Uses ~ to weather- and leak-proof junctions and abutments
between separate elements and components that may be subject
to differential movement. Also to gap fill where irregularities
occur.Properties ~- thermal movement to facilitate expansion and contraction
- strength to resist wind and other non-structural loading
- ability to accommodate tolerance variations
- stability without loss of shape
- colour fast and non-staining to adjacent finishes
- weather resistant
Maintenance ~ of limited life, perhaps 10 to 25 years depending on
composition, application and use. Future accessibility is important
for ease of removal and replacement.Mastics ~ generally regarded as non-setting gap fillers applied in a
plastic state. Characterised by a hard surface skin over a plastic
core that remains pliable for several years. Based on a viscous
material such as bitumen, polyisobutylene or butyl rubber.
Applications include bitumen treatment to rigid road construction
joints (page 135) and linseed oil putty glazing (page 380). In older
construction, a putty based joint may also be found between WC
pan spigot outlet and cast iron socket. In this situation the putty
was mixed with red lead pigments (oxides of lead), a material now
considered a hazardous poison, therefore protective care must be
taken when handling an old installation of this type. Modern push-
fit plastic joints are much simpler, safer to use and easier to
apply.Sealants ~ applied in a plastic state by hand, knife, disposable
cartridge gun, pouring or tape strip to convert by chemical
reaction with the atmosphere (1 part) or with a vulcanising additive
(2 part) into an elastomer or synthetic rubber. An elastomer is
generally defined as a natural or synthetic material with a high
strain capacity or elastic recovery, ie. it can be stretched to twice
its length before returning to its original length.Mastics and Sealants