Joshua Baker

11th Grade

February 11, 2014

RMSST Student

Showcase

Optimization of Concrete Composites using CCBs as Additives

• Each year, hundreds of millions of tons of coal-fired power plant waste is dumped into landfills

• Has potential to leach into groundwater and contaminate water supplies

• Little is ever reused, though much of it can be

• Carbon footprint can be greatly reduced if some byproducts are reused

Introduction

Image 1: A coal waste landfill in Henrico County, VA

Purpose

• To determine the structural impact of coal combustion byproduct additives at the “optimal” replacement rate, 25-30%

Rationale

• Management of CCBs in coal-reliant nations must be addressed before they pose an environmental hazard

• Concrete is a versatile building material with potential for integration of numerous additives

• Successfully using CCBs as additives at a 25% replacement rate would greatly decrease human environmental impact and provide a strong, environmentally responsible composite that can be adapted to new uses

Introduction

• Independent Variable: Concrete Composition

• Dependent Variable: Concrete Performance

• In an ongoing experiment, it is being determined whether it is plausible to create cement-free concrete using geopolymers, eliminating the CO2 released when normal concrete hardens

Background

Procedures – Concrete Mixing

Image 2: Mixes 1 (Portland Cement, Sand, Stone) and 2 (75% Portland Cement, 25% Class C Fly Ash, Sand, Stone) in their mid-mixing stages.

Procedures – Air Content

Image 3: Unit Weight container with Air Content gauge attached

Procedures - Slump

Image 4: Slump test; the bottom of the metal rod (right) is used as the starting point for determining how far the concrete falls and spreads out.

Procedures – Compressive Strength

Image 5: The hydraulic press, used for compressive strength testing (right); an example of Class 5 fracturing (left) and Class 2 fracturing (center).

Control Fly Ash Bottom Ash0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

54606.6666666667 55350

42946.6666666667

79870

93276.67

73530

Average Ultimate Load

Ultimate Load (lb) - Day 7Ultimate Load (lb) - Day 56

Figure 1: The average ultimate load of each composite mix, which is a direct measurement the maximum load a sample can withstand before fracturing.

 

Control Fly Ash Bottom Ash0

1000

2000

3000

4000

5000

6000

7000

8000

4343.33333333333 4403.33333333333

3416.66666666667

6356.67

7420

5850

Average Compressive Strength

Compressive Strength (psi) - Day 7Compressive Strength (psi) - Day 56

Figure 2: The average compressive strength of each composite mix, a calculated measurement of the maximum force a sample can withstand before fracturing.

Control 25% Class C Fly Ash 25% Bottom Ash0

0.5

1

1.5

2

2.5

2

1.2

2.1

Air Content

Mix Type

Air

Conte

nt

(%)

Figure 3: The percentage of air entrained in a unit of concrete, 1 ft3. The percentage of air in a mixture contains impacts both the flexural strength and the overall weight of the concrete.

Control 25% Fly Ash 25% Bottom Ash0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

3.5 3.5

4.25

Slump

Mix Type

Slu

mp (

inches)

Figure 4: The measured slump of each concrete mix, a measurement of mix consistency. This variable is most significant when comparing mixes of similar composition.

Control 25% Class C Fly Ash 25% Bottom Ash136

138

140

142

144

146

148

150

152

147.6

146.4

141.7

149.8

150.7

145.8

Density

Target DensityMeasured Density

Mix Type

Densit

y (

lb/f

3)

Figure 5: The calculated (blue) and target (red) densities of each mix, a measure of the mass of a cubic foot of a given mix design. It is used when determining factors that influence the strength of concretes.

• Group 2 (Fly Ash additive) outperformed control in ultimate load/compressive strength tests at both testing times

• Group 3 (Bottom Ash additive), on average, performed either similarly to (Day 56) or worse than (Day 7) the control in ultimate load/compressive strength tests

• Fly ash group continues to show trend of gaining strength over long periods of time

Data Trends and Analysis

• Based on the currently available data from experimentation and from data analysis, Mix 2 performed within the 20% margin of similarity to the control for its average compressive strength and ultimate load, thus rejecting the null hypothesis

• The data gathered for Mix 3 performed outside of this margin, supporting the null hypothesis

• Final ultimate load and compressive strength data will be collected at the 90 Day curing point

Discussion and Conclusion

• Determining the chemical leaching capability of CCBs and their flammability at different burn stages

• Investigating the environmental effects of using CCB-containing concrete composites

Future Research

RMSST:

• John Hendrix

TEC Services:

• Steven Maloof and Technicians

• Brian Smith

• Brian Wolfe

Ernst Enterprises of Georgia:

• Tony Dowdy

Acknowledgements

Bumjoo, K., Prezzi, M., & Salgado, R. (2005, July). Geotechnical properties of fly and bottom ash mixtures. Retrieved from https://engineering.purdue.edu/~mprezzi/pdf/10900241_geotechnical_properties.pdf

Concrete tests. (2003, September 01). Retrieved from http://www.dot.state.mn.us/materials/manuals/concrete/Chapter5.pdf

EPA – Coal Combustion Products. (May 2013). Retrieved from http://www.epa.gov/wastes/conserve/imr/ccps

Kalyoncu, R. S. (2000). Retrieved from website: http://minerals.usgs.gov/minerals/pubs/commodity/coal/874400.pdf

Kosmatka, S. H., & Wilson, M. L. (2011). Design and Control of Concrete Mixtures: The Guide to Applications, Methods, and Materials. (15th ed.). Washington, DC: Portland Cement Association.

Mohanty, M. K., & Kumar, S. U.S. Environmental Protection Agency, (2011). Sustainable Utilization of Coal Combustion Byproducts through the Production of High Grade Minerals and Cement-less Green Concrete. Retrieved from website: http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/9588/report/0

Sahu, S. P. (2010). Characterization of Coal Combustion By-products (CCBs) for their Effective Management and Utilization. (Bachelor's thesis) Retrieved from http://ethesis.nitrkl.ac.in/1708/1/final_thesis_edited.pdf

References

• Nominated to attend the Governor’s Honors Program for Chemistry

• Prestigious program that bolsters student

interest in their nomination areas

• This program will provide valuable insight into

my field of interest, and help when deciding

how future years will be spent

Achievements - GHP

• 4 on the AP Biology Exam

• 3 on the AP World History Exam

• Shows how my work ethic and study skills have improved as my time at Magnet progressed

Achievements – AP Exams