Issue 52

H. Latifi et alii, Frattura ed Integrità Strutturale, 52 (2020) 211-229; DOI: 10.3221/IGF-ESIS.52.17

Figure 10: Dynamic modulus- wet/dry Ratios via number of cycles. (granite).

Figure 11: Dynamic modulus- wet/dry Ratios via number of cycles. (RAP).

SEM Results To evaluate the morphology of prepared CRMA and consequently have an understanding about the quality of applied mixing process, SEM apparatus was used to take photos from CRMA as investigated sample and HMA/asphalt binder/PC paste, as reference samples. The samples were imaged under a Zeiss, Sigma VP environmental scanning electron microscope (SEM) in the backscattered mode to obtain high resolution micrographs that distinguishes different solid phases. As illustrated in Fig. 12, several high-resolution images were obtained at different magnifications from modified CRMA, unmodified CRMA and PC paste. SEM images of asphalt binder and PC paste are shown in Fig. 12.a and 10.b, respectively. In addition, SEM images of unmodified CRMA are shown in Fig. 12.c. In addition to CRMA, SEM photos were taken from raw asphalt and Portland cement to help having a better understanding about the shape of those materials in micro scale. By knowing the shape of those materials independently, distinguishing them from other ingredients could be easier and more precise. According to Fig. 12.d, it could be understood that asphalt emulsion, Portland cement, RAPs and polymeric additive were mixed properly, and a satisfying homogeneous CRMA was formed. As a result, applied mixing method was a successful one to make a homogeneous CRMA and no agglomeration was observed.

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