Home' MHD Supply Chain Solutions : MHD Nov-Dec 2015 Contents DESIGN CONSIDERATIONS
FOR INDUSTRIAL FLOORS
Industrial floor slabs in warehouses and
distribution centres are integral to the
efficient operation of the facility. They
are the table-top on which an operator runs
his business. On the surface, they appear to
be one of the simplest parts of a structure
to construct. However, this simplicity often
leads to an underestimation of the design and
construction requirements. A well-designed
and constructed floor will increase produc-
tivity, reduce maintenance of the building,
and increase the life of the equipment using
A floor design should be performance-
based, and this starts with understanding the
requirements of how the floor will be used.
Most floor designers will be given a brief from
the warehouse owner to ensure the floor will
take the imposed loads, be flat, long-lasting
and aesthetically pleasing, and it will be their
responsibility to draw up the performance
specification. The specialist flooring contractor
should consider the construction methods,
program, cost and any value engineering
they can bring to the design. Compromises
may have to be made in developing the final
design of the floor, but the result should be
one that is economically designed and built to
meet the performance requirements.
There are two parts to a floor design:
1. Structural design: the ability to withstand the
2. Detailed design: joint design and other perfor-
The structural design of a floor will follow
engineering principles and calculations,
and requires knowledge of the following
in order to determine the slab thickness
1. Ground conditions.
2. Strength of the concrete.
3. Thickness of the concrete.
4. Method of reinforcement.
5. Load transfer capability of the joints.
6. Loading specification and loading pattern.
Guidance on the design of a floor is detailed
in the UK Concrete Society's Technical Report
34 (TR34) 4th edition.
Detail design covers key performance require-
1. Joint layout and joint design.
2. Construction methods.
3. Method of reinforcement.
4. Surface regularity (flatness and levelness).
5. Abrasion resistance.
Advice from all the stakeholders of the
floor should be sought before the design
Structural design in detail
Suitable ground conditions are essential for
ground-supported slabs, and it is therefore
important that a ground investigation is carried
out and interpreted by a competent geotechni-
cal engineer. The geotechnical engineer must
advise on the suitability of the ground along
with any recommendations for ground improve-
ments. Particular attention should be paid to
the long term settlement of the ground under
load, an important element often not considered
The primary purpose of the sub-base is to
provide a level base for the floor slab. It should
be capable of carrying construction traffic
without rutting. The sub-base should be a
minimum of 200-250mm thickness of well-grad-
ed material. The level tolerance of the sub-base
is of great importance. A high sub-base gener-
ally means a thinner concrete floor - 0--25mm
Slip membranes are used to reduce friction
between the slab and the sub-base, so as to
reduce the restraint to drying shrinkage, thus
reducing the risk of unplanned cracking. 300μm
plastic sheeting is recommended. In the case
of jointless slab design, two sheets of 200μm
There are comprehensive standards for the
specification and testing of concrete. High-
strength concrete is not needed and should
be avoided, because it tends to have higher
cement content and is more likely to shrink
than lower strength concrete. This is particularly
important in the case of jointless slab designs,
as higher shrinkage increases the size of the
joint opening. High-strength concrete can also
be difficult to finish.
Concrete shrinks as it dries out over the first
12-18 months of its life. Fresh concrete has
more water than is needed for the chemical
process of hardening, and some of this excess
water leaves the concrete, causing it to shrink.
Therefore the amount of cement and water in
the concrete should not be excessive.
MHD SUPPLY CHAIN SOLUTIONS --- NOVEMBER / DECEMBER 2015
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