Chemical soil stabilization has been widely used in many states and countries. This process comprises of the incorporation of hydraulic binders, such as cement, and lime that in turn improve the physical properties of the soil.
How Does It Work?
Chemical stabilization eliminates the need to eradicate naturally weak soil sub grade and replace it with processed and quarried granular material. The soils best suited to this method usually include slit and clay, and have the ability to lose strength as the water content raises. Once treated with cement or lime, the improvements to the properties of the soil are vast and some of the most important improvements include decreased susceptibility to increased water content, increase in strength to volume changes, and enhanced durability.
This method isn’t only cost effective, but also reduces the demand for non-renewable resources, minimizing the environmental footprint of a constructional project. Though the method has been proved and widely adopted, it is still not utilized throughout the world, but only in European and US countries, not in Canada.
Need for Chemical Soil Stabilization
The successful construction of roads needs the construction of a structure, which is capable of carrying imposed traffic loads, like few important layers, such as sub grade and actual foundation. Where the sub-grade is initiated in a weak soil, this material is replaced by a stronger granular material. This technique can be time consuming and costly too. Where aggregates are scarce, the use of non-renewable sources is identified as non sustainable, especially if transport distance is important. In few countries, a landfill tax and aggregate tax is applied to construction projects, thereby making this removing sub-grade from weak soil and replacing it with stronger material process less economically viable.
How Does Chemical Stabilization Work?
Chemical stabilization is an alternative option to this ‘remove and replace’ technique that avoids the need to replace the material, ensuring that the engineering properties and performance of the host material is improved to allow for chemical stabilization within the pavement structure. It is a method in which hydraulic binders are intimately mixed with an appropriate quantity of water into the soil. The most commonly used binders include hydrated lime, quicklime, cement kiln dust (CKD), fly ash, and Portland cement. CKD and fly ash are usually used as partial replacement for the more expensive binders, like Portland cement and lime. Once mixed into the soil, a chemical reaction takes place, which modifies and stabilizes the material.
Historic Perspective
Romans were the first ones to use this method; weak soils were combined with volcanic ash containing silica, alumina, and lime to enhance its bearing capacity. The modern treatment procedures began in late 1950s in the United States when clays were mixed with hydrated lime. The innovation and development of construction components since these early years has seen noteworthy utilization of the process globally.
On the Whole
It is the most effective method as the inherently weak compounds are removed and replaced with materials that have superior engineering traits. The mineralogy and type of the soil will say all about the binder, which is utilized. To identify the binder concentration and type, laboratory blend designs are performed. Many chemical reactions take place when hydraulic binder is mixed with soil and appropriate water content, including cat-ion exchange, flocculation, and agglomeration. Once the soil is modified, adding sufficient hydroxyl and calcium ions, strong stabilization of the soil can totally transform its abilities.
So, next time when you try to deal with soil erosion, and want to carry out any kind of soil stabilization, give it a try to the chemical soil stabilization methodologies.
