Development of Soil-Water Characteristic Curve for Flexible Base Materials Using the Methylene Blue Test
Publication: Journal of Materials in Civil Engineering
Volume 27, Issue 5
Abstract
This study describes an experimental investigation of the methylene blue test to determine the methylene blue value (MBV) and quantitatively generate the soil-water characteristic curve (SWCC) for unbound aggregate material based on the predicted percent fines content (PFC). The traditional methylene blue test has been improved significantly in terms of time, sample size, and method for analyzing the results. These improvements enable the methylene blue test to be not only a laboratory test but also a field test. This improved methylene blue test methodology is used to generate the SWCC for unbound aggregate material. The relationship between the MBV and the PFC value is established. The principles of unsaturated soil mechanics are taken into account to develop regression models for determining the four fitting parameters in a previously developed SWCC equation by using the predicted PFC value, which are then used to generate the SWCC for the unbound aggregates. The proposed method is validated by a comparison between the measured and predicted suction values for various unbound aggregate materials. This method is capable of generating the SWCC far more efficiently than any previous laboratory method, and it can even be used in field investigations because the methylene blue test requires limited portable test equipment. These improvements widen methylene blue test applications and allow for the development of the SWCC without requiring difficult laboratory experiments. Finally, the slope parameter, , in the SWCC equations is found to be associated with the moisture susceptibility of flexible base materials. A higher value indicates that the material is more moisture susceptible. This finding is successfully validated by the results from the permanent deformation test.
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Acknowledgments
The authors would like to thank the Texas Department of Transportation (TxDOT) for providing financial support for this study through the TxDOT 0-6621 project investigated by Dr. Jon Epps. The authors gratefully acknowledge the help and support of Stephen Sebesta, Bailey Hewes, Xue Luo, and Narain Hariharan from Texas A&M Transportation Institute during the study.
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Published In
Journal of Materials in Civil Engineering
Volume 27 • Issue 5 • May 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Nov 27, 2013
Accepted: May 21, 2014
Published online: Aug 11, 2014
Discussion open until: Jan 11, 2015
Published in print: May 1, 2015
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