Introduction of Bricks - Brickwork superior or inferior to stonework??

Bricks:

General: The bricks are manufactured by moulding the clay in the rectangular blocks of uniform size and then by drying and burning these blocks. Bricks are easy to work with because of their uniform size and light weight. They do not require the dressing and the brickwork can be done by the non-skilled workers. Stones are not easily available so if clay is available bricks can be manufactured and utilized.

The bricks are very old Civil engineering material which were utilized in many historical buildings of the Roman Empire and also in the Chinese Civilization burnt bricks and Sun dried bricks were utilized to construct the Great Wall of China (210 B.C.). Wood was used earlier but due to its fire catching risks it was replaced with the bricks. The great fire of the London in 1666, converted the city from the wooden city to the brick city.

According to the data provided in a book titled “Engineering Materials” by India has more than about 45000 local kilns and has a capacity of about 10,000 crores of brick production. Further it says that this sector is un-organized so there are not many improvements in the methods of manufacturing and technology utilized for the manufacturing of bricks. The fuel cost is high so one cannot care much about the quality of the bricks.

Is brickwork better than stonework?

It is superior to stone work in the following ways:

• Bricks are easily available at many places but building stones are not easily available everywhere.
• The brickwork can be can out by the less skilled workers so the cost of construction can be reduced due to the lower wages to be paid.
• Light weight bricks can be easily lifted but other materials requires mechanical ways.
• Bricks can be manufactured to resist higher temperatures as compared to the stones.
• Similarly higher durability bricks can be manufactured which can prove to be more durable than the stones.
• Bricks need thin mortar joint so the structure becomes more durable.
• Connections and openings can be constructed easily in case of the brickwork than stonework.

Brickwork is inferior to the stone work in the following ways:

• Bricks absorb more moisture as compared to the stone, so it may result in the dampness of the building.
• For monumental structures the stone create a solid appearance which bricks cannot create, in those cases the stones are useful than the brickwork.
• The stonework has more strength.
• The stone work is cheaper at places when the stones are easily available.

Uses of Stones as Civil Engineering Material

The stones are used in the construction of buildings from the ancient times and most of the ancient temples, forts and mosques of India were built with stones as the major material. The Taj Mahal, Red Fort, Jama Masjid, Parliament house and Rashtrapati Bhawan at Delhi and various other prominent structures spread throughout the length and breadth of our country furnish us the awesome examples of uses of the stone as building material. At present, they are largely used as the basic material for the manufacturing of the other construction materials like concrete, bricks etc.

Following are the various uses to which stones are employed:-

1. Structural elements: The stones are used for foundations, walls, columns, lintels, roofs, floor, damp proof courses etc.
2. Facing: The stones are adopted to give massive appearance to the structure. The walls are of bricks and facing is done in stones of desired shades. This is known as the composite masonry.
3. Paving: The stones are used to cover floor of buildings of various types such as residential, commercial, industrial etc. They are also adopted to form paving of roads, footpaths etc.
4. Basic Material: The stones are disintegrated and converted to form a basic material for cement concrete, moorum of roads, calcareous cements, artificial stones, hollow blocks etc.

Miscellaneous uses :

In addition to the above uses the stones are also used as:

1. Ballast for railways,
2. Blocks in construction of bridges, piers, abutments, retaining walls, light houses, dams etc.
3. Flux in blast furnaces.

Why Stones are losing their Popularity

Stones are losing their popularity as the building material because of the following reasons:

1. The dressing of stones proves to be tough, laborious and time consuming.
2. The stones of desired strength and quality are not easily available at reasonable rates, especially in plain areas.
3. The alternatives to stones namely, R.C.C. and steel have proved to be stronger, less bulky, more durable and more suitable for present day construction of multistory and important buildings.
4. The structures constructed of stones cannot be rationally designed as in case of R.C.C. or steel structures.   

General characteristics of marble, Kota stone, granite, basalt etc

You can/may find here the following stone's characteristics discussed below:
(1) Marble (2) Limestone (3) Sandstone (4) Granite (5) Basalt (6) Slate  (7) Kota Stone

(1) Marble: 

A view of Taj Mahal(built with Marble)from the bank of the Yamuna river.

(a)Marble is a metamorphic rock formed    after after the metamorphism of the limestone. Under high temperature and pressure, re-crystallization of  calcite and dolomite takes place to a compact structure.
(b) It is largely used for the ornamental, carvings and molding works.
(c) It is available in many color from white to black including, red, green, yellow, blue and gray.
(d) It is porous to some degree and more after getting the polish.
(e) It has lustrous and glossy appearance.
(f) It is used as flooring, wall linings, table roofs, bath tubs, and sculpture making etc.
(g) Limestone(CaCO3) being the main compound it is liable to acid attacks, if MgCO3 is the major constituent then it is more acid resistant.
(h) Its specific gravity is 2.72
(i) Its crushing strength varies from 50 to 60 MN/m2

(2) Limestone:

(a)Limestone is a sedimentary and calcareous variety of rock. With CaCO3 it may contain MgCO3, and if both are present in equal proportion then it is known as dolomite.
(b) Generally it has  a stratified structure.
(c) It is available in few colors.
(d) It is used in the blast furnaces of many manufacturing industries like cement and bricks.
(e) It is used to get the pure lime.
(f) It is not suitable for use near industrial areas for building construction due to its chemically reactive property.
(g) Its specific gravity is 2.6.
(h) Its crushing strength is 52 MN/m2.

(3) Sandstone: 

(a) It is a type of rock which has the quartz or the sand bound together with the cementing minerals like mica, feldspar etc.
(b) It is a sedimentary rock
(c) Its color depends upon that of the feldspar.
(d) It can be used as a road metal if the higher quality stones like basalt and granite is not available.
(e) It is fire resistant.
(f) Its specific gravity is 2.25
(g) Its crushing strength varies 35 to 40 MN/m2.

(4) Granite: 

(a)It is a igneous rock of the plutonic variety.
(b)It contains the feldspar in abundance.
(c)It has a coarse grained crystalline structure.
(d)It is very hard, tough, durable and has a high specific gravity,
(e) It is used as a road metal, fine grained granite can be used for the masonry work.
(f) It has less fire resistance, so it cracks at high temperatures.
(g) It is best suited for industrial towns.
(h) The life of granite is over 300 years.
(i) Its specific gravity is  2.64.
(j) Its crushing strength varies 110 to 140 MN/m2.

(5) Basalt:

(a)It is a kind of igneous rock of the volcanic variety
(b) It possess a very fine grained and almost non crystalline structure.
(c) It is tougher and has more specific gravity than the granite.
(d) It is non water absorbent.
(e) Crushed basalt is highly used as road metal.
(f) Its specif gravity is 2.96.
(g) Its crushing varies from 70 to 80 MN/m2

(6) Slate:  

(a)Slate is a metamorphic rock obtained after the metamorphism of the shale which is a sedimentary             rock of the argillaceous variety.
(b) It is a foliated rock and can be split  into thin sheets.
(c)  It is available in grey or dark blue color.
(d)  It is widely used as the roofing material in the hilly areas, cisterns and urinal separations.
(e) It is non water absorbent and smooth surfaced.
(f) Its specific gravity is 2.8.
(g) Its crushing strength varies from 60 to 70 MN/m2.

(7) Kota Stone:

(a) Kota stone is a kind of the limestone which is available in the Kota district of the Rajasthan.
 (b) It has fine grained structure, so it can be polished and is famous as the flooring, wall lining, paving material.

Types of Cement

Cement is a Civil Engineering Material which is worldwide used to form concrete and mortar and other soil stabilization works. It is  possible after the invention of the cement to get the structures with high strength and of various attractive architectural shapes at the same time. The strength of cement depends on its constituents and their relative proportions.

1.Ordinary Portland Cement:

Ordinary Portland Cement(OPC) is used for the normal concrete works. It has cohesive and adhesive properties when mixed with water. After the evaporation of water it forms a solid mass. OPC manufactured by burning the following materials in a definite proportion:

(a) Siliceous Materials 

(b) Argillaceous Material (containing clay)

(c) Calcareous material (Containing Lime) 

The mixture of the above constituents is burnt to a temperature of about 1400 degrees celcius in the Rotary kiln which results in the formation of the clinker.  The clinkers so obtained are cooled and crushed to form the powder form which is known as cement. Cements of different kinds are obtained by mixing the above constituents in different proportions.

Constituents of OPC : 

(i) Lime : 60% to 67%

(ii) Silica: 17% to 25%

(iii) Alumina: 3% to 8%

(iv) Iron Oxide: 0.5% to 6%

(v) Magnesia: 0.1% to 4%

(vi) Soda and Potash : 0.2% to 1%

(vii) Sulphur tri-oxide: 1% to 2.75%

(viii)  Free lime: 1% to 1%

Cement constitutes chemical compounds formed after the burning of the above mentioned ingredients. The main constituents found in cement are as follows:

(1) Tri-Calcium Silicate (C3S)

(2) Di-Calcium Silicate(C2S)

(3) Tri-Calcium Aluminate (C3A)

(4) Tetra calcium Aluminoferrate (C4AF)

About 70% to 80% of cement is contributed by the C3S and C2S which are responsible for the strength of the concrete. C3S or Tri-calcium Silicate has the property to hydrate rapidly so mainly it is responsible for the early strength of the cement and also responsible for the ultimate strength of cement.

Di-Calcium Silicate has the property to hydrate slowly and provides strength after a period of seven days. Tri-calcium Aluminate also helps in gaining early strength due to early hydration but it is said to retard the ultimate strength, and is susceptible to the alkali and salts attacks.

Tetra-calcium alumino ferrate do not provide any strength to the cement and is said to be an unwanted compound in the cement.

2.Rapid Hardening Cement (IS:804)

This is manufactured in the similar manner as we do OPC, however it differs in its constituents, it contains more lime and is burned under a better controlled temperature over a longer time. The clinkers are ground to much finer extent. The quick rate of gain of the early strength is due to the higher content of tri-calcium silicate.  It gains the same strength in 3 days which OPC gains in 7 days for the same water cement ratio, and it gains the strength in 7 days what the OPC gains in 28 days. Advantages of using this type of cement is when the shuttering is to be removed early on to save the time, it is best.
Second it is best for the cold regions, where the frosting conditions occur. In case of roads it can be used to open the road to traffic at lower time period.

3.Low Heat Portland Cement(IS: 269)

In the mass concrete structures like Dams, retaining walls and abutments, if we use the normal cement which generates a large amount of heat(about 80 cal/gm at the end of 3 days), will result in the shrinking of the concrete and may affect the water tightness of the structure. Low heat Portland cement is specifically made for such uses because it generates a heat of about 75 cal/gm at the end of 28 days. Its setting rate is slower than the OPC. It is due to the fact that it contains low percentage of C3S and C3A, which are responsible for the early strength strength of concrete. So its strength is less than OPC in the early days but with the time it gains the same strength as that of the OPC. To ensure the rate of strength code recommends a specific surface requirement of 3200 cm^2/gm.

                                                 4. Portland Blast Furnace Slag Cement(IS: 455)

This cement is manufactured by mixing the blast furnace slag with the OPC clinkers. The properties of the cement are not affected by the blending of the blast furnace cement however it enhances its properties, but the content of the blast furnace slag cement is kept less than 65%. Blast furnace slag has latent hydraulic property which is highly activated when mixed with the cement clinkers. This cement can be used almost everywhere where the OPC is used and in addition to that it can be used in the huge mass concrete structures like dams, retaining walls, foundations and abutments of bridges. This cement has a good sulphate resistance and is very suitable for use in constructions in sea water.

                  5. Portland Pozzolana Cement (IS: 1489)

This cement is made either by blending and grinding the OPC cement clinkers and Pozzolana or by intermixing the OPC and fine pozzolana. Intergrinding must be preferred because it forms a uniform composition while blending forms non uniform composition. The blending should be preferred only when the uniform blending is assured by some mechanical process.  Content of Pozzolana varies from 10 % to 25% by weight of cement. Pozzolana in itself do not have the cementing properties but it forms the cementing material with the lime. When mixed with OPC it reduces the amount of free lime in cement and therefore it reduces the chances of the chemical attacks. It also lowers the heat of hydration and resists the sulphate attacks and was popularly used in the construction of the Bhakra Dam.

Bricks- civil engineering material

Bricks are the civil engineering materials used worldwide, you might have used them while you constructed your home. As you know building stones are not available everywhere so there is always a need for the material which can be used in the masonry work in place of stone. Bricks are manufactured using easily available raw materials like clay, silica, lime iron oxide etc.  You have to control the constituents like lime because excess of lime can result in poor bricks. You should avoid the impurities like pebbles, organic matter and iron pyrite. Various major steps you have to go through are:
(1)collecting raw material
(2)preparation of brick earth and moulding.
(3)Burning the bricks and cooling.
In the first step you have to dig the top surface up to a depth of 20cm to avoid any organic impurities and then take out any other impurities present.
Second step you can complete by two methods Hand moulding and machine moulding. Machine moulding is done using machine.  Afterwards the bricks are dried to gain a certain strength to make them ready for kiln burning.
There are two famous kilns available for burning:
(1)Bull's trench kiln
(2)Hoffman's kiln
A good brick is reddish in color, produces ringing sound when striking with another brick.  Remember it has a water absorption value less than 20%. You should make sure that you get the Indian standard(modular) size brick 19*9*9 cm3 or 19*9*4 cm3.
Burned bricks are classified as 1st class, 2nd class and 3rd class bricks.
You can search for the details please.

Need for new Civil Engineering materials.

Hi,
I search my books for the various civil engineering material, and they provide me the information and the techniques to produce and use the materials like, cement, bricks, tiles, timber, steel, paints and varnishes, and stones etc. These are the materials which are used worldwide for the construction of the houses or any other buildings and the massive structures.
Now if we look at the procedures to get the materials like cement, then you will see that it needs the clay, limestone and few other materials in smaller proportion, and then it needs a lot of heat energy to burn this mix at a very high temperature.  This temperature is gained with the help of the burning fuels like coal, which is a non-renewable resource of energy.
The coal on burning produces a large amount the pollutants. The gases which are released with the burning of this material are very much harmful for the environment and ultimately to this whole earth. It is not hidden from anybody then the production of the cement alone produces a large percentage of the total carbon production of the world.
It has made me to think for a while. I think there is a need for a material having the good binding properties and which can be produced safely without harming our environment. There is a need of research in this field. The technology must advance in this direction to save our earth. If there comes a new material which can give the better performance, then it will be accepted everywhere.
Thanks.

Fibre Saturation Point of Timber or wood

In wood there is the moisture present either in the cavities in between the fibers or is chemically bonded to the fiber cells. This moisture is removed by using the seasoning techniques.

There is a particular moisture content(%) when all the cavity water is removed and after that the wood starts gaining more strength and starts shrinking, this moisture content is the fiber saturation point(FSP).

The properties of the timber changes with the moisture content if the moisture content<= FSP

but the properties are not effected by change in the moisture content in the range>FSP.

So it is an important term related to Timber.