Research Activities: 2012

Extending the Usage of High Volume Fly Ash in Concrete

 Status Complete                         View Final Report: PDF
Sequential Number R336
Identification Number 00042492
Matching Research Agency

Oklahoma Department of Transportation (ODOT) and Oklahoma State
University (OSU)

Principal Investigator

Kamal H. Khayat
Missouri University of Science and Technology
224 Engineering Research Lab
Rolla, MO 65409
(573) 341-6223

Student Involvement

One post-doctoral researcher


Project Objective
Evaluate novel techniques to improve the widespread use of high volume fly ash concrete in highway applications.

Project Abstract
Concrete mixtures that contain a high volume of fly ash (greater than 30%) have become more desirable for the increase in sustainability and economy of these mixtures. Extensive work has been completed by PI Volz for the Missouri DOT under several previous projects to show that there are many applications where high volume fly ash can be used to provide satisfactory performance.
However, several additional additives had to be included in the concrete mixture to improve the reactivity and subsequent strength gain of the mixture. While these additives did improve the performance of the mixtures, there was still a measurable difference between the high volume fly ash mixtures and concretes that use traditional volumes of fly ash. Furthermore, during the durability testing of these mixtures, there
was poor performance of these mixtures in the ASTM C 672 salt scaling test. These differences in performance in these materials provide significant barriers between low and high dosages of fly ash that
will not allow their usage in bridge decks, pavements, sidewalks, or any element with a time sensitive strength gain.
Recent work has been completed by Silva, Cheung, and Roberts of W.R. Grace to introduce a new and promising method of pre-treating fly ash by soaking it in water or other solutions before using it in concrete. This treatment allows the fly ash mixtures investigated to show improved early and later age reaction rates and subsequent strength gain. This methodology needs to be investigated with a larger number of fly ash sources and also the mechanisms need to be better understood. If the benefits of this method could be achieved in a practical manner, then this would greatly improve the ability to use high volume fly ash concrete and would address several of these critical issues with delayed strength and
Even if these issues are addressed then there will still be problems with the subsequent scaling of these mixtures. While there are a number of different ways to address this problem, it would be better if there was a greater understanding of the mechanisms of salt scaling with high volume fly ash and why it is more severe than low volumes. In order to investigate this, the research team will use X-ray computed tomography techniques to image samples during freezing and thawing cycles. This technique can make 3D maps of materials with a scale of 1 micron and has been a significant focus of research of PI Ley at OSU. This technique will allow direct observations to be made of the crack initiation sites and their
subsequent growth under freezing cycles. Once the scaling mechanism is better understood, then this will give much greater insight to guide future solutions.

Relationship to other Research/Projects

This is a standalone project under the advanced materials
theme of the Center for Transportation Infrastructure and Safety, National University Transportation Center at Missouri S&T.


Transportation-Related Keywords

Bridge Decks, Concrete Pavements, Fly Ash, Sustainability, Durability

Technology Transfer Activities

The technology transfer activities will include a final research report,
a PowerPoint presentation for internal use and possible webinar, presentation and poster for the CIES/NUTC annual conference, and dissemination of the findings through national conferences and
journal publications.


Project Deliverables

A report documenting the research program, results, findings, conclusions, and recommendations as well as guidelines to improve the usage of high volume fly ash concrete.

Anticipated Benefits

High volume fly ash concrete will be able to be used in larger volumes. This will lead to subsequent improvements in economy and sustainability of concrete mixtures.


Project Start Date: 10/01/2012
Project End Date: