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Conspectus 2 0 0 1
64
Mr JERZY BASIURSKI
Mr. Jerzy Basiurski, BSc(Honours), MSc, MBA. worked in a scientific
environment for multinational companies in the aluminium and glass
industries. For more than 20 years since then, he has been involved in
construction chemicals. Combining practical skill, experience and
theoretical knowledge, he has given lectures about foamed concrete
and carried out demonstrations in several countries.
Dr DANIEL WELLS
Dr Daniel Wells, BSc(Honours), PhD, obtained his PhD in the field of
Molecular Reaction Dynamics at The University of Manchester. For
the past three years he has been involved in technical marketing
of construction chemicals, in particular of foaming agent, and
has built up an extensive knowledge on foamed concrete.
EAB Associates, England
EAB Associates, England
The Use of Foamed Concrete inConstruction and Civil Engineering
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The Use of FoamedConcrete in Constructionand Civil Engineering
Over the past 15 years or so foamed concrete has become accepted as an
important material for use in the construction industry. Both the amount
of foamed concrete used and the variety of applications that it has been
used for have increased dramatically. For many applications foamed
concrete can provide cost and performance benefits when compared with
traditional building materials.
This paper describes what foamed concrete is and how it is made. The
advantages and technical specifications of foamed concrete are reported.
Applications for which foamed concrete can be used are discussed,
including the use of foamed concrete in building construction, roads,
bridges, void filling, ground stabilisation and land reclamation. Case
studies of foamed concrete usage are described in detail. The case studies
consider the use of foamed concrete for ground stabilisation in Japan,
trench reinstatement in Singapore and an evaluation of foamed concrete
for bridge strengthening in the United Kingdom.
Abstract
...............................................................................................................................................
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I N T R O D U C T I O N
Foamed Concrete is a versatile, lightweight, building material. It can be made with a wide range of densities and
compressive strengths and it is used for a many different applications. In many cases foamed concrete can provide
cost and performance benefits when compared with traditional building materials. This paper describes what foamed
concrete is and provides details of how it is made, what its advantages are and its technical specification. In order to
demonstrate the potential of foamed concrete, three case studies where foamed concrete has been used are discussed.
These case studies illustrate foamed concrete’s superiority over traditional fill materials when used for ground
stabilisation, trench reinstatement and arch masonry bridge strengthening.
W H AT I S F O A M E D C O N C R E T E ?
The most basic definition of foamed concrete is that it
is ‘mortar with air bubbles in it.’ The air content of
foamed concrete may be up to 75% air by volume.
In general terms, foamed concrete can be described as
a lightweight, free flowing material which is ideal for a
wide range of applications. It can have a range of dry
densities, typically from 400 kg/m3 to 1600 kg/m3 and a
range of compressive strengths, 1 MPa to 15 MPa (1).
Foamed Concrete can be placed easily, by pumping if
necessary, and does not require compaction, vibrating
or levelling. It has excellent resistance to water and
frost, and provides a high level of both sound and
thermal insulation. It is very versatile, since it can be
tailored for optimum performance and minimum cost
by choice of a suitable mix design.
The fact that foamed concrete can be made using
different mix designs means that it is not a single
product. With the exception of pre-cast units, foamed
concrete cannot be bought ‘off the shelf’. Foamed
concrete is nearly always made on-site and it is made
using a mix design specifically selected for each
application or job.
Although the material is called foamed concrete, it is
not really concrete at all. Foamed concrete is actually
foamed mortar, where the mortar is made from either
cement and water or sand, cement and water. Foamed
concrete does not contain aggregates.
Foamed Concrete is not the same as conventional
concrete and does not have the same characteristics.
Foamed concrete is much lighter and does not have the
same strength as conventional concrete. For this reason
foamed concrete and conventional concrete are
generally used for different applications, although there
are applications where either may be specified.
Foamed Concrete is not the same as autoclaved aerated
concrete, which is a common building material that is
frequently confused with foamed concrete. Foamed
concrete is a much more versatile material than
autoclaved aerated concrete, the latter being restricted
in its form and where it is made.
A P P L I C AT I O N S O F F O A M E D C O N C R E T E
Foamed concrete is a very versatile material and there
are many different applications for it. Please refer to
Table 1 for typical dry densities and compressive
strengths of foamed concrete for a range of applications.
Foamed Concrete in Building Construction
Roof Insulation Screed
It has long been recognised that lightweight foamed
concrete has excellent thermal insulation properties
which make it an ideal material for roofing insulation.
It is a low density material, and so does not add
significantly to the overall weight of the roof. As well
as providing insulation, foamed concrete is also used
to lay flat roofs to falls. This particular application is
very popular in the Middle East.
Walls
More recently reinforced foamed concrete has been used
to build structural and non-structural walls in houses
and apartments. Whilst it is possible to build walls from
pre-cast foamed concrete elements, foamed concrete
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can be used much more efficiently by casting entire
foamed concrete walls in-situ. Foamed concrete walls
are both lightweight and low in cost. Low cost housing
has been built in this way in Africa and The Middle East.
Floors
Solid, cast in-situ floor slabs can be made from foamed
concrete. Also floor levels can be raised and uneven floor
surfaces levelled using foamed concrete. When used in
flooring it is important to cover foamed concrete with
a normal finishing screed or hard floor tiles because
foamed concrete has a low resistance to abrasion and
point impact.
Fire Breaks
Foamed concrete is fire resistant and can be used to
make fire breaks within the under-floor service ducts
of modern buildings or in the space above old style lath
and plaster ceiling in old buildings. Foamed concrete
can also be sprayed onto or poured into shuttering
around structural steelwork for fire protection.
Decorative Panels
In the Czech Republic decorative wall panels are made
out of foamed concrete. These panels are lightweight
and can be used to enhance the appearance of buildings
without adding much extra loading to the structure.
Table 1: Typical Dry Densities and Compressive Strengths of foamed concrete for a range of applications
Roads, Highways and Bridges
Trench Reinstatement
In 1991, following the publication of the Horne report (2)
United Kingdom government legislation (3) specified the
use of foamed concrete for trench reinstatement (this
is the filling of trenches dug in roads when pipes are
laid, or repairs carried out). Traditional methods of filling
trenches in roads, i.e. the use of granular fill materials,
result in settlement and damage to both the road and
the pipes. Trenches that have been reinstated using
foamed concrete have shown no signs of settlement and
have not required any remedial work (4). Table 2 shows
the layer thickness and crushing strength requirements
for foamed concrete that is used for trench
reinstatement in the UK. Other advantages of using
foamed concrete are that it is quick to place, fills hollow
sides, fills under higher services and is easy to re-excavate.
Road and Pavement Sub-Bases
Foamed concrete is lightweight (densities can range
from 400 kg/m3 to 1600 kg/m3), and because of this it
has been used for the construction of the road
foundations for roads built on soft ground. Roads built
using foamed concrete can be constructed in such a
way that by choice of a suitable depth of sub-base they
weigh less, and so do not sink into the soft ground, unlike
Dry Density Rangekg/m3
400 - 6001200 - 1600800 - 16001200 - 1600400 - 1200400 - 1000
10001200
400 - 1000400 - 1650400 - 1600600 - 1000400 - 1600
Application
Roof Insulation ScreedStructural WallsNon-Structural WallsFloor SlabsRaising Floor LevelFire BreaksDecorative PanelsTrench ReinstatementRoad Sub-BaseBridge AbutmentsVoid FillGround StabilisationHarbour Fill
Compressive StrengthRange MPa1.0 - 2.56.5 - 12.03.0 - 10.04.5 - 10.01.0 - 4.51.0 - 3.53.5 - 5.54.5 - 5.51.0 - 3.01.5 - 10.01.0 - 10.02.0 - 5.51.0 - 10.0
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Table 2: Layer Thickness and Crushing Strength Requirements (3, 5)
roads built in the traditional way, using roadstone as
the sub-base. The access roads to Canary Wharf in
London’s Docklands were built on foamed concrete
foundations as are many roads in Holland.
Bridge Abutments
Foamed concrete was used in the construction of a
bridge abutment in Colchester, United Kingdom with
great success (6). With traditional abutments, there is
a lot of sideways pressure against the bridge walls
caused by the materials used, and their compaction.
With foamed concrete, this lateral load is practically
eliminated, so the bridge walls do not have to be as
thick. This in turn means that the bridge foundations
can be made less massive. Huge cost savings can be
achieved by reducing the thickness of the walls, and
the size of the foundations, so the use of foamed
concrete is much cheaper than the use of traditional
materials.
Void Filling
Foamed concrete is a perfect void filling material,
because of its placement characteristics. Foamed
concrete is free flowing, it fills every gap and can be
applied even through small openings. The fact that
foamed concrete is fluid and can be placed through
narrow openings, by gravity or by ordinary concrete
pumps, means that the job can be tackled without too
much disruption at the surface and does not leave any
hidden gaps. When foamed concrete sets and cures it
does not collapse or shrink and it does not impose large
lateral loads. Void filling jobs fall into two categories -
planned and emergency (7).
Planned Void Filling
Typical planned void filling work includes the filling of:
• old underground fuel tanks, which would otherwise
have to be dug out, cut up, hauled away and scrapped,
which is time consuming and potentially dangerous
work;
• redundant sewers, pipelines, culverts and tunnels;
• the gap between the old sewer wall and the new
insert pipe within it (in a sewer re-lining job);
• any large open “hole” to enable the area to be
redeveloped - typical examples of such work include
swimming pools, water reservoirs, surface mine
workings and mine shafts;
• hidden, irregular, unexplored underground voids
which threaten subsidence;
• cavities in structures - service ducts in bridges; cellars
and basements in old buildings;
• voids left behind on old industrial sites.
Emergency Void Filling
Emergency repair work usually arises because something,
usually some structure, starts to show signs of collapsing,
or when a previously unknown underground void comes
to light and is seen to present a risk to whatever is above
or close by. In emergency repair work the foamed
concrete usually provides support as well as filling the
void.
Foamed concrete can be placed quickly and safely so
that the emergency situation can be dealt with without
Layer
Roadbaseand Sub-baseRoadbasealoneSub-baseand/or below
1450 mm
C4Not
allowed150 mm
2450 mm
C4Not
allowed150 mm
C2
3450 mm
C2300 mm
C2150 mm
C2
4450 mm
C2300mm
C2150 mm
C2
Footwayor Cycletrack
N/A
N/A100mm
C2C4 - Minimum 4 MPa crushing strength at 28 days.C2 - Minimum 2 MPa crushing strength at 28 days.
Maximum 14 MPa crushing strength at 28 days.
Road Type
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unnecessary delay. The foamed concrete can either be
left in place as a permanent foundation, or if a different
long term solution is required, because of its cellular
structure, the foamed concrete can easily be re-
excavated.
Foamed concrete was used for emergency void filling
at Heathrow Airport, United Kingdom when a tunnel
collapsed during the construction of a new underground
railway line. A volume of 12,000 m3 of foamed concrete
was placed in 2 weeks in order to stabilise the ground.
In Lublin, Poland, a recently constructed roadway built
over a previously inadequately compacted trench
reinstatement was in danger of collapse when heavy
rains washed away the ground beneath it (7). A large
void was created under the roadway which remained
suspended in mid air over a distance of 30 metres. Using
traditional methods the repair would have taken 3 weeks
to complete, including the dismantling and re-assembly
of the road structure, which consisted of paviors bedded
in mortar. Using foamed concrete the whole job was
completed and the road re-opened in 48 hours. The cost
of the emergency void fill using foamed concrete was
one tenth of what it would have been using traditional
methods.
Ground Work
Ground Stabilisation
As with void filling, ground stabilisation may be either
planned or emergency work. Planned work can involve
using foamed concrete as a foundation for building on
soft ground. The soft ground can be excavated and
replaced by foamed concrete that has a lower density
than the soft ground. When a structure is subsequently
placed on top of the foamed concrete foundation, the
total loading can be matched so that it is similar to
that of the soft ground which was removed. Typical
emergency ground stabilisation work can involve
consolidating embankments following a landslide.
In Gniezno, Poland, the cathedral is situated on a hill.
In 1996 the hill started to slide. The cathedral is built
on a site of national heritage since it is the birth place
of Polish Catholicism. It was of utmost importance that
the cathedral did not collapse. In order to protect the
building the hill had to be stabilised. A layer of soil
2 metres thick was removed and replaced with foamed
concrete of a dry density of 900 kg/m3. The foamed
concrete was poured in stages, forming small terraces.
In total 4,500 m3 of foamed concrete was placed for
this job. This reduced the weight of the hill by
6,000 tons and stopped the landslide.
Land Reclamation and Harbour Fill
Land reclamation is another area where foamed concrete
is finding a use. Foamed concrete has been successfully
used for large harbour fills where it has the advantage
that it does not sink into the soft sub-soil in the way
that traditional materials (usually sand and stones) do.
This means that the site can be redeveloped months or
even years sooner than would otherwise be possible.
A D VA N TA G E S O F F O A M E D C O N C R E T E
Foamed Concrete in its Fluid State
• Non-hazardous
• Large or small amounts can be placed quickly
• Can be easily placed by pouring, or can be pumped
long horizontal or vertical distances
• Free flowing, spreads to fill all voids
• Does not settle, hence requires no compaction
• Does not require vibrating when placed
• Reliable quality control so batches are easy to
reproduce
• Made on site, so mix design can be optimised for site
conditions, if required
Foamed Concrete in its Solid State
• Non-hazardous
• Lightweight, does not impose large loading
• Excellent load spreading characteristics
• Does not impose lateral loads
• Excellent sound and thermal insulation properties
• Excellent fire resistant property
• Low water absorption over time
• Excellent resistance to freeze-thaw
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For the WET method all the ingredients are loaded into
a high speed blade mixer and thoroughly mixed, before
being transferred to the readymix truck. The WET method
gives a better quality slurry.
The mortar slurry is then transported to site, and the
foam is added there, and not at the batching plant.
Some batching plants are reluctant to make mortar
slurries, as they can stick to the insides of the drum,
making them hard to clean. However, this is not a
problem when making foamed concrete for several
reasons:
• more water is used in the slurry making it less
likely to stick
• when the foam is added, the foamed concrete
is very fluid
• the foam itself has a cleaning action.
Making the Foam
Foam for foamed concrete is made from a concentrated
Foaming Agent. Foaming Agents are based on protein
hydrolyzates or synthetic surfactants or both. The foam
is made using a foam generator. In the foam generator
the foaming agent is diluted in water to make a pre-
foaming solution and then the pre-foaming solution is
expanded with air into foam. The foam is stiff, like
shaving foam, with a density in the region of 45 g/litre.
The bubbles are stable and able to resist the physical
and chemical forces imposed during mixing, placing and
hardening of the foamed concrete. Between 75 and 85%
of the bubbles are of 0.3 to 1.5 mm in diameter (8).
There are two methods of making foam and hence two
types of foam generator. The methods used are the DRY
and WET methods. These terms have no relation to the
wet and dry methods that are used for making slurry.
The DRY method is where foam is created by forcing
the pre-foaming solution through a plastic mesh with
compressed air. The foam created using the dry method
is uniform and very stable. Figure 1 is a schematic
diagram that shows how foam is made using the dry
Cost Benefits of Foamed Concrete
• Highly cost effective compared with other methods
• Contains a large amount of air making it inexpensive
• Ingredients readily available
• Enables fast work
• Once placed requires no maintenance
H O W T O M A K E F O A M E D C O N C R E T E
The first step is determine whether there are any
required parameters, such as density and compressive
strength. A theoretical mix design is formulated and
site trials are undertaken. The results from the site trials
are used as a control for making the foamed concrete
that is to be used for the work that is to be carried out.
The next step is to make a cement slurry or a sand-
cement slurry that is appropriate for the mix design.
The second step is to make suitable foam. The foam is
made separately from the slurry. Once the foam has been
made it is blended in to the slurry to make foamed
concrete.
Making the Slurry
The cement used for the slurry is usually Type 1 Portland
Cement although other cements can be used. If sand is
specified in the mix design ideally it should be fine with
2mm maximum size and 60 to 90% passing through a
600 micron sieve (8). Other ingredients such as
Pulverized Fuel Ash (PFA) can also be used. The
water:cement ratio of the slurry is usually between 0.5
and 0.6. If necessary more water can be added to
increased the workability. However it is important not
to use too little water in the slurry since this can cause
water to be drawn out of the foam.
The slurry can be made using a readymix truck mixer.
Firstly, the cement mortar slurry is made at the batching
plant, according to the mix design, by either the DRY or
WET method.
When using the DRY method the ingredients are loaded,
in their correct proportions, by ‘ribbon feeding’, into
the drum of a ready mix truck, where they are mixed
together.
The Use of Foamed Concrete inConstruction and Civil Engineering
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method. In contrast, the WET method of creating foam,
which is based on the Venturi effect, does not involve
compressed air and does not produce such good quality
foam.
Making Foamed Concrete
It is important to make the slurry first, before making
the foam. Ideally the foam should be generated and
delivered directly into
the mixer of the
readymix truck that
contains the slurry. The
mixer should be rotated
at approximately 10
revolutions per minute.
All of the foam should
be allowed to blend into
the slurry. A sample of
the foamed concrete
should be tested for its
wet density. I f the
density is too low, more
foam can be added.
When making subsequent
batches the amount of foam added can be adjusted.
Figure 2 shows a schematic diagram of foamed concrete
being made and placed on site.
F O A M E D C O N C R E T E - T E C H N I C A LS P E C I F I C AT I O N
Foamed concrete can have a range of dry densities,
typically from 400 kg/m3 to 1600 kg/m3 and a range of
compressive strengths, 1 MPa to 15 MPa. Table 3 shows
typical properties for foamed concrete. In general, the
higher the density of foamed concrete then the higher
its compressive strength will be. However this is not
always true because the mix design used to make the
foamed concrete will also affect the compressive
Figure 1: Making foam from foaming agent, water and compressed air.
Figure 2: A Schematic diagram showing the stages involved whenmaking foamed concrete.
strength. For example, by using a cement only mix design
to make foamed concrete with a dry density of 800 kg/m3
you can achieve a higher compressive strength than if
you make foamed concrete with a dry density of
1000 kg/m3 using a 1:1 sand:cement mix design.
Performance requirements for foamed concrete have
also been published by The American Society for Testing
and Materials (ASTM) (9).
C A S E S T U D I E SLandslide Repair on
Nagano Expressway,
Japan
A section of the Nagano
Expressway in Nagano
Prefecture, Japan, is
built along a hillside. In
order to build the road
an embankment with a
volume of about 6000 m3
w a s p l a c e d . A n
e m b a n k m e n t w a s
constructed using
traditional fill materials. Following the placing of this
embankment there was a landslide 80m long, 50m wide
and 9m deep. The unexpected landslide meant that the
design of the embankment had to be altered. Instead of
using traditional fill materials a lightweight material
needed to be used. Foamed concrete was specified to
re-build the embankment.
Terraces were dug into the subsoil in order to provide a
solid base support for the foamed concrete fill. Drainage
mattresses with impervious sheets on top were placed
on the subsoil to stop water from penetrating into the
foamed concrete. A retaining wall was constructed from
hollow concrete panels. Lightweight foamed concrete
with a density of 650 kg/m3 was poured into the void
Air Compressor
Foaming Agent Water
FoamGenerator
Pre-foamingsolution
Foaming Lance
Foam
Air
Site Mixer
Slurry
Truck Mixer
WORKSITE
Foamed Concretepoured or pumped
Foam isadded to theslurry in thetruck mixerAIR COMPRESSOR
WATERFOAMING AGENT
Lance
FoamGenerator
Concrete Batching Plant
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The Use of Foamed Concrete inConstruction and Civil Engineering
The trench at NUS was a new trench that contained
new telecommunications cables. The cables were
enclosed in pipes that were encased in dense concrete.
(Normally when foamed concrete is used for trench
reinstatement the pipes are encased in sand. Marker
tape is laid over the top of the sand to give warning of
the position of the pipe in the event that the pipe has
to be re-excavated.) Foamed concrete with a wet density
of 1320 kg/m3 was used to reinstate the trench (Figure 4).
The trench was on a gradient and, although foamed
concrete is fluid, the foamed concrete was placed such
that none flowed out of the trench.
After just 2 hours the foamed concrete had set and was
hard enough to walk on. Once the foamed concrete sets
and has gained a compressive strength of 1 MPa a
wearing course can be laid down. This will be the final
DryDensity
(kg/m3)Dry4006008001000120014001600
7-dayCompressive Strength
(MPa)0.5 - 1.01.0 - 1.51.5 - 2.02.5 - 3.04.5 - 5.56.0 - 8.07.5 - 10.0
ThermalConductivity*
(W/mK)0.100.11
0.17 - 0.230.23 - 0.300.38 - 0.420.50 - 0.550.62 - 0.66
Modulus ofElasticity(kN/mm2)0.8 - 1.01.0 - 1.52.0 - 2.52.5 - 3.03.5 - 4.05.0 - 6.0
10.0 - 12.0
DryingShrinkage
(%)0.30 - 0.350.22 - 0.250.20 - 0.220.18 - 0.150.11 - 0.190.09 - 0.070.07 - 0.06
Figure 4: Foamed concrete being used to fill atrench at the National University of Singapore
Table 3: Typical Properties of Foamed Concrete compiled by the British Cement Association (8)
Figure 3: A cross-section of the Nagano Expressway, Japan.The original design, landslip and the new foamed concrete
design are shown.
New PlanFoamed Concrete 650kg/m3
27m
Original PlanTraditional Materials
Retaining Wall
80m x 50m x 9mLandslip
Wall (8m)
Hillside
A = Road Surface LayerB = Basecourse
A = 0.4mB = 0.3m
between the hillside and the retaining wall. A basecourse
layer of 0.3m thickness was placed on top of the foamed
concrete and a road surface layer of 0.4m thickness was
placed on top of the basecourse. Figure 3 shows a
cross-section of the hillside indicating the original
design, the landslip and the foamed concrete design.
The revised design stopped the landslide movements and
the expressway was opened to traffic in March 1993.
Trench Reinstatement at National University of
Singapore
In 1995 Trench reinstatement work was carried out by
the author at the National University of Singapore (NUS)
as a demonstration to engineers from the Public Works
Department (PWD).
Traditional methods of filling trenches in roads, i.e. the
use of granular fill materials, result in settlement and
damage to both the road and the pipes. Foamed concrete
does not require compaction, it does not settle and will
fill irregular gaps in the trench, even if the trench is
undercut.
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C O N C L U S I O N
Foamed concrete can be described as a lightweight, free flowing material which is ideal for a wide range of applications.
It can have a range of dry densities, typically from 400 kg/m3 to 1600 kg/m3 and a range of compressive strengths,
1 MPa to 15 MPa. Foamed Concrete can be used for a wide range of applications including housing, roads work,
bridges, void filling and ground work. In many cases foamed concrete has cost and performance benefits over
traditional materials. The trench reinstatement case study shows that costs benefits of foamed concrete include ease
of placement and that no maintenance needs to be carried out after placement. The landslip and arch masonry bridge
case studies demonstrate performance benefits of foamed concrete over traditional materials.
wearing course. Since foamed concrete does not settle
there is no need to return to the trench 6 months later
to place the final wearing course as is the case with
traditional fill materials. This minimises disruption to
traffic and saves money since there is less work to be
carried out.
Arch Masonry Bridge Strengthening Evaluation
An evaluation into arch masonry bridge strengthening
was undertaken by the Transport Research Laboratory
in Berkshire, United Kingdom (10). A series of 5m span,
2m wide, three ring brick arches were built and load
tested to failure. After the arches were constructed they
were filled with filling material. One of the arches was
filled with foamed concrete having a wet density of
1000 kg/m3 and a target strength of 1 MPa.
After full curing the bridge was loaded until it failed at
a loading of 1000 kN/m2, which equates to 170 tonnes/m2.
The same test was carried out with a traditional infill
material. The traditional infill material was compacted
to a 5 MPa compressive strength. Despite being
theoretically 5 times stronger with the traditional infill
material , the structure of the bridge fai led at
approximately half the loading that it did with foamed
concrete strengthening the bridge arch. The foamed
concrete transmitted the load much more effectively to
the structural elements of the bridge than the traditional
infill material.
REFERENCES
1. EABASSOC Lightweight Foamed Concrete Handbook, EAB Associates, 1996.
2. Horne, M.R., Review of Public Utilities Street Works Act 1950, London, HMSO, November 1985, 255 pp.
3. Department of Transport, The Scottish Office and The Welsh Office. Highways Authorities and Utilities Committee (HAUC). New Roads andStreetworks Act. Specification for the Reinstatement of Openings in Highways (A Code of Practice). The Stationery Office, London, 1992.
4. Hudson, K.C., Foamed Concrete for Trench Reinstatement, New Zealand Concrete Construction, July 1991, p6-9.
5. Foamed Concrete A Specification for Use in the Reinstatement of Openings in Highways, British Cement Association, 1991.
6. Parker, D., J. New Civil Engineer Concrete Supplement, July 1995, p4.
7. Basiurski, J.R., Foamed Concrete for Void filling, Insulation and Construction, University of Dundee Concrete Technology Unit, Foamed Concrete:Properties, Applications and Potential, Seminar Notes, March 2000, p42.
8. Foamed Concrete Composition and Properties, British Cement Association, 1994.
9. ASTM C 869-91. Standard Specification for Foaming Agents Used in Making Preformed Foam for Cellular Concrete, 1991.
10. Aldridge, D., Foamed Concrete for Highway Bridge Works, University of Dundee Concrete Technology Unit, Foamed Concrete: Properties,Applications and Potential, Seminar Notes, March 2000, p38.
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