalt under the condition of different cement proportions and curing time. The research would provide the support for understanding the natural properties of CEACB and promote the improvement of the mechanical performance of cold recycled asphalt pavements.
Highlights
Road and Traffic Engineering Institute, College of Engineering, Zhejiang Normal University, Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology & Equipment of Zhejiang Province, Zhejiang Normal University, Jinhua 321004, China
The results indicate that the peaks at 2922 cm−1 and 2853 cm−1 are the main characteristic absorption peaks of emulsified asphalt evaporation residue (EAER) corresponding to the stretching vibration absorption peak of C–H bond
It is worth mentioning that the absorption peaks at 1111 cm−1 and 1026 cm−1 in Cement emulsified asphalt composite binder (CEACB) denote the ettringite (AFt) and the calcium silicate hydrate (C–S–H), respectively, which mainly derive from the new groups of SiO3 2− generated by the hydration of cement [40]
Summary
Road and Traffic Engineering Institute, College of Engineering, Zhejiang Normal University, Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology & Equipment of Zhejiang Province, Zhejiang Normal University, Jinhua 321004, China. The objective of this study was to explore the interaction behaviors and mechanism of cement-emulsified asphalt associated with microstructural characteristics and to assess the interaction ability of cement-emulsified asphalt by performing macro-rheological measurements. The research would provide the support for understanding the natural properties of CEACB and promote the improvement of the mechanical performance of cold recycled asphalt pavements. Various internal and external factors such as temperature, water evaporation, cement composition, cement proportion, emulsifier type, emulsified asphalt content, etc., affecting the process and the degree of the cement hydration and the emulsified asphalt demulsification occurred in the cement emulsified asphalt materials had been widely concerned [16,17,18]. Kuz’Min et al [24,25]
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