Strengthening Concrete with Keratin Fibers from Chicken Feathers
Austin Allen
Kennesaw Mountain High School

Table of Contents Research Problem 3 Chapter II: Literature Review 4 Keratin Fibers 4 Concrete 4 Compressive Strength 5 Tensile Strength 5 Chicken Feathers 5 Structure 6 Glossary 6 Chapter III: Methodology 6 Analysis Plan 7 Validity 7 Assumptions 7 Scope and Limitations 8 Chapter IV: Analysis 8 Chapter V: Conclusions and Recommendations 9 References 10

Strengthening Concrete with Keratin Fibers from Chicken Feathers
Chicken feathers are primarily used for making feather meal for farm animals; however, chicken feathers are also used in the production of plastics, fishing flies, biodegradable pots and plastics, bio-diesel fuel, hurricane-resistant roofing, and the stuffing in pillows (Fan, 2008). Applying these uses of chicken feathers to concrete could increase the strength and life of the structure built; for example, an office building could potentially last years longer if the concrete used to construct it (contained more strength) to hold up the structure. Furthermore, the wear and tear of the strength of the building would be approximately the same; however, the capacity to support the structure would be greater due to an increased initial strength (Fan, 2008).
Worrell, Price, Martin, Hendricks, and Meida (2001) reported that approximately five percent of the global carbon dioxide emissions come from the pouring of Portland cement. Consequently, replacing a portion of the cement for feather reinforcements could reduce emissions and reduce ozone depletion. Introducing chicken feather reinforcement to concrete could eliminate approximately 2 million tons of chicken feathers from being dumped in landfills (Hu, Ready, Yan, & Yang, 2011). Averaging thirty to thirty five dollars per ton, to dispose in landfills, the purposeful utilization of feathers would be financially beneficial (Fan, 2008).
Research Problem
There will be a correlational study designed to determine if adding keratin fibers derived from chicken feathers to concrete will increase the compressive strength of the concrete. This could possibly reduce greenhouse gas emissions (Worrel et al., 2001) reduce the costs of feathers in landfills. Conclusions could be useful to architects who are designing a building and deciding the strength concrete should be able to withstand, which is usually about 4500 psi; however, there could also possibly be pavement, driveways, and asphalt that are feather-reinforced that aid the environment by reducing greenhouse gas emissions (Schreiber, 2012, personal communication).
Chapter II: Literature Review
Keratin Fibers
Keratin fibers are natural fibers that compose fingernails and the quill (rachis) of feathers (McGovern, 2000). Because chicken feathers are naturally tensile, with an average tensile strength of 203 mega pascals (Zhan & Wool, 2011), adding them to the concrete, with an average tensile strength of 60 mega pascals (Fields & Bischoff, 2004), will possibly increase the average tensile strength of the concrete. Increasing the tensile strength of the concrete will enable the use of concrete in driveways, sidewalks, and roads by increasing the load limits. However, less Portland cement may be able to utilize more aggregate and fiber reinforcement, reducing greenhouse gases emitted by the pouring of the cement. Huda and Yang utilized the quill and barbs as reinforcement in several different composites. Their research was used to support the fact that the feather reinforcements increased tensile strength of the composites they tested; however, the application of the tensile properties of the feathers must be utilized in the addition to the concrete mixes (2009).
Concrete
Concrete is a mixture of Portland cement, aggregate, and water utilized by most of the construction business, mostly for buildings and civil works, such as bridges, roadways, and dams. Milton Schreiber reported that concrete is relatively low in tensile strength, not being able to stretch far without cracking. In addition, the low tensile strength of concrete is made up for by the compressive strength, which can reach values of over 10,000 pounds per square inch (2012).
Compressive Strength The National Ready Mixed Concrete Association (NRMCA) reported that the compressive strength is the measurement of the maximum load that can be put on the concrete before it fractures. Based on this data, engineers utilize compressive strength in order to calculate exactly how strong the buildings they are designing need to be. Testing the compressive strength of concrete follows the American Society for Materials and Testing (ASTM) standard C 39, standard test method for compressive strength of cylindrical concrete specimens. ASTM C 39 states that a concrete cylinder be made and put into a compression-testing machine and applying a load until the cylinder breaks, which is recorded on the digital display of the testing machine (2003). Forrest Waters of Geo-Hydro Engineers stated that the specimens cure for a period of 28 days in a 100% humidity and 70 degree F environment, because the compressive strength after 28 days of curing is an industry-standard specification, where curing for 7 days may yield 50%-80% of the twenty-eight day compressive strength (2012).
Tensile Strength
Tensile strength is defined as the force required to pull something, such as a rope, wire, or structural beam, to the point where it breaks. Milton Schreiber stated that tensile strength of concrete is about one tenth of compressive strength, because concrete is naturally lacking in tensile properties, while its compressive properties are not (2012). Laboratory tensile strength of concrete is typically determined by a flexural test. This test utilizes a concrete beam that is rested on two points, with a load that compresses the beam exactly halfway between the points, which is in the exact middle of the beam. Typical values of tensile strength range from 2 to 5 MPa (Raphael, 1984).
Chicken Feathers Purslow and Vincent measured the elastic properties of pigeon feathers and reported that the values ranged from 7.5-10 giga pascals on dehydrated feather shafts. Using these values, the elasticity, similar to tensile strength, is relatively high for bird feathers, especially pigeon. However, the results are applied to assume that the elasticity is relatively the same to that of chicken feathers. Due to this natural elasticity, the feathers can possibly pose a solution to the low tensile strength of concrete, allowing for more strengthened buildings and structures (1978).
Structure
Feathers are comprised of three main components: rachis, barbs, and barbules. The rachis is often referred to as the quill of the feather, for which it is often used. The rachis is composed of a keratin shaft, filled with keratin fibers. Barbs are branches joined to the rachis, increasing surface area. Branching from the barbs are barbules, which are microscopic self-organizing structures that allow the feather to have a low specific gravity and density (Fan, 2008)).
Glossary
Aggregate: material, usually crushed rock or sand, that is mixed with cement to create concrete
Curing: placing the concrete in a moist environment, after the pouring of the concrete, to increase its hardness and strength gradually Keratin fibers: fibrous protein found in the outer layer of skin, in hair, nails, feathers, hooves, etc.
Load limits: the maximum weight of loading that is applied to concrete before fracturing
Specific gravity: ratio of density of a substance to the density of a reference substance
Tensile strength: the resistance of a material expresses as the greatest longitudinal stress it can bear without fracturing
Chapter III: Methodology
A correlational study will be conducted to gather information about whether chicken feather fibers (keratin fibers) affect the compressive and tensile strength of concrete. In order to test the compressive strength, Quikrete will be mixed and made ready for making cylinders. However, the researcher will simulate the strength of chicken feathers by utilizing coffee stirring straws, which Milton Schreiber reports are similar to the quill of chicken feathers (2012). Nine cylinders will be made: three 4x8 without reinforcement, three 4x8 inch cylinders with straw reinforcement, and three 6x12 inch cylinders with straw reinforcement. After the cylinders have remained in the lab for one day, the researcher cuts the concrete from the cylinders, and places them inside a 70 degree Fahrenheit room to cure for seven days. After the cylinders have cured, a machine, which measures the compressive strength of concrete, will assist in measuring the strength of the different specimens.
Analysis Plan
The researcher will report the data as ratios, comparing the strength of the reinforced concrete to the strength of the control group of concrete without reinforcement. By utilizing this method, there will be a more visually pleasing graph, clearly illustrating the change in compressive strength.
Validity
Validity is maintained by constructing a normal probability plot of the diameters of the straws, which proved to be normally distributed. However, one variable that would cause problems in this method is the length of the straws that were in the concrete and how many there were compared to the other cylinders.
Assumptions
Throughout the experiment, the assumption that the straw diameters follow a normal distribution, as do the diameters, is to be maintained.
Scope and Limitations There were not enough companies willing to distribute chicken feathers in order to complete this research; therefore, the experiment with chicken feathers had to be simulated with stirring straws. If the researcher were given more time, then the researcher could have obtained more feathers, allowing for more accurate results and results that are more reliable.
Chapter IV: Analysis The table below (Figure 1) notes the compressive strength of the three straw-reinforced concrete samples and the average of the control samples. A one-sample t test was conducted on the ratios of f'cf'ccontrol for samples 1 through 3, where the hypothetical mean was 1.0. For the test, a p-value of .0096 was obtained for a 95% confidence interval, showing that there is a statistically significant difference between the mean ratio of the three samples and the control ratio of one. As predicted before, there is a statistically significant difference between the experimental samples and the control samples; however, the actual results were in the opposite direction of the predicted results.

Figure 1: Strength of Straw-reinforced Concrete Sample | Size (in x in) | f'c (psi) | f'cf'ccontrol | 1 | 4 x 7.8 | 1340 | .531 | 2 | 4 x 7.8 | 880 | .349 | 3 | 4 x 7.8 | 930 | .368 | Control (average) | 4 x 7.8 | 2523.33 | 1 |

Chapter V: Conclusions and Recommendations The results of the research provided evidence that there was definitely a significant decrease in compressive strength of the experimental group of concrete. This suggests that using straws in the concrete has an effect to lower the compressive strength of the concrete. Results obtained from this research reject the hypothesis initially posed, which suggested that the strength will increase by being statistically significant with the addition of straw reinforcement; however, the strength of the concrete decreased, as shown by figure 1, significantly with the implementation of straws in the concrete samples. There are logical explanations for why the variation between the experimental and control groups differed so much. The straws did not stick in the concrete as much as expected, possibly due to the slick texture on the outside of the straw. There were apparent voids in each sample of concrete, which could have caused a massive decrease in compressive strength due to empty space that concrete could have filled. Furthermore, not as much concrete filled the straws, if any, than anticipated; the problem with the straws not filling with concrete is the straws would not be reinforced, and there would be air pockets inside the straws. There is room for improvement in the aspect of the type of reinforcement. If time permitted, the researcher could gather enough chicken feathers from poultry processing plants to implement them in the concrete to test whether the keratin would benefit the concrete’s strength or be a detriment to the strength. Testing with the feathers will provide more of a solid conclusion that can be carried over to other research, and possibly inspire those in civil engineering to test or use feather-reinforced concrete.

References
Fan, X. (2008). Value-added products from chicken feather fibers and protein. Retreived from: http://etd.auburn.edu/etd/bitstream/handle/10415/17/Fan_Xiuling_15.pdf?sequence=1
Fields, K., & Bischoff, P. H. (2004). Tension stiffening cracking of high-strength reinforced concrete tension members. American concrete institute, 101(4), 447-456. Retrieved fromhttp://www.concrete.org/PUBS/JOURNALS/OLJDetails.asp?Home=SJ&ID=13330
Hu, C., Reddy, N., Yan, K., & Yang, Y. (2011). Acetylation of chicken feathers for thermoplastic applications. Journal of Agricultural and Food Chemistry, 59(19), 10517–10523. doi: 10.1021/jf2023676
Huda, S., & Yang, Y. (2009). Feather fiber reinforced light-weight composites with good acoustic properties.JOURNAL OF POLYMERS AND THE ENVIRONMENT, 17(2), 131-142. doi: DOI: 10.1007/s10924-009-0130-2
McGovern, V. (2000). Recycling poultry feathers: More bang for your cluck. Environmental Health Perspectives, Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/
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Purslow P.P., Vincent J.F.V. (1978). Mechanical properties of primary feathers from the pigeon. J Exp Biol; 72:251–60.
Raphael, J. M. (1984). Tensile strength of concrete.American concrete institute, 81(2), 158-165. Retrieved from http://www.concrete.org/PUBS/JOURNALS/OLJDetails.asp?
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Worrell, E., Price, L., Martin, N., Hendricks, C., & Meida, L. O. (2001). Carbon dioxide emissions from the global cement industry. Annual Reviews, 26, doi: 10.1146/annurev.energy.26.1.303
Zhan, M., & Wool, R. P. (2011). Mechanical properties of chicken feather fibers. Polymer composites, 32(6), 937-944. doi: 10.1002/pc.21112