Advanced Construction Technology
By Professor Chris Gorse – licensed under the Creative Commons Attribution – Non-Commercial – Share
Alike License
http://creativecommons.org/licenses/by-nc-sa/2.5/
Raft foundations
These slides should be read in conjunction with Emmitt, S. and Gorse, C.
(2010) Barry’s Advanced Construction of Buildings. Oxford, Blackwell
Publishing
Raft foundations
Raft foundations.
Continuous reinforced
concrete raft
Reinforced concrete raft foundations spread the load over the
whole building area reducing the load per unit area. Raft
foundations are used where building loads are high or ground
conditions are poor.
Solid slab raft foundation
Solid slab raft foundation
Reinforcement runs in
both directions
Reinforced concrete raft
40-50 concrete blinding seals surface
and provides level platform to fabricate
the reinforcement matt and cages
Well compacted hardcore
Reinforced raft foundation
The load is distributed over the whole area of the
building
Steel reinforcement runs in
both directions under the
whole floor area of the
building adding tensile
strength to the floor
Solid slab raft foundation with
downstand beam
Reinforcement cages are
constructed to act as beams
within the raft foundation
Downstand beams or edge thickenings can be
used to add rigidity and stability to the raft
foundation. Where brick or block walls sit
on the raft the extra load can be
accommodated by a beam within the raft.
Reinforced concrete raft
40-50 concrete blinding seals surface
and provides level platform to fabricate
the reinforcement matt and cages
Raft foundation with extended toe to
carry brickwork
Toe cast in to slab to carry
brickwork cladding. Hides
the concrete raft below the
ground
Edge beam and reinforcement extended
to carry brickwork cladding.