Using fine aggregate matrix mortars to predict the curing behaviour of cement bitumen treated materials produced with different cements

Asphalt fine aggregate matrix (FAM) is a predominant component directly related to field performances of hot asphalt mix (HMA), it is necessary to investigate material properties of FAM. Prior to preparing FAM specimens, the asphalt content was calculated by keeping the filler–bitumen (FB) ratio the same as in the corresponding HMA. A non-destructive fabrication method instead of coring and cutting methods was developed to compact FAM cylinders, and the joint base was designed to be concentric with the loading axis of testing system. Rheological responses of FAM were studied using the dynamic shear rheometer (DSR). Two repeated tests prove that the FAM compactor and the jointed base meet the requirement of data validation. Results show that rheological performances of FAM are significantly affected by asphalt content, gradation, air void content, and testing frequency. Air void is concluded to be the decisive factor which influences the stability of FAM, and the fiber is demonstrated to play a role on enhancing the flow resistance of FAM-F even though with the richest asphalt content.

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Experimental Testing and Analysis Procedure to Determine the Apparent Film Thickness of Asphalt Binder in Fine Aggregate Matrix Mixtures

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198121994856 ◽

2021 ◽

Vol 2675 (7) ◽

pp. 166-179

Author(s):

Lucas Henrique Vieira ◽

Thiago Delgado de Souza ◽

Alexis Jair Enríquez-León ◽

Francisco Thiago Sacramento Aragão ◽

Otávio da Fonseca Martins Gomes ◽

...

Keyword(s):

Film Thickness ◽

Asphalt Concrete ◽

Experimental Testing ◽

Asphalt Binder ◽

Analysis Procedure ◽

Fine Aggregate ◽

Concrete Mixtures ◽

Proper Design ◽

Fine Aggregate Matrix ◽

Imagej Software

The fine aggregate matrix (FAM) is an important constituent of an asphalt concrete mixture; the FAM is where some key damage phenomena such as cracking start and propagate. The proper design and fabrication of isolated FAM testing samples that are representative of the material existing within asphalt concrete mixtures requires the objective determination of key characteristics such as the apparent film thickness (FT) of the asphalt binder and the specific surface area of the aggregates. These relevant parameters facilitate the estimation of the binder content. This study presents an experimental testing and analysis protocol to determine the apparent FT that covers particles of fine aggregate in FAM mixtures. The method is based on tests using a scanning electron microscope and a digital image analysis procedure using the open-source Fiji/ImageJ software. The results indicated that apparent FT ranged between 0.5 µm and 30 µm. An additional validation effort was pursued and demonstrated the applicability of the proposed methodology, which can provide meaningful information to improve volumetric-based FAM mix design methods and generate materials that are more representative of those existing in the asphalt concrete mixtures.

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