Engineering Characterization of Cement Kiln Dust and Lime Kiln Dust for Soil Stabilization
Cement kiln dust (CKD) and lime kiln dust (LKD) are
industrial byproducts produced during the energy-intensive processes used to
produce lime and cement. These
byproducts have cementitious properties and their use as a substitute material
for modification and stabilization actions can provide significant cost savings. Their use also has the environmental benefit
of reducing the need for lime or cement.
These advantages have been recognized and these products are in use in
multiple states, particularly in the private market. However application rates tend to be a fixed amount
without regard to soil type or application, rather than a design percentage. Additionally, as industrial byproducts, these
materials may have different compositions depending on the plant, and
potentially on the raw materials used.
Given that treated subgrades are significant contributors to
pavement performance, understanding the benefits obtained from treatment with CKD
and LKD, compared with more traditional stabilization agents, is necessary to
developing a cost-effective design that performs as desired. Some of the knowledge that would be helpful
for understanding these materials and how to design with them include:
What is the typical composition of LKD and CKD, and are the
components, such as calcium, in a form that is readily available to react in a
How does the performance of LKD and CKD compare with lime
and cement? How does the performance compare with lime/flyash
stabilization? What tests are most
appropriate to make this comparison? Can
a relationship be developed that would permit substitution of one for the other
such that comparable performance can be expected?
Is there a standard process for extracting LKD and CKD? Is
further refinement preferred or required before it can be used? If so,
determination of emissions caused by further refinement needs to be documented.
How consistent are CKD and LKD products, both from a given
plant and between plants?
Are there substantial differences between the long-term
performance of soils stabilized with CKD and LKD and those stabilized with lime
What are the best practices for incorporating these
materials in to the subgrade?
The objectives of this research are to (1) categorize the
predominant characteristics and variability of lime kiln dust and cement kiln
dust based on the geology/source location of the raw materials and the
production plant, and (2) develop guidance, based on a review of public
information and new research, for substituting CKD and LKD for lime, cement,
and other products, and (3) summarize recommendations for methods of
application to achieve optimum performance with these materials.
Extended subgrade and pavement life
Increased savings on subgrade
Reduced energy usage, carbon emissions, and consumption of natural materials when
compared with traditional stabilizers
A variety of research projects have been conducted on other
stabilizers and some work has been published on LKD and CKD. This work can proved a foundation on which the
proposed research can be developed.
Task 1. Literature Review
Task 2. Survey of Plants Producing LKD and CKD. Plants will
be surveyed to determine material composition over time, intra- and interplant
variability, and any variations in methods of LKD and CKD harvesting and
Task 3. Sampling. Obtain
samples from representative plants for chemical analysis to determine
Task 4. Testing. Develop and conduct a test plan comparing
the benefits of LKD and CKD with lime, cement, and lime/flyash mixes with regard to strength,
modulus, and swell control, and other engineering properties.
Task 5. Best Construction Practices. Survey stakeholders to determine best
practices for application.
Task 6. Final Report.
Prepare a final report with recommendations for when to use LKD and CKD,
how to select the proper application percentage or substitution percentage when
used in place of other materials, default design values to be assigned to stabilized
layers, and best application practices.
Use of industrial byproducts such as LKD and CKD have the
potential to provide significant construction savings and to reduce the energy
footprint for road construction. Lack of
familiarity with these materials has slowed their incorporation into the suite
of options available to road designers. Funding of this research project would
facilitate adoption of these materials as viable stabilization substitutes and
would potentially provide significant savings to departments of transportation.
Use of alternative soil stabilization agents is potentially relevant to all states as well as aviation, rail, local agencies, and other transportation stakeholders.
|Sponsoring Committee:||AFS80, Stabilization of Geomaterials and Recycled Materials
|Research Period:||24 - 36 months|
|RNS Developer:||Robert Parsons (AFS80 Chair, University of Kansas), with James Brennan (AFS10 Chair, KDOT), Will Carruth (US Army ERDC), Wayne Adaska (Portland Cement Association), Robin Graves (Vulcan Materials), Dar-Hao Chen (AFS80 CRC).|
|Source Info:||Robert Parsons, Chair AFS80 University of Kansas|
James Brennan, Chair AFS10 Kansas Department of Transportation
|Index Terms:||Kiln dust, Cement, Limestone dust, Soil stabilization, Waste products, Subgrade materials, |
|Cosponsoring Committees:||AFS10, Transportation Earthworks|