Using soil in concrete typically involves substituting it for the fine aggregate, which is traditionally sand. Yes, it is possible to make mortar or concrete using soil instead of sand. This approach leverages the binding properties found within the soil itself.
Replacing Sand with Soil
In conventional concrete or mortar mixes, the main components are cement, water, coarse aggregate (like gravel), and fine aggregate (sand). When using soil, the soil acts as the fine aggregate, taking the place of the sand.
Key Components in Soil-Based Mixes:
- Cement: The binder that reacts with water to harden.
- Water: Needed for the chemical reaction (hydration) and workability.
- Coarse Aggregate (Optional): Gravel or crushed stone for strength, though some soil mixes focus only on soil and cement (more akin to stabilized earth blocks or certain mortars).
- Soil: Replaces sand as the fine aggregate.
Here's a simplified comparison:
| Component | Traditional Concrete Mix | Soil-Based Mix | Role |
|---|---|---|---|
| Binder | Cement | Cement | Binds ingredients |
| Water | Water | Water | Activates binder |
| Coarse Agg. | Gravel/Stone | Gravel/Stone (Optional) | Provides bulk/strength |
| Fine Agg. | Sand | Soil | Fills voids, aids workability |
Importance of Soil Composition
Not all soils are equally suitable for use in concrete or mortar. The composition of the soil significantly impacts the final product's strength and durability.
To ensure adequate strength and durability, it is recommended to use soil with a higher clay content, as it provides better binding properties.
- Clay Content: Clay acts as a natural binder. A certain amount of clay helps the soil particles stick together effectively when mixed with cement and water. Too little clay might result in a mix that crumbles, while too much can lead to excessive shrinkage and cracking as it dries.
- Particle Size Distribution: Like sand, the mix of different particle sizes in the soil (including silt and sand within the soil) influences how well the mix compacts and hardens.
Using soil instead of sand is often explored in specific construction methods, particularly in areas where sand is scarce or for environmentally focused building techniques like stabilized earth construction. Proper mix design and testing are crucial to achieve the desired properties when incorporating soil.
