Clay refers to a naturally occurring material compound composed primarily of

fine grained minerals, which is generally plastic at appropriate water contents

and will harden when dried or fired. Due to the abundance of clay in the tropical

region of which nigeria belongs clay has naturally found itself wiven into the

architecture of the cultures across nigeria, because of its plasticity (clay can be

moulded into any preferred shape), availability and durability.

clay over the years has proved itself to be a sustainable material due to its

properties it is not difficult to unearth from its source and little preparation is

required which implies that energy and tedious cycles is decreased. They are

flexible, energy proficient, tough, stylish and affordable. Saving expenses on

energy consumption is additionally conceivable given that building structures

will serve more energy with clay as a warmth separator satiated that clay

structures don’t utilise more power than required this would permit homes to

keep up their warmth throughout cold weather months and keep up agreeable

temperatures throughout the mid-year months. Clay earth is perceived as an

economical assurance building material since it gives amazing protection

properties and warmth stockpiling limit, assists with lessening energy utilization

in structures, it’s building materials are healthy, stable and warmth protections.

In this way, structures made of clay earth building items can last over 100

years’ life expectancy.

The formation of clay takes a long period of time which is a result of what is

known as the chemical weathering of silicate rocks by low concentrations of

diluted solvents like carbonic acid it is through this process clay minerals are

formed. The origin of clay dates back to 20,000 years ago when pottery

fragments were found at xianren dong cave in the jiangxi province of china. In

nigeria clay can be found naturally in large deposits in a few states like lagos

abuja kaduna sokoto borno etc.

The abundance of clay minerals in nigeria support its rich prehistoric traditional

pottery industry that dates from the stone age. Native pottery is a vibrant

traditional art practice and an established cottage industry for clay wares. Clay

has served as an indispensable raw material for the production of products

varying from red bricks for building and decorative purposes and pottery both at

industrial and local levels.

Clay properties

Clay itself is a naturally occurring material of a long period of chemical

weathering of silicate rocks and has a few characteristic property which makes

it suitable for achieving sustainability one of which is;

Plasticity
By plasticity we mean that clay, when wet has the ability to be permanently

deformed without cracking. Although plasticity is the most important physical

property of clay, there is no metric method of measuring it to satisfy its

parameters however the amount of water required by different clays to produce

the most plastic condition varies from 5% to 35%.

Shrinkage

Another property is shrinkage just like every other material that requires the use

of water in their preparation for example concrete. The knowledge of shrinkage

in clay both in drawing and burning is required to produce a product of required

size. The shrinkage in drying is dependent upon pore spaces within the clay and

upon the amount of mixing water. While fire shrinkage is dependent upon the

proportion of volatile elements textures and the way the clay burns. The

addition of sand or ground burnt clay lowers shrinkage increase the porosity and

facilitates drying also the amount of shrinkage in drying is dependent upon pore

space within the clay and the amount of mixing water

Porosity

Porosity of clay is the ratio of the volume of pore space to dry volume. Since

porosity affects the proportion of water required to make clear plastic it would

directly influence air shrinkage large pores allow the water to evaporate more

easily and consequently permit a higher rate of drying compared to small pores.

Inasmuch as the rate at which the clay maybe safely dried is of great importance
in manufacturing clay products the effects of porosity on the rate of drying

should be considered

Tensile strength

During the processing of clay, it is subjected to stress in moulding handling and

drying nz high tensile strength is desirable this test is carried out by determining

the strength of specimens which have been moulded into briquette form and

very carefully dried.

Texture

Texture of clay is measured by the fineness of its grains, very fine grains are

free from sand and as results are more plastic and shrink more than those

containing coarse material.

Types of clay
there are majorly 4 types of clay; earthenware clay; ball clay( which is abundant

our study area lagos), stoneware clay & porcelain clay.

Ball Clay

Ball clays are the most plastic and contain very limited mineral impurities. They

contain a large perce5 of kaolinite and quartz 2ith around 10 – 25% mica. Ball

clay occurs naturally as sediments or deposits containing very fine materials,

materials like lignite can be found in ball clays. Ball clays are commonly used

for floor tiles, toilet bowls, vases, kiln furniture and tableware.

Earthenware Clay

Earthenware Clay is characterizedby it’s warm colours, they are the oldest clays

used by potters and early settlers and it happens to be the most common partly
due to its plasticity. In comparison to other clay types, earthenware Clay is fired

anywhere from 99 to 1142°C

Stoneware Clay

Stoneware clay contains koalinite with small quantities of mica and quartz, they

vary in colour from white grey and all the way to brown when wet. Stoneware

clays are moderately plastic, hard and non porous being named because of its

stone like qualities. A popular use of stoneware clay is in the use of tableware

Porcelain Clay

Porcelain clay or chinese ceramics are incredibly popular especially in the

making of dinnerware. They are created with a large part of pure koalin and are

characterized by their subtle and light colours (off-white to white.) Though hard

to work with and requires mixing with other minerals to increase workability’s

it is popularly used in the making vases and decorative objects.

Applications of clay

clay though a sustainable material usually ready for industrial use because it’s

unstable state in its raw form, hence there is a need for some form of processing

before it can ne used. We would therefore examine the various ways in which

clay can be prepared for industrial use before discussing the areas of its

application.
Processing of clay

Clay being a versatile raw material can be processed in different ways to

achieve variations in strength, durability, shape, colour physical and chemical

properties. The following steps highlights a general procedure through which

clay can be processed considering that several methods and procedures exists to

achieve desirable qualities in its products and it as been subdivided into three

major steps.

Preparation stage

The clay is prepared and any trace of sand, stones, metal scraps, plant materials

and all other impurities must ne removed before it’s use. The clay is then mixed

with an appropriate amount of water and thoroughly pounded to remove air

bubbles and make the clay either smooth or more plastic to suit it’s final product

and also increase its workability during the moulding process. The sand and air

bubbles are removed to prevent cracking during the period of heating. After

which the clay is passed in to the next stage of processing.

Shaping/moulding stage
The moulding stage involves the use of the prepared clay to mould in shapes

either by hand in the case of pottery and art related sculpting or by moulds in

the production of bricks, slates, tiles etc.

Firing stage.

This stage involves heating the moulded clay to harden them. Firing is done

after shaping/moulding and drying of the processed clay. Thus process is

usually carried out in a kiln (either modern or clay kiln) or using the traditional

method of heating with firewood . Usually the temperature range is about 900°c

to 1100°c which can be regulated to suit specific conditions of production.

We can therefore discuss the application of clay in the built environment:

Wall Materials

Clay can be processed into common clay bricks, perforated clay bricks, porous

and perforated stiff mud bricks, hollow clay dry press brick, perforated plastic

moulded ceramic stine’s and light weight building brick which can be use to for

partition walls or structural walls in building construction. Statistics have shown

that clay bricks account for half the total output of wall materials. They are

suitable for insulation especially in low temperatures due to their properties and

can reduce heat losses though air-filled voids.

Façade decoration
Clay can be processed into facing brick, ceramic stones, plates and tiles which

is can be used for the decorations of building façades.

Interior decoration

Clay after undergoing through processing can serve as a decor item in form of

sculptures, pottery etc others examples includes the use of large floor tiles,

mosaic floor tiles.

Sanitary clay items

Clay is a main raw material in the manufacture of sanitary wares which is

formed mainly by white-burning refractory clay, kaolins, quartz and feldspar.

There are three groups of sanitary ceramics: faience, semi-porcelain and

porcelain, which differ in degree of caking and, as a consequence, in porosity.

Items from faience have a porous shell, and items from porcelain, a solid shell,

while those from semi-porcelain are of intermediate densities. The various

degrees of caking of faience, porcelain and semi-porcelain, made of the same

raw materials, are due to the latter’s different proportions in the working mass.

Solid faience is used mainly to manufacture toilet bowls, wash basins, toilet

tanks and bath tubs. Items are glazed, since unglazed faience is water

permeable. Semi-porcelain items feature excellent hygienic and mechanical

properties being intermediate between those of faience and porcelain. Porcelain

outer shell is impervious to water and gases and possesses high mechanical

strength and resistance to heat and chemical agent. Porcelain is used to

manufacture insulators for power transmission lines, chemical laboratory

vessels, etc.

Aggregate for Concrete

Creamiste (manufactured from low-heat clay), a light weight porous material

forms excellent aggregate for light weight concrete.

RELATED RESEARCH TO OUR FIELD OF STUDY

References

 Stephen Guggenheim & R.T Martin ; Clay and Clay minerals. 1995 .

Definition of clay and clay minerals : Joint Report of the AIPEA

Nomenclature and CMS Nomenclature Communities

 M.Y Muntari & A.O Windapo, 2021 : Clay as a sustainable building

materialand it’s benefits for protection.

 Pottery- Wikipedia

 Clay Natural Depositions in the Nigerian states and it’s uses.-

Finelib.com

 Oluwafemi Samuel Adelabu ; 2012. Application and Utilisation of clay

minerals in Kaduna State Nigeria

 Chapter: Civil construction Materials; modern materials, physical

properties of clays. Brainkart.com

 What are the four types of clay . Potterycrafters.com

 Tsetimtheo . 2020 : processing of clay ceramics and glass.

Tansicollege.edu.ng