Cost Analysis of Precast Prestressed Composite Pavement on U.S. Highway 14-bypass

Because of the increase in heavy truck traffic, the need has developed for a stronger pavement to carry increasing wheel loads. These loads have usually resulted in thicker pavements which increases the cost. In some parts of the country the aggregates needed for pavements are scarce, making it necessary to transport the aggregates over long distances to the construction site. This longer haul increases the pavement cost and makes it necessary to investigate other methods of construction. A recent pavement development utilizes prestressed concrete. Prestressed concrete is composed of concrete prestressed with high strength steel. Concrete has a high compressive strength while steel has a high tensile strength. By prestressing, the high compressive strength of the concrete and the high tensile strength of the steel are obtained. Prestressing can be introduced by either pre-tensioning or post-tensioning. In pre-tensioning, the steel tendons are anchored against abutments or stressing beds and tensioned by hydraulic jacks. The concrete is poured, and as soon as it has cured the steel tendons are cut. This process applies a compressive stress to the concrete. Post-tensioning is a method of prestressing in which conduits are installed before the concrete is poured. After the concrete has been poured, the steel tendons are put through the conduits and tensioned against the cured concrete, thus introducing a compressive force to the concrete. Through utilization of the compressive-strength, the prestressed concrete slab can be thinner and have the same load-carrying ability as ordinary concrete pavement. Such a reduction in thickness means a saving in aggregate as well as a saving in construction time. As the loads are increased, prestressed concrete pavements should become economically competitive with the present day methods of construction