Building Materials In Construction
Building Materials in construction are important part of civil engineering. The Civil engineering career of site engineer completely revolves around these materials. He/she should be knowing thoroughly each and every aspect of these materials.
The Various Building materials in construction are as below and we shall learn about them .
Cement is the most important construction material without which its not possible to construct. Cement acts as a Binding Material. Cement is prepared by drying and burning of Clay and chalk at very high temperature of upto 1800 deg F. Now a days the common cement i.e. Portland cement is prepared by using a mixture of Lime, Silica and alumina.
The Main Process in manufacturing of cement are
The two main process of manufacturing cement are Dry Process and Wet process.
Main components of cement are
- Lime – 60 % approx.
- Silica, Alumina – 30 %
- Magnesia and other alkalies – 10 %
Following are the characteristics of good Quality cement
- Ideal Portland cement shall be of green colour.
- The Sp gravity of cement is in the range from 2.2 -3.0
- Initial and final setting times shall be 30 min and 10 hrs respectively.
- Weight of cement shall be between 1200 to 1800 Kg/ cum
Routines checks carried out at site to check the quality of cement
- If we put our hand in a bag of cement, feeling shall be cool.
- Handful of cement, when thrown in tub of water, it should sink and not float.
- Blackish colour of cement indicates presence of foreign materials.
The various important types of cement available in the market are as below
- Ordinary Portland cement- Regular use
- Quick Setting cement – Used in underwater construction and initial setting time is 2min.
- Rapid Hardening cement – Quickly hardens used preferable in flowing water.
- Low heat cement – produces lot of heat, hence used in Dam construction.
- Sulphate Resisting cement- Better in resisting chemicals, used in structures where sewage or any waste comes in contact.
Sand is obtained due to weathering of rocks. Main component of sand is silica. Sand is fine aggregate, often found is various shapes i.e. round or angular, mainly available from River and Sea.
River sand Characteristics – River sand are mostly round due to action of water movement. This type of sand is often used in the finishing works.
Sea sand characteristics – Sea sand as name suggests is obtained from sea bed. This sand is mostly salty nature. This type of sand is not used in regular construction work.
The following aspects needs to be taken care
- Colour of sand
- Fineness of sand is checked by sieve analysis.
- Voids present in sand
- Amount of salts present in sand
- Silt check
Bricks are made by burning and drying of clay in Kiln. The various types of bricks are
First class bricks
The Main characteristics of first-class bricks are
- These are of proper shape and with proper rectangular edges.
- First class bricks should not break when dropped from 1m height.
- A metallic ringing sound is heard, when bricks are hit against each other.
Second Class bricks
- These bricks are not that rectangular in shape.
- Small cracks and finger nail marks can be made on these bricks.
Third class bricks
- These are regularly obtained bricks which are not regular in shape,
- Edges are not very rectangular.
- Also, the colour is a pale and under burnt.
Brick earth is used for making of bricks and contains 40 % of Alumina and 60 % of Silica. This brick earth is properly made in correct proportions and is placed in mould and then is dried and burnt in Brick Klin.
Properties and Characteristics of Good Bricks
- The standard size of brick is 19 cm X 9 cm X 9 cm
- An indent on top of brick is called FROG.
- A brick when immersed in water for 24 hrs shall not absorb water more than 10 % of its weight.
- Crushing strength of brick shall be not less than 11 N/sq.mm
- The surface of brick shall be smooth and with square corners.
The raw form of timber is LOG. The log is basically the bark of a tree when cut and used.
Starting from outer the various layers of Trunk of tree are
- Bark – The outer most portion of trunk
- Cambium layer
- Annual Rings
- Sap Wood
- Heart Wood
- Pith – Inner most portion of trunk
Characteristics of Timber
- More weight
- Close annual rings
- Free from cracks and blemishes
- Should not have wide space between rings.
- Dull sound should not come when stuck against each other.
- Colour shall be dark and not light .
List of various defects in Timber
- Radial shakes
- Heart shakes
- Star shakes
- Ring shakes
- Rind galls
Types of timber and their uses
- Converted Timber – Sawn and cut into various sizes
- Standing timber – The timber which we see on living tree is standing tress
- Rough Timber- Timber obtained after tree falls to ground.
Types of timber used in construction
Bamboo – This is strong timber and used for Roof of structures and Scaffolding purposes
Banyan – Used in door panels and good against resistant to moisture.
Deodar – Railway sleepers are made
Mahogony – Easily workable and hard used to make ornamental furniture.
Mango – Brown in colour used often in Door and window frames, furniture.
Sal -Used in bridges, Posts,Piles etc
Sandal – Scented yellow colour and used in making Boxes and fancy items.
Teak – Extremely durable, Dark brown used in buildings, railway carriages etc
Advantages and Disadvantages of Timber
- Advantages –
- Molded to different shapes
- Light in weight
- Aesthetically good
- If locally available,its economical.
- Easily movable from place to place.
- Fire Risk
- Not suitable for extremely cold and moist places
- Lot of care and maintenance is necessary
- Cost implication if timber is not locally available.
Interview Questions Related to Building Material and construction
- Main constituent of Portland cement is – Lime
- Le ch-atelier’s device is used for determining – Soundness of cement
- Material responsible for initial setting of cement – Tri calcium illuminate
- Initial setting time of cement is – 30 min
- Final setting time of cement is – 10 hrs
- Best retarder used is cement is – Gypsum
- The fineness of cement is known by – Air Permeability test
- Pozzolana in Ordinary Portland cement causes – Shrinkage
- Vicats apparatus is used to test – Initial and Final setting time
- For dams what type of cement is used – Low heat cement.
- No of bricks in 1 cum volume – 500 nos
- Pug mill is used for preparation of – Clay
- The process of mixing clay, water and other ingredients is called – Kneading
- Indent provided on top of the brick is called – Frog
- The percentage of silica in good brick clay is – 50-60%
- What is efflorescence – Formation of salts on brick surface
- Which soil is good for making bricks – alluvial
- Central part of trunk section is called – Pith
- Seasoning of timber is done to – improves strength of timber
- Due to dry rot – timber often becomes powder
- The trunk of tree after cutting all branches is called – Log
- Number of days required for seasoning of timber – 120-150 days
- The age of tree can be known by – its annular rings
- Tell types of soft wood -chir and deodar
- The strength of timber is maximum in which direction – Parallel to grains