Suitability of β-Keratin from Chicken Feathers as Surface Sealant for Dust Control on Gravel Roads

Abstract

Dust from unpaved roads has adverse effects like health and costly routine maintenance of re-grading and re-gravelling of unpaved roads for smooth flow of traffic. This study focused on suitability of β-keratin (from chicken feathers) as surface sealant for dust control on gravel roads. It involved evaluating the mechanical, chemical, and physical properties of β-keratin, gravel properties when mixed with β-keratin and cost implications of using β-keratin gravel. In previous studies, cement-feather mix for concrete works containing 5% to 10% fiber or ground feather (with β-keratin) at water-cement ratio (W/C) of 0.60 showed good workability, allowing formation of a paste that coated all feather fibers or particles with cement. β-keratin is a hygroscopic product, extracted from chicken feather fibers by analysis of amino acids. The chemical properties were determined by distillation of residue using high performance thin layer chromatography (HPTLC) method. The Physical properties (absorbance and wavelength) were determined using Ultraviolet Visible Spectrometer (UV-ViS) method. For test of its mechanical properties, using an emulsifier carboxymethyl cellulose (CMC) to enhance the tests; the viscosity test was conducted as per ASTM D2170 and AASHTO T201 standards, the penetration test was conducted as per ASTM D5 and AASHTO T49 standards. Finally, the penetration test was conducted as per ASTM D113 and AASHTO T51 standards. For comparisons of gravel properties containing β-keratin from chicken feathers as an alternative to MC30 sealants for dust control in gravel roads, california bearing ratio (CBR), optimum moisture content (OMC) and maximum dry density (MDD), and finally atterberg limits were carried out on β-keratin mixed with gravel at 0, 1.5, 2.0, 2.5 and 3.0% by dry weight of gravel respectively. Also, cost analysis for producing β-keratin from chicken feathers and its comparisons with MC30 sealants in gravel roads was done. The absorbance and wavelength of β-keratin solution of 1:10 (1 ml proportion of β-keratin to 10 ml proportion of distilled water) concentration gave results of 0.4295 and 275.4 nm respectively. β-keratin is a protein polymer made up of amino acids as building blocks, a hydrocarbon with a chemical formula C28H48N2O32S4 which melts and burns easily under fire. 1 litre of β-keratin mixed with CMC (55 and 65 g/liter) yielded acceptable results of between 30-60 Kg/s.m viscosity at 600c as per ASTM D2170 and AASHTO T201. Optimum percentage mix of β-keratin in gravel mixture was found to be 2.0% giving a CBR value of 57% which was acceptable as per BS 1377-9:1990, had the least swell (0.3%) at MDD of 1850 kg/m3 (above 1500 kg/m3), and the OMC corresponding was taken as 15.8% all acceptable as per BS 1377: 2-1990. The cost of extraction of pure 1 litre of β-keratin was found to be kshs.172.40, cheaper than MC30 currently (Kshs. 239- Kshs. 283) depending on the Kenyan region. Also, it was established that when one litre of pure β-keratin is dosed with 55 and 65g of CMC the results meet range of specification, and this was the recommended dosage rate. Also, 10% dilution with water for use as surface sealant on gravel roads was recommended for better results as per the tests results, but more field tests and numerical analysis on the results achieved was recommended.