What is the best backfill material for foundation in ground improvement or for any other construction? How to select the most suitable construction material.

This is a debatable topic and there is no specific answer to this question. However, based on certain criteria, we can select the type of material depending on our requirements.

What is the Best Backing Material for Foundation 

The following materials can be listed as the most appropriate and commonly used.

  1. Soil
  2. Sand
  3. Quarry Dust
  4. ABC

Soil as Backfilling Material

The soil is the most readily available material for these purposes. It can be found anywhere, and it is very easy to find it from required quantity and condition.

We cannot use all the soil types for backfilling. We generally used the gravelly soils for backfilling as they do not have the long-term settlement such as consolidation settlement.

Further, it is very easy to compact.

When the there is no water table closed by, we can use these materials for ground improvement as best backfilling material for foundation.

With the presence of the water table, compaction of soil is very difficult, there for when we need to do backfilling below the water table, we usually do not used soil.

Further, optimum compaction of the soil can be achieved for optimum moisture content. Therefore, we cannot use the soil with water.

Sand as Backfilling Material

Sand is a best backfilling material for foundation.

  1. It does not have secondary settlement other than immediate settlement.
  2. If can be compacted very easily.
  3. It is kind of self-compacting material.
  4. It can be used with the presence of the water.
  5. General compaction methods can be used for compaction above the water table.
  6. It can be compacted by vibration with poker vibrator (small scale work) with the presence of the ground water.

The main issue with the sand is the cost. Further, there is difficulty in finding the sand for these purposes.

Quarry Dust as Backfilling Material

Quary dust and the sand can be considered as same category materials. Both the materials behave in the same manner.

However, when the cost of construction is considered, quarry dust is cheaper than the sand.

Therefore, quarry dust is most widely used as backing material in ground improvement works.

ABC as Backfilling Material

Aggregate Base Couse, ABC is also most widely used and one of the best backfilling materials for foundation in road construction work.

Even for the road work, it is used above the soil filling to improve the load bearing capacity of the road.

Based on the ground condition, and the as per the road design, the thickness of the ABC layer is determined.

Summary

In conclusion, all the type of materials that we discussed can be used for ground improvements.

However, soil and the ABC can be used if there is no ground water present. It very difficult to haddle soil and the ABC if ground water is present.

Sand and Quarry dust can be used for any condition. Out of these materials, quarry dust is cheaper, and it is readily available for use.

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