What Materials Are Used as Backfill in Construction?

What are backfill materials? These are materials that are added to a foundation or trench after excavation occurs. These materials serve as an extra layer of protection. There are many different materials construction companies use for backfill, including coarse-grained soils, rock and shale.

The type of material needed can depend on the scope of the construction project. For example, some backfill materials are better suited to projects that require drainage than others.

Read on to learn more about the different types of backfill materials used in construction:

  • Rock: Crushed rock is a common type of backfill material, used mostly in construction projects that require drainage. This backfill material allows for great drainage while preventing erosion. Construction projects that typically use crushed rock or stone as a backfill material include driveways and dams.
  • Fine-grained soil: This material is often used in construction projects that don’t require drainage. It’s easy to compact fine-grained soil, which results in a strong, firm base for construction. Materials considered fine-grained soils include organic clays of low to medium plasticity, inorganic silts and fine sands of low plasticity.
  • Coarse-grained soil: Perfect for projects that require compaction and foundation support with a little bit of drainage, coarse-grained soil is one of the most common types of backfill material. Sandy soil types and gravel soils are both considered coarse-grained soil.
  • CLSM (Controlled low strength material): These self-compacting materials are often used as an alternative to compacted fill. Other characteristics of CLSM include that it’s flowable and low strength. Common materials found in CLSM mixtures include water, fly ash, Portland cement, coarse- and fine-grained soil. These mixtures are mostly used as void fills and utility bedding.
  • Commercial byproducts: These are perfect for use in areas where one can’t find natural backfill materials. Common types of commercial byproducts include furnace slag and fly ash. These materials are often lightweight and can be used as additives to highly plastic clay.

The backfilling process

The backfilling process should take place after the foundation has cured for at least five to seven days. Cracks can occur if you start the backfilling process too soon. The area where the backfill will go should be cleaned, which means removing loose rocks, grass and other debris. It’s also important to pump out all water.

Next, a construction company will decide on the backfill material. Backfilling starts at the corners of the foundation and is distributed evenly over the entire surface. After this, they will compact the backfill. Generally, this process involves adding layers of backfill materials on top of each other.

Notably, this process can vary depending on the construction project. The engineers on a project will usually determine the method used for backfilling.

Work with the right construction company

When working on a construction project, it’s always best to work with professionals. Professionals know the best backfill material to use for most kinds of projects. A good construction company will also provide fair prices for all their services.

If you’re looking for top-quality construction work, including recommendations on what materials would best be used as backfill on your construction project, contact Randy Roan Construction Inc. today to arrange a consultation.