- Author
-
Nguyen, T.
|
Byrd, W. E.
|
Bentz, D.
|
Seiler, J., Jr.
- Title
- Development of a Technique for In Situ Measurement of Water at the Asphalt/Model Siliceous Aggregate Interface.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Sponsor
- National Research Council, Washington, DC
- Report
-
NISTIR 4783,
March 1992,
62 p.
- Distribution
- Available from National Technical Information Service
- Keywords
-
aggregates
|
water
|
asphalt
|
spectroscopy
|
bonding
|
diffusion
|
FT-IR
|
asphalt
|
asphalt/aggregate interface
|
in situ measurement
|
water absorption
|
water susceptibility
|
quantitative analysis
- Abstract
- A technique based on Fourier transform infrared (FTIR) spectroscopy in the multiple internal reflection (MIR) mode was developed for measuring water in situ at the interface between an asphalt and a model siliceous aggregate. The technique required the coating of an asphalt layer of known thickness on an internal reflection element (IRE), which served as an optical guide to obtain an infrared spectrum. A water chamber was attached to the asphalt-coated IRE, and FTIR-MIR spectra were taken automatically at specified times without disturbance of the specimens. In situ water measurements for five Strategic Highway Research Program (SHRP) core asphalts (AAC-1, AAD-1, AAG-1, AAK-1 and AAM-1) on a hydrated, SiO2-covered Si IRE, which served as the model siliceous aggregate, were carried out using the technique. An FTIR-MIR study of water at different concentrtions and experiments on water absorption in SHRP asphalts were also done for the quantitative analysis. Calculations were made to demonstrate that the water detected was at or near the asphalt/siliceous aggregate interface. The results have shown that the technique can detect and quantify water in situ at the asphalt/siliceous interface, and provide unique information on the transport properties of water through an asphalt layer attached to a substrate. The technique developed here should be useful for evaluating asphalt/siliceous model aggregate mixtures in terms of 1) water susceptibility of an asphalt/aggregate mixture, 2) effectiveness of antistripping agents, 3) effects of aggregate surface contamination and environmental temperature on water stripping, and 4) water diffusion through asphalts on an aggregate. The technique should also be effective in obtaining quantitative information on the transport of water and other compounds, both organic and inorganic, through a layer of any thickness of asphalt/aggregate mixture, cement, and concrete attached to a substrate. Results of an exploratory test method for measuring the bond strength of an asphalt on an aggregate in the presence of water are given.