Soil Reinforcement with Recycled Carpet Wastes

Abstract

A root or fibre-reinforced soil behaves as a composite material in which fibres of relatively high tensile strength are embedded in a matrix of relatively plastic soil. Shear stresses in the soil mobilize tensile resistance in the fibres, which in turn impart greater strength to the soil. A research project has been undertaken to study the influence of synthetic fibrous materials for improving the strength characteristics of a fine sandy soil. One of the main objectives of the project is to explore the conversion of fibrous carpet waste into a valueadded product for soil reinforcement. Drained triaxial tests were conducted on specimens, which were prepared in a cylindrical mould and compacted at their optimum water contents. The main test variables included the aspect ratio and the weight percentage of the fibrous strips. The results clearly show that fibrous inclusions derived from carpet wastes improve the shear strength of silty sands. A model developed to simulate the effect of the fibrous inclusions accurately predicts the influence of strip content, aspect ratio and confining pressure on the shear strength of reinforced sand.

References

Al-Refeai, T. (1991): Behavior of granular soils reinforced with discrete randomly oriented inclusions . Journal of Geotextiles and Geomembranes, 10, 319–335 .

Andersland, O.B. & Khattak, A.S. (1997): Shear strength of kaolinite/fiber soil mixtures . In: Proceedings of the International Conference on Soil Reinforcement, Paris, France.

Consoli, N. & Prietto, D.M. (1998): Influence of fiber and cement addition in sandy soils . Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 124,

Frost, J.D., Wang, Y., Murray, J. & Jones, A. (1999): Utilization of carpet, textile & apparel waste for soil reinforcement . In: Proceedings of the Fourth Annual Conference on Recycling of Fibrous Textile and Carpet Waste, Dalton, GA.

Gardner, H.C. (1995): Carpet recycling technology . International Fiber Journal, August, 36 .

Gray, D.H. & Maher, M.H. (1989): Admixture stabilization of sands with discrete, randomly distributed fibers . In: Proceedings of XIIth International Conference on Soil Mechanics and Foundation Engineering Vol.2, Rio de Janeiro, Brazil, pp. 1363–1366 .

Gray, D.H.Ohashi, H. (1983): Mechanics of fiber reinforcement in sand . Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 108, 335–353 .

Gray, D. & Al-Refeai, T. (1986): Behavior of fabric versus fiber reinforced sand . Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 112, 804–820 .

Hoare, D.J. (1979). Laboratory study of granular soils reinforced with randomly oriented discrete fibers . In: Proceedings of the International Conference on Use of Fabrics in Geotechnology, Paris, France, pp. 47–52 .

10.

Ladd, R.S. (1978): Preparing test specimens using undercompaction . Geotechnical Testing Journal, ASTM, 1, 16–23 .

11.

Maher, M.H. & Ho, Y.C. (1994): Mechanical properties of kaolinite/fiber soil composition . Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 120, 1380–1393 .

12.

Maher, M.H. & Gray, D.H. (1990): Static response of sand reinforced with distributed fibers . Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 116, 1661–1677 .

13.

McGown, A. et al. (1978): Effect of inclusion properties on the behavior of sand . Geotechnique, 28, 323–346 .

14.

Ranjan, G., Vasan, R.M. and Charan, H.D. (1996): Probabilistic analysis of randomly distributed fiber reinforced soil . Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 122, 419–426 .

15.

Schut, J.H. (1995): Big plans for carpet . Plastics World, December, 25 .

16.

Shewbridge, S.E. & Sitar, N. (1989): Deformation characteristics of reinforced sand in direct shear . Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 115, 1134–1147 .

17.

US Environmental Protection Agency (1990): Report PB90-215112, Springfield, VA.

18.

Verma, B.P. and Char, A.N. (1978): Triaxial tests on reinforced sand . In: Proceedings of a Symposium on Soil Reinforcing and Stabilizing Technique, Sydney, Australia, pp. 29–39 .

19.

Wang Y. (1997): Carpet waste for soil stabilization . In: Proceedings of Second Conference on Recycling of Fibrous Textile & Carpet Waste, May, Atlanta, GA.

20.

Wang, Y., Cho B.S. &. Zureick A.H. (1993): Fiber reinforced concrete using recycled carpet industrial waste and its potential use in highway construction . In: Proceedings of the Symposium on Recovery & Effective Reuse of Discarded Materials & By-Products for Construction of Highway Facilities, Denver, CO, pp. 4.111–4.117 .

21.

Wang, Y., Zureick, A.H., Cho, B.S. & Scott, D.E. (1994): Properties of fiber reinforced concrete using recycled fibers from carpet industrial waste . Journal of Material Science, 29, 4191–4199 .