Characteristics of mortars from ancient bridges

Abstract

Mortars from two medieval bridges (Charles Bridge in Prague and a bridge in Roudnice) and two Roman bridges (Ponte di Augusto in Narni and a bridge in Sardinia) were analysed using various techniques to obtain their chemical and physical characteristics. The analysis of binder quality was based on thermogra-vimetric analysis, using a methodology which enables the hydraulicity of the mortar to be expressed by the CO2/H2O ratio. The mechanical tests were performed on non-standard mortar specimens. The ratio binder/aggregate was determined dissolving the binder by an acid, and a sieving analysis was applied to the separated aggregate. The material characteristics of mortars from historic bridges were compared with each other, taking into account the requirements for mortar strength according to construction function and degree of exposure. © RILEM 2012.