Success starts with a solid foundation.
For many construction projects, however, solid foundations don’t come standard. Soil may have high moisture content or low structural density. It may vary in quality and consistency even across small areas, or it may be significantly impacted by local environmental conditions.
Soil treatments enhance ground stability to reduce the risk of foundation failures. The challenge? Selecting the right soil improvement method for your project. In this piece, we’ll break down the basics of soil treatments, why these treatments matter, and explore some of the most effective soil stabilization options.
Stable soil is essential for both road and building construction. On roads, sudden soil failure can result in sinkholes. In buildings, unstable soil can render dwellings, offices, or warehouses unsafe.
Soil treatment and improvement help create uniform consistency, improve subgrade shear strength, and control for shrink-swell properties. This reduces the chance of construction delays due to soil issues and improves the stability of projects over time.
Soil stabilization is typically comprised of five steps:
It’s also worth noting the role of geotechnical engineering in soil treatment processes. Put simply, not all soils are the same. Even within a single construction site, soil types, densities, and moisture levels may vary greatly. Geotechnical analysis helps determine which methods will provide the best outcomes.
Consider a large-scale building construction project with unstable soil. Analysis reveals a topsoil layer that is both high-moisture and unstable, followed by a three-foot layer of buried organic material, and finally a layer of stable subgrade.
One approach to solving this problem is the use of caissons that would extend from ground level to the subgrade. The problem? While caissons are stable, they require significant time and effort to install and often come with unexpected costs.
Another option is soil remediation and stabilization. In this case, three steps are required. First, unstable soil is removed and stockpiled for re-use in other projects. Second, the organic layer is removed and hauled away. Finally, silty sand (SM) fills are layered into the ground using the collected unstable soil treated with additives. The result is a stable, level surface for construction.
Soil stabilization is a critical first step in any construction project. While starting construction without considering soil conditions can accelerate timelines, it can end up costing more effort and time in the long run.
For example, if a road construction project fails after six months due to soil erosion, construction agreements typically dictate that the cost of repairs falls to the original contractor. If soil issues are significant, the cost of post-construction stabilization can offset any project revenue.
Choosing soil treatment offers several benefits for companies:
Enhanced safety
Stable soil is less prone to sudden shifts or cracks, which improves safety for workers during construction and for building owners when projects are completed. Crews can drill holes, pour foundations, and bring in heavy machinery without fear of damaging foundations.
Improved project timelines
When soil is properly treated, project timelines are improved. Team leaders don’t need to worry about sudden project stoppages due to excessive soil moisture or areas of differing soil consistency.
In addition, soil stabilization techniques using in-depth analysis and targeted additives can take 10% to 50% less time than traditional methods such as caissons.
Reduced costs
Targeted soil treatments are significantly less expensive than their traditional counterparts. For example, drilling caissons into 18’–20’ subgrade often requires complex underground piping structures that are costly and require regular maintenance.
Soil stabilization also reduces the risk of post-project costs due to soil slippage or failure.
Increased longevity
Comprehensive soil treatments provide consistent soil density and moisture content. This improves the ability of construction foundations to bear weight and pressure over time, in turn increasing project longevity.
Just as there are multiple types of soil, there are multiple techniques to improve stability. Common options include:
Lime stabilization
Traditional lime stabilization relies on pozzolanic reactions between calcium hydroxide (lime) and the silica and alumina in clay minerals. Over time, these reactions ensure soil strength and stability.
Cement stabilization
Cement stabilization hydrates cement particles to create calcium silicate hydrates (CSH) and calcium aluminate hydrates (CAH), which rapidly bind soil particles together.
Enzyme-based stabilizers, geopolymers, and recycled materials
Emerging solutions such as enzyme-based stabilizers and geopolymers offer a more sustainable alternative to traditional cement or lime. Enzyme-based additives are derived from biological materials, making it possible to improve soil properties with minimal environmental impact. Geopolymers, meanwhile, are derived from industrial waste materials and offer similar performance to cement.
In addition, the use of recycled concrete aggregates can help offset the carbon footprint of new cement production.
New technologies
New soil stabilization methods are also being developed to help reduce environmental impact. For example, the digital twin modeling using AI can help pinpoint the optimal amount of cement and other binders to use, given soil composition and construction needs. Real-time monitoring systems, meanwhile, can help track and monitor soil conditions to optimize treatment processes.
The right soil treatment method for your project depends on factors such as:
Project type
The type of project you’re undertaking informs the ideal treatment method. For example, if you’re building an airport runway or multilane highway, superior soil strength is the top priority. Smaller residential or commercial construction projects, meanwhile, may prioritize soil moisture content.
Soil composition
Soil composition is also critical. For example, cement outperforms lime stabilization in granular or silty soils, while lime is better for clayey soils.
Budget
The cost of soil stabilization varies based on the compounds and tools used. Structural reinforcement techniques are typically the most expensive, followed by cutting-edge solutions such as geopolymers or blended cement binders. Lime and cement stabilization are the most cost-effective, especially for larger project areas.
Timeline
For projects requiring a quick turnaround, cement is often the best choice. Cement-stabilized soils achieve significant strength in just a few days, allowing construction to begin as soon as possible. If your project requires significant lead time and materials sourcing, meanwhile, lime stabilization may be a more cost-effective choice.
Environmental regulations
The type and location of your project may mean it is subject to environmental regulations. For example, if you’re building a new hotel near a protected water source or wetland, you may be required to use specific soil treatment methods that minimize ecological risk.
Soil treatments improve stability, reduce risk, and help minimize cost and time overruns. While lime and cement stabilization remain the most common additive-based approaches to soil improvements, new developments in ecofriendly materials and monitoring technology are streamlining the process, making it easier for companies to start on solid ground.
