Investigation of Reclaimed Asphalt Pavement Binder Contribution to the Asphalt Emulsion Slurry System Using X-ray Micro-Computed Tomography

Abstract

The state of practice to combining RAP into slurry surfacing usually considered RAP binder as inactive and thus the RAP was used as ‘‘black rock” This is because that the mixing process of the micro-surfacing was done in the ambient temperature that there is no high temperature can provide energy level to mobilize the RAP binder However during the service period of the micro-surfacing the elevated pavement surface temperature and diffusion mechanism contribution of RAP binder to the micro-surfacing makes possible Therefore the main objective of this study is investigate the level of contribution of the RAP binder to the cold mix asphalt-emulsion slurry system using direct observation and rheological of binder The study was carried out in two pathways The concept of using aggregate size to distinguish virgin aggregate and RAP and using the titanium dioxide (TiO2) as tracer The other pathway was to employ the idea of diffusion zone and the sandwich sample concept to design four diffusion stages The average thickness of the RAB layer calculated from the single artificial RAP aggregate was 100 μm and was used as a reference distance of RAB layer in the slurry mixture Thus the distance of the TiO2 outside the RAB layer to the boundary was calculated using CTAn software The average distance of TiO2 for UCDN and CDN specimen are 190 μm and 500 μm respectively It indicates the diffusion mechanism exist in both conditioning cases It can also observed that the TiO2 in the CDN specimen moved 2 5 times further than in the UCDN specimen The relative migration distance of TiO2 in micro-CT respect to half distance between two artificial RAP aggregate was calculated The percent travel was considered as diffusion depth and converted into three layer diffusion model as used in the DSR test The ratio between diffusion layer and RAB layer was correspond to the ration between diffusion layer and RAB layer This value was used in the interpolation to estimate the G* at such diffusion state from the G* at 25?C and 60?C spectrum for UCDN and CDN specimen respectively The G* of UCDN specimen and CDN specimen was 2 17-E06 Pa and 1 35-E05 Pa respectively

Date of Award	2018 Jul 27
Original language	English
Supervisor	Shih-Hsien Yang (Supervisor)