Restoration of masonry arch bridges

Abstract

Experience with the study of more than 30 masonry arch bridges and their repair is presented. The oldest of these bridges date back to the thirteenth century, while the most recent were constructed in the 1930s; they form an important part of the cultural and historical fabric of the region. Many of these bridges required restoration to make them fit for current and future traffic, using methods, modern materials and techniques that are compatible with stone masonry. This paper describes the procedures for inspecting and assessing arch bridges including foundations, stone and mortar, pavements and waterway hydraulics. Means of repairing masonry, such as the use of specialised mortar and impregnating masonry with stabilising chemicals, are discussed. The strengthening of stone arch bridges by adding internal arches of lightweight concrete is described. Methods of reconstructing roadway pavements and sealing the entire bridge against excessive moisture intrusion are also covered. Examples are given of recently completed projects intended to extend the service life of masonry arch bridges by many decades.