RNS
Browse Projects > Detailed View

Engineering Characterization of Cement Kiln Dust and Lime Kiln Dust for Soil Stabilization

Description:

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 beneficial manner?

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 and cement?

What are the best practices for incorporating these materials in to the subgrade?

Objective:

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.

Benefits:

Extended subgrade and pavement life

Increased savings on subgrade construction

Reduced energy usage, carbon emissions, and consumption of natural materials when compared with traditional stabilizers

Related Research:

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.

Tasks:

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 refinement.

Task 3. Sampling. Obtain samples from representative plants for chemical analysis to determine cementitious properties.

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.

Implementation:

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.

Relevance:

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
Research Priority:High
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
Date Posted:01/05/2019
Date Modified:01/29/2019
Index Terms:Kiln dust, Cement, Limestone dust, Soil stabilization, Waste products, Subgrade materials,
Cosponsoring Committees:AFS10, Transportation Earthworks
 
Subjects    
Highways
Materials
Pavements
Geotechnology

Please click here if you wish to share information or are aware of any research underway that addresses issues in this research needs statement. The information may be helpful to the sponsoring committee in keeping the statement up-to-date.