Concrete has been used in construction for over 2000 years when it was widely used by the Chinese and the Romans. In fact the dome of the Pantheon and the Colosseum in Rome as well as nearly 5,600km of Roman roads largely consist of a concrete material. However, with the fall of the Roman Empire the use of concrete largely disappeared for nearly 13 centuries until a method for producing Portland cement was patented in 1824. This was quickly followed in 1849 when Joseph Monier combined metal with concrete to create reinforced concrete. Since then, it has become the major construction material for bridges, as it has for most structural and civil engineering applications, with its intrinsic versatility, design, flexibility and above all, natural durability.
During the second half of the nineteenth century, concrete bridges were almost entirely arch structures as they required little tensile strength and in many instances unreinforced concrete was used in place of stone to construct large arched viaducts, such as at Souillac in the south of France. Concrete was simply poured into timber formwork to create monolithic structures quickly and cheaply. However, the problems with this new material soon became apparent as it was noted that it could easily crack due to differential movement and drying, leading to corrosion of the embedded steel.
In the first decade of the twentieth century reinforcement, as we know it today, was introduced and allowed for more diverse geometries to be developed as well as the capacity to transmit significant tensile forces. Much of the large scale use of reinforced concrete during this time was pioneered by the French builder Francois Hennebique. It was at around this time too that the use of precast concrete was developed for the first time with the Mizen Head Footbridge, built in 1908, an outstanding example of one of the first precast reinforced concrete structures. For nearly 30 years the use of reinforced concrete developed rapidly worldwide. The flexibility of the material meant that for the first time functional aesthetics began to be explored to complement the structural form. Some of the most famous examples of this new trend are the elegance and simplicity of the bridges designed by Robert Maillart in Switzerland in 1930 (Maillart’s Salginatobel Bridge is shown below).
The outstanding feature of concrete bridges designed during the 1930’s, 40’s and 50’s was the advent of prestressed concrete construction. Eugene Freyssinet developed a more scientific understanding of the creep properties of concrete and demonstrated the potential of this material in the 1930s with the construction of the Plougastel Bridge, which consists of 3 spans of 188m each in prestressed concrete which up to then could only have been considered in steel. It had been demonstrated that extremely large span structures could be constructed successfully such that by the end of the 1960’s prestressed concrete had largely superseded reinforced concrete as being the dominant structural form.
The expansion of the motorway network in Europe during the latter half of the twentieth century demanded large numbers of concrete bridges, a functional and cost effective solution to society’s needs. The main emphasis on bridge design became economy and durability rather than style. This inspired any number of developments and construction techniques, mainly involving precast segmental construction, resin joints, match casting, incrementally launching and cable stayed construction. Prestressing techniques continue to undergo significant technical development today together with increasingly higher strengths of concrete and steel which has led to larger and larger span structures.