All of these pipes are made from fiberglass. They are the basis of the ductwork for the heating and cooling system of the library. Now that the foundation is laid, the dirt right inside the foundation is dug out of the floor area. The trench is compacted with a vibrating plate packer as seen in the first picture.Â Sand will then be laid on the bottom of this trench. This helps to provide a solid base in which to lay the ducts and is easily graded to lay the pipe at a 1% slope for drainage.
However, before the ducts are laid, the workers need to sand the edges of the ducts and connect them by means of fiberglass field joints.Â Once the field joint is cured, the pipe can be laid in the trench. Â The ducts are laid in the sand in the third picture and ready for the clean rock to be put on top.
Clean rock is one type of backfill that can be used which doesnâ€™t put a lot of pressure on the sides of the pipes. The slab concrete floor will then be poured on top of the clean rock. Installed correctly, fiberglass ductwork below ground will outlast the building.