In the contemporary world where urbanization is spreading fast across all kinds of territories and where buildings and urban constructions are placed in the areas that used to be rural or empty, soil stabilization is critical. In particular, soil stabilization stands for the processes and activities that are implemented for the purpose of securing the soil on which construction will be carried out in order to ensure its stability.
Namely, soil stabilization is required for the purpose of preventing movements and swelling of soil so that it serves as solid support for pavements and foundations of buildings. In turn, the constructions placed on stabilized soil are safe for people who use them and will serve for long periods. All in all, stabilized soil carries numerous benefits, some of which include lower permeability and reduced plasticity.
These qualities allow the areas with stabilized soil to be accessed for construction and use in any kind of weather without becoming difficult to navigate. Also, soil stabilization helps to save costs for pavements as the thickness of pavements placed on supported areas can be significantly lower than on the unsupported ground. Finally, the stabilized soil has a higher level of resistance, which makes it more efficient, sustainable, and practical for use.
The process of soil stabilization includes the addition of stabilizers that are selected based on the composition of soil on the areas used for reclamation. In order to determine the most suitable additives that will be used as stabilizers, it is necessary to study the type of soil that will be processed. One of the types of additives used for the improvement of physical qualities of soil is represented by waste materials. They provide a wide range of physical properties for different construction and engineering projects and help reuse and recycle solid waste generated by the modern population and production.
Waste Materials as Stabilisers
Waste materials such as fly ash, rice husk ash, and phosphogypsum have been used in soil stabilization for many decades (Jaya et al. 2011; Subbarao et al. 2011). However, the growing cost of soil stabilization using these materials encouraged the search for new types of stabilizers that could be more affordable and just as effective. As a result, plastic waste, bamboo, rubber tires chips, polyethylene waste, and fiber materials started to be explored as means helping to enhance the supportive and bearing properties of soils. As it was mentioned previously, soils are highly diverse, inhomogeneous, and unpredictable. A thorough investigation and a series of tests are needed in order to select the suitable materials to be used as support.
In addition, different areas have varied requirements as to what kinds of impacts the stabilized soils are expected to withstand. For instance, soil stabilization in hot countries needs the enhanced ground to endure severe heat; in such cases, plastic waste stabilizers can help (Kumari, Sonthwal & Rattan 2016). In a rainy and humid climate, soil used for construction needs to have low permeability and remain solid regardless of the influence of water, which makes copper slag one of the suitable options (Kumari, Sonthwal & Rattan 2016).). Freezing and thawing are the processes that destroy soils and pavements in countries with colder climates where Green Bayburt Stone waste can be employed (Yilmaz, Kamiloğlu & Şadoğlu 2014). In some areas, flexible pavements are a necessity as well.
Types of Stabilisers
Rice husk ash (RHA) is one of the commonly used waste materials used as soil stabilizers. It is comprised of one of the common and widely spread kinds of waste that are difficult to dispose of and can cause various negative effects on the environment and human health. In that way, the use of RHA in for the enhancement of the physical properties of soil is an effective way to recycle it. RHA can be used separately or as a part of admixture with cement and lime. It provides excellent support that is enduring and long-lasting (Singh & Mittal, 2014).
Another popular stabilizer is fly-ash. This is produced by electric generating facilities powered by coal. This byproduct is generated in large quantities and requires a proper way of reusing. In contrast to RHA, fly-ash does not have a good binding capacity and cannot be used as a stabilizer on its own (Makusa 2012). Fly-ash is used as a part of mixtures with activators that boost its strengths and cementitious qualities.
Green Bayburt Stone (GBS) is a waste material that occurs in the mining of Bayburt stone due to a high rate of rejection. It is used in soil stabilization due to its pozzolanic qualities, which make it good as enduring the destructive freezing and thawing processes (Yilmaz, Kamiloğlu & Şadoğlu 2014). GBS is used in combination with lime for the best results. Another popular type of material used as stabilizers is represented by solid plastic waste and plastic fiber.
These materials are added in mixtures with cement and in bituminous mixtures (Kumari, Sonthwal & Rattan 2016). They help create flexible and well-enduring surfaces that withstand high temperatures and have the excellent load-bearing capacity. Plastic fiber can be employed for the fortification of concrete. Apart from providing good soil stabilizing properties, plastic waste also helps reuse and recycle a harmful and ubiquitous kind of solid waste that is cheap and easy to access is large quantities.
References
Jaya, D, Ashraf, A, Sunil, & Veena, M 2011, ‘Soil stabilization using raw plastic bottles,’ in Proceedings of Indian Geotechnical Conference, Kochi, pp. 489-492.
Kumari, B, Sonthwal, V & Rattan JS 2016, ‘Soil stabilization by using waste material: a review,’ International Journal of Engineering Science Invention Research & Development, vol. 3, no. 1, pp. 85-90.
Makua, GP 2012, Soil stabilization methods and materials. Web.
Singh, M & Mittal, 2014, ‘A review on the soil stabilization with waste materials,’ International Journal of Engineering Research and Applications, pp. 11-16.
Subbarao, GV, Siddartha, D, Muralikrishna, T, KS, Sailaja, KS & Sowmya, T 2011, ‘Industrial wastes in soil improvement,’ Civil Engineering, vol. 2011, pp. 1-5.
Yilmaz, F, Kamiloğlu, HA & Şadoğlu, E 2014, ‘Soil stabilization with using waste materials against the freezing-thawing effect,’ Acta Physica Polonica, vol. 128, no. 2, pp. 392-394.