Stem Wall Backfilling With Cellular Concrete

Lynchburg, Virginia

The Job

This work was associated with the construction of a new academic building at a school in Lynchburg, Virginia.

The Challenge

Due to a sloped site, there was up to an 8′ difference in elevation between the existing ground and the desired finish floor elevation. Various options for filling the CMU stem walls included soil, aggregates and EPS foam blocks. EPS foam blocks were chosen to reduce loads on the footings, which would have required deep foundations in the case of soil or aggregate backfilling.

Due to the extensive sub-slab plumbing, the design called for EPS blocks cut to fit the curved walls & uneven ground profile, and then backfilled with 18″ of stone dust, to allow for the plumbers to dig and install the plumbing.

The Solution

CJGeo proposed installing 23lb/cuft cellular concrete to speed up the installation, reduce supply chain risks, and reduce the loads applied to the foundations and underlying soil.

CJGeo placed 1914CY of cellular concrete over three days onsite. All material was walkable within 12 hours, and the project saved approximately 3 weeks relative to the original design’s timeframe.

The cellular concrete was brought all the way to the bottom of the 6″ stone layer below the slab, and the plumbers were then able to excavate through the cellular concrete with a mini excavator and hand tools to install the plumbing, and the trenches were backfilled with 57 stone.

The total load using cellular concrete was reduced by approximately 120lbs/sqft relative to the EPS/stone dust backfill design.

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