the future of indigenous building materials · efforts to identify appropriate native building...

THE FUTURE OF INDIGENOUS BUILDING MATERIALSby Pliny Fisk

Pliny Fisk runs an outfit in Austin, Texascalled the Center for Maximum PotentialBuilding Systems. In this paper he discussesnative building materials in an exciting newlight. He shows us that the potential forbuilding our structures from locally availableresources is far more extensive than most ofus realize and that, rather than being primitiveor backwards, such approaches can be farmore sophisticated and appropriate than the"modern" techniques we now practice.

The method he outlines for mapping andutilizing local building materials can beapplied to other resources as well. It can beused to chart a region's potential for selfsufficiency in food, energy and other areas.

SUNPAPER NOVEMBER/DECEMBER 1982

Too often at conferences that have to do withlife support technologies, we are presentedwith massive amounts of data, lists of hardcore experiences, or, if we are lucky, somehistorical perspective of how it all came to be.Rarely do we press one another forperspective or collectively direct our effortstoward a developmental continuum, and evenmore rarely do we admit to or even possess anoverall methodology to track our work, toshare it responsibly or even responsively.

If the future of indigenous building materialsis to be properly addressed, we must dealwith the subject on both a policy andtechnological level.

On the policy end, we have to realize that thebenefits of miniaturizing or regionalizing oureconomy to produce jobs did not start andstop with the solar movement. In fact, theorigin, destination and use of materialsthemselves is probably the first step not onlyof the creation of stabilized local economies,but also in the reduction of much of theenvironmental impact resulting from the by-products of manufacturing.

As to the technical level, we must admit tosome standardized testing, especially for earthmaterial building. We must understand thetechnical options and limitations ofproduction equipment and be able to matchthese levels to the scale of need in a givenregion.

Although this presentation cannot possibly dojustice to the number of factors needingattention in the realm of indigenous building,we will begin by offering a conceptualframework for the development of thisemerging discipline. We will then surveysome of the trends that

are emerging in this exciting field.

The mapping and analysis method describedbelow is discussed largely as it applies to ourefforts to identify appropriate native buildingmaterials for the state of Texas. Readers shouldkeep in mind that this method can be appliedin any region and to many resources inaddition to building materials e.g. food andenergy.

METHOD

This paper presents indigenous buildingmaterials in the context of an overallenvironmental approach. The approach ispartially based on mapping as a medium ofinformation exchange. Mapping is the toolwhereby plant taxonomists record species,geologists record minerals, and soil scientistsrecord soil data. Mapping is a statistical basefor identifying areas of poverty, jobs, skills,manufacturing, retail, etc. It is generally thebasis from which physical land use plans aremade, and environmental impact statementspresented. But, most importantly, mappingallows us to cross disciplinary boundaries and

look at all of the above at the same time inone comprehensive picture.

As a tool for identifying the indigenousbuilding materials and techniques best suitedto a region, mapping tells us not only where aresource is, what area it covers, and itsgeneral quantity, but can also tell us whethera local extractor, fabricator or mason exists.If many indigenous materials are mapped, theuser can know how many different buildingcomponents can be derived from a givenlocale, who has used them and in whatcombination(s). As a networking tool,depending on the information recorded,mapping can help someone gain access tosomeone else's experience in a similar regionwith a similar set of resources.

In our mapping we identify three basic kindsof resources. Area resources are the actualphysical resources such as forest and soiltypes, quantities and locations. Pointresources are the special human skills andknowledge related to the area resources beingmapped. For example, who and where are


the people in an area experienced in workingwith, a particular indigenous buildingmaterial. Network resources pertain to theeconomic and social infastructure of theregion as it relates to the subject under study.Network resource maps look at the scale andtype of trade (e.g. monetary, barter,reciprocity, capital intensive etc.) takingplace in the region and the availability ofrelated goods, services and information.These three levels of resource identification--area, point and network--allow us to assessthe needs of a region and offer possible localsolutions.

The needs assessment determines whatresources must be developed first and in whatareas of life support, e.g. food, fuel, shelter. Italso cross-relates their importance to bothpopulation and environment. In order tounderstand the various relationships justdescribed, we use an interaction field matrixwhich compares issues identified in a needsassessment with a region's three resourceareas. If, for example, a need is establishedand the area resources to fulfill that need areidentified but the local population knowslittle about them, some amount of training isrequired in the area of testing, fabricationand/or skill development.


There is not room here to fully describe thecross-referencing process we use. The earthenbuilding materials interaction field illustratedabove gives the reader an idea of the variablesthat should be considered when choosing ordeveloping a technology for a specific region.Let's now take a look at some of the specificapproaches we've taken with indigenousbuilding materials in Texas.

THE OCCURRENCE OF MASSIVEBUILDING MATERIALS IN TEXAS

(1) Caliche is a high calcium carbonate soilcharacteristic of lower soil horizons in arid,semi-arid environments. It is estimated thatthese soils comprise 14% of the earth's surface,and over one-third of Texas' land mass.

Caliche can be fabricated into very strongbuilding blocks. The mix for caliche blockdepends on the calcium carbonate content.With a good caliche, a mix of eight parts sand,nine parts caliche and one part cement isadequate. The cement is used as a stabilizer,but even it can be replaced with a locallyavailable mixture of pozzolan and lime.

(2) Stabilizable Earth ranges from 20% to 55%clay and can be stabilized chemically or bypressure. Earth with this range of clay contentcomprises about 60% of the Texas land area.

(3) Pozzolan is a fine grain, amorphous silicawhich, when mixed with lime, is calledRoman cement. A typical pozzolan mixture is5% lime, 25% pozzolan, and 70% sand/gravelaggregate. Pozzolan is 1400 feet thick inMission, Texas, and decreases to 2 feet thicknorth of Houston. Pozzolan was the principalcementaceous material used to build theRoman Empire.

(4) Flyash is similar to pozzolan but is notreally an earth material since it is derived as awaste from coal burning plants. However, ifTexas energy policies continue as per presentplans, we will literally be knee deep in thestuff in no time. The material has been used tomake brick.

(5) Sand Lime is an autoclaved pressuremolded mixture of sand, lime and water: 8% to12% lime, 88% to 92% sand and 3% to 5%water.

(6) Sulfur is a subsurface mineral of whichTexas possesses a reported one-fifth of theworld's supply. Sulfur is mined by drilling,and presumably could be utilized from thewell on-site in sprayed form, foamed formand as building block. Sulfur block is madeby combining 65% to 70% sand and 30% to35% sulfur. Several different fireproofingmethods for sulfur are available at relativelylow costs.

Gypsum is not specifically mapped butusually occurs in parallel geologic formationsto sulfur. It is first calcinated over fire andthen ground and mixed with water (Plaster ofParis).

(7) Adobe is a sandy clay soil containingvirtually no organic matter. It is characteristicof arid and semi-arid climates. At its best,adobe contains about 20% clay and 80%sand, but a wide variety of mixes are usedwith the resulting need for higher stabilizingrequirements as one departs from this ratio.Adobe makes up approximately one-third ofTexas' land surface.



CASE STUDY

Now let us examine the design and constructionof a real building. Myriad materials and materialcombinations are required. If one were to studythe headings and subheadings categorized in ourinteraction field cited earlier, one would realizethe range of questions needing to be asked.Remember, the main purpose of this building weare about to describe is to develop the use of awide variety of local resources and to show whatimpact this approach would have on local energyconsumption and job production.

The building diagrammed below describes incross section some of these material systems.Drawings that follow describe such materialcombinations as well as utilities in more detail,and key these components into spatial maps. Letus start with the building shell.

The building shell, which is now complete andlocated in Carrizo

Springs, Texas, contains six regional systems.They include a trickle-type re-radiating roof,bamboo for reinforcing of foundation and fordoor and window lintels, caliche for use asmass and structural building block, andmesquite hardwood for parquet-type tilefloors, and as a sawdust-base for exteriorinsulating block.

The trickle-type reradiating roof, is coupled topipes in the heat absorbing foundation slab.The performance of the roof depends on theability of white-painted corrugated roof metalto re-radiate heat and evaporate the watertrickling over it at night. This water is thencycled through pipes in the slab foundation.The performance also depends on how manyBTU per square foot of roof area the night skyis able to absorb. In the area of CarrizoSprings, this roof is able to lose approximately100 BTU per square foot which isapproximately equivalent to the daytime heatgain per square foot of floor area of a wellinsulated building in this region.

Bamboo, which requires a lot of water, can begrown only along the banks of rivers in ourdemonstration area. The bamboo must be cutas close as possible to its dormant season inorder to reduce the amount of water in itsstems. Bamboo is capable of withstanding 18thousand pounds per square inch in tension. Itis stabilized with asphalt emulsion and thenused in place of rebar as reinforcing materialin cement or calcrete (caliche/concrete orcaliche/pozzolan) block. No stems beyond3/4" diameter are used. When the bamboo isgreater than 3/4", the bamboo reed is split.

Mesquite is a hardwood that grows prolificallyin this border region. Our group has organizedcommunity wide gathering of mesquite to beused in six low income rural towns in SouthTexas. At 13,200 BTU per pound, mesquitemakes about the


best charcoal in the U.S. It is an extremelyhard wood, comparable to mahogany. We haveincorporated mesquite into this building intwo ways: 1) as a floor tile and 2) as a materialbase for insulating sawdust block. Sawdust is ahighly available waste material in the region.The tiles are made by using the rough cuttingcapability of a local mesquite sawmill and abandsaw that slices 6" x 6" x 2-1/2" pieces into1/2" tile. The completed sawdust blocks weighabout one-third less than caliche block, whichweighs about 20 pounds per 8" x 10" x 3-1/2"block.

Cedar does not grow in our study area andmust be imported from a neighboringbioregion. The cedar is required because the.local mesquite tree rarely grows straight anddoes not produce good lumber, whereas cedaris the material in closest proximity which canbe used to fulfill structural uses. It also isfavored since it is rot resistant.

INSULATING MATERIALS WHICHOCCUR NATURALLY IN TEXAS

(A) Mesquite, Pine: Mesquite and Pine areboth usable in insulating block when mixedwith cement and a base material such as sand.Mesquite sawdust must first be neutralized bysoaking it in an alkaline solution of lime water,and then mixed in a solution of one partcement to eight parts stabilized sawdust. Pinesawdust can be mixed dry in proportions of sixsand, two Portland, two lime, eight sawdust.Both blocks must be protected from theweather with latex paint. These sawdustinsulating bricks are fireproof but have notbeen subjected to long term weathering effectsas far as we know.

(B) Oak and Cedar sawdust or chips can besoaked in Boric Acid for fire-proofing andthen used as insulative fill in hollow walls.

(C) Diatomaceous Earth is the deposit ofsilicious fossils whose dry weight is 10 to 28pounds per cubic foot. It is mixed with threeparts sawdust, three parts shavings, one-partcement, one part diatomite and one part clay. Itcan be used in the form of poured walls orblocks.

(D) Vermiculite is a micaceous mineral whichexpands upon exposure to heat of about 300degrees C. It can be used directly as an infillinsulation.

(E) Pumice is a lightweight, porous volcanicaggregate which can be mixed with cement.

One important measure of the usefulness of amassive indigenous material is the amount ofheat it can store when used in solar buildings.Another factor to consider is the amount ofenergy required to manufacture and transport abuilding material to a building site. While theenergy consumed for transportation of adobe,caliche, sand lime, gypsum,


diatomaceous earth and cement are aboutequal the energy used in the manufacture andapplication of these materials varies widely.We are working on a chart which lists thesecharacteristics as well as the structural andthermal qualities of materials. Asconventional energy costs soar, these kindsof considerations will become increasinglyimportant.

Iron ore is another material which must beimported, in the form of corrugated tinroofing. It is required for the night skycooling roof system. When painted with highemmisivity white acrylic or lime basedpaints it is far better at releasing heat to thenight sky than any locally available material.

Our window/wall unit uses resources similarto the building shell. The on1y majordifference is our dew catchment techniquewhich automatically waters vines that areused to shade east and west facing windows.This technology works only in coastal andnear-coastal regions where water vapor ishigh enough in the early morning hours tocollect as condensation on surfaces that cancool to the night sky. The planter box ismade of mesquite because of its resistance torot. Bamboo is used as reinforcing but thistime in cantilever lintels and as a trellis forthe vines.


CONCLUSIONS FROM CASE STUDY

The chart on the next page compares theenergy costs of conventional and indigenouswall units and foundations. The comments inthe right hand column clearly show thatindigenous materials use far less energy andcreate far more jobs than their conventionalcounterparts.

We found that bamboo takes approximately170 times less energy to produce than itsequivalent in steel reinforcing bar. If allfabrication methods are properly


followed, bamboo will take about 18 thousandpounds per square inch (p.s.i.) tension ascompared to common steel at 23 thousand p.s.i.Our cantilevered lintels and our roof trussesare under tension and we have strong reasonto believe that they will last for 50 years.

Similar comparisons can be made for otherproperties as in a material's ability to store heator cold. Caliche walls contain more heatcapacity than conventional brick walls butrequire only 25% as much energy to fabricate.

EQUIPMENT

The equipment needed to build with thesematerials is quite different from that normallyassociated with the building industry. Themachinery has to be highly responsive to thespecific characteristics of a region's materialsand to the technical capabilities of the localpopulation. One can begin to see how ourinteractive matrix discussed earlier is needed todetermine a technology appropriate to a specificregional condition.

Surprisingly, most of the equipment andconstruction techniques presented below arewidely considered to be new. However, many ofthem are based on ancient techniques. While wecan't possibly discuss all of the indigenousbuilding techniques and devices, we offer arepresentative sampling to give an idea of howregional conditions can be met.

PUDDLE BLOCK TECHNOLOGY

Puddle block is a generic term for buildingblocks made by pouring a moist material into aform and allowing the blocks to dry. Althoughthe process is an ancient one, many variationshave evolved from the traditional hand releasedgang mold.

For instance, while two people with hand moldscan produce about 200 blocks per day, theMini-Molder, developed by Howard Scogginsof Alamagordo, New Mexico, can produce 300to 500 blocks per day. The Mold Master (a MiniMolder with travelling hopper) can produce1,000 to 5,000 blocks per day (depending on size)using five laborers. The Mudder-Cutter (anovergrown pizza cutter), developed by JackDameron of Austin, Texas, has the capacity toproduce from 5,000 to 10,000 blocks per dayusing five to six laborers. This machine lays acontinuous ribbon of earth (or cementaggregate) about four feet wide, which is thensliced horizontally and perpendicularly by a setof round blades. Another


device similar to the Mold Master was designedby Hans Sumpf of Madera, California. Thismachine has a peak capacity of 18,000 blocks perday using a seven person crew. Equipment costs,complete with trucks, front end loaders, pumps,etc., run between $200,000 and $250,000. Rumorhas it that a new machine, similar in productioncapacity to the Sumpf, has been developed byHoward Scoggins.

These puddle block machines are easier tooperate and maintain, and produce bricks ofcomparable strength (depending on the earthmaterial used) to facilities which produceconcrete block or fire bricks in kilns. The energycosts of puddle blocks are lower also. Acomparison


of energy costs of traditional buildingtechniques with soil cement building andrammed earth appear, below. The importanceof energy costs will escalate as the dollarcosts for energy increase.

These low energy block making methods dorequire considerable skill. One needs tounderstand the stabilizer needs of a particularearth and how the combination of indigenousmaterials can sometimes fulfill that need. Forinstance, we have successfully stabilizedcaliche with lime and pozzolan (no cement),pozzolan with lime and sand, and we've evenmade blocks from nothing but fly ash, sandand water that withstand 8,000 p.s.i.

By really understanding an earth material youcan transcend traditional earth buildingtechniques. For instance, a good caliche, 80%to 90% calcium carbonate, will need only 5%to 7% cement (with an average compressionstrength of 960 p.s.i.), as compared to 10% to16% cement needed for typical soil/cementcombinations. Other skills such asunderstanding the precise amount of waterrequired by liquid limit and slump tests,determine whether much of the equipmentcited above will even work.

Puddle block methods do have theirdisadvantages. One is the large amount ofspace they require. The biggest drawback isprobably their water requirement. For everycubic yard of material produced, about 22gallons of water are needed. Since earthblock structures function best in arid andsemi-arid zones, this water requirement canbe a significant problem. While earthmaterials require far less water than steel andconcrete, we still need to keep this limitationin mind.

The fact that each of these earth techniques isadapted to a specific mix of social andnatural resources is brought home by theMexican cement block machine illustratedbelow. This machine makes block composedof a lightweight volcanic aggregate (of whichthere are extensive deposits around MexicoCity) mixed with cement. Using a vibratingmotion and a small amount of pressure thismachine makes blocks that can be stackedimmediately after they are molded. In anurban area where space is limited this is idealbecause the blocks can be stacked at the endof the street as they are made. The otherprocesses described above wouldn't work inthis situation because they produce longribbons of

brick which take up lots of room and must drybefore being stacked.

Another feature of this machine is the smallamount of physical labor it requires. No formshave to be lifted and since the blocks are aboutone-third the size of adobes they aren't veryheavy. So, built around specific spacerequirements and locally available materialswe find a machine that can produce 6,000blocks per day with the labor of ten people.Incidentally, women were running theoperation that we saw in Mexico City.

RAMMED EARTH BLOCK MACHINES

Because they skirt many of the problems ofpuddle block machines, rammed earth blocktechniques are receiving renewed interesttoday. They pose virtually no space storageproblems since the ramming equipment can beused on any site where the soil has a 20% to55% clay content. A flat yard is not requiredas with puddle block methods. And perhapsmost importantly, little water is required.

Several ramming machines have beendeveloped over the years. Perhaps the bestknown is the Cinva Ram. However, I havefound this hand operated unit to be extremelyfrustrating and tiresome to work with. It onlyproduces 300 blocks per day (if you're lucky)and it produces a block far stronger than


is needed. Caliche blocks can come out of aCinva Ram with a compression strength of 1,400 p.s.i. which is enough to build an eightstory building. I must say that we don't see thefuture of the brick industry in the Cinva Ram.

However, there are some good rammed blockmachines available. In the 1950's the WingetWorks in England invented the Wingetpressed block machine which produced 1,120blocks per day. Its only drawbacks were its

weight and the inability of small equipment toefficiently move it from site to site.

A more recent development is the Hallomeca,from France. It has a production rate of 8,000to 16,000 blocks per day. Not much is knownabout this machine in the U.S., but informationon it can be traced through one of the Frenchearth building groups cited below.

Recently, in the U.S., the M&M MetalCompany introduced an hydraulic unit using a200,000 p.s.i. press. The machine is mobile,contains an integral mixer and produces about2,000 blocks per day. However, its reputed useof 5% to 70% clay materials seems to beincorrect in that we received a shipment of 7%clay block of which about one-third arriveddamaged. We suspect, though, that thismachine will make an excellent block whenusing soil with higher clay content. Its majordrawback is cost: $50,000 plus front endloader.

One can also track down the GermanBrostholm; a stationary pressed block machinewith a reported production rate of 10,000 to72,000 blocks per day. For more informationon the European machines mentioned here,contact: Centre d'Etude du Batiment et desTravaux Publiques, 12 Rue Brancion, Paris 15;Group de Recherche et d'EchangesTechnologiques, 34 Rue Dumont d.'Urville,75016 Paris; and TTL Technologie Transfer,Leistelle am I.P.A., Holzgartenstir 17, D-7000,Stutgart 1 Germany. Also consult thebibliography cited at the end of this article.

RAMMED EARTH WALLS

Another earth building technique growing inpopularity is that of the rammed earth wall.This is an ancient technique going back in theU.S. to at least 1773 and in the Middle East tothe time of Hannibal 247 B.C. Variousmodifications of this technique have beendeveloped

over the centuries. They all use some kind ofvertical form mounted over the foundationinto which earth is placed and tamped. Entirewalls and even entire building shells can berammed as one solid piece. As with rammedearth blocks, this process has the advantage ofbeing adapted to almost any site and it usesvery little water.

This technique can be very fast. With the useof a front end loader and pneumatic tampers,entire building shells having been known to goup in one day. But this equipment is expensiveand thus adds to the cost of the process.However, all of the fabrication techniquesdiscussed here require some equipment. So toproperly compare the different techniques,you must consider prices of the materials andequipment as well as the skills required andconstruction procedures used.

THE FUTURE OF INDIGENOUSBUILDING MATERIALS

To envision a future for indigenous buildingmaterials there must be sufficient evidencethat the emerging state of- the art as describedin this paper forms both practical, immediatesolutions while solving basic problems thatprevious attempts have been unable to do. Oursuccess in Texas leads us to believe thatindigenous materials hold just such a promise.Ready material availability, low energy cost,simplicity of equipment, and


flexibility in production rates give indigenousmaterials a pretty rosy future.

But many questions still remain and these gowell beyond even our present buildingtechnology standards. We need to look at therecyclability of materials, once a structure'suseful life is over. We should consider theflexibility of structures in response tochanging uses. Issues of psychological andgroup response to the scale of space isproving to be more of an influential factor onthe long term success of buildings than wasfirst imagined. Yet, few means to cope withthis issue exist in the context of presentbuilding methods.

The list could go on. The main questionbefore us, though, is how a concentratedeffort on the development of indigenousmaterials places a different light on the futureof building in general and offers solutions tosome of the problems outlined above.

It is obviously difficult to bolt or unbolt earth.It is difficult even to move it. But thesequestions reflect a narrow mindset of whatbuilding technology is all about. We mustthink on a different plane. We must considerthe inherent characteristics of the materialswe are using.

Let us begin with a simple, straightforwardway to open our minds to some of thepotentials. The landscape around us alreadypossesses major structural forms. Why createmore? Why add our ticky, tacky, usually uglyway of dealing with the built environment tothe major forms which exist around us andcould lead us if we would only let them?

Availability? There is probably more massiverock in the form of mesas than there is earthin many parts of the western states. Energyuse in building? Recent work with simplyspraying water at very high pressure


from 5,000 to 25,000 p.s.i. has shown thatmassive amounts of rock can be cut atrelatively high speed using 1/500th the energyneeded to produce concrete block of similarsize. But why produce block at all? Usingtechnology from the mining industry we canbuild into cliffs and mesas. Simply leave yourwalls and cut your doors, windows and stairs.The technology to do this exists today,recycles water back into the jet and is smallenough to fit into a pick up truck.

But we can go even farther in our pursuit ofrecyclability, reversability and humanresponsiveness. If indigenous materials existedthat could be built into appropriate forms andthen dissipated, our goals could possibly betterbe realized than by using rock. Let us look attwo contenders: sulphur and calcium,respectively the 14th and 5th most availableelements on Earth.

Depending on location, sulphur can becollected at surface, mined using the Fraschmining process, or collected from coalcombustion generating plants as a result ofemissions control. At a national level, in1973, 16 million tons of sulphur dioxide wereemitted into the atmosphere and 33 milliontons were produced by other means.

It is also interesting to note that in 1973, 75.4million tons of concrete were used in the U.S.This is important when one realizes thatcement can be replaced by sulphur at up to 80times less energy cost. Sulphur also has otherqualities that make it uniquely suited to ourcriteria of wide availability and flexibility.

But sulphur's most impressive characteristic isits chemical composition. Essentially, it is athermoplastic. This means that it can bemelted and formed, then

remelted and shaped into a different form.Sulphur can be sprayed into shell structureswhere design compression strengths can be ashigh as 6,500 p.s.i. (as compared to 2,500 to3,400 p.s.i. for concrete). You can form it intoinsulation. You can color it and even transferinks from printed materials directly into itssurface. Sulphur is 100% water resistant andtherefore usable for tanks, cisterns, and boats.And, it is an effective natural pesticide.Buildings and entire communities can be builtout of sulphur and then remelted, reshaped,moved or even returned to the earth after theiruseful life is over.

Calcium is another readily available andextremely versatile material. Calciumcarbonate comprises approximately 14% ofthe Earth's surface on land and as ocean reefs.Calcium carbonate and brucite, among otherminerals, can form a rock hard (4,200 p.s.i.)surface when


electrolytically accreted onto wire mesh. Thisprocess simulates the formation of ocean reefs.Recent experiments using relatively lowamounts of energy (1 kw/ 1/9 kg of materialaccreted) show the feasibility of fabricatingartificial reefs, boat hulls, island extensions,off-shore stabilization, land reclamation, andmore.

As with sulphur, structures of this material canbe dissipated, by reversing the electricalcurrent. Thus, this process has the potential toadapt a structure to a wide variety ofenvironments and can continually respond tochanging human needs.

As the structure ages and begins to haveselective failure, selective electrolysis canreaccrete more material and repair the damagein much the same way that bones are healed.


We've presented a lot of information here,both on work already in progress and on ideasthat could well lead to major changes in theway we conceive and construct our builtenvironment. It is impossible to reference allthe information presented here in a concisebibliography. We have prepared for sale anextensive 50 pagebibliography on indigenous buildingmaterials We would also appreciate anycomments readers may have on this paper.Many of the topics presented here and thebuildings referred to are ones with which weare directly involved. Please get in touch withus if you are interested in pursuing this work.Our organization's survival is dependent onsuch support.

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