This work as associated with the replacement of Scaife Hall, at Carnegie Mellon University, in Pittsuburgh, Pennsylvania.
The H-pile and precast lagging wall was situated at the top of a steep slope, which had a Class I railroad at the base. Because of site constraints, an HDPE stormwater detention structure was situated within the fill area, along with extensive stormwater pipes and manholes.
In order to optimize the drilled shafts for the H-piles by reducing the lateral loads, the designer sought a lightweight, permeable backfill material that would not apply lateral loads once in place.
CJGeo proposed 20lb/cuft permeable cellular concrete to minimize lateral loading on the wall during construction, buoyancy of of the stormwater system components, and ensure a free draining material.
Because the material is permeable (modified ASTM D-2434 2.0cm/sec), it is freely draining and reduces hydrostatic loads on adjacent structures.
620 cubic yards of lightweight backfill were placed over two mobilizations.