A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
reject the entry of these materials. In fact, the occurrence of this is not
uncommon because joint sealant from time to time is found to be torn off
because of poor workmanship or other reasons. The presence of rubbish
or dirt inside the joint is undesirable to the concrete structures as this
introduces additional restraint not catered for during design and this might
result in inducing excessive stresses to the concrete structure which may
fail the structures in the worst scenario. Therefore, joint filler serves the
purpose of space occupation so that there is no void space left for their
accommodation. To perform its function during the design life, the joint filler
should be non-biodegradable and stable during the design life of the
structure to enhance its functioning. Moreover, it should be made of
materials of high compressibility to avoid the hindrance to the expansion of
concrete.
6. What is the reason of using bond breaker for joint sealant? (J2)
Joint sealant should be designed and constructed to allow free extension
and compression during the opening and closure of joints. In case joint
sealants are attached to the joint filler so that movement is prohibited, they
can hardly perform their intended functions to seal the joints against water
and debris entry. Polyethylene tape is commonly used as bond breaker
tape.
To facilitate free movement, it can be achieved by adding bond breaker
tape in-between the joint sealant and joint filler. Primers may be applied to
the sides of joints to provide a good bond between them.
Fig. Bond breaker tape for concrete joints.
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