The best defense against the need for maintenance is extreme care in proportioning, mixing, and placing the concrete. Careful placement of reinforcing is equally important. Cracks should be sealed with a commercial compound recommended for this purpose. The foundations of a bridge include those structural units that transmit the loads from the superstructure to the underlying soil. Piers are the intermediate supports for multispan structures.
Abutments are the end supports.
The types of piers and abutments to be discussed are shown in Figures 9 and 10. Piling is then used to carry the footing loads to a deeper and firmer stratum. The use of piling requires someone skilled in soil evaluation and boring procedures. This person performs a soil evaluation at the site to determine what kind of piling would be the most economical and what equipment would be required to install the piling. A gravity abutment carries its load through compression, and a cantilever abutment through a combination of bending and compression.