Meso-structure of Cement Stabilized RAP Materials Based on CT Images

Studying the influence of reclaimed asphalt pavement(RAP)on the composition and structural characteristics of mixtures can provide theoretical support for their application in pavement structure layer and material parameter design. This paper proposed a method for identifying the meso-structure of cold recycled mixtures,both new and old aggregates,based on the X-ray CT and image processing technology. The differences in the meso-structure characteristics of RAP,old aggregates,and new aggregates were analyzed,and the effects of RAP on the meso-structure characteristics of the cement-stabilized RAP materials were studied. The results demonstrate that the proposed meso-structure recognition method can accurately identify the void,mortar,new aggregate,and old aggregate in the section image of cement-stabilized RAP material and completely retain the original outline,size,and shape information of new and old aggregates. Compared with the new aggregate,the old aggregate has a higher flat ratio and angular coefficient. Further,several micro air voids and cracks are present in RAP-granular. The addition of RAP increases the number of micro air voids (volume less than 0. 01 mm3)and large voids (volume greater than 100 mm3)in the recycled mixture,resulting in the reduction of material compactness;further,the asphalt mortar content of the material increases,the average mortar film thickness of the recycled mixture improves,and the internal force conduction of the mixture skeleton becomes more uniform. Increasing the proportion of RAP materials stabilized with cement can reduce the average void volume and increase the average mortar film thickness,thereby improving the skeleton filling status of the recycled mixture. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.