Bottom Ash as Aggregate Replacement in Concrete

Status

Sequential Number

Identification Number

Matching Research Agency

 Ameren Corporation

Principal Investigator

Student Involvement

One graduate student

Project Objective

The objective of the proposed study is to evaluate bottom ash as a partial or total replacement of the fine and coarse aggregate in concrete. This program will characterize and evaluate available bottom ash sources as potential replacement of both the fine (sand) and coarse (stone) natural aggregates traditionally used in the construction of bridges, roadways, culverts, retaining walls, and other transportation-related infrastructure components.

Project Abstract

Although relatively unreactive compared to fly ash, bottom ash does have the potential to replace either all or a portion of the natural aggregates used in concrete. This study will evaluate the fresh and hardened properties of concrete containing bottom ash as a partial or total replacement of the fine and coarse aggregate. The properties that will be studied include workability, finishability, air content, air-void system, strength gain, and durability. The investigation will begin with mortar mixes and then, based on the results, progress to concrete mixes and evaluation of the properties mentioned.

In particular, the study will focus on durability of the final material, as the porous surface structure of most bottom ashes has the potential to negatively impact freeze-thaw resistance of the concrete. The study will also include a complete physical, chemical, and mineralogical characterization of the different bottom ash sources to aid in the investigation.

Sustainable alternatives to traditional concrete construction are necessary to address the current state of our nation’s crumbling infrastructure. The use of bottom ash as aggregate replacement in concrete will reduce the need for virgin materials and remove a material from the solid-waste stream, increasing the sustainability of concrete construction. Consequently, the concretes developed in this study will be compared to traditional concretes used in infrastructure-related applications, such as bridges, roadways, culverts, and retaining walls. These comparisons will determine whether concrete containing bottom ash offers a viable, sustainable alternative to help rebuild our nation’s infrastructure.

Anticipated Benefits

Reduction in concrete’s carbon footprint and removal of material from the solid waste stream. Bottom ash is not currently used as a recycled material to the same extent as fly ash and, as a result, the vast majority is disposed of in landfills. 

Milestones

Project Deliverables

Test data, guidelines, and specifications for the use of bottom ash as aggregate in concrete in transportation-related infrastructure.

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).

Transportation Research Board Keywords

Aggregate, Concrete, Durability, Fly Ash, Supplementary Cementitious Materials, Sustainable Development, Transportation Infrastructure