Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Microstructure Analysis and Strength Characterization of Recycled Base and Subbase Materials Using Scanning Electron Microscope

Version 1 : Received: 22 July 2020 / Approved: 25 July 2020 / Online: 25 July 2020 (11:07:49 CEST)

A peer-reviewed article of this Preprint also exists.

Imtiaz, T.; Ahmed, A.; Hossain, M.S.; Faysal, M. Microstructure Analysis and Strength Characterization of Recycled Base and Sub-Base Materials Using Scanning Electron Microscope. Infrastructures 2020, 5, 70. Imtiaz, T.; Ahmed, A.; Hossain, M.S.; Faysal, M. Microstructure Analysis and Strength Characterization of Recycled Base and Sub-Base Materials Using Scanning Electron Microscope. Infrastructures 2020, 5, 70.

Journal reference: Infrastructures 2020, 5, 70
DOI: 10.3390/infrastructures5090070

Abstract

The reuse of recycled crushed concrete aggregate (RCCA) and reclaimed asphalt pavement (RAP) can provide a sustainable solution for the disposal of C&D materials instead of sending it to landfill. More importantly, it will save energy and reduce impact on the environment. Several states in USA are using RCCA and RAP as base materials for years, focusing on the quality of the recycled materials. The structure of Recycled Aggregate (RA) is more complex than Natural Aggregate (NA). RAs have old mortar adhered on them that forms a porous surface at interfacial transition Zone (ITZ) and prevents new cement mix from bonding strongly with the aggregates. The objective of this work was to correlate microstructural properties like micro-porosity, inter and intra aggregate pores with the unconfined compressive strength (UCS) of RAP and RCCA molds, mixed at different proportions. In this paper, the quantity of micro-pores and their effect on the strength of mixed materials is used as the basis of microstructural analysis of recycled concrete and reclaimed asphalt. Microstructural properties obtained from the analysis of scanning electron microscope (SEM) images were correlated with unconfined compressive strength. Intra-aggregate and inter-aggregate pores were studied for different ratios of cement treated mixture of RAP and RCCA. The results show that the number of pores in the mixture increases considerably by adding RAP, which eventually causes reduction in unconfined compressive strength. In addition, significant morphological and textural changes of recycled aggregates were observed by SEM image analysis.

Subject Areas

recycled crushed concrete aggregate; reclaimed asphalt pavement; unconfined compressive strength; Microstructure; scanning electron microscope; image analysis

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