A Guide to Backfill in Mining and Construction

What is Backfilling? A Guide to Backfill in Mining and Construction

Last Updated on November 16, 2022 by Admin

In the multi-billion dollar mining and construction industries, the underlying processes that make structures such as mines and buildings are often overlooked in the broader schema of development. However, these pieces are essential to the mining process – while backfill may seem like a dirty word, in fact, it’s critical to mining in a safe environment.


While processes such as backfilling form an essential part of the mining and construction sectors, often they are overlooked for more engaging processes, such as the design of a complex or the retrieval of valuable material such as ores, coal, and gold from mines.

Let’s take some time to explore an often undervalued part of mining and construction – simply put, the process of backfilling. How does it form an essential part of mining and construction operations – where is it used, and what are the potential pitfalls of such a process?

What is backfilling?

While the name can seem a little confusing, backfilling involves refilling holes that are dug up during a building process. This can vary drastically, depending on the industry.

In construction, backfilling involves the replacement (or, in some cases, the reuse) of soil used in construction to further support a structural base. For example, soil excavated in a building may be reused to firm up the ground surrounding a freshly laid slab.

In the mining sector, backfilling can vary, depending on the need. In many cases, it’s simply the process of refilling holes that have been dug up or found (mining voids) during the mining process. In others, it may involve mixing soil with other products (such as cement or binding agents) to create specific backfilling solutions.

What are the advantages of backfilling?

Backfilling has a number of advantages that make it a beneficial process in the construction and mining industries. As a result of this, backfilling is often practised in many projects across the globe.


Some of the benefits of backfilling include the following:

  • Improved structural support when mining. As a result of backfill processes, previously mined areas can be reinforced and supported with correctly used backfill. As a result, mining around backfilled environments can be made geologically safer, reducing the risk of landslips.
  • Correctly used backfilling can also reduce the risk of acid rock drainage. By undertaking a backfilling process, correct compacted backfill can reduce the likelihood of contaminated wastewater from metal or coal mines leaking into underground water supplies, such as aquifers.

What are some backfilling processes?

There are a number of different backfilling processes that are used across the industry. Each typically uses a mix of wet and dry components – from the waste product of ore mining to binding agents such as concrete and water.

Two of the most commonly occurring backfill composites are dry rock backfill and paste backfill. Each uses different types of materials to produce a type of backfill that is useful for different purposes – in this case, cut-and-fill and subsurface backfill, respectively.

What are some of the hazards involved with backfilling?

While backfilling is often used in the mining sector, there are a number of hazards to be mindful of when undertaking the backfill. Incorrectly applied backfill can be hazardous and potentially fatal for your team. It’s important to therefore be mindful of the risks when considering backfilling processes as part of your project. Incorrectly applied backfill can be hazardous and potentially fatal for your team.

Some of the hazards that must be considered when backfilling include the following:

  • Backfill segregation can occur when coarse and fine particles separate. This can potentially arise as the backfill cures, the result being that the backfill may end up geotechnically unsound. This presents an increased risk of landslips if not managed correctly.
  • Pipeline clogs, bursts and failures – these can occur when the backfill is pumped at an in with an incorrect amount of pressure. Pumping in the backfill too fast can result in the holes used to fill the backfill getting blocked. Alternatively, too much pressure on a clogged pipe result in bursts and further damage.
  • Bulkhead failure – while rare, this can happen when a bulkhead is not designed to handle the pressure of backfill. This can present potentially unsafe conditions for workers in a mine, and as a result, it’s imperative for engineers to develop bulkheads to an appropriate standard.

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