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My office is afforded a prime view of a construction project where the workers are currently covering the leveled ground in a wire mesh, raking gravel across the entire mesh, and then covering that gravel layer in another layer of dirt.

What is the function of this, engineering-wise? I know gravel in a foundation typically is used to help with water runoff, but I can't guess why the mesh is being rolled out underneath, and this is going to become the foundation of a 3-story health pavilion, not some single-family house or storage shed (the entire footprint here with gravel and mesh will have a building on top of it, not a parking deck or a parking lot).

Is this simply a base layer of some kind, upon which concrete and rebar will be placed?

enter image description here

I am in the United States, in Georgia.

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  • $\begingroup$ The ground reinforcing is done to improve the soil strength yon which the entire structure will rest. The geotechnical engineer probably recommends it due to the soil test results for liquid limit and soil structural strength. $\endgroup$
    – Rhodie
    Jun 27 '19 at 15:06
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You are correct, this is the subbase that the foundations will be built on top of.

The gravel can be used as you say for water run off but it also allows for a level base on which to lay the concrete. In areas where the ground becomes highly saturated it can protect the concrete foundation from erosion.

The wire mesh is usually used for load-bearing concrete, simply to give it some extra strength and prevent cracking.

The dirt going on top of the subbase is the base material. This is used to help the workers get the correct grade and to keep the foundation flat. It also supports the workers and equipment during the concrete pouring.

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  • $\begingroup$ I think he is referring to the wire mesh "covered with dirt", not wire mesh covered with concrete? $\endgroup$
    – Jem Eripol
    Jan 6 '18 at 0:23
  • $\begingroup$ That's what I am referring to as well. It is put in the subbase of the foundation for extra strength. It prevents the gravel from moving too much which would cause cracks. $\endgroup$
    – loogle1
    Jan 6 '18 at 9:17
  • $\begingroup$ The mesh could possibly be a rock grid. This requires to be covered in a rock gravel to work properly. I've used it in projects where the soil is prone to differential settlement, but it has many other soil stabilisation applications. It basically let's the terrace act in a homogeneous manner and in very simplistic terms acts as rebar in concrete. The brochure in the link explains it quite clearly. $\endgroup$
    – ChP
    Jan 9 '18 at 12:25
  • $\begingroup$ @CharlPretorius The mesh was square, rather than triangular, but yes otherwise I would say based on loogle's answer that that's exactly what it is for. $\endgroup$
    – TylerH
    Jan 18 '18 at 15:38

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