In order to increase Typically, a small brick-size formwork is thermal insulation, straws with rigid shoots loosely filled with a straw loam mixture. This are preferred, since they do not deform eas- is then weighed after drying and divided by ily, and hence keep air trapped inside.
The between. When drying, vertical settling occurs, since there is always some edge erosion leading to gaps on top of wall elements during cutting and handling. Working with this material is fairly labori- puted accordingly. Since, in reality, densities ous. This is four times the labour 4. Straw Weight Compressive strength 0. In a moderate or humid climate, fungus machinery. It is especially appropriate, hence, growth occurs after only a few days, emit- for do-it-yourself construction. This can, in strengths of loams and extreme cases, give rise to allergies.
After the walls have loam as an alternative to straw; these in relation to their plastici- dried completely, which might take several include expanded clay, foamed glass, ty CRATerre, 4. It is possible to achieve a shrinkage loam by adding cut straw stops producing spores. However, spore for- ratio of 0 i. All other techniques of earth through leakage, or from inside through construction require consideration of shrink- condensation. Fungus growth can be inhib- age. Another advantage of the material is that — Walls thicker than 25 cm may appear dry the mixture can be pumped into a form- on the surface, even though they are rotting work, thereby greatly reducing labour input.
As investments on machines are higher, 2. The densities ally too low to effectively grip nails or dow- generally achieved vary from to 1, els, as is often required. The mix is In some industrialised countries, expanded ready in three to five minutes. The slurry clay is a low-cost and easily available addi- needs to have a rich clay content and bind- tive.
It has a bulk density of about ing force. Grain size distribution Foaming occurs due to the sudden heating, The grain size distribution of mineral aggre- which causes the water of crystallisation gates affects the properties of lightweight and the pore water to evaporate, creating mineral loam. The surface of these expanded ed clay fractions of 8 to 16 mm diameter. Nearly all of The quantity of loam slurry has to be the pores in these expanded clay balls are designed so that the volumes between closed, and are therefore unsusceptible to aggregate particles are not completely filled, water and frost.
The equilibrium moisture that is, the aggregates are only glued content by volume is only 0. However, blocks of this additional foaming agents. A stronger mixture is obtained with 24 rock found in Europe, on the Greek island parts expanded clay 8 to 16 mm , 5 parts of Milos and in Hungary. To achieve higher evaporates and enlarges the former value density, expanded clay fractions 4 to 8 mm 15 to fold. The vapour diffusion resistance is case, it is advantageous to thin the loam about 2.
The meth- Expanded lava is similar to expanded perlite ods of preparing and handling this mixture of volcanic origin, except that its bulk densi- are explained in greater detail in chapter As timber has a higher density case of expanded clay. The dan- require considerable energy for production. The of branches and portions of trees not other- element embodied energy of timber is computed to wise used in structural work.
However, be 6 times as high as that of mineral wool, these contain fairly large quantities of bark, and twice as high as expanded clay for the and are therefore susceptible to fungus same volume Turowski, ; Weller and growth and rotting. Foamed loam In making an overall assessment of the con- In order to foam loam, it has to be free of struction energy entailed by a given project, sand and gravel, and in a plastic state. As then, we must remember that while it may loam in this consistency needs a long period be technically true that loams with artificially to dry, it is hardly possible to foam it using expanded minerals use more energy than the regular agents such as those used for those containing other aggregates, this dif- foaming concrete.
Therefore, the loam ference is negligible when compared, for needs to be given additives which quicken instance, to the total energy input involved the drying process, such as the geopoly- in the processing, production and trans- mers described in this chapter, p. This material hardens within aggregates. It is an ideal material to ture of cork, diatomite, and straw, along form pre-cast earth elements of a large size. The thermal insulation. Products with densities measured k-values are 0.
German words is Stampflehmbau. Refined work, BRL Minke, cm thick, and then compacted by ramming. For ecological, and sometimes for eco- nomic reasons as well, mechanised rammed earth technology may be a viable alternative to conventional masonry especially in those industrialised countries where high stan- dards of thermal insulation are not required. Many firms employ this technology in the southwestern USA and in Australia.
In comparison with wet loam techniques see chapter 9 , the shrinkage ratio of rammed earth is much lower, and strength much higher. In comparison with adobe masonry see chapter 6 , rammed earth — since it is monolithic — provides the advan- tage of longer life. Techniques for rammed earth wall and dome construction are described in the fol- lowing sections. A special earthquake-resist- ant bamboo-reinforced rammed earth tech- nique as well as rammed earth floors are described in chapter As shown in 5.
With a special formwork, rounded corners and curved walls can also be formed 5. Common formwork systems used in con- crete technology can also be used for rammed earth, but usually turn out to be too heavy and expensive. In Europe, timber panels of 19 mm thickness are commonly used. They need to be stiffened by vertical members at approximately 75 cm intervals. If this is not done, they will bend outwards during ramming. Therefore, it might be 5. These spacers pierce the thus preventing it from being spoiled by 5. Further- rounded and curved in after removal of formwork.
A system with more, it is neither desirable to have a surface walls very thin tensile spacers 4 x 6 mm pene- that is too rough such as saw-cut timber , trating the wall has been developed at the nor one that is too smooth such as var- 5. Therefore, the formwork should allow varying lengths of wall to be 5. If conical or wedge-shaped rams are used, the different layers are better mixed and, provided there is sufficient moisture, a bet- ter bond is obtained. However, this takes more time than ramming with flat-based rams. Walls rammed with flat-based rams 5.
The base should be used in Ecuador no smaller than 60 cm2, and no larger than 5. The weight of the ram should be between 5 and 9 kg. It is preferable to man firm Wacker, was often used in former use a two-headed ram with a round head times for rammed earth work, and has been on one side and a square one on the other. It has a hammer- This allows the ram to be used with the like action with a lift of 33 mm, and a fre- round side for general work, and with the quency of strokes per minute.
The ram square edge to compact corners effectively. Electric and pneumatic rams were used as In Australia in the s, a pneumatic ram early as the second quarter of the 20th cen- was used 5. This acts like a jackhammer, tury in Germany, France and Australia. The has a frequency of strokes per minute, electrical ram shown in 5. Tools which Atlas-Copco only vibrate might be suitable for sandy 5.
Heuser The pneumatic rams shown in 5. All the rams illustrated the upper course than in the lower, leading formwork is disman- require a pressure of 6 bar and an air flow to horizontal shrinkage cracks at the joint tled rate of 0. Due to their high 5. This can be dangerous, since capillary 5. As can be only for larger building projects. An electrical seen in the same figure, vertical cracks can vibration ram has been developed at the also occur in such walls.
Its engine has a frequency was solved by using a layer of lime mortar of to cycles per minute. The above each course before laying a new one.
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It can between sections of the course is made 5. Another method to avoiding horizontal shrinkage cracks is to ram in a way that the wall is produced vertically. This is described in greater detail below. Shaping of openings The formwork can be dismantled immedi- 5. At the same time, this rammed earth can be Method of construction shaped easily by scraping, cutting, scooping or scratching. Normally, inserts are left in In nearly all traditional rammed earth tech- the formwork to create openings. However, niques, the formwork is removed and with rammed earth, the opening can be re-erected horizontally step by step.
This cut with much less effort with a knife or a means that earth is rammed in layers from barbed wire used as a saw. This technique 50 to 80 cm high, forming courses of that also allows shaping of jambs and sills, as height before the formwork is moved. It should be mentioned that When one course is complete, the next at this stage rammed earth has already course that is rammed is moister than the achieved sufficient strength to grip nails one already in place, which is partially dried they can be driven into the wall without out.
Therefore, there is a higher shrinkage in making a guiding hole with a drill. This technique avoids horizontal joints, and the vertical joints that occur are closed only after the shrinkage is complete. For lateral stability, the vertical joints are made in a tongue-in-groove pattern.
No shrinkage cracks occur within the panels for these sizes. The reduction of length due to shrinkage is only visible at the joint. The joint acts like a pre-designed contraction joint. In order to avoid a formwork that would have to be an entire storey in height, 5. Illus- tration 5. The firm Rammed Earth Works has built formwork for rammed The formwork is spaced at the bottom with several rammed earth houses in California earth panels BRL 5.
The top space is plywood, as shown in 5. Earth was filled USA positioned above the top level of the wall into the forms by a dumper and compacted 5. As by a pneumatic ram. Germany, 5. In recent decades, Terrastone version made from steel, which also allows more than a hundred rammed earth build- fine adjustments of distance at the top.
Illustration built at the University of Kassel in 5. The earth was by the firm Ramtec.
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As seen in 5. The linear are made from rammed earth. Raadschelders, D. Oliver , where all linseed oil. A roof overhang of 60 cm and walls are made of unplastered rammed a plinth of 50 cm were sufficient to ensure earth 5. It is also At the Centro de Pesquisas e Desenvolvi- advantageous if this formwork can con- mento, CEPED in Salvador, Brazil, a simple tribute to a substantial increase in thermal technique was developed to construct thin insulation.
The stiffness of this lost formwork rammed earth infill panels. It was used in has to be sufficient to take care of the later- several low-cost housing projects in Brazil. Illustration The posts and ring beams were normally 5. The first two cases show an The sides of the formwork were directly inner leaf built of adobes or soil blocks and mounted on the posts. Thus, the thickness an outer rammed earth layer made with of the wall was the same as that of the post lightweight mineral loam which is directly 5.
In this case, the loam was stabilised plastered. In the second case, a somewhat better stiffness of the Wall construction with lost formwork inner adobe or soil block leaf is attained As with rammed earth techniques, the cost due to the bonding pattern in the compo- of the formwork is quite high. In some nents. In the section shown on the right, 5. The inner leaf can be made from adobes or soil blocks, larger pre-fabri- cated loam elements, or stiff plywood boards, fibre-reinforced gypsum boards, or Magnesite or cement-bonded wood particleboard.
Protection of the wall surface against the elements can be achieved by plaster, masonry or timber panelling with air cavity. The formwork of the wall was custom-designed according to the Probably the first rammed earth dome was plan of the dome, as seen in 5. The earth built by the BRL in Kassel, Germany, in was rammed into the formwork using a using a special technique developed vibrator, described on p. This consists of a rotating see 5. The walls, automatically adjusted the radius and incli- which form a hexagon on the inside, were nation of the formwork 5.
In order to transfer the thrust from the dome to the foundation, buttresses were integrated with Drying the walls. The shaping of the top of the but- tresses as well as the windows was done It is seldom possible to say when a loam with a kitchen knife soon after the form- wall is dry, but the drying process is in any 5. Given dry Plaster Bricks warm weather and sufficient air movement, Soil blocks Lightweight loam shrinkage stops after just a few days.
After Thermal insulation Thermal insulation three weeks, the wall feels completely dry, Lightweight loam Mud plaster although water content is still slightly higher Soil blocks than the equilibrium moisture content. By refining the form- work system and using the electrical vibra- tor described on p.
With the highly mechanised techniques explained above see p. Thermal insulation The thermal insulation capacities of solid rammed earth walls using normal soil is not 5. The U-value of a cm-thick rammed earth wall is as much as 1. To achieve a U-value of 0. In cold climates, therefore, either a thick wall of 5. If compared to walls made using other earth exterior surfaces thus treated are sheltered construction techniques. As a rule, it is from rain by roof overhangs and against neither necessary nor advisable to plaster splashing by a plinth, a coating of paint is a rammed earth wall.
If the surface is sufficient to protect them against the ele- sponged with a moist felt trowel immedi- ments. Care should be taken that coatings ately after dismantling the formwork, neither peel nor crack. Specific applications of these different types of blocks in walls, floors, vaults and domes are described in chapter History Building with earthen blocks is widespread in all hot-dry, subtropical and moderate climates. Earth block buildings dating from 6. For centuries, Pueblo Indians in Taos, of the city of Shibam, Some countries have standardised measure- New Mexico, built their houses using the Yemen ments for these blocks.
The two sizes used earth from the sites themselves, the water most commonly in Germany, for example, from nearby streams, and straw from the are: fields 6. In Scandinavia and in England, building with sod was common in the 17th and 18th cen- turies. These houses were constructed of blocks cut from the top layer of loamy soil together with the grass growing on it. The blocks were inverted and used as bricks to form walls without mortar. European immi- grants brought this technique to the USA, where a large number of sod houses were built in the 18th and 19th centuries 6.
Some settlers also adapted the same idea from North American Indian nations such as the Omaha and Pawnee, who for cen- turies had used the method to cover their 6. In New Mexico, silty soil blocks cut from riverbeds, and containing a network of roots which act as reinforcement, were used for building walls. These blocks are called terronis or terrones, and were sometimes used in Mexico and Central America as well. David Gilly pub- terronis. An official circular introducing the moist lumps of earth into them.
Different use of adobes in walls was published in types of moulds can be used; some of these are shown in 6. They are usually made from timber. The throwing technique is commonly used in all developing coun- tries 6. Here, a sandy loam is 6. The 6. The surface is smoothed either by 6. Illustration 6. It permits simultaneous production of three blocks. Despite mechanised production 6. In India, one person can produce as many as blocks per day using a double mould designed for a small- er brick. In order to facilitate work, bricks can be moulded on a table, as was traditionally the case in Germany 6.
Another easy method uses moulds with handles 80 cm in length, which enables workers to manu- 6. Techniques for producing compressed soil blocks were known in Europe in the 18th The advantage of these mechanised press- century. This makes it possible soil block press. Since then, numerous to stack blocks immediately after production. This is necessary because of the absence of either sufficient water or adequate dynamic impact capable of signifi- cantly activating the binding forces of the clay minerals. Without cement, pressed blocks usually have dry a compressive strength lower than that of handmade adobes see p.
If com- in sufficient quantities. Otherwise, capital, 6. For more Gilserberg, Germany information about pressed soil blocks, see 6. With this method, loam is pre- pared to a pasty consistency in a forced mixer and then poured into a large funnel that moves over a grid of moulds. A lever changes.
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This leads to variations in the lifts this grid, leaving the separated blocks heights and strengths of the blocks. After a preliminary Fully automatic block-making presses such drying period, the blocks can be turned on as those shown in 6. However, In mechanised brick plants, crushed soil is they require large investments and may be mixed and pushed by rollers into an extrud- difficult to maintain, especially in developing er, where it is again mixed and pressed countries.
To assure even loam consisten- through a vacuum-operated mouthpiece cies, such machines often require separate into long profiles, which are then sliced by a crushers and mixers. Drying is accomplished in ovens using Fully automatic presses are only economical commercial energy. But at the same time, there must be enough clay to create sufficient binding force for the block to be handled. Laying earth blocks It is important to shelter earth blocks from rain on site. In industrialised countries, as a rule, green bricks ordered from factories, are palletised and covered entirely in plastic.
Earth blocks are laid with either loam mor- tar, hydraulic lime mortar or high-hydraulic lime mortar. While small quantities of 6. With simpler too rigid and brittle. To avoid shrinkage production processes and open-air drying, cracks inside the mortar during drying, the on the other hand, it was possible in at least mortar should contain sufficient quantities one German case, to obtain green bricks of coarse sand. The formation of shrink- ular fired bricks.
Lime mortar, however, attacks the skin and may also The loam used in common brick plants cause allergies. Illus- tration 6. When loam of this composition is used for earth block work, it creates swelling and shrinking problems upon wetting and dry- ing respectively. The soil grain size distribution of a leaner sandy loam appropriate for earth blocks is shown in 6. Generally, it can be stated that earth blocks should have enough coarse sand to allow them to achieve high porosity and there- 6.
These soaked felt trowel, exposed earth block masonry blocks can be simply stacked, as with any with uneven surfaces or joints can be easily dry masonry work, and they will bind. Such smoothened. Plastering is not advisable, work, however, requires a very fine eye and since it interferes with the capacity of loam skilled workmanship, for it is difficult to con- walls to balance internal air humidity see trol the horizontal joints and the pattern, chapter 1, p. However, exposed earth since no tolerance of mortar thickness is block masonry can, if not aesthetically available.
This wash also impacts example, as seen in 6. In place of a saw, a groove can also be scored with a trowel or a knife before using the hammer. Due to their good thermal insulation effects, they are used for exterior walls in cool or cold climates. The more porous and humid the material, the easier one can drive a nail through it. Green bricks tend to split more easily than soil blocks and adobes. If very thick nails are used, it is advisable to drill a hole into the block. Heavy shelves or wall- hung cabinets can be fixed to the wall easily using screws and dowels.
Dowel holes, 6. The rounded corners and the corbelling effect of the bricks 6. Using such blocks, a cm-thick wall gives a U-value of 0. Dufter guided several do-it-yourself projects using these blocks. In one case, the owner-builder family produced blocks in five weeks, sufficient for their entire house. Lightweight mineral loam blocks measuring 15 x 15 x 30 cm, which are made of loam and expanded clay, have been produced in Hungary utilising egg layers of the type used in making concrete blocks 7. Such 7. Therefore, several ideas involving developed by the author of this book, are loam larger prefabricated elements have been shown in 7.
These can be used either in developed. Large blocks Provided they are light enough to be carried in one hand, or at most in both, larger blocks can be laid faster. Lightweight aggregates and cavities can be used to reduce weight. For easy handling, grip holds should be incorporated in block shapes. Lightweight straw blocks, 50 x 60 x 30 cm, used in several projects by the German architect Sylvester Dufter, are more efficient for making walls. Though each block weighs 26 kg, they are produced under cover and close to the wall, and can then be almost 7.
In Hungary in , the author of this book developed load-bearing infill elements with cement-stabilised light- weight loam. Illustration 7. Cavities reduce weight and increase thermal insulation, while simultaneously providing grip holds for easy handling. Prefabricated wall panels 7. These should 7. An extremely light element with 7. They measure The German firm HDB Weissinger produces 1-m-wide and up to 3- m-high timberframe wall elements filled with lightweight loam 7. One advan- tage is that since they are already dry, shrink- age only occurs in joints.
Miller, Grigutsch and Schulze , p. Methods of increasing surface hardness are described in chapter 14, p. Extruded loam slabs Illustration 7. They are extruded 3 to 10 cm thick, 50 cm wide and cut into lengths of up to cm or more. The following sections explain how pre-designed shrink- age cracks of smaller dimensions, or the use of curved elements can help to reduce or even avoid such cracks.
The theory involving reducing shrinkage by modifying loam com- position is explained in chapter 4, p. Traditional wet loam techniques While in the case of earth block work, dry elements are built up with mortar joints, no mortar is used with wet loam work. Plastic 8. It therefore presents a creative chal- technique is still in use today: using a lenge to designers and builders. It is 8. Since no tools are required to then spread by hand in layers from 2 to 8.
As the paste dries fairly quickly from wet loam primitive technique. The prepared mixture is in the sun, the wall can be built continuous- 8. Its In northeast Ghana, another technique is after drying 8. The higher the clay simply by stacking and pressing 8. After the wall dries, the surface is plas- enbach, no date the greater the shrinkage. Thick loam paste tered on both sides and then smoothed 8.
Illustra- rubbing movement. Illustration 8. Here, clods of straw loam are shaped by hand and thrown with strong impact to build the wall in such a way that they are compacted and adhere to the base, forming a homogenous mass. The surface is often beaten and com- pacted by hammering with a kind of wood- en trowel. Hill describes this tech- nique as follows: a man stands with a three- pronged pitchfork on the plinth of the wall, 8.
The second man then throws loam construction, technique. Where neces- no date 8. Here, sary, he also compacts the wall with his feet. To give an even finish, the surface no date one 8. The rooms of these houses are is sliced. Wall thicknesses are generally more or less rectangular, and have rounded 45 to 60 cm McCann, Illustration corners 8. A lime plaster several layers using this technique in The first A similar technique called Wellerbau, has such house was built in 8.
Within been known in German since medieval the next five years, more than houses times, and was especially widespread in were built by co-operatives, formed by Thuringia and Saxony. Here, the straw loam unemployed workers on the initiative of von is not formed into clods as in the cob tech- Bodelschwingh. The entire families of the nique, nor compacted by throwing as with members participated in production and the zabur technique, but is directly stacked construction.
The wall is built up in lay- ers of 80 to 90 cm. After a short drying peri- od, the surface of these layers is smoothed 8. They inspired Gustav von Bodelschwingh, a German missionary, to adapt them to German conditions. Here, wet loaves of loam are stacked in masonry patterns, but without mortar. In order to provide better bonding to the plaster that is applied later, a conical hole is made on the outer face of each loaf using 8. Walls, vaults and domes horizontal arrangement, as seen in 8.
The Production of stranglehm elements material is then moved into a worm gear, In order to produce wet loam profiles, an which creates sufficient pressure to force the extrusion apparatus was developed by the material out of the extrusion mouthpiece. However, the addition of whey increased output slightly, and gave better water resistance and surface hard- ness.
Casein powder and water can be sub- stituted for whey. The mix for this technique must have higher clay content than that for rammed earth blocks. Loam ele- ments with lower clay contents showed cracks at the corners. The content has to be optimised so that the finished profile is dry enough to be handled, yet wet enough to adhere when being stacked into the wall.
Laying the elements 8. The joints were finished by extruder for extruded the surface with a wet pressing them with bare hands or with loam profiles Heuser sponge a modelling stick. Since the weight of the 8. Since this 8. The extruder were used. The results showed that at this was positioned at the centre of the house length, and with pre-designed contraction to minimise transportation distances.
They act as tongues fitting into the loam elements to provide lateral stability. In order to ensure separation of these elements during the drying process a cut is made with a trowel, so that the joints act as pre-designed con- traction joints. Upon drying, this gap widens due to shrinkage, and can be favourably filled when dry with a mixture of lime, 8. It is very easy to smooth the surface of these elements with a moist sponge 8. Walls composed of these elements can be shaped easily in a wet state; a fin- ished example is shown in 8. The walls of this project are framed in timber with posts at 2.
The panel thus formed is divided into 8. Solution C in this figure is only intended for exterior walls. The space between the two extruded loam walls can be filled with light- weight bulk material such as cork particles, expanded clay, pumice etc. Structural elements can also be positioned in this space. If the other walls illustrated need to be provided with thermal insulation, a common solution is given in 8. Illustrations 8.
Due to the production process, this loam had to have higher clay content, causing a large number of shrinkage problems; 8. Such structures consist of vertical and hori- zontal members that form a network. Euro- pean systems usually employ vertical timber members interwoven with twigs 9.
Loam, usually mixed with cut straw, and sometimes with fibres, is thrown or pressed onto this network so that it covers at least 9. If this cover is not thick enough and cracks are not well- Plastic loam has been used for thousands of repaired, walls quickly deteriorate 9. In traditional European Fachwerk surface. If the diameter of the flattened disc timber-framed houses, as well as in Ameri- thus formed measures 13 to 14 cm, the can, African and Asian wattle-and-daub consistency is just right.
As shown in this chapter, there exist apart , and there is an exterior and an many variations of this technique. Modern interior network. The spaces in the grid thus techniques of infill that use mechanical formed are filled in with clods of loam. The type of wall shown in 9. Thrown loam techniques have been used in all tropical, sub-tropical and moderate Sprayed loam climates of the world, and are probably older than rammed earth and earth block Since wattle-and-daub techniques are very practices.
These wattle-and-daub tech- labour-intensive, various attempts have been 9. This is less labour-intensive then the wattle- and-daub technique, and has the added advantage that hardly any shrinkage cracks occur. Two main systems are used: either a loam dipped straw rope is wound helically around 9. The main problem with all of these is rolled onto a batten. The labour inputs of house of the Pueblo techniques has been the common occur- these techniques is still higher than those Indians, 3rd century rence of shrinkage cracks. A variation of the rolling technique was manian, 9.
It used a loam mortar nique after Vorhauer, with dry sawdust from a separate nozzle.
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The loam was pasted onto the mesh in Venezuela 9. Another spray- around a bamboo stick to form infill Germany able lightweight loam used for enhancing elements 9. Surprisingly, 9. The ends of the bundles are then lifted up around the loam, which formed into bottle-like shapes and covered with loam. The bottle is then held horizon- tally, and the neck wound around the verti- cal member, while the bottom is pressed against the neck of the previous bottle. The lightweight additives are described in chap- ter 4, pp. Infill with stranglehm and earth- filled hoses Modern solutions of filling the openings in timber skeleton structures or timber-framed houses with stranglehm or earth-filled hoses are described in chapter 8, p.
Various possibilities are shown in horizontal section in In order to reduce the number of boards, climbing formwork is often used. Four types of this system are illustrated in When working with lightweight mineral loam, it is even possible to use only a one- sided formwork. This could be done with a board on the outside, in which case the mixture can be thrown onto it from the inside by hand or with a trowel.
The mixture is thrown into ber elements The different types of lightweight either by hand or more usually with a loams are examined in chapter 4, while pitchfork, and compacted with lightweight chapter 9 discusses how lightweight loam hand tampers. Sprayed plasterwork is loam mixtures tend to settle, so that the described in chapter Special designs for gaps that form must be be inspected and walls which give high insulation are dis- later refilled.
The one-metre-high test ele- cussed in chapter 14, and additional thermal ment shown in Illustration After some months, when the outside appeared to be completely dry, the core was chased for an electrical instal- lation, and was found to be rotting. Even the structural timber member had been attacked by micro-organisms to depths of 2 cm Schmitt, Solidity is a particularly attractive quality at a time of disorientating change.
But — like any good thing in excess — it can create more problems than it solves. At times an unyielding ally, at times a false friend, concrete can resist nature for decades and then suddenly amplify its impact. Take the floods in New Orleans after Hurricane Katrina and Houston after Harvey, which were more severe because urban and suburban streets could not soak up the rain like a floodplain, and storm drains proved woefully inadequate for the new extremes of a disrupted climate.
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It also magnifies the extreme weather it shelters us from. Among materials, only coal, oil and gas are a greater source of greenhouse gases. But other environmental impacts are far less well understood. In cities, concrete also adds to the heat-island effect by absorbing the warmth of the sun and trapping gases from car exhausts and air-conditioner units — though it is, at least, better than darker asphalt. It also worsens the problem of silicosis and other respiratory diseases. Limestone quarries and cement factories are also often pollution sources, along with the trucks that ferry materials between them and building sites.
This touches on the most severe, but least understood, impact of concrete, which is that it destroys natural infrastructure without replacing the ecological functions that humanity depends on for fertilisation, pollination, flood control, oxygen production and water purification. Concrete can take our civilisation upwards, up to storeys high in the case of the Burj Khalifa skyscraper in Dubai, creating living space out of the air. But it also pushes the human footprint outwards, sprawling across fertile topsoil and choking habitats.
The biodiversity crisis — which many scientists believe to be as much of a threat as climate chaos — is driven primarily by the conversion of wilderness to agriculture, industrial estates and residential blocks. For hundreds of years, humanity has been willing to accept this environmental downside in return for the undoubted benefits of concrete.
But the balance may now be tilting in the other direction. T he Pantheon and Colosseum in Rome are testament to the durability of concrete, which is a composite of sand, aggregate usually gravel or stones and water mixed with a lime-based, kiln-baked binder. This was later combined with steel rods or mesh to create reinforced concrete, the basis for art deco skyscrapers such as the Empire State Building.
Rivers of it were poured after the second world war, when concrete offered an inexpensive and simple way to rebuild cities devastated by bombing. This was the period of brutalist architects such as Le Corbusier , followed by the futuristic, free-flowing curves of Oscar Niemeyer and the elegant lines of Tadao Ando — not to mention an ever-growing legion of dams, bridges, ports, city halls, university campuses, shopping centres and uniformly grim car parks.
In , cement production was equal to that of steel; in the years since, it has increased fold, more than three times as fast as its metallic construction partner. The politics of concrete are less divisive, but more corrosive. The main problem here is inertia. Once this material binds politicians, bureaucrats and construction companies, the resulting nexus is almost impossible to budge.
Party leaders need the donations and kickbacks from building firms to get elected, state planners need more projects to maintain economic growth, and construction bosses need more contracts to keep money rolling in, staff employed and political influence high. Hence the self-perpetuating political enthusiasm for environmentally and socially dubious infrastructure projects and cement-fests like the Olympics, the World Cup and international exhibitions. At first it was a cheap material to rebuild cities ravaged by fire bombs and nuclear warheads in the second world war.
Then it provided the foundations for a new model of super-rapid economic development: new railway tracks for Shinkansen bullet trains, new bridges and tunnels for elevated expressways, new runways for airports, new stadiums for the Olympics and the Osaka Expo, and new city halls, schools and sports facilities. This kept the economy racing along at near double-digit growth rates until the late s, ensuring employment remained high and giving the ruling Liberal Democratic party a stranglehold on power. The political heavyweights of the era — men such as Kakuei Tanaka, Yasuhiro Nakasone and Noboru Takeshita — were judged by their ability to bring hefty projects to their hometowns.
Huge kickbacks were the norm. Yakuza gangsters, who served as go-betweens and enforcers, also got their cut. Bid-rigging and near monopolies by the big six building firms Shimizu, Taisei, Kajima, Takenaka, Obayashi, Kumagai ensured contracts were lucrative enough to provide hefty kickbacks to the politicians. The doken kokka was a racket on a national scale. But there is only so much concrete you can usefully lay without ruining the environment.
In his book Dogs and Demons, the author and longtime Japanese resident Alex Kerr laments the cementing over of riverbanks and hillsides in the name of flood and mudslide prevention.
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That is the reality of modern Japan, and the numbers are staggering. He said the amount of concrete laid per square metre in Japan is 30 times the amount in America, and that the volume is almost exactly the same. Traditionalists and environmentalists were horrified — and ignored. Everyone knew the grey banked rivers and shorelines were ugly, but nobody cared as long as they could keep their homes from being flooded. Which made the devastating Tohoku earthquake and tsunami all the more shocking.
At coastal towns such as Ishinomaki, Kamaishi and Kitakami, huge sea walls that had been built over decades were swamped in minutes. Almost 16, people died, a million buildings were destroyed or damaged, town streets were blocked with beached ships and port waters were filled with floating cars. It was a still more alarming story at Fukushima, where the ocean surge engulfed the outer defences of the Fukushima Daiichi nuclear plant and caused a level 7 meltdown. Briefly, it seemed this might become a King Canute moment for Japan — when the folly of human hubris was exposed by the power of nature.
But the concrete lobby was just too strong. Construction firms were once again ordered to hold back the sea, this time with even taller, thicker barriers. Their value is contested. Engineers claim these metre-high walls of concrete will stop or at least slow future tsunamis, but locals have heard such promises before. The area these defences protect is also of lower human worth now the land has been largely depopulated and filled with paddy fields and fish farms.
Environmentalists say mangrove forests could provide a far cheaper buffer. Tellingly, even many tsunami-scarred locals hate the concrete between them and the ocean. He described them as an abandonment of Japanese history and culture. And now the Japanese government has decided to shut out the sea. T here was an inevitability about this. Across the world, concrete has become synonymous with development. Green building research is being done by national laboratories, private companies, universities, and industry. According to a USGBC report published in , over 70 percent of the green building research is focused on energy and atmosphere research.
The next largest category of research is materials and resources. Indoor environmental quality, including issues pertaining to air, is also being studied. EPA has a number of programs that provide resources to help you learn more about the components of green building and how to incorporate these green building concepts into different types of buildings. EPA's Green Building Workgroup was formed in July to bring together the many programs across the Agency that work with the building and development sectors to improve their environmental performance.
The Workgroup seeks to build effective EPA leadership in the green building movement by jointly informing, coordinating, and guiding the development of Agency policies, programs, partnerships, communications, and operations that influence building and development. To ensure that EPA's buildings and practices reflect the mission of protecting human health and the environment, EPA continuously works to reduce the environmental impact of its facilities and operations, from building new, environmentally sustainable structures to improving the energy efficiency of older buildings.
A number of EPA facilities are actively pursuing or demonstrating green building principles. Green Building Research Green Building and EPA More Information Definition of Green Building Green building is the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building's life-cycle from siting to design, construction, operation, maintenance, renovation and deconstruction.
Impacts of the built environment: Aspects of Built Environment: Consumption: Environmental Effects: Ultimate Effects : Siting Design Construction Operation Maintenance Renovation Deconstruction Energy Water Materials Natural Resources Waste Air pollution Water pollution Indoor pollution Heat islands Stormwater runoff Noise Harm to Human Health Environment Degradation Loss of Resources Green buildings are designed to reduce the overall impact of the built environment on human health and the natural environment by: Efficiently using energy, water, and other resources Protecting occupant health and improving employee productivity Reducing waste, pollution and environmental degradation For example, green buildings may incorporate sustainable materials in their construction e.