The modern joint sealant has been developed from polymers which were developed first in the 1930s and 40s. The type of the joint sealant that should be used to seal any gap depends on the materials in which the gap exists, the environmental factors to which the sealed gaps are going to be exposed, the wear and tear that the substrates are going to be subjected to and a host of other factors. Thus joint sealant and the application of the various sealants available is a technical subject that is part of the civil engineering technology studied and practiced by civil engineering students.
Some of the common materials that are used to make joint sealant are tar, pitch, mortar, latex and synthetic materials such as silicone, urethane, acrylic etc. The type of joint sealant that would be required completely depends upon the need that it will be used for.
Joint sealant is an important requirement in airfield maintenance as well. The concrete exterior surface of the airfield can develop cracks which could be dangerous and have to be sealed thoroughly and immediately. The joint sealant used for airfield maintenance has to pass many tests of durability, strength, performance under stress and immunity to the vagaries of nature.
Many types of formulations for joint sealant have been developed that perform ideally in airfield maintenance. While one type of joint sealant is used in the open areas of the airfield, others could be used in maintenance of the buildings that are an integral part of the airport. The properties of the material on which the joint sealant is manufactured have to be carefully considered before choosing the joint sealant especially if it has to be used for high-priority tasks such as airfield maintenance.
Another category of joint sealant is the preformed variety. This joint sealant comes in the form of gaskets and seals. These types of sealants are used to seal metal panels and also used in some of the equipment that is used at airfields. Changing or introducing preformed joint sealant is also part of airfield maintenance.
Synthetic, high performance joint sealants are frequently used in airfield maintenance when repairing runways or joints between pavement and aprons in airports.
In Airport maintenance, selection of joint sealant according to the surfaces to be sealed, the environmental factors and the actual application of the sealant to seal the gaps is not only a science but also a skill that is developed with knowledge and experience.