The Design of a Flexible Surface Mix for Use at Bridge Expansion Joints
Leakage at bridge joints causes corrosion and enhanced by rock-salts has caused major structural problems in the infrastructure. Development of a flexible surfacing material was considered to be a possible alternative to restrict the ingress of water, i.e. the material could accommodate the changes in movement experienced without cracking. This paper reports the work carried out in designing a flexible surfacing mix known as ‘H-MAC’. It initially summarises the requirements of bridge joints and the use of conventional surfacing methods. Using the limitations of existing materials and the structural requirements of the joint, the development of the flexible mix is outlined. Comparative laboratory testing is discussed using various binder types and aggregate gradings. These resulted in a single sized 6·3/3·35 mm mix using 23% Icosit Membrane H as a binder. Bridge joint trials were carried out using this prototype mix and the results reported.
KeywordsRubber Brittle Shrinkage Compaction Polyurethane
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