Joint filler in concrete expansion joints - a must??

Presence of joint filler is required to the proper functioning of concrete joints however some may doubt its value. For a concrete expansion joint with no joint filler, there is a high risk of rubbish and dirt intrusion into the joint in the event that first line of defence which implies joint sealant fails to reject the entry of these materials. As a matter of fact occurrence of this is not uncommon since joint sealant from time to time is found to be torn off due to poor workmanship or other reasons. Presence of rubbish or dirt inside joint is undesirable to concrete structures as this introduces extra restraint not catered for during design and this may result in inducing excessive stresses to concrete structure that may fail the structures in the worst scenario. Consequently joint filler serves the purpose of space occupation sothat there is no void space left for their accommodation. To perform its function during the design life, the joint filler must be non-biodegradable and stable throughout the design life of structure to enhance its functioning. Furthermore it must be made of materials of high compressibility to avoid the hindrance to the expansion of concrete.