The Evolution of Soil Stabilisation
From Ancient Civilisations to Modern-Day Construction
The remediatory technique of soil stabilisation has been implemented across the construction and building sectors for thousands of years, and 2000-odd years later, it’s just as prevalent as ever.
In fact, early examples of this technique date back as far as Mesopotamia and Ancient Egypt – the suspected pioneers of this technique – before being later adapted and expanded by the Greeks and Romans to ferry people across even the harshest of environments. Many sections of our roads today were built on the basis of this very technique!
Although there have been advancements in soil stabilisation since these ancient civilisations, the fundamental purpose of the practice remains unchanged, and its importance remains paramount even today. Soil serves as the foundation for any construction project, whether it involves road building, property maintenance, or various other endeavours. While ancient civilisations had their methods, how has soil stabilization evolved in the 21st century?
To shed light on this, John Rodgman, managing director of the geotechnical drilling company, Borehole Solutions – has offered his insight.
The Three Main types of Soil Stabilisation
The soil stabilisation process involves the addition of various stabilising agents to the soil, such as cement, lime, and fly ash, to improve its strength and load-bearing capacity, reduce its susceptibility to erosion, and improve its resistance to weathering. Today, soil stabilisation can be summarised into three main categories.
Biological Stabilisation
This stabilisation category is predominately used in areas where the soil is particularly prone to damage from the weather. Otherwise known as forestation, biological soil stabilisation involves planting trees, seedlings, and plants in barren areas with the purpose being that of erosion control.
Where this technique is an entirely natural and organic process, other stabilisation techniques should accompany it throughout the plant’s early life. Without this, these plants are at serious risk of their development being hindered, or even being carried away by strong winds or water flow.
Physical Stabilisation
This technique modifies the size and natural characteristics of soil particles with the intention of increasing an area’s gradation and solidity. There are five main techniques incorporated under physical stabilisation:
- Compaction: Air voids present in the soil are removed to improve its load-bearing capacity.
- Pre-wetting: A moisture-rich environment is created for the soil to absorb water, swell, and create a non-harmful and constantly maintained soil heave.
- Soil reinforcement: Weak soil is stabilised using interlocking fibrous materials to enhance the stability of the soil.
- Wetting dry cycles: Soil is repeatedly saturated with water until it swells, and then dried back to its original moisture content until the point where an equilibrium state is reached.
- Solid wastes: Municipal waste in the form of plastic, glass powder, e-waste, plant waste, and more are added to the soil.
Chemical Stabilisation
Where chemicals can be prominent in other forms of soil stabilisation, as the name suggests, this method relies on it more heavily than the rest. Stabilisers such as lime, fly-ash and cement are added to soil particles to increase the overall resistance of the area.
Upon being exposed to water, a chemical reaction transforms the area, strengthening it and improving its resistance to even the most extreme of weather conditions. How effective this process is, however, is dependent on the type of chemical reaction that occurs, so matching the right stabilisers to their corresponding soil type is essential.
How Soil Stabilisation Benefits a Project’s Durability and Longevity
Stabilising soil using the appropriate corresponding materials significantly improves its strength and load-bearing capacity. This is a particularly crucial consideration for projects involving heavy structures such as buildings, bridges, and highways. By enhancing the soil’s ability to withstand applied loads, it significantly reduces the risk of settlement and structural failures occurring over time. Failure to adequately reinforce the soil can lead to unevenness and even deformities within the project’s foundations, compromising its long-term stability.
Furthermore, soil stabilisation techniques are particularly fruitful in enhancing the durability of projects within particularly challenging environmental conditions. In regions with strong winds or high groundwater levels, for example, stabilising soil helps to prevent excessive seepage whilst ensuring the project’s structural integrity remains intact. Similarly, in areas prone to freeze-thaw cycles, soil stabilisation reduces the risk of frost heave and its corresponding damage to foundations, pavements, and other structures.
Cost-saving applications
Soil stabilisation techniques bring about the potential for significant cost saving throughout a project’s lifecycle. By enhancing the relevant properties of the soil, and addressing any relevant challenges early on, the need for costly and time-consuming remediatory solutions can be greatly reduced, or even eliminated in the long term.
Rather than resorting to costly alternatives such as shipping and placing large quantities of aggregates or other fill material, for example, soil stabilisation enables you to use locally available soils. By treating and modifying existing soil, it becomes suitable for construction purposes, therefore reducing the need for additional materials and the associated expenses they bring with them.
Also, soil stabilisation works to enhance the long-term durability of the project, therefore resulting in a reduced frequency of maintenance and repair work. The treated soil is better equipped to resist setting, erosion, and other damaging effects. Because of this, fewer ongoing maintenance costs are required, not to mention the associated costs involved should serious structural failures occur, ensuring noticeable savings in the long run.
