BARIUM SOLIDIFICATION/STABILIZATION OF LEGACY FLY ASH A Thesis Presented to The Graduate Faculty of The University of Akron In Partial Fulfillment Of the Requirements for the Degree Master of Science Ariya Reza Fathi May, 2018 BARIUM SOLIDIFICATION/STABILIZATION OF LEGACY FLY ASH Ariya Reza Fathi Thesis Approved: Accepted: Advisor Dean of the College Dr. Stephen Duirk Dr. Donald P. Visco Jr. Faculty Reader Dean of the Graduate School Dr. Christopher Miller Dr. Chand Midha Faculty Reader Date Dr. David Roke Department Chair Dr. Wieslaw Binienda ii ABSTRACT A legacy fly ash pile in Ashtabula County has 20,000 – 30,000 cubic yards of material and contains barium and other various heavy metals. The concentrations of barium in the fly ash are below Regional Screening Levels (RSLs) for soil, but if the barium leached out it would pose a threat to human health. Solidification/Stabilization (S/S) of the ash was investigated with concrete and sulfate. After physical/chemical characterization, the fly ash was identified as class F fly ash, meaning it has no self- stabilizing/cementing characteristics, and had barium concentrations ranging from 0- 1,500 mg/kg. Fly ash was used as a replacement for either cement or fine aggregate at 10-50%. Cement replacement did not achieve a compressive strength above 3,000 psi when using a 6,500 psi concrete mixture when cement to waste ratios exceeded 20% replacement. When fine aggregate replacement was investigated, fine aggregate to waste ratios up to 40% was effective at achieving above 3,000 psi concrete. X-ray diffraction (XRD) revealed the barium present was already in the insoluble barium sulfate form. Therefore, the Toxicity Characteristic Leaching Procedure (TCLP) and accelerated leaching procedure were used to access the potential for barium to leach form the ash and from the concrete mixtures. Barium concentrations never exceeded the U.S. EPA drinking water maximum contaminated level (MCL) for 2 mg/L. Concrete made with ash spiked with 1,500 mg/kg had increased barium leached but still below the primary drinking standard with the highest concentration being 1.79 ± 0.44 mg/L. Therefore, the ash can be handled as solid waste if no beneficial use can be identified. iii ACKNOWLEDGEMENTS I would like to express my sincere gratitude to my advisor, Dr. Stephen Duirk, for his support, direction, and instruction throughout my master’s studies. Thank you to my committee for their support and advice: Dr. Stephen Duirk, Dr. David Roke, and Dr. Christopher Miller. Furthermore, thank you to all my associates, and friends, for all of the collaboration and support during this research: Elizabeth Crafton, Nana Ackerson, Deepak Aryal, and George Carleton. Finally, my deepest appreciation is felt for my parents, Alireza and Cecelia Fathi, and my sister, Sussian Quackenbush for all their support and assistance. TABLE OF CONTENTS Page ABSTRACT ....................................................................................................................... iii INTRODUCTION .............................................................................................................. 1 1.1 Background ............................................................................................................... 1 1.2 Problem Statement .................................................................................................... 3 1.3 Specific Objectives .................................................................................................... 4 LITERATURE REVIEW ................................................................................................... 6 2.1 Background and Regulations .................................................................................... 6 2.2 Exposure to Heavy Metals and Health Effects .......................................................... 8 2.3 Fly Ash Classification and Composition ................................................................. 10 2.4 Barium Chemistry and Health Effects..................................................................... 11 2.5 Concrete Overview .................................................................................................. 13 2.6 Solidification/Stabilization of Heavy Metals .......................................................... 14 3.1 Chemicals and Basic Laboratory Equipment .......................................................... 18 3.2 Fly Ash Characterization ......................................................................................... 19 3.2.1 Fly Ash Homogenization .................................................................................. 19 3.2.2 Sieve Analysis .................................................................................................. 20 3.2.3 X-Ray Diffraction (XRD) Analysis .................................................................. 22 3.2.4 Characterization of Heavy Metals in the Fly Ash ............................................ 24 3.3 Experimental Methods ............................................................................................ 24 3.3.1 Mortar Strength ................................................................................................. 25 3.3.2 Concrete Compressive Strength ....................................................................... 27 3.3.3 Toxicity Characteristic Leaching Procedure (TCLP) ....................................... 29 3.3.4 Accelerated Leach Test .................................................................................... 30 3.3.5 Leached Barium with Sulfate Additions .......................................................... 31 RESULTS AND DISCUSSION ....................................................................................... 33 4.1 Introduction ............................................................................................................. 33 4.2 Mortar compressive strength with effects of ash .................................................... 33 4.3 Concrete compressive strength with ash replacement ............................................. 37 4.4 Leaching Tests results ............................................................................................. 40 4.4.1 Acid Digestion .................................................................................................. 40 4.4.2 TCLP results ..................................................................................................... 42 4.4.3 Accelerated Leaching Test ............................................................................... 54 4.5 Sulfate Stabilization ................................................................................................ 60 CHAPTER V .................................................................................................................... 64 CONCLUSIONS AND RECOMMENDATION ............................................................. 64 5.1 Introduction ............................................................................................................. 64 5.2 Conclusions ............................................................................................................. 65 5.3 Recommendations ................................................................................................... 66 BIBLIOGRAPHY ............................................................................................................. 68 APPENDIX A ................................................................................................................... 72 A.1 Turbidimetric Barium Analysis .............................................................................. 72 A1.1 TCLP Turbidimetric Barium Results ................................................................ 72 A.1.2 Accelerated Leaching Test Turbidimetric Barium Results.............................. 73 A.2 Compressive Strength ............................................................................................. 77 ii A.2.1 Concrete Compressive Strength ...................................................................... 77 iii LIST OF TABLES Table Page 3.2: Mortar composition of cement replacement (C/W) by weight ................................. 26 3.3: Concrete Composition - Fine Aggregate Replacement (S/W) .................................. 27 3.4: Concrete Composition - Cement Replacement (C/W).............................................. 28 A.1 cement replacement (C/W) compressive strength ...................................................... 77 A.2 fine aggregate replacement (S/W) compressive strength ........................................... 77 LIST OF FIGURES Figure Page 3.1: Sieve analysis of fly ash from the Cristal processing plant in Ashtabula, OH. ........................................................................................................................................... 21 3.2: Sieve analysis of the same fly ash performed by Geotechnical Testing Services Inc 22 3.3: XRD results for barian celstine and celestine from the Cristal fly ash. .................... 23 Figure3.4: XRD results of calcite in the Cristal fly ash. .................................................. 23 4.1: Compressive strength of mortar cubes with cement replacement (C/W) 10– 50% on day 3 and 7 compared to the control group. ...................................................................... 35 4.2: Compressive strength of mortar cubes with fine aggregate replacement (S/W) 10– 40% on day 3 and 7 compared