Older concrete bridges deteriorate because of vibration and earth movement.
Some bridges deteriorate due to weather and because so many trucks and cars drive over it and it creates stress on the bridge
Iqbal Husain has written: 'Performance of integral abutment bridges' -- subject(s): Abutments, Bridges, Bridges, Concrete, Concrete Bridges 'Semi-integral abutment bridges' -- subject(s): Abutments, Bridges, Bridges, Concrete, Concrete Bridges
Roy Edward Towe has written: 'Concrete bridge design' -- subject(s): Bridges, Bridges, Concrete, Concrete Bridges, Design and construction
Brian C Best has written: 'Abnormal loading on composite slab bridges [by] B.C. Best and R.E. Rowe' -- subject(s): Bridges, Concrete, Concrete Bridges, Strains and stresses, Testing 'Tests of a prestressed concrete bridge incorporating transverse mild-steel connectors' -- subject(s): Bridges, Concrete, Concrete Bridges, Models, Prestressed concrete, Testing
Paul Mondorf has written: 'Concrete bridges' -- subject(s): Concrete Bridges, Design and construction, Prestressed concrete construction, Reinforced concrete construction
John R. Salmons has written: 'End connections of pretensioned I-beam bridges' -- subject(s): Bridges, Concrete, Concrete Bridges, Design and construction, Prestressed concrete beams
Vernon Peter Jensen has written: 'Ultimate strength of reinforced concrete beams as related to the plasticity ratio of concrete' -- subject(s): Reinforced concrete, Girders, Testing, Strains and stresses 'Highway slab-bridges with curbs' -- subject(s): Girders, Bridges, Concrete, Strains and stresses, Concrete Bridges 'Solutions of certain rectangular slabs continuous over flexible supports' -- subject(s): Girders, Bridges, Concrete, Strains and stresses, Concrete Bridges
David B Beal has written: 'Failure test of a jack-arch bridge' -- subject(s): Arched Bridges, Bridges, Arched, Bridges, Concrete, Concrete Bridges, Testing
Luis Saenz Duplace has written: 'Puentes prefabricados de hormigon armado para carreteras' -- subject(s): Bridges, Bridges, Concrete, Concrete Bridges, Precast concrete construction, Tables
K. P. Dellos has written: 'Legkie betony v mostakh' -- subject(s): Concrete Bridges, Lightweight concrete, Concrete bridges
The steel rods are there to strengthen the concrete - making it reinforced concrete.
The asphalt used to waterproof the concrete has also begun to deteriorate.