For various construction purposes soils may be improved through the addition of chemical binders. These chemical additives range from waste products to manufactured materials and include mainly lime, fly ash, Portland cement and cement kiln dust (CKD). They bind soil particles together in order to make the soil matrix more water and pressure resistant. Soil binder has two functions: erosion control and soil stabilization. The success of common soil binder applications varies significantly depending on the local conditions and use of stabilized soil.
Lime in certain forms can be used as soil binder. These forms are quicklime, hydrated lime and lime slurry. Lime soil stabilization is suitable for fine-grained clay soils with a minimum of 25% passing the 74mm sieve and a Plasticity Index greater than 10. Additionally, soils containing around 1% or more of organic material or more than 0.3% sulphates may require additional lime and/or special construction procedures. Large water demands associated with lime stabilization may be technical or financial problem in areas without a nearby water source. Hydrated lime is in form of fine particles. This means that lime dust will be generated during soil treatment as well as during road use if road stays unpaved. For this reason hydrated lime soil stabilization is not suitable for populated areas. If the treated material is not protected from runoff, some lime could be washed into the surrounding environment and have an impact by raising the pH.
Portland cement stabilization is not applicable to a wide naturally occurring range of soils due to various particle size distributions. Highly demanding controlling measures are needed during application. This method has high carbon footprint due to energy demanding production of cement and large need for transportation of ex situ material. Off-site soil material, increased amounts of cement or pulverization is usually necessary to satisfy requirements regarding soil particle sizes.
Fly ash as soil binder is categorized into two classes: class C which is self-cementing and class F which is non-self-cementing. Class C contains significant amount of lime (more than 20%), while class F fly ash contains less than 20% lime and thus additives such as Portland cement, quick lime, or hydrated lime must be added, as a source of free lime. Fly ash used as soil binder is potentially harmful to environment as it contains heavy metals and other compounds, which can leach into soil and water bodies. Fly ash can damage vegetation adjacent to the treated areas. Many studies have shown that heavy metals have been leached from fly ash into ground water and underground aquifers.
Cement kiln dust (CKD) occurs in forms of various chemical contents, but for the purposes of soil stabilization, it has to contain certain concentration of lime. Performance of this soil binder is poor in regions with freeze-thaw cycles. Cement kiln dust must be applied carefully to prevent environmental contamination. The toxicity of CKD must be determined for every case separately. The same as with fly ash, stabilization of soil with CKD has caused and may continue to cause, contamination of nearby soils, surface water and ground water.
Traditional soil binders have sincere influences on environment through high carbon footprint and/or natural resources contamination. Soil binders certified environmentally friendly by Environmental Resource Management (ERM) and with low carbon footprint are offered by Global Road Technology (GRT). Good performance of common soil binders is limited to certain range of soils and certain local conditions. GRT soil binder is applicable to all types of soil and treated terrains are more robust, resilient and flexible than terrains treated with common stabilizers. They accommodate movement, moisture and temperature that would crack other surfaces and survive through extreme weather conditions. Construction with GRT products is impressively quick and terrains are operational within a few hours of GRT’s stabilization products being applied. Soil binder by Global Road Technology has accumulative affect, decreasing the needed amount for retreatment during time. Besides stabilizing, GRT soil binder is also good for dust control, thus resolving two different problems by one application.
For more information regarding Global Road Technology or soil binder for erosion control and soil stabilization please contact: https://globalroadtechnology.com/contact-grt/