When it comes to constructing roads and pavements, a strong foundation is always crucial. The foundation itself must be made of a durable material that can withstand years and years of traffic flow while also maintaining its dependability. This can be achieved by utilizing a material known as soil-cement.
Soil cement is used to strengthen underlying soil conditions to support traffic loading. Cement stabilized base is also a common application to strengthen the base section directly underneath rigid or flexible pavements. Soil-cement can be used when paving roads, parking lots, airports, residential streets, and more. It’s a cost-effective pavement base known for its strength and durability.
What is soil-cement made of?
Soil-cement is a simple but highly-compacted mixture made up of soil, cement, and water. As the cement is mixed with the other two elements, it strengthens the properties of the soil, giving the final material its durable qualities. This all depends on the type of soil used, how much cement is added, how much moisture is present, and the compaction of the mixture. A variety of soil types and combinations can be utilized such as subgrade soils, aggregate bases, and pulverized in-place materials.
How is soil-cement created?
First, rigorous laboratory tests are conducted to determine the cement and moisture content required to achieve the design compressive strength at a specific compactive effort. This analysis is then frequently referred to throughout the construction process to ensure that the soil-cement is of the highest quality.
Once the specific components of the mixture are decided, the material is mixed either in a central mixing plant or in-place. With central mixing plants, the soil-cement is first mixed and then brought to the job site. With in-place soil-cement construction, the mixing is done on-site. This involves first spreading the cement on the in-place soil. The cement, soil, and water are then mixed to a uniform consistency. During the final stages, the mixture goes through processes of compaction within a specified time limit and is cured. The curing process ensures that the soil-cement created is at its maximum strength.
Some soil-cement applications also require a process called “micro-cracking”. Micro-cracking of the soil-cement layer reduces the rigidity of the layer and the potential for cracking to reflect from the layer to the pavement.
What are the benefits of soil-cement?
Soil-cement can be an extremely cost-effective solution. A common application of soil-cement is called Full-Depth Reclamation (FDR) with cement. This process allows the in-place pavement (Existing asphalt, base, and subgrade) to be pulverized, mixed with cement, and compacted. Then a new pavement is placed on top of the FDR layer. The FDR process eliminates the costly process of removing existing pavement and replacing it with new pavement and aggregate base.
Another application that can be cost-effective is the treatment of certain subgrade soils that have poor capabilities to support pavement loading. In traditional construction practices, the poor soil would be removed and replaced or a thicker pavement section would be required. The cement treatment of certain poor soil with cement can eliminate the need for a thicker pavement section or additional subgrade preparation.
Important Items that Effect Soil-Cement Quality
The construction of soil-cement can be challenging at times, and there are important areas that should be checked and verified during the construction process.
First, care should be taken to identify areas where different soil conditions are encountered. Different soil conditions can cause several issues during construction:
- Compaction issues due to different maximum density or optimum moisture content.
- Insufficient cement content or soil that reacts with cement poorly. This will lead to material that does not meet the design requirements for compressive strength.
Proper Mixing operations and timely compaction are also factors that must be verified during the construction process. If the material is not uniformly mixed, there may be varying compressive strength characteristics in the layer. Also, if the material is compacted too late, the cement reaction process may have already begun, reducing the effectiveness of the treatment.
G3 Quality has experienced staff who can assist in the quality control or assurance monitoring and testing for cement-treated material construction.
Materials Design at G3 Quality
At G3 Quality, our material experts are active in California’s evolving specifications. Our team has extensive knowledge of local materials, environmental conditions, and material production. With this experience, we are able to offer a multitude of specialized materials design and research services.
We are industry leaders who are always embracing change and excellence. We are an elite team of engineers and professionals who provide world-class quality management, pavement engineering, materials design, construction inspection, and testing on infrastructure projects throughout California and the western United States.
To learn more about how G3 Quality can contribute knowledge, expertise, consulting, and professional services to your project, contact us.