General Advice
Large format pavers are generally considered to be pavers with a surface area in
excess of 0.16 m2 (400x400) and pavers of 1 m2 or more are not uncommon.
Driven by design these large format pavers have become popular with architects
designers and customers, unlike paving contractors who are left to deal with the
practical dilemmas of handling and installing these monolithic elements.
The following is general information, designed to assist customers and contractors in
avoiding the more common problems associated with large format pavers.
Weight
Ranging from 30 – 125kg each, the large element paver requires more than one
person to lift, and sometimes three or four depending on positioning. Forward
planning is required for both site handling and laying.
Handling
Movement and handling of these pavers requires a higher degree of care, due to their
large surface area to thickness relationship. They have a tendency to crack more
readily if not handled with care and efforts should be made to reduce double handling
of these units wherever possible.
Placement
Final placement of these pavers again must be done with care. As these pavers are
large but relatively thin, repeated hammering with mallets will invariably lead to
hairline cracks which may not be visible immediately but that will develop over time
with expansion and contraction. Pavers should be gently positioned and pressed down
with hands into a less firm mortar bed.
Curvature
Curvature of large format pavers is quite common particularly oblong shaped units.
This occurs when pavers still curing are laid on a wet mortar bed on high temperature
days. The result is that the back of the paver cures more slowly than the face which is
exposed to high temperatures, causing the face to contract more quickly and therefore
curve the paver. This manifests itself at the edges of the pavers with lipping of paver
joins and breaking away of the grouting and can also be the cause of drumming or
poor bonding.
Movement (Expansion and Contraction)
As concrete pavers are a cementicious product they are subject to constant expansion
and contraction throughout their life. Large format pavers are even more so due to
their large surface area as they draw in and expel heat during temperature and weather
changes. Pavers will crack if stressed by being layed in large segments without due
consideration to the use of expansion joints. These flexible joints allow movement
pressure to be absorbed without cracking pavers.
Grouting
As previously mentioned, early movement of large format pavers is common and this
can sometimes lead to grout breaking its bond from the side of the pavers.
Consideration should therefore be given to grouting the pavement at the last possible
opportunity, and in cooler weather conditions that are suited to good curing and
bonding.
