Prestressed concrete is a combination of high strength concrete and tensioned steel strands. This combination makes a very strong structural material that is used in the building of roof slabs, bridge girders and railroad ties. Prestressed concrete was invented and patented in 1886 by Henry Jackson, a San Francisco engineer. This type of concrete became the material of choice in Europe after World War II, due to the shortage of steel. The Walnut Lane Memorial Bridge, built in 1951 in Philadelphia, Pennsylvania, became the first structure in America made of this type of material.
Walls can be built off SpanWright slabs in most cases. The type of wall construction depends largely on the span of the slabs. The SpanWright design division will indicate on each customer drawing whether concrete block, lightweight block or studwork partitions are suitable.