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CONSTRUCTION PROCESS
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• The formwork is constantly removed and placed on the next set of horizontal timbers where the process is
repeated. Once the formwork has been moved on, the horizontal timbers are removed from the wall leavingcharacteristic holes. Upon completion of one horizontal level the formwork is moved vertically, the mass of standing
wall being known as a lift.
• The wall is so solid that, if desired, the forms can be removed immediately. This is necessary if wire brushing toreveal texture is desired otherwise walls become too hard to brush after around 60 minutes.
• Walls take some time to dry out completely, but this does not prevent further work on the project.
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FORMWORK BRACING TECHNIQUES
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DESIGN CONSIDERATIONS• Rammed earth walls have low tensile
strength, and should be reinforced by
providing a bond or collar beam.
• Beams can be constructed of concrete,
wood or steel.
• Vertical reinforcing may also be done,
and may be required by some building
officials.• All openings in rammed earth walls, such as
windows and doors, must have lintels to
span the opening width.
• Water flow and moisture control is
critical to protect structural walls. Special
detailing to accommodate manufactured
windows may be necessary to accommodate
wall thickness.
REINFORCEMENT PROPORTIONS
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• All openings for doors and windows will require a frame.
Wood, as opposed to metal, is recommended due to the
corrosive action of moisture from the soil material.
• Careful attention to both roof and opening details is
necessary to protect the structure from water damage.
• Foundations required by most codes are concrete
reinforced with steel.
• Soil block material may be used as a filler material
between piers of a reinforced concrete pier and beam
foundation.• Historically, many structures built with earth materials had no
foundation, or used sand and gravel foundations. The
latter are excavated trenches filled with two parts sand to
three parts gravel. Trench bottoms were graded to providepositive drainage.
• Soil material block should not be used in below grade walls
unless supported on both sides. Natural moisture from the
ground may infiltrate the block, resulting in reduced
compressive strength.
OPENING PROPORTIONS
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BAMBOO REINFORCED RAMMED EARTH• A Rammed earth wall is erected over a bamboo reinforced
monolithic stone foundation, using a special T-shaped steel slip
form.
• The 31 inch wide wall sections are rammed continuously until the
final wall height is reached so that no horizontal shrinkage cracks can
occur.• Each section is separated by a ¾ inch gap to provide for
independent movement during seismic activity.
• Four vertical bamboo rods act as
reinforcement for the wall sections, and togetherwith the gap give sufficient stability against
horizontal loads created by seismic activity.
• The bamboo is interconnected with the
reinforcement of the foundation as well as with the
ring beam that connects the tops of all the wall
sections.
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BENEFITS OF RAMMED EARTH
• Reduced CO2 Emissions
• Thermal Mass
• Noise Reduction
• Strength
• Durability
• Low Maintenance
• Fire Resistance
• Pest Resistance
• Cost Effective
• Rapid Construction
• Environmentally Friendly
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CO2 Emissions• Using rammed earth as a construction material
greatly reduces the amount of CO2 released during the
construction of the building.• The manufacture of cement requires the burning oflimestone and produces CO2 as a waste product.
• Around 10% of global CO2 emissions are from thecement industry.
• In using soil taken directly from the site, there is notransport requirement, directly reducing CO2emissions and taking vehicles off the road.
Thermal Performance• The high thermal mass of rammed earth walls mean they
act to naturally regulate the internaltemperature of a building.
• If a rammed earth wall is designed into the heatingsystem of a structure, the energy required to both heat
and cool the building can be greatly reduced, whichfurther reduces the CO2 emissions of the building.
• Rammed earth naturally regulates the internalrelative humidity of the building, producing an
improved air quality.• This contrasts greatly with air conditioning systems,which act to dry the air in a building and contribute toharsh working and living environment.
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Structural Performance• Rammed earth is perfectly able to act as
load bearing members within a
structural system.• The strength of dry,
un-stabilized rammed earth is
close to 1MPa.
• The strength and stiffness of
the material reduce greatlywith increasing watercontent, and thus the building must
be well designed in order tomaximize the structuralpotential of the rammed earth.
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Feasibility• Rammed earth complies
with Building Regulations
for insulation,strength, waterresistance, fire andacoustics.
• Not all soils are suitablefor use as rammed earth.The soil must becompacted at a particular
Embodied Energy
• The inherent recycle-ablilityof rammed earth, and thereduction in CO2 emissions duringthe lifetime of the structure, thehigh thermal mass and thus lowoperating costs all mean thatrammed earth has a much lower
embodied energy than comparablebuilding materials.
water content to
ensure optimumcompaction, and thiswater content should bepredetermined beforeconstruction begins.
• Structural design oframmed earth buildings isusually very simple, with
walls acting incompression, but
detailing is important toensure the rammed earthis used to its maximumpotential.
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GREEN BUILDINGSVineyard ResidenceVictoria, Australia• Architect: John Wardle Architects
• Completion: 2002• Area: 400 m2
• Rammed Earth Walls angling outward evokes
the impression of continuing into the landscape.
• Cross ventilation is achieved throughout all theareas, between the walls.
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Center for Gravity Foundation Hall
Jemez Springs, New Mexico
• Architects: H. Predock, J. Frane• Completion: 2003
• Area: 279 m2
• The thick Rammed Earth Walls act as thermal
composites, keeping unwanted summer heat out during
the day and re-radiating it at night.
• Cooling is achieved thru cross ventilation by opening the
sliding panels to the east and the entry doors to the west.
• In the winter, heat is generated by geothermal water.
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Chapel of Reconciliation
Berlin, Germany
• Architect: Reitermann + Sassenroth• Completion: 2000
• Area: 315 m2
• The interior is of oval shape, and is
delimited by a rammed earth wall 7.2min height and .6m in thickness.
• The Rammed Earth wall contains large
fragments of broken brick from the
former church, as well as gravel, whichtogether constitutes 55% of the
material. This coarse-grained
mixture reduces material
shrinkage to only .15%.• The admixture of flax fibers and
intensive compaction with a tamping
roller was able to produce a
compressive strength of
3.2N/mm2.
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