Research Activities: 2012

Development and Testing of Synthetic Riprap Constructed from Coal Combustion Products (CCPs)

 Status Complete                            View Final Report: PDF
Sequential Number R327
Identification Number 00041444
Matching Research Agency Ameren Corporation
Principal Investigator Jeffery Volz
Assistant Professor, Civil, Architectural and Environmental Engineering
Missouri University of Science and Technology
Rolla, MO 65401
(573) 341-3280
Student Involvement

One graduate student


Project Objective
Even with an increase in the amount of coal combustion products (CCPs) used in concrete construction, soil stabilization, and other applications, the coal power industry must dispose of a significant amount of fly ash and bottom ash.  One potential avenue for the material is to develop a riprap to armor shorelines, streambeds, bridge abutments, and pilings against scour and ice damage. The objective of the proposed research is to evaluate the feasibility of constructing riprap containing 90% CCPs such as fly ash and bottom ash

Project Abstract

Since the 1930’s, fly ash – a pozzolanic material – has been used as a partial replacement of portland cement in concrete to improve the material’s strength and durability, while also limiting the amount of early heat generation. From an environmental perspective, replacing cement with fly ash reduces concrete’s overall carbon footprint and diverts an industrial by-product from the solid waste stream. Unfortunately, only about 40% of fly ash is reclaimed for beneficial reuse, with the remaining 60% disposed of in landfills.

In some instances, the reason for only a 40% use rate is the lack of a viable market, but in other instances, it is because the fly ash does not meet the required specification for use in concrete or as soil stabilization. For instance, current specifications limit the carbon content of fly ashes used as partial replacement of cement in concrete to less than 6%. However, Ameren Corporation’s (Ameren) Sioux Power Plant and other plants containing cyclone-fired boilers produce ash with very high levels of unburned carbon, often in the 20 to 50% range. Furthermore, activated carbon injection for mercury control will usually increase the carbon content of fly ashes from conventional boilers, reducing potential sales of ashes from these plants as well. In general, higher carbon contents reduce the reactivity of the ash and the efficacy of air-entraining admixtures.

There are several ranges of potential products depending on the specific applications, such as armoring shorelines, streambeds, bridge abutments, and pilings against scour and ice damage. Scour is particularly critical for bridge abutments and pilings, as it is the number one cause of bridge failures. The proposed project will include evaluation of CCPs from several Ameren power plants, product development, mix design development, and small-scale specimen construction and testing. This research project will serve as a proof-of-concept for synthetic riprap constructed from 90% CCPs.


Relationship to other Research/Projects

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


Transportation-Related Keywords

Bridge Piers, Bridge Substructures, Foundations, Recycled Materials, Riprap, Scour, Waterways.

Technology Transfer Activities

The technology transfer activities will include a final research report and dissemination of the findings through a national conference via technical presentation(s) and publication(s).


Project Deliverables

Test data, guidelines, and specifications for evaluating, selecting, and specifying riprap constructed from 90% coal combustion products.

Anticipated Benefits

Recycling of waste materials into viable construction products.


Project Start Date: 1/1/2013
Project End Date: