CAEE Department Research Scientist Pieter Billen (PI), Associate Professor Sabrina Spatari (co-PI), and Professor Grace Hsuan (co-PI) (pictured left to right) were recently awarded a NSF Early-concept Grant for Exploratory Research (EAGER) titled “EAGER: Spherical Porous Reactive Aggregates from Coal Bottom Ash,” Grant #1550723. The award amount is $150,000 and the project duration is two years, beginning in September 2015.
This project will focus on producing spherical porous reactive aggregates (SPoRA) for lightweight structural concrete using a waste substance known as coal bottom ash. Coal power plants generate large amounts of bottom ash with no engineering value and a high environmental cost to the society. Bottom ash is the non-combustible, large particle size residue from a furnace or incinerator. The goal of this project is to convert this waste material into value-added reactive aggregates that will improve the cracking resistance of concrete by strengthening the bonding between the aggregate material and hardened cement. A unique sintering process will be used to produce SPoRA, melting the bottom ash to a material that has a crystalline core surrounded by a glassy layer, and subsequently combusting the internal carbon, yielding pores. The glassy layer of the aggregate exhibits similarities to pozzolana, which is a porous type of volcanic ash used to make cement. The projected outcome is that this sintering process will enhance the chemical makeup of the coal ash, increasing its strength and durability as a cost effective and sustainable aggregate for concrete. This material’s response to the sintering process could yield additional research potential pertaining to the use of other lightweight aggregates.
Included in this research will be an evaluation of the savings in energy, greenhouse gas emissions, and landfill waste when this bottom ash is used for construction materials. Researchers will also benchmark its life cycle environmental impacts against conventional lightweight aggregates. The PIs of this project intend to facilitate co-op positions and encourage student participation for freshman and senior design projects at Drexel.