MUD COSNTRUCTION
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Why Mud?

"One of the wonderful and endearing things about mud is that there is a wide range of muds and every single one has its own individual characteristics. All of it is god made and not machine made, so it is not standardized and it is almost limitless in quantity. Therefore to many, especially to the engineering world, it is maddening rather than endearing because you have to know your own mud and how to handle it.

All ladies have beautiful eyes and bewitching hair and shapely lips but ideally you have to learn to live with, love, cherish and understand your own particular woman.

Treat your mud as you should treat your wife and you will have a wonderful house for life."

Man has always built with natural materials; building with mud /earth, the most natural of all building materials, poses a special challenge. Architecture today, is dominated by cold hard, machine made building materials. While all previous attempts to replace these with a more plastic, environment- friendly material have resulted in a negation of the structural/technical dimension of Architecture, building with mud offers the unique possibility of a synthesis. As a an exploration into the possibilities of mud as a building material is especially relevant in a country like India where more than 80% of the population are sheltered in structures built with biomass.

The advantages and possibilities of mud construction are endless. Mud is environmentally the most sustainable material. Besides its obvious eco friendly nature, its easy availability makes it almost a ‘no cost’ material, abundantly present, generally on the site itself. This cost-effective material is also energy efficient and can be used to produce aesthetically very appealing structures. Its unique plasticity that allows it to be molded, its texture and earthy feel lend its structures a certain timeless quality. Buildings made of mud are also extremely comfortable, both in warm and cool weather, due to its thermal characteristics. Conceptually the material can be used to combine traditional elements in a contemporary context. The architecture strikes a subtle balance between technical appropriateness on the one hand and modern standards of services and space organization comforting to people on the other. To most people, however, to think of mud houses is at once to think of decrepit and crumbling structures, possibly in a slum or similar setting with the result that construction in mud is often dogged by a certain stigma. A greater understanding of the possibilities of the material and the great strides it has made with respect to application and use will enable a constructive redefining of its suitability for different types of construction. Construction with mud is the answer to many of our vexing housing problems and presents an exciting and down to earth alternative to the perpetuation of the concrete jungle.

Suitability of various soils for construction

Mud is the mixture of one or several kinds of soil with water. This moist plastic mixture can be used with or without stabilizing additives for the production of mud bricks (adobe) or mud walls. The soils of the tropics show great variability even over small areas. Much of this variability, however, is important for agriculture while it is of less concern for the earth house construction. Soils suitable for construction are however found in most areas. The different soil qualities may produce different shear strengths, which can be suitably modified through the addition of water and the stabilization process to produce building material of the requisite strength. In areas with large changes in climate, hot summer, freezing winters and much rain, mud construction must be made with great care and great attention must be given to the choice of soil type and the process of stabilization.

Type of Soil	Description	Suitability
GRAVEL	Small pieces of stone. Size varying from that of a pea to an egg.	Not good.
SAND	Smaller pieces of stone. Smaller than pea, but each grain still visible to the eye.	Sand alone- Not good, but with clay- Good
SILT	Same as sand, but so fine that individual grain is not visible.	Silt alone- Not good, but with stabilizer- Good
CLAY	Soils that are sticky when wet but are very hard, when dry.	Clay alone- Not good, but with sand- Good
ORGANIC SOIL	Composed of organic matter, dark in colour and have a musty smell.	Not good.

Sources of mud

One of the most endearing facts about mud is that we can use the mud from our own plot to make our own house. A 25 sq.m house on a 250 sq.m plot would require about 60 cubic metres of mud for its walls. By digging all over the plot except the basement area to a depth of 0.266m (10 inches), you have the right amount of mud to build your house.

Manifestations of mud

Depending on the characteristics of the mud available, availability of supporting materials and technology used, different manifestations of mud are used. These include Adobe or Sun-dried bricks, Cob, Rammed earth, Pressed bricks, Wattle and Daub etc.

1. Cob

A large lump of clay is roughly molded into a ball. A row of these cobs of mud is placed side by side. The second layer is laid on the depressions of the first layer. The building should proceed only slowly, allowing sufficient time for hardening.

2. Adobe / Sun- dried blocks

This is one of the most widely used forms of mud. The stiff clay is squashed into a small box or mould of wood or metal and then turned out to cure and slowly dry.

3.Rammed earth

This is an improvement on the Cob since it regularizes the thickness and is more compressed. Here, two parallel planks form the formwork, into which the stiff mud is thrown. This is then rammed down using a ramrod.

4.Wattle and Daub

This system uses mud as a plaster to cover thin panels of cane/split bamboo which has been woven together and held in place by poles.

Need for stabilization

Every material has its own inherent drawbacks that do not allow it’s ideal use in all situations. As far as mud is concerned, its drawback is its susceptibility to moisture and termites. With the advancement of technology in these modern times, it is possible to combat this problem effectively to arrive at a practical solution. Nearly all types of mud can be made into excellent building materials by a process known as Stabilization.

Stabilization

The quality of mud can be remarkably increased by means of stabilization. Nearly any soil can be made into a better building material by the addition of the correct stabilizer. This is done by adding sand, cement, etc to mud. Stabilization helps in cementing the particles of mud together, thereby increasing its strength. It also helps in decreasing its susceptibility to moisture. Furthermore, stabilization reduces the shrinking and swelling of mud.

Stabilizers

A great number of substances may be used for soil stabilization. Because of the many different kinds of soils and the many types of stabilizers, there is not one answer for all cases.

The commonly used stabilizers are sand, clay, lime, cement, sodium silicate etc. In addition to these materials, locally available materials like straw, coconut oil, cow dung, cattle urine etc are also used for strengthening mud. The stabilization of mud depends on a number of factors that include the quality of mud, the type of construction it is used for, the climate and the availability of materials.

Stabilized mud blocks – features: -

• Environmentally sustainable and eco-friendly material
• Cost – effective
• Energy efficient material
• 20-30% cheaper than fired bricks
• Good stability
• Good resistance to hurricane and rain
• Suitable for all climates
• Low skill needed
• The technology involved is interesting and based on the self-help method.

Making stabilized mud blocks Stage 1- Ascertaining the suitability of soil

The suitability of the soil is checked by various tests such as Sedimentation test, Compaction test, Ribbon test, Box test etc.

Stage 2- Mixing of stabilizer and selected soil and enough quantity of water

The stabilizer should be mixed thoroughly with the selected soil, which has been previously sieved and tested for organic matter and clumps. Add just enough water to make it workable.

Stage 3- Mechanical process of compression

The prepared earth is loaded into the mould box and the mix is compressed. The finished product is ejected and gently removed. It is then placed on edge on the curing site.

Stage 4- Stacking and curing

The proper curing of stabilized mud blocks is important for its stability. The blocks should dry out as slowly as possible to avoid cracks etc. While curing, the blocks should be shaded. Cement stabilized blocks should be sprinkled with water during the first few days. Curing time is around two weeks. After that the bricks should be stacked in such a way that maximum air circulation is facilitated. Dry storage should last at least two weeks.

Quality control

• Ascertain the suitability of the soil before use. Make sure that it is free from organic matter.
• Select the lowest amount of stabilizer that will make the blocks good enough to satisfy the requirements.
• All forms of mud are less prone to cracking if dried slowly in the shade and not in the strong sun.
• After the blocks are made, they should be stacked in such a way as to facilitate maximum air circulation

Our experiences with mud

We at Habitat Technology Group have been closely associated with mud as a building material, for the past fifteen years. The initial fascination for the material which has been in use in traditional Kerala architecture for hundreds of years has now grown into a strong respect for its qualities that makes it relevant in our present time. Mud is definitely the answer to the need for eco-friendly sustainable building materials that will not leave behind more problems for our future generations, but give them something to cherish and uphold. Our past experiences with mud has strengthened our convictions, simultaneously helping us convince the others. The work that we have done with this beautiful material has slowly but irrevocably changed the attitude of the public towards this ‘poor man’s material’ .We are proud to say that the response of the public towards mud has changed a lot and more and more people are coming forward now to accept this material.