The effect of mica on the aging of asphalt binder
type: CreativeWork
description: Asphalt Concrete (AC) consists of approximately 95% aggregate, by weight. Of this 95%, about 6% is smaller than 0.075 mm in size (passing the #200 sieve and called fines). The fines often contain mica. Mica is a formation of silicate minerals having perfect basal cleavage. It can be peeled apart in very thin sheets and is usually found in deposits of granite, quartz and other rock that is commonly used for aggregate. Mica has been shown to reduce the strength of asphalt concrete. This study evaluates the effects of mica on asphalt materials subjected to aging. A total of five different concentrations of mica in fines are examined using X-ray diffraction (XRD) technology. These mica-fines are combined with two asphalt binders to make mastics. Mastics are aged at four different levels and examined with the Scanning Electron Microscope (SEM). Bending Beam Rheometer (BBR) and nanoindentation tests are conducted on mastics mixed with one of the binders and various concentrations of mica-fines aged at different levels. In this study, SEM images of mastic are taken. During the mixing of the mastics, it is found that as the concentration of mica in the fines increases, so does the absorption of the binder. This is probably because mica has a flat surface that increases the surface area of the total aggregate. As the weight percentages of aggregate to binder is held exactly constant in the experiments conducted in this study, the mastics with lower concentrations of mica are found to be very rich while the higher concentrations are dry. SEM images show that cracks in broken mastic seem to follow uncoated mica flakes. The number of uncoated flakes increases only slightly with aging, but quite dramatically with mica concentration. XRD is used to identify and roughly quantify the amount of mica in aggregate. Spectra from samples of single-source fines, containing varying quantities of mica, clearly indicate the change in mica content. However, when a known quantity of mica is a…
abstract: Asphalt Concrete (AC) consists of approximately 95% aggregate, by weight. Of this 95%, about 6% is smaller than 0.075 mm in size (passing the #200 sieve and called fines). The fines often contain mica. Mica is a formation of silicate minerals having perfect basal cleavage. It can be peeled apart in very thin sheets and is usually found in deposits of granite, quartz and other rock that is commonly used for aggregate. Mica has been shown to reduce the strength of asphalt concrete. This study evaluates the effects of mica on asphalt materials subjected to aging. A total of five different concentrations of mica in fines are examined using X-ray diffraction (XRD) technology. These mica-fines are combined with two asphalt binders to make mastics. Mastics are aged at four different levels and examined with the Scanning Electron Microscope (SEM). Bending Beam Rheometer (BBR) and nanoindentation tests are conducted on mastics mixed with one of the binders and various concentrations of mica-fines aged at different levels. In this study, SEM images of mastic are taken. During the mixing of the mastics, it is found that as the concentration of mica in the fines increases, so does the absorption of the binder. This is probably because mica has a flat surface that increases the surface area of the total aggregate. As the weight percentages of aggregate to binder is held exactly constant in the experiments conducted in this study, the mastics with lower concentrations of mica are found to be very rich while the higher concentrations are dry. SEM images show that cracks in broken mastic seem to follow uncoated mica flakes. The number of uncoated flakes increases only slightly with aging, but quite dramatically with mica concentration. XRD is used to identify and roughly quantify the amount of mica in aggregate. Spectra from samples of single-source fines, containing varying quantities of mica, clearly indicate the change in mica content. However, when a known quantity of mica is a…
author: Sobien, Helen
language: English
keywords: Pavements, Asphalt concrete--Materials, Asphalt concrete--Performance, Asphalt emulsion mixtures, Binders (Materials)--Testing, Mica.
date published: 2012-07-03T07:00:00Z
date modified: 2026-07-24T05:26:55Z
provider: University of New Mexico
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of New Mexico

PropertyValue
property ID: Handle
value: http://hdl.handle.net/1928/20789