06 Chapter 03 Building Materials

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In terms o green building, we need to rerame the question to: how much does it cost your city

not to have a green building policy.

Barbra Batshalom, Executive Director o The Green Roundtable, speaking at the U.S. Green Building Council in Chicago

(November 8. 2007)

by Pierre Roux and Alex Alexander: Anyway Solutions

SuStainablebuilding MaterialS

Sustainable building materials can be dened as materials with overall superior perormance in

terms o specied criteria. The ollowing criteria are commonly used:

Locallyproducedandsourcedmaterials

Transportcostsandenvironmentalimpact

Thermalefciency

Occupantneedsandhealthconsiderations

Financialviability Recyclabilityofbuildingmaterialsandthedemolishedbuilding

What are SuStainable

building MaterialS?

chapter 3


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Wasteandpollutiongeneratedinthemanufacturingprocess

Energyrequiredinthemanufacturingprocess

Useofrenewableresources

Toxicemissionsgeneratedbytheproduct

Maintenancecosts

This chapter introduces the concept o sustainable building materials and technologies, and suggests the

followingasgoodexamples:

recycledmaterialsandbricksmadefrombuildingrubble

earthbagconstruction

abobebricks

stabilizedearthblocks

compressedsandbricks

Hydraformbricks

Inourcurrentglobalsetting,buildingconstructionandoperationresultsin50%ofallCO2 emissions world-

wide.Fivetotentonsofcementareusedtobuildtheaveragemiddleclasshouse,andforeverytonof

cementmanufactured,atonofCO2isreleased,(DepartmentofLocalGovernmentandHousing.2007),

Thermallyefcient,lowCO2emission,structurallysoundandinexpensivematerialsandtechnologiesexist,

someofwhichhavebeenusedforcenturies.Materialsthathavegreatpotentialforbuildingincludeadobe,

sandbagconstruction,cob,thatch,brick,stone,hempandtheuseofrecycledmaterials.Otherlow-cement

options,includingSABSapprovedcompressedearthblocks(CEBs)arecurrentlybeinginvestigatedandproposed or sustainable neighbourhood designs.

SuStainable building policy

The innovative Western Cape Sustainable HumanSettlementStrategy (WCSHSS), objective

8,includeseco-designprinciplesinanofcialpolicydocument(forthersttime).Itrequiresthatallnew

buildings, inrastructure and open spaces be planned according to ecological design principles, and that

existingbuildings,especiallyinthepublicsector,be retrotted.Eco-designprinciplesemphasizedinclude

orientation,insulation,roofoverhangs,sustainablebuildingmaterialsminimizingembodiedenergy,thermalmassinwallmaterialandenergysavingdeviceslikePVandsolarwaterheaters.


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Background:EmbodiedEnergy

Thekeyindicatoroftheenvironmentalimpactofbuildingmaterialsisprovidedbytheconceptofembodied

energy. This is the amount o energy consumed to mine, manuacture and transport a particular product.

Theembodiedenergyofglass,steel,concreteblocks,bricksetc.,oranentirehousearemeasurable.The

VictoriaUniversityofWellington,NewZealandprovidesthefollowinglistofembodiedenergygures1.

eMbodied energy coefficientS MJ/

Material MJ/kg

Adobe block 0.47

Concrete block/bricks 0.94

Ceramic brick 2.5

Glazed brick 7.2

Cement 7.8

Glass 15.9

Steel (structural) 35.0

GJ = giga joule, a unit o energy, 1GJ = 278 kWh

1 Victoria University o Wellington, New Zealand. 2007

Bricksareredwitheithercoaloroilinclampkilnsathightemperaturesoverlongperiodsofupto3days

accountforthebulkofabuildingsembodiedenergy,andyetremainthematerialofchoicefordevelopers

and homeowners.Low-cost housing is mostly built using concrete blocks with relatively low-embodied

energyandemissions,comparedwithbrickandconcretemiddleandhighincomeresidentialandcommercial

buildings.

exaMpleS of SuStainable SolutionS

It is important to use local and unprocessed building materials that minimize transport and

manufacturingenergyandairpollution.Thisalsocreateslocalemployment.Themorelocalizedtheproject,

themoremoneystayswithinthecommunity.Thenextsectionexploresbuildingoptionsthatuselocalandrecyclable materials which are thermally ecient and cost eective.


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RecycledBuildingMaterials

Recyclingisanessentialingredientofgreenbuildingthatreducesnon-renewableinputs,especiallymining

activities, energy use and transportation costs. This includes the use o waste products and used building

materials.Itisespeciallyimportanttoreuseenvironmentallyunfriendlymaterialsthatleachtoxicmaterialsinto

the soil and ground water, or release methane into the atmosphere when dumped in landlls.

caSe Study

Alow-costhomebuiltfromrubble,Mbekweni,Paarl

ArubblehouseknownastheStonehousewasbuiltinDecember2005byCapeTownarchitects

VernonCollisandAssociates,todemonstratetheconstructionof alow-costaestheticallypleasing

andenergy-efcienteco-homeusingrecycledbuildingmaterials.ItwasaPeoplesHousingProcess

(PHP)projectoftheWesternCapeHousingDepartment.

The innerwalls werebuiltwithdumped bricks recovered froma locallandlland the outernorthand south elongated walls were built with natural stone ound on site. The side walls were recycled

concreteplasterbricksfromCapeBrick.

Building rubble was used in the oundation trenches to enhance thermal mass. An insulated ceiling

was installed using recycled carpet under-elt, and the ceiling consists o industrial wood pallets. The

windowframeswereconstructedfromlocalwoodoff-cuts,withrecycledglazing.

The Stonehouse in Mbekweni under construction, with

Cape Brick masonry in the oreground

Photo: Pierre Roux


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Recycledconcretebricks

Itmakesenvironmentalsensetorecoverrubblefromdemolishedbuildingsandreuseitinrecycledconcrete

bricks.Notonlyaresubstantialenergysavingsachievedinthebrick-makingprocess,butbuildingrubble,

otherwise dumped in landlls, can be recycled.

CapeBrickinSaltRivermanufacturesrecycledreinforcedconcretebricksandarangeofSABS-approved

concrete products rom building material recovered at demolition sites in and around the city centre. Ater

separating materials such as wood, paper, plastic and metals, the demolition waste consisting mainly o

reinforcedconcreteaggregate(RCA)iscrushedandreusedintheirmasonryproducts.Thebrickmaking

processusingbuildingrubbleisdescribedbyCobusKotzeinOnemanswasteisanothermanstreasure,

(Kotze,C.2008).

Cape Bricks crushing

acility in Salt River,

Cape Town is 5 km rom

the CBD, where most

demolition takes place.

Photo: Pierre Roux

Quarriedmaterialisbecomingincreasinglyscarceandexpensive,asithastobeminedandtransportedfrom

quarriestocitiesandbuildingsites,whichtaxestheroadsystemandincreasesgreenhousegasemissions.

CapeBricksourcesmostofitsdemolitionwastewithin5kmofitsplant,resultinginsignicanttransport

energysaving.TheirgreenbrickhasthelowestembodiedenergyofanyconcreteproductintheWestern

Cape(CapeBusinessNewsonline.2008).

Tofurtherreduceembodiedenergy,CapeBrickuse50%recycledcementslagintheirmix,makingthe

embodiedenergyvalueoftheirgreenbricklessthanhalfthatofastandardconcreteblock,andasixththat

ofaclayredbrick.CapeBrickrecyclessome70000tonsofreinforcedconcreteandmanufacturesabout

30millionconcretebricksandblocksperyear.ItshighcompressivestrengthbricksareapprovedbytheSABSandtheConcreteManufacturesAssociation(Kotze,C.2008).


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Earthbagconstruction

Earthbagconstructionhasrecentlybecomeapopularnaturalbuildingtechnique.Sandbagshavelongbeen

usedbythemilitarytocreatebunkersandotherstructures.Theyareliterallydirtcheap,astheyuselocalsand

andlow-costpolypropyleneorgeo-fabricbags.ThetechniqueisidealinsandyareassuchastheCapeFlats.

Nobricksorconcreteblockshavetobemoved,whichmeansthereisnoenergyembodiedintransport.

An eco-beam sandbag house

under construction

Photo: Eco Beam Technologies

website

EcoBeamTechnologiesinEppingdevelopedasandbaghomebuildingkitandaprocessconsistingof

three steps. A structure is erected using eco-beams/lattice beams made o two wooden struts connected

withzig-zaggedaluminiumstripstoproviderigidityandstrength.Theframeisthenlledinwithsand

bagstoformthewalls.Thebagsrestoneachotherandarenotcementedtogetherlikeconcreteblocks.

Plumbingandwiringarerouted throughthetimberuprights.Thesandbagwallsarethencoveredwith

chickenmeshwire,dampenedandplastered.Sandbagwallscannotcrack,arereproof,goodinsulators

and resist water penetration.

Sandbag structures are strong

and can even build mansions

Photo: Eco Beam Technologies

website

Constructionismuchcheaperthanwithbrickorconcreteblocks,andsandbaghousesareeco-friendly.

Sandbag building is adaptable to a wide range o site conditions and available ll materials. It demands

fewerskills,sandbagconstructioniseasytolearnandsandbagbuildingscanbebuiltmuchfasterthan

conventionalbrickandmortarbuildings.Theecobeamsystemissuitedforhousingdeliveryonscaleand

providesjobopportunitiesinlocalcommunities.Thisbuildingmethodhasgreatpotentialinthelow-costhousing sector in SA.


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caSe Study

Sandbaghouses,MitchellsPlain

SandbaghouseshavebeenerectedinFreedomPark,MitchellsPlainusingeco-beamtechnology,

and10moreunitsareplanned.TheyweredesignedbyMMAArchitects,CapeTown,asaDesign

IndabaprojectwhichwonaninternationalinnovativedesignawardfromtheUniversityofKentucky,

CollegeofDesign.Theeye-catching52mdouble-storeyhouseshavealivingareaandkitchenonthe

ground foor, two bedrooms upstairs, and a balcony that can be turned into another room. They cost

lessthanthegovernmentfullhousingsubsidyofR43000.00forconstructionofthetopstructure.

Photos: Pierre Roux

Adobebrickbuilding

Adobebricksaremadeofearth,wateranddriedinthesun.Theycanbemadeinvariousways,depending

on the local climate, site, available materials, tools and labour.

McHendry,aMexicanarchitectinKennedy(2002)providesthefollowingguidance:

Thesimplestwayiswithasinglemould.Mudismixedandplacedinthemouldsbyhandonasmoothsurface.

Themouldisremovedandthebricksallowedtodrysufcientlytostandonedge,afterwhichtheyaretrimmed

andallowedtodrycompletelybeforestackingoruse.

Thewholeprocesstakesaboutoneweekinmostfavourabledryclimates.Thebrickmakingprocesscanbe

expandedwiththeuseofshovels,wheelbarrows,multipleforms,front-endloadersandconcreteorplaster

mixers.Theuseofahydraulicpressingmachinethatcancreatealargenumberofbricks(compressedearth

blocks)upto4,000adayisanotheroption.

Oncetheyaredry,adobebricksarestackedtomakewalls.Thebricksarecementedtogetherwithamud

mortarmadeupofwaterandscreenedsoiltakenfromthesamesourcesasthesoilusedtomakethebricks.

. Adobe walls should be built on a oundation o concrete or stone to protect them rom moisture damage.Framesforwindowsanddoorsaresetinplaceasthewallgoesup.


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caSe Study

LynedochEcovillage,nearStellenbosch

AnumberofadobebrickhomeshavebeenerectedforstaffmembersoftheSustainabilityInstitute

andtheLynedochcommunity.Adobebricksweremadeonsiteusingasinglehandholdformand

thencuredforafewweeksonthepremises.Adobesoilscontainamixtureofclay,silt,sandand

aggregate.Clayprovidesthegluewhichholdsthebrickstogether.Itisimportantthattheyshouldbe

dry,hardandcrack-free.

Adobebrickshavethecapacitytoabsorb,storeandreleasesolarheat,i.e.thermalmass,though

theirthermalcapacityismuchlowerthanthatofclay-redbricksorconcrete.Thewallswerebuilt

onaconcretefoundationandsetonatwo-brickpre-walltoprotecttheadobebricksfrommoisture

damage(damp).Theexternalwallswerealsoprotectedbyalimeandclaymixplaster.Insulated

woodenceilingwereinstalled,andcorrugatedroofcladding.Vinesandtreescanbegrowntoprotect

themfromdrivingrains.Vineoverhangsalsoprovideshadingfromthesunonnorth-facingwindows

during the summer months.

Insulation can include building cavity walls lled in with materials such as mineral wools, strawboard,

wood,glassbre,andcellulosebreorrecycledcarpetunderfeltasusedintheStonehouseproject.

However, insulationis onlyreally necessary in thecolderclimate regionsofNorthern Europeand

America.(Roaf,Setal.2003).InSouthAfricaslowcosthousingsectortheonlyissueistoprovide

ceilingswithproperinsulationinordertoreducethethermalcomfortoftin-roofedmatchboxRDP

houses(Theenvelopeeffect).

Adobe brick homes, Lynedoch Ecovillage

Photo: Pierre Roux

Adobe can be used to build a luxury double-story house

as can be seen at the Lynedoch Ecovillage

Photo: Pierre Roux


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Adobeisatrulynaturalbuildingmaterial,andbecausethebricksareoftenmadebyhandonsite,energy

use is minimal.

TheTlholegoDevelopmentProjectnearRustenburgintheNorthWestProvinceisasustainableecovillage

described in Building without Borders by Joseph Kennedy (2004). The building system used is locally

manufacturedmud-brickwallsbuiltonconcreteblockandstonefoundations.Thewallswererubbeddown

withwatertoreducecracksandthencoatedwithlinseedoilandturpentineforweatherresistance.Insulated

timberceilings were installed, with corrugated iron roofs. Passive solar techniques were used like solar

orientation, thermal mass and overhangs.

Stabilizedearthblocks

Earthen buildings have been built for thousands of years, and there is a strongtradition of earthen

structures on the Arican Continent. Traditional mud huts were the most common orm o building beore

theadvent ofmodern architecture and planning. Earthbuildingsstillsheltermorethana thirdof the

worlds population.

Recently there has been a worldwide resurgence of interest in earth building, especially in developing

countrieswherelocalearthisthemostaccessiblesourceofbuildingmaterial.However,mostsoilsdonot

containthemixofclay,siltandsandrequiredforgoodbrickmaking.

Modernstabilizationtechnology(suchasAnyWaySoilBlock-anon-toxicchemicalstabilizer)hasbroadened

therangeofnaturalsoilssuitableformakingcompressedstabilizedearthblocks(CSEBs),andincreased

their strength and durability.

Compressed stabilized earth blocks have the ollowing advantages:

Anearthblockwallingsystemismuchcheaperthanbricks.Theuseoflocalsoilandon-sitemanufacturing

saves on transport costs and uel consumption, especially in remote areas with poor road inrastructure.

Pressedearthblockshavealowembodiedenergyvalueofaround0.42MJ/kgandanegligiblecarbon

oot print.

Earthstructureshavegoodthermalpropertieswhichsaveonheatingandcoolingcosts.Astudybythe

InstituteofTechnology,UniversityofFortHarefoundthattraditionalmudhutsofferbetterthermalcomfort

thanlow-costRDPhouses,andashbrickhouseshadabetterthermalperformancethanRDPhouses

(Makaka,G&Meyer,E.2006).

AnyWaystabilizedblockmakingisanon-toxicandenvironmentallysafeprocess.

Earthblocksarere,noiseandbugresistant.

Itisalabour-intensivebrick-makingprocessthatcanbeeasilytaught,andthestabilizercanbeusedinremote areas to create earth building material.


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caSe Study

PilotProjectinSimunyeTownship,Westonaria

(Gauteng)

Astabilizedearth-blockhousewasconstructedinDecember2006byAnyWaySolutionstogetherwith

theSinqobileCommunityYouthDevelopmentTrustintheSimunyetownshipofWestonaria(Gauteng).

Unemployedpeopleweretrainedtomanufacturecompressedstabilizedearthblocks(CSEBs)onsite

with local soil, using a manually-operated press. A low-cost home was built and plastered with earth

mortar. The structure was tested by the SABS and ound to comply with the requirements o the

NationalBuildingRegulations.

For CEBsto bind,6% stabilizer isrequired. The stabiliser issoldin 25kgbags@R58 per bag.

StudentsattheSustainabilityInstitutemanufactured51blocksusing418kgofsoilandone25kg

bagofstabilizer,i.e.atacostofR1.13perblock-farlessthanthecementequivalent,nottomention

theCO2 reduction gained by using local soil.

TheSimunye Project wonthe Canadian InternationalCooperationPrixd ExcellenceAfrica 2007

Award or demonstrating a more socially transormative and environmentally sensitive approach to

community development that urthered entrepreneurial opportunities or women in Arica. It was also

oneof15nalistsfortheInternationalInstituteforSustainableDevelopmentandUNDP2008SEEDAward(www.seedinit.org).

Training given to community members Sieving the local soil Mixing soil and stabilizer and addingwater

Pressing the earth blocks Stacking blocks or humid curing Training on building with CSEBs and

local earth mortar


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LocalbrickyardforruralhousinginLimpopo

Riversand, stoneandcementaremixed and concrete

bricks manufactured on site. Two wheelbarrows of

sandandstonearemixedwith25kgofcementanda

bucketofwaterinaPanMixer.Thisisthenpouredinto

ahydraulicpressthatproducescompressedsandbricks.

Thefacilityis5kmfromaruralvillagewhere115low-cost

houseswereconstructed.Thebrickyardemploys32local

people.Thesandissourcedandcarriedbydonkeycarts

andtractor-drawntrailersfromariverbed2kmaway.The

bricksaresolardriedinthehotbushveldsun.

Plastering with local earth plaster

(natural colour o local soil)

SABS rainwater penetration testing

SABS sot body impact testingPhotos: Alex Alexander, Anyway Solutions

Compressedsandbricks

Wheresuitablesoilisnotavailable,riversandcanbemixedwithcementtomanufacturecompressed

bricks on site. The picture below shows a four room 50 m house built from compressed bricks in

LimpopoProvincebytheTzaneenMunicipality,aspartofaPeoplesHousingProcessproject.Thebrick-

makingprocesshasalreadybeendescribed.

50 m compressed sand-and-cement brick house.

Photo: Pierre Roux


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Hydraformbricks

Hydraformbricksaremanufacturedbyhydraulicallycompressingasoil-cementmixtureinablock-making

machine. Hydraform inGauteng sellsa rangeof machines, from a hand-heldto sophisticated hydraulic

machinesforblockyards.Hydraformbrickscanbemanufacturedonsiteanddry-stacked,reducingthe

embodiedtransportandcuringenergysignicantlytoaround0.635MJ/kg.Theproductcontainsa small

percentageof cementwhich largely accounts for itsembodiedenergy component.Hydraformalsohas

a block yard producing over 2 million bricks per year that comply with SA national building regulation

requirements or strength, durability and stability.

Hydraform brick house, Lynedoch Ecovillage,

Stellenbosch

This house at Lynedoch Ecovillage used dry-

stacked Hydraorm bricks made rom a local clay

soil and cement mixture, using a single-orm

hand-held press

FlyAshBricks

Flyashbricksaresometimesusedintheconstructionoftoiletsandotherstructuresinthelow-costsector.

Thiscement-basedbrickmakingprocesshasatypicalembodiedenergyvalueof0.632MJ/kg.Flyashis

awasteproductfromcoalpowerstations,andisanenvironmentalpollutant.Generallythesebricksareof

poor quality and uniormity, and cannot be plastered as they contain magnesium, which reacts with water,

makingthebrickspopout.

Ashbricksareveryabrasiveandbrittleandanailcannotbedrivenintothem.Otherunsolvedproblemswith

yashbricksarethattheytendtohaveahighwaterabsorptionrateandporosity,butlowreresistance.

Thereareonlyafewprojectsworldwideusingyashinbuildingbricks,andmoreresearchisrequiredonthe

healthimpactofthesebricks,astheycancontainhazardoussubstances.

Otherapplications

Whilerammedearth,strawbale,hempconstructionandcobbingarewidelyrecognisednaturalbuilding

methods,especiallyintheNorthernHemisphere,theyarenotcommonlyusedintheSouthAfricanlow-cost

housingsector.Theseapplicationscanbelabour-intensiveandsomemayrequirehighlyskilledandqualiedartisanexpertiseideallymoresuitedtothededicatedgreenowner-builder.


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Thislittlegum,wattleandhemphousewasbuiltatOuden

Molen,inPinelands,CapeTown.Ithasagumpoleframe

with an interlocking wattle basket weave (both invasive

aliens),lledinandplasteredwithlocallysourcedclayand

painted with lime.

Photo: Pierre Roux

Notonlynewbuildingprojects,butalsoexistingneighbourhoodsinevitablyrequirenewinfrastructure,orthe

upgradingofexistinginfrastructure.Similartotheemergenceofsustainablealternativestoconventionalbuilding

methods,roadbuildinghasalsoengagedwiththeconstraintsimposedbyscarcityofresources.Landllsare

struggling to meet the demands or the disposal o building rubble, and our top soils are also being depleted.

Thenextsectionwillspeaktosustainablematerialsuseinroadconstructionataneighbourhoodlevel.

Soil StabiliSation for

roadS, parking areaS andinfraStructure

Soil stabilisation applications can be used to improve the mechanical and physical properties

o sub-standard soils so that they can be incorporated into or orm the basis or road, rail and building

inrastructure. The improvement o in situ soils to required engineering specications has a ar smaller

environmentalimpactthanthealternativeofrejectinglocalsoilsasunsuitable,andimportingotherselected

materials. The benet o In-situ soil stabilisation technologies includes the possible decrease in transport and

building material costs, the conservation o natural resources and the reduction o harmul emissions. The

followingareexamplesofsuccessfulapplicationsofsoilstabilizationinconstructionprojects.

ThelevelsofunemploymentandpovertyinSA,theexistingskills-baseofmanyunemployedpeopleandthe

needforsocialinfrastructuremakeapersuasivecaseforfargreateruseoflabour-intensiveconstructionand

effectiveskillstransfer.ThisisrecognizedbyGovernmentandformspartofstatedpolicy.

Soilstabilizationempowerslocalpeopletoxlocalproblemswithlocalsoil,afewsimpletools,andtheirown

labour.Suitablytrainedsmallteams/SMMEscanundertakemanyaspectsofinfrastructuredevelopmentthatdirectly improves their lives.


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caSe Study

RoadsandParking,ResidentialComplex,

PretoriaNorth

InternalroadsandparkingareaswererequiredinaresidentialdevelopmentinWolmerExt.1totaling

35,000m. The in situ material, a problematic clayey, silty, sandy soil with a high swell potential

(commonlyknownas black cottonsoil), presenteda difcultengineeringchallenge.Theoriginal

designproposedcuttingandspoilingtheupper350mmofinsitusoil,followedbyconstructionof

500mmofpavementlayers,with350mmofselectedimportedaggregates.

Acheaper,faster,moreefcientandenvironmentally-friendlysolutionwasproposed,usingAnyWay

NaturalSoilStabilizer(ANSS)inthefollowingmanner:

thetop120mminsitusoilwasstrippedandspoiled

120mmofselectedG6materialwasimportedandplacedoninsitusoil

ANSSwasappliedatarateof3%ontopoftheG6material

theinsitusoil,G6materialandANSSweremixedusingarecyclerandwatercart,tocreatea

250mmstabilizedlayercompactedto95%MODAASHTO,overa2weekperiod.

This design had the additional benet o providing sound roads or use by construction vehicles in

all weather conditions during the house-building phase which eliminatied rain-induced delays on theproject.Onceconstructioniscompleted,theroadsandparkingareaswillbesurfacedwith60mm

concrete pavers.

Savings using stabilization

overall cost saving of 40% on the roads and parking

areas

atimesavingof3monthsontheconstruction ofthe

road/parkingarea

furthertimesavingonprojectbyall-weatherroaduse

pavementthicknessisreducedfrom50to25cm.

Environmental savings

8,050mlesssoilspoiledtolandllsite

8,050mlessselectedaggregateimportedfromquarries

avoidanceof1,208X20-tontruckjourneysthroughexisting

residential area saving road wear and trac congestion

asavingof14tonsCO2 emissions (global environmental

impact).


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caSe Study

TownshipRoads,DihlabengDistrictMunicipality

DihlabengDistrictMunicipalityhasaprogrammeupgradingtownshiproadsinits5localmunicipalities.

Previously,theinsituclayeysoilhadtobecuttoadepthof200mmandspoiled,anda200mmlayer

ofselectedaggregatewasthenimportedfromadistantandexpensivesource.AstheMunicipality

wanted to use its own limited road-building equipment and manpower, and reduce costs, it decided

tostabilizetheinsitusoilinstead,withgreatsuccess.

TheMunicipalRoadsDept.isnowabletoconstructa 1kmstabilizedun-surfacedroadin2days,

whichpreviouslytook15dayswiththespoilandimportmethodandlimitedequipment.Theun-

suraced road instantly provides a sae, less dusty, non-slippery wearing surace in all weather. At

alaterstagetheroadsareprovidedwithaside-drainandsurfacedwith60mmconcretepavers

producedbyalocalcommunity-operatedbrickyard.

Savings using stabilization per 1 km road

completedin2days,insteadofprevious15days

acostsavingof50%+onroadlayers(surfacingidenticalinbothdesigns)

Stabilizedroadimmediatelyusable,surfacingdonewhenconvenient.

Environmental savings per 1 km road

1,000mclayeysoilnotspoilttolandllsite

1,000mselectedaggregatenotimportedfromquarries

avoidanceof200X20-tontruckjourneys,savingdiesel,reducingroadwearandtrafc

congestion

asavingof2tonsCO2 emissions(globalenvironmentalimpact).

Original township

road

The road ater

stabilization and

compaction, providing a

sae, all-weather driving

Constructing the

side-drain next

to the stabilized

road

The fnished road, sur-

aced with 60mm pavers

made by a community-

operated brickyard.


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caSe Study

GundoLashuProject,Limpopo,2005

ThiswasajointprojectbytheInternationalLabourOrganisationandRoadAgencyofLimpopo,with

CouncilforScienticIindustrialResearchparticipation,todevelopeffectiveandappropriatelabour-

based road constructionmethods.Various soilstabilizers andapplicationmethods wereused to

upgradetheexistingun-surfacedgravelMakopaneRoad.

TheAnyWaytrialsectionusedinsitusoilnexttotheroadway,whichprovidedsoilforroadlayers

aswellascreatingadraintoremoverainwaterfromtheroad.Onlymanuallabour,handtools,steel

shuttersandawalk-behindcompactingrollerwereused.Followingstabilization,theroadwasleftun-

surfacedfor1yearandthensurfacedwithanOttaseal.

Mixing the stabilizer with the in situ soil Shaping the stabilized layer

Compacting with walk-behind roller The Otta seal-suraced road, still in good condition

three years later


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concluSion

Sustainable building materials by denition are materials that are locally produced and sourced

(which reducestransportationcosts andCO2 emissions),they can includerecycled materials, theyhave

a lower environmental impact, they are thermally ecient, they require less energy than more modern,

conventionalmaterials,theymakeuseofrenewableresources,theyarelowerintoxicemissionsandtheyare

nancially viable.

Methodsofsustainablebuildingandtechnologiescanincludebuildingwithrubble,sandbagconstruction,

abobebrickconstruction,theuseofstabilizedearthblocksandcompressedearthblocksandtheuseof

Hydraformbricks.

Sustainable building materials should be utilised appropriately and contextually in each neighbourhood

development. The use o sustainable building materials not only reduces transport costs , carbon emissions,

andinmostcasesmaterialscosts, italsoprovidesemploymentandskillsdevelopmentopportunitiesfor

community members.

06 Chapter 03 Building Materials

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