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Effect of Laboratory
Conditioning and Compaction Characteristics on Projects Specifications
for Cement-Treated Materials (click here)
Improvements in
Design and Construction Procedures for Cement-Treated Soils (Click
here)
Development of Procedures to Evaluate Cement Stabilization
of Difficult Soils
Principal Investigator: Tom Scullion
Background
In stabilizing soils with cement, occasionally soils are encountered
that are anomalies or have some special characteristic that makes
them difficult to stabilize. The reason for the difficulty is usually
a set of chemical conditions that interfere with the proper bonding
of the cementitious gels to the soil particles.
The special sets of conditions for difficult soils can be broken
down into the following groups:
- Low pH soils. This is often caused by Tannic Acid in the soil,
and the low pH will require an excessive amount of cement for stabilization.
This is sometimes corrected through the pre-treatment of the soil
with chlorides.
- Highly organic soils. Soils with high organic contents are also
difficult to stabilize. However, the test methods for identifying
the problem soils, and methods for correcting the problem, are not
well understood.
- Soils with sulfates. Introducing cement to stabilize soils with
high clay and sulfate contents can result in excessive expansion
of the treated soil. Procedures have been developed to identify
the problem soils, but the proper steps to mitigate the problem
are still under investigation.
- Micaceous silts. Silts formed from parent mica are often difficult
to stabilize, and some locations consider this material unsatisfactory
to treat with cement.
- Unusual soils. In some projects excessive amounts of cement have
been necessary to stabilize the soil, without a clear reason why
normal cement contents did not work.
Objective
The objective of this project will be to develop procedures to
guide the engineer through the process of identifying and mitigating
problems associated with stabilizing difficult soils using cement.
Market Significance of Project
When problems occur on a cement stabilization project due to the
unsuitability of the soil, the result is often the perception by
the owner that cement stabilization does not work. It is important
to the industry to know about these conditions before the start
of the project rather than afterwards when problems are much more
difficult to solve.
Having clear procedures that allow designers to identify and mitigate
problems with difficult soils will improve the ability of the industry
to avoid problems with projects and to design the proper corrective
action.
Utilization of Results
The results from this project will be utilized through improved
procedures for designing and construction of cement-treated soils.
Project Description
- Review the considerable literature that exists relative to identification
and treatment of problem soils.
- Develop a conceptual framework for guidelines that would assist
a designer in identifying and treating problem soils with cement.
- Determine which type of investigative equipment and procedures,
particularly involving the interactive chemistry of cement and different
soil conditions, would be useful in developing guidelines for this
project.
- Perform laboratory studies to develop and verify procedures for
identifying and mitigating the effects of difficult soils.
- Develop guidelines for a comprehensive procedure for cement treatment
of difficult soils.
- Prepare final report documenting the project and recommending
the guidelines.
- Prepare an Executive Summary of the work performed.
Delivery Date
The project will be completed over a 2-year period, beginning in
March 2007. The final project deliverables and documentation will
be completed by March 2010.
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