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
to comply with this requirement results in overstressing the joint sealants.
For instance, if the expected movement to be accommodated by a certain
movement joint is 4mm, the minimum design joint width can be calculated
as 4÷30% = 13.3mm when the movement accommodation factor is 30%. If
the calculated joint width is too large, designers can either select another
brand of joint sealants with higher movement accommodation factor or to
redesign the arrangement and locations of joints.
4. What is the function of primers in joint sealant? (J2)
Most joint sealants applied in concrete joints are adhesive and the
recommended joint width/depth of joint sealant is from 2:1 to 1:1 as given
by BS6213 and Guide to Selection of Constructional Sealants. When joint
sealant is applied on top of joint filler in concrete joints, additional primers
are sometimes necessary because [12]:
(i) Primers help to seal the surface to prevent chemical reaction with
water;
(ii) It provides a suitable surface for adhesion of joint sealant.
Fig. Primer in joints.
5. Is joint filler essential in concrete expansion joints? (J3)
The presence of joint filler is essential to the proper functioning of concrete
joints though some may doubt its value. For a concrete expansion joint
without any joint filler, there is a high risk of rubbish and dirt intrusion into
the joint in the event that the first line of defense i.e. joint sealant fails to
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