TYPES OF MUD WALL CONSTRUCTION
MUD…
MUD IS A LIQUID OR SEMI LIQUID OF WATER AND SOME COMBINATION OF SOIL, SILT AND CLAY. ANCIENT MUD DEPOSITS HARDEN OVER GEOLOGICAL TIME TO FORM SILTSTONE OR SOLID, MUDROCK LUTITES.
WHEN GEOLOGICAL DEPOSITS OF MUD ARE FORMED IN ESTUARIES THE RESULTANT LAYERS ARE TERMED BAY MUDS. MUD IS CLOSELY RELATED TO SLURRY AND SEDIMENT.
MUD, IN THE CONSTRUCTION INDUSTRY, REFERS TO WET PLASTER, STUCCO, CEMENT OR OTHER SIMILAR SUBSTANCES.
MUD IS SIMILAR TOMUCK, BUT LACKING SIGNIFICANT QUANTITIES OF HUMUS, AND OFTEN CONTAINING HIGHER PROPORTIONS OF SAND.
CLASSIFICATION
THE MAIN CLASSIFICATION SCHEME USED BROADLY SEPARATES THE MUD INTO 3 CATEGORIES BASED ON THE MAIN COMPONENT THAT MAKES UP THE MUD: 1)‘WATER BASED MUD’ (WBM). THIS CAN BE SUB DIVIDED INTO DISPERSED AND NON-DISPERSED 2)‘NON AQUEOUS’ OR MORE COMMONLY OIL BASED MUD’ (OBM) THIS ALSO INCLUDES SYNTHETIC OILS (SBM). 3)GASEOUS OR PNEUMATIC MUD.
TYPES OF MUD WALLS
COB
WATTLE AND DAUB
RAMMED EARTH
ADOBE
STABILIZED BLOCKS
COB A LARGE LUMP OF CLAY IS ROUGHLY MOULDED INTO A BALL A ROW OF THESE COBS OF MUD ARE NEATLY PLACED SIDE BY SIDE SIDES ARE SMOOTHENED AFTER 3 OR 4 LAYERS
COB •
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For cob construction you mix straw and often small gravel into a sandy soil. You form the mixture into lumps or cobs, which you then throw on to the wall and stamp or work into the previous layer. The rough surface is later trimmed up, and usually rendered to give a smooth surface. The result is often a softly undulating surface, which can follow whatever shape you choose to build into the wall. Cob builds extra thick or curved walls easily, and it is common for them to taper inwards towards the top. This technique is also very shrinkage sensitive and a mixture has to be found that minimises shrinkage. Because of the comparative lack of modern experience in New Zealand with cob, it is included in the Earth Building Standards only as an informative section, so careful analysis of materials and design is required.
RAMMED EARTH(pise) AN IMPROVED TECHNIQUE COMPARED TO COB & IT REGULARISES THE THICKNESS & IS MORE COMPRESSED STIFF MUD IS THROWN IN BETWEEN TWO PARALLEL PLANKS HELD TOGETHER AND RAMMED DOWN USING A RAM ROD IT IS BETTER TO FOLLOW A BONDING PATTERN THE THICKNESS OF THESE WALLS ARE AROUND 600mm BUT RECENTLY WALLS BUILT FROM EARTH STABILISED WITH CEMENT ARE AROUND 300 mm
RAMMED EARTH
RAMMED EARTH BUILDINGS ARE COMMON IN ARID REGIONS WHERE WOOD IS SCARCE . IT INVOLVES A PROCESS OF COMPRESSING A DAMP MIXTURE OF EARTH THAT HAS SUITABLE PROPORTIONS OF SAND, GRAVEL AND CLAY. TRADITIONAL STABILIZERS SUCH AS LIME OR ANIMAL BLOOD WERE USED TO STABILIZE THE MATERIAL, BUT CEMENT HAS BEEN THE STABILIZER OF CHOICE FOR MODERN TIMES. IN MODERN VARIATIONS OF THE METHOD THE RAMMED EARTH WALLS ARE CONSTRUCTED ON TOP OF CONVENTIONAL FOOTINGS OR A REINFORCED CONCRETE BASE.
RAMMED EARTH •
Rammed earth walls are constructed by ramming a mixture of earth, with gravel, sand, silt and clay, into place between formwork. Ramming is done with manual or mechanical rammers.
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Sand is added to most soils to reduce shrinkage which can otherwise be a problem. Stabilised rammed earth has 5-10% cement added to give extra strength and durability.
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they can be stuccoed, plastered painted or left natural and sealed to better waterproofing them.
RAMMED EARTH •
The mixture must be carefully mixed and almost dry. The formwork can be removed immediately after the wall is finished.
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Earth buildings should not contain any organic matter. This will rot, allowing mould and fungi to grow, and also weakening the structure.
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Rammed earth walls are limited to the shapes that can be built with your removable shuttering External walls are usually 30cm thick, and internal walls may be 20cm. Curved walls are possible but need more expensive formwork. The appearance of rammed earth walls depends on the materials used. It often has a stratified look caused by the ramming process.
WATTLE & DAUB
THIS SYSTEM USES MUD AS A PLASTER TO COVER THIN PANELS OF CANE/SPLIT BAMBOO THAT ARE WOVEN TOGETHER AND HELD IN PLACE BY POLES
WATTLE & DAUB
THIS IS USED PARTICULARLY FOR MEETING HOUSINGREQUIREMENTS IN AREAS PRONE TO CYCLONES OR EARTHQUAKES. WATTLE IS USED TO FORM THE STRUCTURE OF THE HOUSE AND MUD IS USED TO DAUB THE WALLS. DURING THE RAINS, THE DAUB MAY BE WASHED AWAY BUT IT IS EASILY REPLACED. THE WATTLE CAN WITHSTAND ANY EARTH TREMORS. THE WATTLE IS MADE BY WEAVING THIN BRANCHES (EITHER WHOLE, OR MORE USUALLY SPLIT) OR SLATS BETWEEN UPRIGHT STAKES. THE WATTLE MAY BE MADE AS LOOSE PANELS, SLOTTED BETWEEN TIMBER FRAMING TO MAKE INFILL PANELS, OR IT MAY BE MADE IN PLACE TO FORM THE WHOLE OF A WALL.
ADOBE OR SUNDRIED BRICKS A SMALL BOX OR MOULD OF WOOD OR METAL IS USED AND THE STIFF CLAY IS SQUASHED INTO THE MOULD AND THEN
ORDINARY MOULD
TURNED OUT TO CURE AND SLOWLY DRY. USE SAME AS BURNT BRICKS OR CEMENT BLOCKS
ONE TIME MOULD FOR SEVERAL BLOCKS
ADOBE OR SUNDRIED BRICKS • •
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Adobe bricks are made by blending together soil and water into a goopy mix. Often straw or other fibres are added to help reduce cracking.. You can cast different shapes of bricks to create wedges for corners or arches, 45-degree corners, or rebates for jambs. You can cut holes in newly cast bricks for reinforcing or services Once they are firm enough you lift the bricks onto their sides, trim them, and then stack them to air-dry and cure
ADOBE OR SUNDRIED BRICKS •
Any shrinkage occurs during this drying. In the summer, it takes about a week of hot, dry weather for the bricks to cure adequately before they can be handled and used. In the summer, it takes about a week of hot, dry weather for the bricks to cure adequately before they can be handled and used.
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Mud bricks are laid with a thick layer of mud mortar between them. This mortar is also rubbed over the walls to fill in any gaps and cracks.
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Mud brick allows a greater range of soils to be used compared with rammed earth.
STABILIZED MUD BLOCKS F E A T U R E S
20% - 30% CHEAPER THAN FIRED BRICKS
MEDIUM TO GOOD STABILITY
GOOD RESISTANCE TO HURRICANE AND RAIN
LABOUR INTENSIVE
SUITABLE FOR ALL CLIMATES
TECHNOLOGY BASED ON SELF-HELP METHOD
STABILIZED MUD BLOCKS MAKING STABILIZED MUD BLOCKS TESTING THE SUITABILITY OF THE SOIL MIXING OF STABILIZER, SOIL AND WATER MECHANICAL PROCESS OF COMPRESSION STACKING AND CURING
STABILIZED MUD BLOCKS •
Stabilized mud blocks (SMBs) are manufactured by compacting a wetted mixture of soil, sand, and stabilizer in a machine into a highdensity block. Such blocks are used for the construction of loadbearing masonry. Cement soil mortar is commonly used for SMB masonry. This paper presents the results of an experimental investigation in characterizing the properties of SMB masonry using cement-soil mortars. The compressive strength, stress-strain relationships, and elastic properties of SMB masonry using three types of SMBs and cement-soil mortars are discussed. The influence of a cement-soil mortar's composition and strength on masonry characteristics is examined. The results of masonry using cementsoil mortars are compared with those using conventional mortars (cement mortar and cement-lime mortar).
STABILIZED MUD BLOCKS •
Some of the major findings are: (1) SMB masonry strength is sensitive to block strength and increases with increase in block strength; (2) the strength of SMB masonry using cement-soil mortars is more sensitive to the cement content of the mortar than to the clay fraction of the mortar mix; (3) the masonry modulus increases as the block strength increases; and (4) SMB masonry with cement-soil mortars shows higher modulus than the masonry using cement mortar and cement-lime mortar.
SUPERADOBE •
Super Adobe is a form of Earthbag Construction that was developed by Iranian architect Nader Khalili. The technique utilizes long snake-like sand bags to form a beehive shaped compressive structure that employs arches, domes, and vaults to create single and doublecurvature shell structures that are strong and aesthetically pleasing. It has received growing interest for the past two decades in the Natural building and Sustainability movements. Due to Super Adobe’s inexpensive nature, ease in construction, and use of locally available materials, it has also been proposed for use as a long term emergency shelter. Super Adobe is also known as Superadobe, and Superblock.
PRESSED EARTH •
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One of the more modern additions to the earth building scene, dating from last century, the making of compressed earth bricks in manually or engine-operated presses is now a widespread practice around the world. make the bricks from a dry mix, often stabilised with up to 10% cement. The compression given by the machine compacts the soil particles together to make dense regular shaped bricks, usually around 300 x 300 x 130mm in size. Most presses will enable some variety of shapes to be made so holes for reinforcing and rebates for window jambs can be preformed, but bricks of a different size are usually difficult to produce. You can produce the bricks on-site using a manual ram, or
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buy them from a manufacturer
PRESSED EARTH •
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Being hard, dense and regular, earth bricks can be laid up very precisely to form geometric shapes, or laid more loosely depending on the aesthetic results required. These bricks are the nearest things in earth building to concrete blocks in design and finish considerations. You can sometimes use a sand/cement/earth mix for the mortar, although often a mix of hydrated lime, cement and sand performs better.
SUMMARY Cost • •
Earth building uses inexpensive materials but is very labor intensive. It is more cost effective to have a source of suitable earth on-site.
Durability and weather tightness •
Earth buildings can last a very long time and generally require very little maintenance as long as they are not exposed to driving rain. To provide this protection, overhanging eaves or verandahs are needed.
Strength • •
In general, earth buildings are very strong in compression, but not so strong in tension. Earth walls can be reinforced to withstand earthquake loads and are fire resistant and vermin resistant
