What is backfill material?
Every aspect of civil engineering plays a vital role in creating a durable and long-lasting structure. One crucial material is Backfill. Although this material seems to be an underdog, it plays a significant role in filling the gaps in the foundation. Before we delve into the depths of backfill material, let’s understand what it is. To create a foundation, the ground is dug to a certain depth. Wires and fixtures are laid, and the gap between the fixtures is filled with backfill material. Hence, backfill material fills in the gaps in the foundation, resulting in a more robust and durable foundation for the structure.
Different types of backfill materials used in Civil Engineering
Backfill materials are available in different types. Civil engineers use them as per their suitability and applicability.
- Soil: One of the very readily available backfill materials is soil. It is a natural material available in abundance and is relatively cheap.
- Cement is a chemical-binding substance that, when hardened, binds materials together. It is commonly used because of its durability and quick hardening quality.
- Compressed soil is a mixture of sand or rocks. It is the most used backfill material. It enables seamless drainage and provides the best leak proofing.
- Rock dust or compressed stones are ideal for a steady and durable foundation for heavy infrastructures such as sky-high buildings or airports. They are highly capable of bearing heavy loads.
- Recycled concrete: This is a sustainable backfill material option. Recycled concrete is obtained from recycling or reusing the demolished debris.
- Less-weighted fill: Engineers sometimes prefer lighter backfill materials. This fill is mainly used for renovation purposes or reinforcing the existing subgrades.
Selection of backfill material for a specific project
Backfill materials are of various types, as discussed above. When choosing the right one, engineers have to consider several factors carefully. Some of the factors are:
- Load-bearing: The selection of a backfill depends upon the load it will bear. If the structure is heavy, rock dust or recycled concrete is the best option. On the other hand, if the structure does not have a heavy load, the best option is a less weighted fill or liquid fill.
- Sealing the foundation: Compactable backfill material is the best choice for sealing the foundation. In this case, rock dust can help seal the small holes and gaps, leaving the foundation crack-proof.
- Environmental aspects: Keeping the environment in focus, certain backfills have hazardous pollutants that can have adverse effects. To avoid such issues, engineers use recyclable backfill material. This recyclable backfill material is obtained from the concretes of demolished structures or leftovers from a construction site.
- Pocket-friendly: Engineers always prefer cost-friendly backfill material. Therefore, the key is to find a backfill material that best suits their budget.
Engineers sometimes use a combination of different backfill materials. The choice depends on the environment, construction, and material availability. Engineers often depend on soil analysis and its behaviour. If the soil is too moist, concrete material is used, and liquid fill is used if the soil is too dry.
Advantages of using backfill material in civil engineering
Using backfill material is advantageous for a steady and durable structure. Here are some other advantages of backfill material:
- Provides stability: Backfill material provides stability to the structure. It prevents them from falling.
- Robust drainage system: Properly selecting backfill material can give structures a good drainage facility. This prevents the foundation from water logging. The backfill material seals all the potential openings, leaving no space for water to seep in.
- Enhanced load bearing: Compressed backfill evenly distributes the load on the surface. This helps in building a solid foundation and a long-lasting structure.
- Underground material protection: Backfill material provides safety for underground materials like wires and fixtures. The backfill material seals the holes and small openings, preventing moisture or soil displacement.
Disadvantages of not using backfill material
Backfill has many advantages. However, it can cause significant damage to the structure if selected with negligence. Here are some disadvantages of not using backfill material:
- Improper drainage: Failure to use backfill materials can lead to a failed drainage system, which can trap water and destroy the structure’s foundation.
- Low load-bearing capacity: Backfill helps enhance the foundation’s load-bearing capacity. However, it can cause low load-bearing capacity and damage the structure if not used.
Backfill, though it seems to be a simple construction material, plays a significant role in supporting the structure. Selecting a suitable backfill material plays a crucial role. Engineers pay attention to detail while choosing the best backfill material for their structure. These informed decisions lead to durable and long-lasting structures with solid foundations. You can study the importance of backfill material in Strata Geosystems’ case study here.