Defects in Timber - vk

Defects occurring in timber are grouped into following five divisions.

1. Defect due to Conversion

Chip mark Diagonal grain Torn grain Wane

2. Defects due to fungi

Blue stain Dry rot Brown rot Heart rot Sap stain Wet rot White rot

3. Defects due to natural forces

Burls callus Chemical stain Coarse grain Dead wood Druxiness Foxiness Knots Rind galls Shakes Twisted fibres Upsets Water stain Wind cracks

4. Defects Due to seasoning

Bow Check Cup Warp Split Twist Radial Shakes Honey combing collapse Case hardening

5. Insects that cause defects

Beetles Termites Marine borers

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Clamp burning and Kiln burning comparison - vk

 Comparison between Clamp buring and Kiln burning 

No. item	Clamp-burning	Kiln burning
Capacity	About 20000-100000	avg 25000
Cost of fuel	Low as grass, cow dung, litter may be used	High because of coal dust is to be used
Initial cost	Very low as no structures are to be built	More as permanent structures are to be constructed
Quality of bricks	The percentage of good qualtiy bricks is small about 60%	Percentage of good quality bricks is high 90%
Regulation of fire	It is not possible to control or regulate fire during the process of buring.	The fire is under control throughout the process of burning
Skilled supervision	Not necessary through out the process of burning	The continuous skilled supervision is necessary
Structure	Temporary structure	Permanent structure
Suitability	For small scale	For large scale
Time of burning and cooling	It requires about 2-6 months	Actual burning times is 24 hr. and 12 days are required for cooling of bricks.

Notes - About comparison is based on use of these kiln with respect to bricks.

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Bull's trench and Hoffman's kiln comparison - Bricks vk study

 Comparison between Bull's trench and Hoffman's kiln

No. Items	Bull's trench kiln	Hoffman's kiln
Burning Capacity	About 3 lakhs in 12 days.	About 40 lakhs in one season
Continuity of working	It stops functioning during mansoon as it is not provided with a permanent roof	It functions all the year with permanent roof.
Cost of fuel	High as consumptions of fuel is more.	Low
Drying space	It requires more space	It requires less space
Initial cost	Low	High
Nature	It is semi-continuous in loose state.	It is continuous in nature
Popularity	More popular because of less initial cost	Less popular because of high initial cost
Quality of Bricks	Percentage of good quality bricks is small	Percentage of good quality bricks is more.

Note:- 

 These two kiln's are used to burn the bricks.

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Rubber vs. Concrete vs. Steel Material Properties Comparison

Material Properties Comparison: Rubber vs. Steel vs. Concrete

Material Properties

Property	Rubber	Steel	Concrete
Elasticity	High - Can deform significantly under stress and return to its original shape.	Low - Does not deform much under stress and retains its shape even under significant loads.	Low - Has relatively low elasticity, but can experience some deformation under stress.
Modulus of Elasticity (GPa)	~1 MPa to ~100 MPa - Relatively low modulus of elasticity.	~200 GPa to ~210 GPa - High modulus of elasticity.	~20 GPa to ~40 GPa - Moderate modulus of elasticity.
Strength	Lower strength - Rubber is not as strong as steel and may deform significantly under stress but can recover its original shape when the stress is removed.	High - Steel is a strong material, capable of withstanding heavy loads and high-stress conditions.	Variable - Concrete is relatively strong in compression, making it suitable for load-bearing structures, but weaker in tension.
Density	Low - Less dense than steel, making it lighter and suitable for weight-sensitive applications.	Moderate - Denser than rubber, providing more mass and stability in structural uses.	Moderate - Has a moderate density.
Plasticity	Low - Limited plasticity, does not undergo permanent deformation easily.	Moderate - Can exhibit plastic behavior under certain conditions, allowing shaping without fracturing.	Variable - Can exhibit plasticity during curing, limited compared to metals.
Applications	Used in tires, seals, shock absorbers, and flexible components due to its high elasticity and vibration absorption.	Ideal for structural applications like building construction, bridges, machinery, and load-bearing structures due to its high strength and rigidity.	Widely used in construction for foundations, beams, columns, and walls due to its compressive strength and versatility.

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Comparison between Steel and Rubber Material Properties

Material Properties Comparison: Rubber vs. Steel

Property	Rubber	Steel
Elasticity	High - Rubber can deform significantly under stress and return to its original shape.	Low - Steel does not deform much under stress and retains its shape even under significant loads.
Modulus of Elasticity (GPa)	~1 MPa to ~100 MPa - Rubber has a relatively low modulus of elasticity.	~200 GPa to ~210 GPa - Steel has a high modulus of elasticity.
Strength	Low - Rubber is not as strong as steel and is more susceptible to permanent deformation under high stress.	High - Steel is a strong material, capable of withstanding heavy loads and high-stress conditions.
Density	Low - Rubber is less dense than steel, making it lighter and suitable for weight-sensitive applications.	Moderate - Steel is denser than rubber, providing more mass and stability in structural uses.
Applications	Various applications in tires, seals, shock absorbers, and flexible components due to its high elasticity and vibration absorption.	Ideal for structural applications like building construction, bridges, machinery, and load-bearing structures due to its high strength and rigidity.

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Composition of Good Brick Earth and its Properties that affect the Bricks

Composition of Good Brick Earth and its Properties thats effect on bricks

Composition of good  Brick Earth

composition	in percent	properties contribution	property on excess
Silica	50-60%	retaining the shape of brick prevent cracking, shrinkage, warping of raw brick	destroy the cohession between particles and make brick brittle
Alumina	20-30%	plasticity to brick	weak and warp on drying of brick
Lime	10%	prevent shrinkage on drying	melt and brick loose  its shape
Iron Oxide	<7%	gives red color helps lime to fuse with sand	dark blue color
manganese oxide	<1%	yellow tint color decrease shrinkage	decay of brick
sulphur oxide carbon dioxide	very small		spongy, swollen structure in the brick decolored by white  blotches
water	very small
Note	good clay for making the brick is weathered clay.
Alkalies		very small	melt and loose their shape
Organic matter		none	after burning leaving pores and make brick porous
Pebbles, Gravels, Grits		lesser	weak and porous not give uniformity  during mixture

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Find Initial and Final Setting Time of Cement

Type of cement	Initial Setting Time (min)	Final Setting Time (min)
Ordinary Portland Cement	30	600
Portland Pozzolona Cement	30	600
Quick Setting Cement	5	30
Rapid Hardening Cement	30	600
High Alumina Cement	30	600
Sulphate Resisting Cement	30	600
Super Sulphated Cement	30	600
Portland Slag Cement	30	600
Hydrophobic Cement	30	600
Low Heat Cement	60	600
Masonry Cement	90	1440

How to Find Initial and Final Setting Time of Cement
Setting Time Test of Cement

What is initial and final setting time of cement?

Setting time of cement is an important property to knowing the time limit for handling, transportation and placing of concrete. Setting time of cement is divided into two types-

Initial Setting Time of Cement.Final Setting Time of Cement.

But before discussing these types let's understand what is a setting of cement is?

What is the setting of cement?-

When water is added to cement it reacts with water and forms a paste. This cement paste is in a plastic state and can be moulded to any shape. After some time this cement paste starts losing its plasticity and starts to set. This entire process is called the setting of cement.

What is Initial Setting Time of Cement?

Initial setting time is a time from the moment water is added to the cement, to the time that the paste starts losing its plasticity.

Initial setting time of ordinary portland cement (OPC) is 30 minutes.

What is Final Setting Time of Cement?

The time from when water is mixed with cement to the time when cement paste loses completely its plasticity and became hard is called the final setting time of cement.

Final setting time of ordinary portland cement (OPC) is 600 minutes.

Significance of Initial and Final Setting Time of Cement –

Initial setting time of cement gives us an idea about the time limit for handling, transportation and placing of cement on site.After placing cement on site it should not be disturbed up to the period of final setting time of cement.The final setting time of cement plays an important role in the formwork removal period of any structural member.

How to Calculate Initial Setting Time and Final Setting Time of Cement-

We are going to do a setting time test on cement using VICAT Apparatus as per IS 4031(Part 5):1988

APPARATUS-

VICAT Apparatus conforming to IS : 5513-1976.

VICAT mould

Measuring Cylinder of 200ml

Weighing balance with 1g accuracy

Stopwatch

Trowel

Apparatus for initial and final setting time test of cement

Procedure to Find Initial Setting Time of Cement –

1) Take 500g of cement in-tray.

2) Add the amount of water (which is calculated using the formula given below) to cement to make cement paste and start the stopwatch. ( Stopwatch should be started from the moment water is added to the cement).

Amount of water to add = 0.85P % of the weight of cement.

Where P = Percentage of water required to make a cement paste of standard consistency.

3) Pour this cement paste into the Vicat mould using a trowel within 2-3 minutes from water added to cement and level the top surface properly.

4) Then place this mould on the Vicat apparatus under the square needle.

5) Move the needle slowly downwards until the needle touches the top surface of the mould.

6) Then released the square needle and allow it to penetrate into the mould.

7) Now note down the reading on the Vicat scale, initially, it shows zero reading because the needle completely penetrates into the mould.

8) Repeat this procedure at 2 minutes intervals until the Vicat scale shows a reading of 5mm (which means the plunger should stop penetrating 5mm from the bottom of the mould).

9) Now note down the time shown on the stopwatch. This time from the moment water was added to cement to the time needle penetrated the cement mould 5mm from the bottom is theinitial setting time of cement.

Procedure to Find Final Setting Time of Cement –

1) Replace the needle of Vicat apparatus by needle with angular attachment.

2) Move the needle slowly downwards until it touches the top surface of the mould gently.

3) Then released the needle and allowed angular attachment of the needle to make an impression on the top surface of the mould.

4) Now repeat the same procedure at some time intervals until the angular attachment of the needle is failed to make an impression on top of the mould.

5) Note down the time shown on a stopwatch. This time from the moment water is added to the cement to the time at which the circular attachment of the needle failed to make an impression on the surface of the mould is called the final setting time of cement.

Calculations –

Weight of cement sample = …….. gms.

Water required to make cement paste of standard consistency = P = …….. %.

Quantity of water added = 085P = ……. ml.

Sr.NoTimeReading(mm)

The initial setting time of the cement sample is ………..

The final setting time of the cement sample is ………….

Precautions –

Lumps should be removed from the cement sample.Test should be performed away from any vibrations and disturbance.The room temperature should be maintained at 27 ± 2°C at the time of conducting the initial and final setting time of the cement test.The relative humidity of the laboratory should be 65 ± 5%.The needle should be released gently.

FAQs on Initial and Final Setting Time of Cement-

What is the initial and final setting time of ordinary portland cement(OPC) of different grades?

OPC Grade -IST FST
Grade 33     30  600
Grade 43     30  600
Grade 53     30  600

Which IS CODE is used to find initial and final setting time of cement?

The initial and final setting time of cement is calculated using the VICAT apparatus as per IS 4031(Part 5):1988.

What is the difference between the setting and hardening of cement?

The setting of cement is the stiffening process of cement paste. When we add water to the cement sample it forms a paste. This cement paste is in a plastic state. The transformation of the cement paste from a plastic state to a solid state is the setting of cement.

After the setting of cement, it starts to gain strength, this strength gaining process is called the hardening of the cement.

Table of Contents

• What is initial and final setting time of cement?
• What is the setting of cement?-
• What is Initial Setting Time of Cement?
• What is Final Setting Time of Cement?
• Significance of Initial and Final Setting Time of Cement –
• How to Calculate Initial Setting Time and Final Setting Time of Cement-
• APPARATUS-Procedure to Find Initial Setting Time of Cement –
• Procedure to Find Final Setting Time of Cement –
• Calculations –
• Precautions –
• Initial and Final Setting Time of Cement of Different Grades –
• FAQs on Initial and Final Setting Time of Cement-
• What is the initial and final setting time of ordinary portland cement(OPC) of different grades?
• Which IS CODE is used to find initial and final setting time of cement?
• What is the difference between the setting and hardening of cement?
• initial and final setting time of cement?

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Properties of First class brick

Properties of First class bricks

Properties of first-class bricks are given below:

• Dry first-class bricks should not absorb water more than 20% of their own weight when immersed in water for 24 hours.
• No impression should be left on the brick when a scratch is made by finger nail.
• They emit a clear ringing sound when two bricks are struck by each other.
• First-class bricks are table molded and they are burnt in Kilns.
• These are well burnt in kilns.
• The surface of the first-class brick should be smooth and rectangular.
• The edges of the brick are perpendicular (Make an angle of 90°) to the adjoining edges.
• They are regular in shape and size with sharp edges and corners.
• They shall be of uniform deep red color.
• They should be free from any cracks.
• They should be free from chips, efflorescence, flaws, and lumps of any kind.
• The average compressive strength of the first-class bricks should not be less than 100 kg/cm2 and not more than 125 kg/cm2.

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Storage of Cement Bags on Site, How to -

Storage of Cement How to Store Cement Bags on Site

Storage of Cement Bags on Site

Storage of cement bags on site should be done in a proper way. Because cement is climate-sensitive material and it reacts with moisture from the atmosphere and starts the hydration process which makes cement hard.

So there are some precaution should be taken for bulk storage of cement as per IS code 4082: 1996 as follows –

1) Sheds for storage of cement –

2) Arrangement of Cement Bags –

3) Storage Duration –

4) Protection in Rainy Season –

5) Handling of Cement Bags –

6) Use of Cement Bags –

1) Sheds for storage of cement –
On construction site storage of cement should be done in a proper way so they are not exposed to the atmosphere and can be stored for a long time before being used in construction.

Bulk Storage of cement bags on site should be done in buildings or closed sheds whose floor, roof, and walls should be dry, leakproof, and moisture-proof.

The building or shed should have a minimum number of windows and doors. The windows of these sheds are must be small in size and the door should be airtight and kept these doors closed as far as possible.

Proper drainage should be provided for the drainage of water in any case.

2) Arrangement of Cement Bags –

Before the storage of cement bags on site ensure that the shed is completely dry from inside.

Dampness is also responsible for the moisture in cement.

So, the cement bags should be stored on wooden pallets in such a way that as to keep about 150mm to 200mm above the ground level.

Wooden Pallet

Cement bags should be arranged one above the other in a cross arrangement in length-wise and cross-wise fashion to minimize the danger of toppling over.

The arrangement of cement bags should be closed to each other to avoid air circulations.

Cement Bags Arranged on Wooden a Pallet

Stacked bags should be at least 600mm away from the external walls.

These stacked cement bags should not be more than 10 bags in height to prevent the possibility of lumping up under pressure and the width of the stack should not be more than 4 bagsor 3 meters.

Different types of cement should be stored separately.

Different types of packaging bags should be stored separately such as paper bags, gunny bags, and polyethylene bags, etc.

A passage width of 600mm should be provided for easy access.

Section of Shed

Plan of Shed

3) Storage Duration –

Time is also an important factor in the storage of cement. Because the strength of cement is decreased with time.

The table below shows the percentage of decrease in strength of cement with time –

So, Cement should be used before 3 months from the date of manufacturing.

If cement is stored for more than 3 months duration then it is recommended to cement should be tested before using it on site.

4) Protection in Rainy Season –

During monsoon season extra moisture is present in the atmosphere which required extra precautions for the storage of cement.

In the rainy season, cover the stack cement bags with plastic sheets or tarpaulins to protect them from moisture and an accidental sprinkle of water.

5) Handling of Cement Bags –

Do not use hooks while handling cement bags in loading and unloading.

Do not drop cement bags from height as this can damage the packing of cement.

Handle cement bags with care to avoid split of bags and damage of packing.

6) Use of Cement Bags –

Cement bags should be used on a first in first out basis. This means cement bags that are stored first in sheds should be used first for the construction.

A label of the date of receipt of cement should be put on each stack to know the age of cement.

FAQ on storage of cement bags on site –

How long cement can be stored?

It is recommended that cement should not be store for more than 3 months.

How much area required for storage of cement?

Approximately, in 1 cubic meter, 20 cement bags of 50kg each can be stored

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15 Different Types of Cement in India and Their Uses

15 Different Types of Cement in India and Their Uses

In this article, we are going to learn about different types of cement in India, their contents, and their applications in different types of construction work.

As we know cement is the main constituent of concrete which act as a binder. Cement is made from lime, silica, alumina, magnesia, iron oxide, calcium sulphate, alkaline, etc.

By changing the percentages of this constituent of cement the properties of cement like setting time, strength gaining process, colour, resistance against chemical attack, etc. also changes and different types of cement are formed. So it is important to learn the different types of cement in Indiaand choose the right cement for construction.

15 Different Types of Cement In India

1) Ordinary Portland cement (OPC)

2) Portland Pozzolana Cement (PPC)

3) Rapid Hardening Cement –

4) Extra Rapid Hardening Cement-

5) Low Heat Portland Cement-

6) Quick Setting Cement-

7) Sulphate Resisting Portland Cement-

8) High Alumina Cement-

9) Blast Furnace Slag Cement-

10) White Cement-

11) Coloured Cement-

12) Hydrophobic Cement-

13) Air Entraining Cement-

14) Expansive Cement –

15) Waterproofing Portland cement

1) Ordinary Portland Cement

Ordinary Portland Cement

Ordinary portland cement (OPC) is the most commonly used cement worldwide. It is also known as basic Portland cement. It has good strength against cracking and dry shrinkage.

Ordinary Portland cement is available in three grades-

33 grade

43 grade

53 grade

Where the number denotes the strength of the cement after 28 days.

For example, 33 grade OPC has a strength of 33 MPa at 28 days.

Ordinary portland cement (OPC) is used for all types of construction except where a chemical attack is possible.

2) Portland Pozzolana Cement (PPC)

Portland Pozzolana Cement is manufactured by grinding 10-25% of pozzolanic material with ordinary portland cement clinkers. Pozzolanic materials include fly ash and Calcinated clay.

PPC is found to have-

High tensile strengthHigh water tightnessHigher resistance against the attack of chlorides and sulphates.It is low-heat cement.

It takes more time for strength gain as compared to ordinary portland cement (OPC). Hence, it can be used where ordinary portland cement is used Except where early strength is required.

3) Rapid Hardening Cement

As the name suggests rapid hardening cement is gaining strength quickly as compared to OPC.

Rapid hardening cement is manufactured by increasing the C₃S (Tri-calcium silicate) percentage and lowering the C₂S (Di-calcium silicate) percentage in the content of cement.

The strength of Rapid hardening cement at 3 days is same of 7 days strength of ordinary Portland cement (OPC).

Rapid hardening cement is used where high early strength is required like high-traffic road construction.

4) Extra Rapid Hardening Cement

Extra rapid hardening cement is a modified version of rapid hardening cement. This is manufactured by adding 2% of calcium chloride with rapid hardening cement.

When Extra rapid hardening cement is mixed with water it releases a huge amount of heat for a short period of time. Hence, extra rapid hardening cement is preferred to be used in cold-weather constructions.

One or two day's strength of extra rapid hardening cement is 25% more than rapid hardening cement.

It is used for high-traffic road construction. It is also used where the formwork needs to remove early.

5) Low Heat Portland Cement

Low heat portland cement has less lime content than OPC. This type of cement is manufactured by lowering the C₃S content and increasing the C₂S content.

This type of cement produced less heat of hydration and is used in mass concreting work like gravity dams, large raft slabs, etc.

Low-heat portland cement offers 20% lesser heat of hydration than OPC

6) Quick Setting Cement

As the name suggests quick setting cement is set faster than ordinary portland cement (OPC).

This type of cement is manufactured by adding aluminium sulphate and reducing the gypsum amount in cement content.

Quick-setting cement is used for construction where quick setting in a short time period is required like underwater constructions.

7) Sulphate Resisting Portland cement

This type of cement has good resistance against sulphate attack on concrete. This type of cement is manufactured by lowering tricalcium aluminate (C₃A) below 5% in cement content.

This type of cement is used where concrete is subjected to sulphate attack such as the construction of a foundation where soil or groundwater has 0.2% to 0.3% g/l sulphate salts respectively.

8) High Alumina Cement

This type of cement is manufactured by adding high alumina to the cement content. Alumina content should be a minimum 32% and the ratio of alumina to lime should be between 0.85 to 1.30.

This type of cement has high ultimate strength and high resistance against acid and high temperature.

It is used for marine construction, chemical plants, sewer construction and structure which are subjected to high temperatures like workshops, and furnaces.

9) Blast Furnace Slag Cement

Blast furnace slag cement is manufactured by replacing a portion of Portland cement clinkers with blast furnace slag. Hence, it is cheaper than Ordinary portland cement (OPC).

What is blast furnace slag?

Blast furnace slag is the by-product in iron production in blast furnace.

Blast furnace slag cement possesses lower permeability and high durability.

This type of cement is used for construction which requires low heat of hydration. It is also used for mass concreting works like the construction of dams.

10) White Cement

White cement is manufactured by lowering the content of iron oxide in ordinary portland cement.

This type of cement has the same properties as ordinary portland cement. This type of cement is costly and is used for architectural purposes like terrazzo surfaces and decorative work.

11) Coloured Cement

Coloured cement is manufactured by adding 5-10% of pigments to ordinary portland cement content.

It is also called as colcrete.

This type of cement is used for decorative works.

12) Hydrophobic Cement

Hydrophobic cement is manufactured by adding water-repellent film substances such as oleic acid and stearic acid with ordinary portland cement clinkers.

These acids form a layer around cement particles to protect them from the hydration process during transportation or the long storage of cement. This layer breaks when cement is mixed with aggregates.

This type of cement is used in construction under wet climate conditions.

Hydrophobic cement is more expensive than OPC.

13) Air Entraining Cement

This type of cement is produced by adding air-entraining agents such as resins, glues, and sodium salts to ordinary portland cement clinkers.

This type of cement is used for sulphate resistance, deicer-scaling resistance, resistance to alkali-silica reactivity and to improved workability.

14) Expansive Cement

OPC shrinks during the setting of concrete and also after the setting process concrete made up of OPC shrinks for a long period of time. But expansive cement shows the property of increasing in volume after the setting of cement which reduces the shrinkage losses.

Expansive cement is further classified as –

K Type Expansive CementM Type Expansive CementS Type Expansive Cement

15) Waterproofing Portland cement

This type of cement is manufactured by grinding water-repellent materials with Portland cement clinkers

Waterproof Portland cement is used for the construction of foundations, basements, water tanks, swimming pools, etc.

Watch the video for a better understanding of the different types of cement in India.

FAQs on Different Types of cement in India –

What is I.R.S T-40 Cement?

As we learn different types of cement in India which are commonly used in construction. But I.R.S T-40 cement is a special type of cement which is used by the Indian railway for manufacturing concrete sleepers.

This type of cement is produced by fine grinding the cement clinkers and increasing the proportion of C₃S in order to attain early strength.

What is the difference between 33 grade, 43 grade and 53 grade?

Actually these are the types of OPC according to compressive strength of cement at the age of 28 days. 33, 43 and 53 are the numbers that show the compressive strength of OPC at 28 days.

Which cement is best for concrete?

As we discussed above, different types of cement in India are available which are used according to requirements on construction sites. For regular building construction works OPC 43 grade is suitable for plain concrete and OPC 53 grade is good for reinforced cement concrete.

What is MPa in cement grade?

MPa means mega-pascals which is used to measure compressive strength.

MPa = N/mm2

Which cement is used for house construction in India?

Ordinary portland cement(OPC) and Pozzolana portland cement(PPC) are the most commonly used for construction in India.

Table of Contents

15 Different Types of Cement In India
1) Ordinary Portland Cement
2) Portland Pozzolana Cement (PPC)
3) Rapid Hardening Cement
4) Extra Rapid Hardening Cement
5) Low Heat Portland Cement
6) Quick Setting Cement
7) Sulphate Resisting Portland cement
8) High Alumina Cement
9) Blast Furnace Slag Cement
10) White Cement
11) Coloured Cement
12) Hydrophobic Cement
13) Air Entraining Cement
14) Expansive Cement
15) Waterproofing Portland cement

FAQs on
Different Types of cement in India –

What is I.R.S T-40 Cement?

What is the difference between 33 grade, 43 grade and 53 grade?

What is MPa in cement grade?

Which cement is used for house construction in India?

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Walls and Its Type - In Civil Engineering Study

Walls and Its Type - Civil ENGINEERING study

Walls are built to partition living area into different parts.They impart privacy and protection against temperature, rain and theft. 

Walls may be classified as 

• 1. Load bearing walls 
• 2. Partition walls. 

1. Load Bearing Walls: 

• If beams and columns are not used, load from roof and floors are transferred to foundation by walls. Such walls are called load bearing walls. 
• They are to be designed to transfer the load safely. 
• The critical portion of the walls are near the openings of doors and windows and the positions where concrete beams rest. 

    Minimum wall thickness used is 200 mm. It is also recommended that the slenderness ratio of wall defined as ratio of effective length or effective height to thickness should not be more than 27. The effective height and effective length of a wall may be taken as shown in tables respectively.

 

 

Effective height of walls in terms of actual height H

Sno	End Condition	Effective Height
1	Lateral as well as rotational restraint	.75H
2	Lateral as well as rotational restraint at one end and only  lateral restraint at other	.85H
3	Lateral restraint but no rotational restraint at both ends	1.0H
4	Lateral and rotational restraint at one end and no restraint at other ends (compound walls, parapet walls etc.).	1.5H

 

Effective length of walls of length L

Sno	End Condition	Effective LENGHT
1	continuous and supported by cross walls	.8L
2	Continuous at one end and supported by cross walls at the other end	.9L
3	Wall supported by cross walls at each end	1.0L
4	Free at one end and continuous at other end	1.5L
5	Free at one end and supported by cross wall at other end	2.0L

 

2. Partition Walls: 

• In framed structures partition walls are built to divide floor area for different utilities. 
• They rest on floors. They do not carry loads from floor and roof. 
• They have to carry only self-weight. Hence normally partition walls are thin. 
• Table shows the differences between load bearing walls and partition walls.
•  Depending upon the requirement these walls may be brick partition, clay block partition, glass partition, wood partition, and aluminum and glass partition.

 

 

Differences between load bearing and partition walls

S No	Load Bearing Wall	Partition Wall
1	They carry loads from roof, floor, self-weight etc.	They carry self-weight only.
2	They are thick and hence occupy more floor area.	These walls are thin and hence occupy less floor area.
3	As the material required is more,the construction cost is more.	As the material required is less, the construction cost is less.
4	Stones or bricks are used for the construction.	Stones are not used for the construction of partition walls

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Lime - Tests on Limestone

Tests on Limestones 

The following practical tests are made on limestones to determine their suitability:

• (i) Physical tests 
• (ii) Heat test 
• (iii) Chemical test 
• (iv) Ball test. 

 

(i) Physical Test: 

    Pure limestone is white in colour. Hydraulic limestones are bluish grey, brown or are having dark colours. The hydraulic lime gives out earthy smell. They are having clayey taste. The presence of lumps give indication of quick lime and unburnt lime stones. 

 

(ii) Heat Test: 

    A piece of dry stone weighing W1 is heated in an open fire for few hours. If weight of sample after cooling is W2, the loss of weight is W2 – W1. The loss of weight indicates the amount of carbon dioxide. From this the amount of calcium carbonate in limestone can be worked out. 

 

(iii) Chemical Test: 

    A teaspoon full of lime is placed in a test tube and dilute hydrochloric acid is poured in it. The content is stirred and the test tube is kept in the stand for 24 hours. Vigourous effervescence and less residue indicates pure limestone. If effervescence is less and residue is more it indicates impure limestone. 

    If thick gel is formed and after test tube is held upside down it is possible to identify class of lime as indicated below: 

• Class A lime, if gel do not flow.

• Class B lime, if gel tends to flow down. 

• Class C lime, if there is no gel formation. 

 

(iv) Ball Test: 

    This test is conducted to identify whether the lime belongs to class C or to class B. By adding sufficient water about 40 mm size lime balls are made and they are left undisturbed for six hours. Then the balls are placed in a basin of water. If within minutes slow expansion and slow disintegration starts it indicates class C lime. If there is little or no expansion, but only cracks appear it belongs to class B lime.

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Building with Lime: Past, Present, and Potential, Types and Properties

 

Building with Lime: 

Past, Present, and Potential, Types and Properties

Lime

It is an important binding material used in building construction. Lime has been used as the material of construction from ancient time. When it is mixed with sand it provides lime mortar and when mixed with sand and coarse aggregate, it forms lime concrete. 

Lime is a versatile material that finds applications in various fields, including construction, agriculture, and chemistry. There are two primary types of lime: quicklime (calcium oxide, CaO) and hydrated lime (calcium hydroxide, Ca(OH)2). Let's explore some aspects of lime:

Production:

• Quicklime (CaO): Produced by heating limestone (calcium carbonate, CaCO3) at high temperatures (typically around 900–1000°C) in a process known as calcination.
• Hydrated Lime (Ca(OH)2): Produced by treating quicklime with water.

Uses:

• Construction: Lime has been traditionally used in construction for various purposes, such as mortar and plaster. It reacts with carbon dioxide in the air and slowly turns back into calcium carbonate, resulting in a durable and stable material.

• Soil Stabilization: Lime is used to stabilize soil in construction projects, improving its engineering properties and reducing plasticity.

• Water Treatment: Hydrated lime is often used in water treatment processes to adjust pH levels and precipitate impurities.

• Agriculture: Agricultural lime (usually in the form of crushed limestone) is added to soil to neutralize acidity, providing essential nutrients for plant growth.

• Chemical Industry: Lime is used in various chemical processes, including the production of calcium-based chemicals and as a reactant in industrial processes.

Chemical Properties:

• Quicklime is highly reactive and exothermic when it reacts with water, producing heat.
• Hydrated lime is a dry powder that results from the chemical transformation of quicklime in the presence of water.

Safety Considerations:

• Quicklime is caustic and can cause burns. Proper safety measures, including protective equipment, should be used when handling it.

It's important to note that the application and properties of lime can vary based on the specific type of lime used and the intended use.

 

 

Types of Limes and their Properties 

The limes are classified as fat lime, hydraulic lime and poor lime: 

 

(i) Fat lime: 

It is composed of 95 percentage of calcium oxide. When water is added, it slakes vigorously and its volume increases to 2 to 2.5 times. It is white in colour. 

Its properties are:

• (a) hardens slowly 
• (b) has high degree of plasticity 
• (c) sets slowly in the presence of air 
• (d) white in colour 
• (e) slakes vigorously. 

 

(ii) Hydraulic lime: 

It contains clay and ferrous oxide. Depending upon the percentage of clay present, the hydraulic lime is divided into the following three types: 

• (a) Feebly hydraulic lime (5 to 10% clay content) 
• (b) Moderately hydraulic lime (11 to 20% clay content) 
• (c) Eminently hydraulic lime (21 to 30% clay content) 

The properties of hydraulic limes are: 

• • Sets under water
• • Colour is not perfectly white 
• • Forms a thin paste with water and do not dissolve in water. 
• • Its binding property improves if its fine powder is mixed with sand and kept in the form of heap for a week, before using. 

 

(iii) Poor lime: 

It contains more than 30% clay. Its colour is muddy. It has poor binding property. The mortar made with such lime is used for inferior works. 

 

IS 712-1973 classifies lime as class A, B, C, D and E. 

 

Class A Lime: 

It is predominently hydraulic lime. It is normally supplied as hydrated lime and is commonly used for structural works. 

 

Class B Lime: 

It contains both hydraulic lime and fat lime. It is supplied as hydrated lime or as quick lime. It is used for making mortar for masonry works. 

 

Class C Lime: 

It is predominently fat lime, supplied both as quick lime and fat lime. It is used for finishing coat in plastering and for white washing. 

 

Class D Lime: 

This lime contains large quantity of magnesium oxide and is similar to fat lime. This is also commonly used for white washing and for finishing coat in plastering. 

 

Class E Lime: 

It is an impure lime stone, known as kankar. It is available in modular and block form. It is supplied as hydrated lime. It is commonly used for masonry mortar

 

 

Structure where  Lime is Used

One of the most iconic and well-known structures that extensively used lime as a binding material is the Roman Pantheon. The Pantheon is an ancient temple located in Rome, Italy, and is renowned for its architectural and engineering marvel.

The Pantheon:

1. Construction Period:

   • The Pantheon was commissioned during the reign of Emperor Hadrian in 118–128 AD. However, the original structure on the site was built by Marcus Agrippa around 27 BC and later rebuilt by Emperor Hadrian.

2. Architectural Features:

   • The Pantheon is known for its remarkable dome, which was the largest unreinforced concrete dome in the world for many centuries.
   • The dome has a central oculus (circular opening) at the top, allowing natural light to enter the interior.

3. Use of Lime in Construction:

   • Lime played a crucial role in the construction of the Pantheon. The Romans used a type of mortar known as pozzolana mortar, which consisted of lime, volcanic ash (pozzolana), and water.
   • Pozzolana mortar is highly durable and has excellent hydraulic properties. The addition of pozzolana allowed the Romans to create concrete that could set underwater and gain strength over time.

4. Concrete Construction:

   • The Pantheon's dome is made of concrete, and the Romans employed a method of constructing concrete using a mixture of lime, pozzolana, and aggregates such as crushed volcanic rock and bricks.
   • The use of this concrete allowed for the creation of large and stable structures, and the Pantheon's dome is a testament to the engineering expertise of the Romans.

5. Durability and Longevity:

   • The Pantheon stands as a testament to the durability of Roman concrete and lime-based mortar. Despite its age, the structure has survived earthquakes and the test of time.

6. Symbolic Importance:

   • The Pantheon has been repurposed over the centuries and is now a Christian church (Basilica di Santa Maria ad Martyres). Its conversion contributed to its preservation.

The Pantheon remains an architectural marvel, and the use of lime-based materials in its construction highlights the ingenuity of ancient Roman engineers. The properties of lime and the technology used in structures like the Pantheon have influenced construction practices throughout history

 

Historical Use of Lime

Lime has a rich history dating back thousands of years, and its use has evolved over time. Here's a brief overview of the history of lime:

1. Ancient Uses:

   • The use of lime can be traced back to ancient civilizations. The Egyptians used a form of lime for various construction purposes, and evidence suggests that lime mortars were used in the construction of the pyramids.
   • The Greeks and Romans also extensively used lime-based materials in their construction projects. The Romans, in particular, developed advanced techniques for producing lime and pozzolana-based concrete, as seen in structures like the Pantheon.

2. Middle Ages:

   • The knowledge of lime production and use continued into the Middle Ages. Medieval builders in Europe used lime mortar for constructing cathedrals, castles, and other structures.
   • Lime kilns, used to produce quicklime by heating limestone, became more widespread during this period.

3. Renaissance and Early Modern Period:

   • The Renaissance saw a revival of interest in classical architecture, and the use of lime continued to be prominent. The development of lime-based plasters and finishes contributed to the aesthetic aspects of buildings during this period.

4. 18th and 19th Centuries:

   • The Industrial Revolution brought about advancements in lime production. Lime kilns became more efficient, and the demand for lime in construction, agriculture, and industry increased.
   • Lime was a key component in mortar for brick construction during the 19th century, contributing to the growth of urban areas.

5. 20th Century:

   • Portland cement, an alternative to lime-based mortars, gained popularity in the construction industry during the 20th century. However, lime continued to be used in heritage restoration and conservation projects due to its compatibility with historic structures.

6. Contemporary Uses:

   • Today, lime is still utilized in various industries. In construction, lime is employed for mortar, plaster, and soil stabilization. It remains an essential material in the restoration of historic buildings.
   • Agricultural lime, which is crushed limestone or dolomite, is used to neutralize soil acidity and improve crop yields.

Throughout history, lime has played a crucial role in the development of architectural and construction practices. Its enduring popularity is attributed to its versatility, durability, and compatibility with a wide range of materials. The historical use of lime in iconic structures highlights its significance in the built environment.

 

Chemical Constituents of Lime

Lime is a general term that refers to a range of calcium-containing inorganic materials. The two primary types of lime are quicklime (calcium oxide, CaO) and hydrated lime (calcium hydroxide, Ca(OH)2). Let's delve into the constituents of each:

1. Quicklime (Calcium Oxide, CaO):

   • Chemical Formula: CaO
   • Production: Quicklime is produced by heating limestone (calcium carbonate, CaCO3) in a lime kiln at high temperatures (typically around 900–1000°C) in a process known as calcination.
   • Properties:
     • Quicklime is a white, crystalline solid at room temperature.
     • It is highly reactive with water, producing heat in an exothermic reaction.
     • When quicklime reacts with water, it forms hydrated lime (calcium hydroxide).

2. Hydrated Lime (Calcium Hydroxide, Ca(OH)2):

   • Chemical Formula: Ca(OH)2
   • Production: Hydrated lime is produced by adding water to quicklime. This process is known as slaking or hydration.
   • Properties:
     • Hydrated lime is a dry, fine powder.
     • It is less reactive than quicklime but still exhibits some reactivity with water.
     • The chemical reaction between quicklime and water results in the formation of calcium hydroxide.

3. Pozzolana (Optional Constituent in Lime-Based Materials):

   • Definition: Pozzolana refers to siliceous or siliceous and aluminous materials that, in themselves, possess little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties.
   • Examples: Volcanic ash, fly ash, and certain natural clays are examples of pozzolanic materials.
   • Use: Pozzolanic materials are often added to lime-based materials, like mortars and concretes, to enhance their properties, such as setting time and strength.
     

The chemical reactions involved in the production of lime and its subsequent use in construction involve the transformation of calcium carbonate into calcium oxide and, eventually, into calcium hydroxide. These reactions are fundamental to the functionality and versatility of lime-based materials in various applications, from traditional mortar and plaster to more advanced construction techniques.

 

Clay and Lime Reactivity

The presence of clay in Lime Affect:

The presence of clay in lime can significantly influence the properties and performance of lime-based materials. While lime is often used in construction for its binding and stabilizing properties, the addition of clay can affect various aspects, such as workability, strength, and durability. Here are some effects of the presence of clay in lime:

1. Workability:

   • Positive Aspect: Small amounts of clay can enhance the workability of lime mortars. Clay acts as a plasticizer, making the mix more malleable and easier to work with.
   • Negative Aspect: Excessive clay content can lead to poor workability, making the lime mix difficult to handle and apply.

2. Setting Time:

   • Positive Aspect: Clay can contribute to the setting and hardening of lime-based materials by promoting pozzolanic reactions. Pozzolanic reactions involve the combination of lime with silica and alumina in the clay, forming compounds with cementitious properties.
   • Negative Aspect: Excessive clay content may lead to delayed setting times, affecting the construction schedule. It's crucial to find the right balance to achieve a reasonable setting time.

3. Strength:

   • Positive Aspect: The addition of clay can enhance the strength of lime-based materials. Pozzolanic reactions contribute to the development of additional cementitious compounds, improving the overall strength and durability.
   • Negative Aspect: Very high clay content may lead to a reduction in strength and durability, as excessive amounts of clay can disrupt the formation of a well-structured matrix.

4. Durability:

   • Positive Aspect: Properly proportioned clay content can improve the durability of lime-based materials, making them more resistant to weathering and environmental factors.
   • Negative Aspect: Excessive clay content can lead to poor durability, as it may result in shrinkage, cracking, and reduced resistance to freeze-thaw cycles.

5. Compatibility:

   • Positive Aspect: Clay can improve the compatibility of lime with certain aggregates, providing a more cohesive mix.
   • Negative Aspect: Incompatibility issues may arise if the clay content is too high, leading to segregation or poor adhesion with other materials.

In summary, the presence of clay in lime can have both positive and negative effects on properties depending on the proportion and the specific application. It requires careful consideration and proper mixing to achieve the desired balance between workability, strength, and durability. Engineers and builders often conduct tests and evaluations to determine the optimal clay content for a given lime-based material in order to achieve the desired performance.

 

Contact of Lime and Hardened Concrete:

When lime comes into contact with hardened concrete, it can lead to a phenomenon known as delayed ettringite formation (DEF). Ettringite is a crystalline compound that forms as part of the cement hydration process. However, when lime is introduced to hardened concrete under certain conditions, it can react with existing constituents and cause DEF. Here's an explanation of the process and its potential negative effects on hardened concrete:

Delayed Ettringite Formation (DEF):

1. Reaction Mechanism:

   • In the presence of moisture and elevated temperatures, lime can react with tricalcium aluminate (C3A) in the cementitious matrix.
   • This reaction forms ettringite crystals, which expand as they grow.

2. Negative Effects on Hardened Concrete:

   • Expansion and Cracking: The formation of ettringite crystals can lead to the expansion of concrete. This expansion, if significant, may cause internal stresses and cracking within the concrete. Cracking is a critical concern as it can compromise the structural integrity and durability of the concrete.

   • Reduced Strength and Durability: The expansion associated with delayed ettringite formation can result in a decrease in the compressive strength of the concrete. Additionally, the cracking induced by the expansion may allow harmful substances such as water, chlorides, and other aggressive agents to penetrate the concrete, reducing its long-term durability.

   • Aesthetic Issues: Cracking and expansion due to DEF can also lead to aesthetic concerns, impacting the appearance of the concrete surface.

   • Structural Concerns: In severe cases, the internal stresses and cracking caused by delayed ettringite formation may compromise the overall structural performance of the concrete.

3. Conditions Favoring DEF:

   • DEF is more likely to occur under specific conditions, including high temperatures during the curing period, elevated moisture levels, and the presence of reactive aggregates.
   • The use of high-lime-content materials or the introduction of lime after concrete has hardened can contribute to the risk of DEF.

4. Prevention and Mitigation:

   • To minimize the risk of DEF, it's essential to control the mix design, curing conditions, and the quality of materials used in concrete construction.
   • The careful selection of cement types, aggregates, and admixtures can help mitigate the potential negative effects of lime on hardened concrete.

In summary, the interaction of lime with hardened concrete leading to delayed ettringite formation poses challenges in terms of expansion, cracking, and potential reductions in strength and durability. As such, it is crucial to follow good concrete practices, consider material compatibility, and carefully control mix proportions to minimize the risk of DEF and its associated negative effects.

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Common Building Stones - Qualities and Uses

The Qualities and Uses of common Building Stones 

Common Building Stones 

The following are the some of commonly used stones: 

• (i) Basalt and trap 
• (ii) Granite 
• (iii) Sand stone 
• (iv) Slate
•  (v) Laterite 
• (vi) Marble
•  (vii) Gneiss 
•  (viii) Quartzite. 

 

Their qualities and uses of Building Stone

(i) Basalt and Trap: 

    The structure is medium to fine grained and compact. Their colour varies from dark gray to black. Fractures and joints are common. Their weight varies from 18 kN/m3 to 29 kN/m3. The compressive strength varies from 200 to 350 N/mm2. These are igneous rocks. They are used as road metals, aggregates for concrete. They are also used for rubble masonry works for bridge piers, river walls and dams. They are used as pavement.

qualities and uses of Building Stone

 

 (ii) Granite: 

    Granites are also igneous rocks. The colour varies from light gray to pink. The structure is crystalline, fine to coarse grained. They take polish well. They are hard durable. Specific gravity is from 2.6 to 2.7 and compressive strength is 100 to 250 N/mm2. They are used primarily for bridge piers, river walls, and for dams. They are used as kerbs and pedestals. The use of granite for monumental and institutional buildings is common. Polished granites are used as table tops, cladding for columns and wall. They are used as coarse aggregates in concrete.

qualities and uses of Building Stone

 

 (iii) Sand stone: 

    These are sedimentary rocks, and hence stratified. They consist of quartz and feldspar. They are found in various colours like white, grey, red, buff, brown, yellow and even dark gray. The specific gravity varies from 1.85 to 2.7 and compressive strength varies from 20 to 170 N/mm2. Its porosity varies from 5 to 25 per cent. Weathering of rocks renders it unsuitable as building stone. It is desirable to use sand stones with silica cement for heavy structures, if necessary. They are used for masonry work, for dams, bridge piers and river walls.

qualities and uses of Building Stone

 

 (iv) Slate: 

    These are metamorphic rocks. They are composed of quartz, mica and clay minerals. The structure is fine grained. They split along the planes of original bedding easily. The colour varies from dark gray, greenish gray, purple gray to black. The specific gravity is 2.6 to 2.7. Compressive strength varies from 100 to 200 N/mm2. They are used as roofing tiles, slabs, pavements etc.

qualities and uses of Building Stone

 

 (v) Laterite: 

    It is a metamorphic rock. It is having porous and sponges structure. It contains high percentage of iron oxide. Its colour may be brownish, red, yellow, brown and grey. Its specific gravity is 1.85 and compressive strength varies from 1.9 to 2.3 N/mm2. It can be easily quarried in blocks. With seasoning it gains strength. When used as building stone, its outer surface should be plastered.

qualities and uses of Building Stone

 

 (vi) Marble: 

    This is a metamorphic rock. It can take good polish. It is available in different pleasing colours like white and pink. Its specific gravity is 2.65 and compressive strength is 70–75 N/ mm2. It is used for facing and ornamental works. It is used for columns, flooring, steps etc.

qualities and uses of Building Stone

 

(vii) Gneiss: 

    It is a metamorphic rock. It is having fine to coarse grains. Alternative dark and white bands are common. Light grey, pink, purple, greenish gray and dark grey coloured varieties are available. These stones are not preferred because of deleterious constituents present in it. They may be used in minor constructions. However hard varieties may be used for buildings. The specific gravity varies from 2.5 to 3.0 and crushing strength varies from 50 to 200 N/mm2.

qualities and uses of Building Stone

 

 (viii) Quartzite :

     Quartzites are metamorphic rocks. The structure is fine to coarse grained and often granular and branded. They are available in different colours like white, gray, yellowish. Quartz is the chief constituent with feldspar and mica in small quantities. The specific gravity varies from 2.55 to 2.65. Crushing strength varies from 50 to 300 N/mm2. They are used as building blocks and slabs. They are also used as aggregates for concrete

qualities and uses of Building Stone

 

 

 

source - Basic Civil Engineering written by -SS bhavikatti

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Building Materials - All content topic oriented

 Table of Contents

Chapter 1: Concrete and Its Constituents

• Cement
• Aggregates
• Admixtures
• Concrete

Chapter 2: Steel 

• Introduction
• Structural steel and metal
• Uses of steel
• Properties: Mild steel vs hard steel
• Defects in steel
• Steel manufacturing processes
• Mechanical treatment of steel
• Market form of steel and irons
• Different form of irons

Chapter 3: Bricks and Mortar 

• Bricks 
• Mortar and Limes
• Masonry and Tunnels

Chapter 4: Timber 

• Timber
• Structure of a tree
• Processing of timber
• Difference b/w natural and artificial seasoning
• Seasoning and preservation of timber
• Defects in timber
• Qualities of good timber
• MCQ for Timber - 1,2;
• Quick revision of timber

Chapter 5: Bitumen  

• Introduction

Chapter 6: Paint

• Introduction
• MCQ - 1 2 3 4 5 

Chapter 7: Stones and Glasses

• Stones
• Glasses

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Masonry and Tunnel - Related to Brick and Stones

Masonry and Tunnel

Related to Brick and Stones

Stone Masonry

Stone masonry can be classified into two types:

• Rubble Masonry & Ashlar Masonry

Rubble Masonry:

• The type of stone masonry in which either undressed or roughly dressed stone are laid in a suitable mortar is called rubble masonry. In this masonry the joints are not of uniform thickness.

Ashlar Masonry:

• It is the type of stone masonry in which finely dressed stones are laid in cement or lime mortar is known as ashlars masonry. In this masonry are the courses are of uniform height, all the joints are regular, thin and have uniform thickness. This type of masonry is much costly as it requires dressing of stones.

Three types of Rubble Masonry are as follows:

Un-coursed Random Rubble Masonry:

• The random rubble masonry in which stones are laid without forming courses is known as un-coursed random rubble masonry. This is the roughest and cheapest type of masonry and is of varying appearance.
• It is used for construction of walls of low height in case of ordinary buildings.

Coursed Random Rubble Masonry:

• The random rubble masonry in which stones are laid in layers of equal height is called random rubble masonry. In this masonry, the stones are laid in somewhat level courses. Headers of one coursed height are placed at certain intervals. The stones are hammer dressed. CRRM is used for construction of residential buildings, boundary walls etc.

Squared Rubble Masonry:

• The rubble masonry in which the face stones are squared on all joints and beds by hammer dressing or chisel dressing before their actual laying, is called squared rubble masonry.

There are two types of squared rubble masonry:

Coursed Square Rubble Masonry:

• The square rubble masonry in which chisel dressed stones laid in courses is called coarse square rubble masonry. It is used for construction of public buildings, hospitals, schools, markets, modern residential buildings etc. and in hilly areas where good quality of stone is easily available.

Un-coursed square rubble masonry:

• The squared rubble in masonry which hammer dressed stones are laid without making courses is called un-coursed square rubble masonry. It consists of stones which are squared on all joints and beds by hammer dressing. All the stones to be laid are of different sizes. It is used for construction of ordinary buildings in hilly areas where a good variety of stones are cheaply available.

Dry rubble masonry:

• The rubble masonry in which stones are laid without using any mortar is called dry rubble masonry or sometimes shortly as "dry stones". It is an ordinary masonry and is recommended for constructing walls of height not more than 6 m. 

Quoins

• 1. Quoins are large rectangular blocks of masonry or brick that are built into the corners of a wall and is normally 90o to the horizontal.
• 2. They can be used as a load-bearing feature to provide strength and weather protection, but also for aesthetic purposes to add detail and accentuate the outside corners of a building.
• 3. Quoins are external cornerstones at the edges of stone or brick buildings.

King closer: 

• If a brick is cut in such a way that the width of one end becomes half that of a full brick, while the width at the other end is equal to the full width, then it is called as king closer.
• It is obtained by cutting out a triangular portion of the brick between the centre of one end (width side) and the centre of the other end (lay side).

Queen closer:

• When a brick is cut along its length, making it two equal halves then it is called queen closer.
• Squint brick: 
• They are cut on one corner at an angle of other than 90 degrees. They are required for giving shape to an exterior or interior corner in a wall.

Thickness of Damp Proof Course D.P.C.

• A cement concrete layer in the proportion 1: 2: 4 is generally provided at the plinth level to work as a damp-proofing course.
• 
  
• The depth of the cement concrete layer varies from 40 mm to 150 mm. It stops the rise of water by capillary action and it is found to be effective at places where the damp is not excessive.
• 
  
• Here 4 cm, 5 cm, and 6 cm all are the correct answer for the question as they lie in the desirable range of 4 cm to 15 cm of plinth thickness. However, 4 cm distinct as minimum plinth thickness and hence it is the most appropriate option.

Pointing

Struck Pointing:

This is a modification of flush pointing in which the face of pointing is kept inclined, with its upper edge pressed inside the face by 10 mm. This pointing drains water easily.

Recessed Pointing:

This pointing is done by pressing the mortar back from the edge by 5 mm or more. It gives a good appearance.

Beaded Pointing:

This is a special type of pointing formed by steel or ironed with a concave edge. It gives good appearance but is liable to damage.

Tuck Pointing:

This pointing is formed by first pressing the mortar in the racked joint and finishing flush with the face. While the pressed mortar is green, groove or narrow channel, having 5 mm width and 3 mm depth is cut in the center of the groove.

Weathered Pointing:

This pointing is formed by projecting a V-shaped outward projection from the surface of the masonry wall, so as to shed water readily.

Types of Pointing

Thickness of Plastering

Thicker plaster is not recommended as it may strip off from the wall. Recommended thickness of plaster is 12 mm but it should not exceed more than 20 mm.

Note:

Cement mortar proportion of plaster work is 1:3 to 1:4.

Pans: Used for conveying concrete for very small work such as concreting the sidelines of small-sized drains.

Pumps: It is used to transport to raft foundation, tunnel lining, long concrete member, etc.

Belt Conveyors: It has very limited applications in construction as concrete tends to segregate on steep inclines, at transfer points, and at points where the belt passes over the rollers. Also, the concrete tends to dry and become stiff if carried over the longer distance. Therefore, it is suitable for conveying for shorter distance only.

Transit Mixer: It is one of the most popular equipment for transporting concrete over longer distance particularly in RMC. The capacity of each transit mixer is about 6 m3. The rotating speed of the drum is about 4 – 16 revolutions per minute.

Chute: This is generally provided for transporting concrete from ground level to a lower level. The slope of the chute should not be flatter than 1 vertical to 2.5 horizontal.

Skip and Hoist: This is the most widely adopted technique for transporting at a higher level e.g. construction of the multi-story building, etc.

Buckets are never used to conveying concretes.

Tunnel

Tunnel is defined as an underground passage for the transport of passengers, water, sewage minerals, gas, etc.

Based on alignment tunnels are classified as follows:

i) Off-spur tunnels: These are short length tunnels to negotiate minor local obstacles, which cannot be avoided by permitted curves.

ii) Saddle or base tunnels: These tunnels are constructed along the natural slopes till the slopes do not exceed the ruling gradient.

iii) Slope tunnels: These tunnels are constructed in steep hills for economic and safe operations of roads and railways.

iv) Spiral tunnels: These tunnels are provided in narrow valleys in the form of loops in the interior of the mountain so as to increase the length of the tunnel to avoid steep slopes.

The objective of providing a tunnel with permanent lining are manifold:

1. it gives the correct section to the tunnel

2. it withstands soil pressure when driven is soft soils.

3. it reduces losses in fiction and erosive action, and ensure streamline motion when the tunnel has to carry water by providing a smooth passage at a good velocity, free from turbulence.

4. it forms a good protective covering to a certain type of rocks prone to air slacking.

5. it keeps the inside of the tunnel free from water percolation.

6. it supports a large slab of rock which might have become Ioosened during blasting.

Tunnel Jacking:

Tunnel jacking is the process of making a tunnel in already existing bodies such as road and railway area

Immersed Tunnel:

These types of tunnels are partly or wholly under water.

Tunnel Lining:

Tunnel lining is the wall of the tunnel.

It is usually in the form of a ring of a precast concrete segment.

Shield Tunneling:

A shield tunnelling is a protective structure and trailing support mechanism.

Grouting:

It is a method of providing additional support to the drilled mine.

Drift method of Tunneling:

A drift is a small tunnel measuring 3 m x 3 m, which is driven into the rocks and whose section is expanded in the later processes till it acquire the size of the tunnel.

A number of drill holes are provided all around the drift and these are filled up with explosives and ignited so that the size of the drift expands to become equal to the required cross section of the tunnel.

Advantages:

(a) If the quality of the rock is bad or if it contains excessive water, this is detected in advance and corrective measures can then be taken in time.

(b) A drift assists in the ventilation of tunnels.

(c) The quantity of explosives required is less.

(d) A side drift allows the use of timber to support the roof.

Disadvantages:

(a) It is a time-consuming process, as the excavation of the main tunnel gets delayed till the drift is completed.

(b) The cost of drilling and removing the muck from the drift is high, as the work has to be done using manually operated power-driven equipment.

Types of Tunnel Section

1. Circular section:

It can withstand the pressure caused by water, water-bearing soils or soft grounds. It is best suitable for sewers and water carrying purposes.

It is best suitable for non-cohesive soils and for tunnels driven by the shield method.

2. Horseshoe section:

Horseshoe section has a semi-circular roof together with arched sides and a curved invert. It also is suitable for carrying water or sewage. The section is found to be most suitable for soft rocks. This shape is commonly used for highways and railway tunnels.

When lined, this cross-section offers good resistance against external ground pressure and serves to combine the advantages of both D-shaped and circular sections.

3. Egg-shaped section:

It is commonly used for carrying sewage because it gives self-cleansing velocity even in dry weather flow.

4. D-section or the segmental roof section

The risk of failure or collapse caused by external pressure from water or loose or unstable soil conditions on tunnel lining is practically non-existent and it is then convenient to have a section with an arched roof and straight side, Which is called D-section.

It is suitable in hard rock for subways or navigation channels.

Note

Cross-section of the tunnel must be checked at regular interval of 2 - 3 m for maintaining the shape of the tunnel.

When the tunnel diameter is more than 8 m, it is advisable to do the excavation in two stages by heading and bench method.

Certain factors that must kept in mind in the tunneling procedures are:

Like Gradient

1. The best and economical alignment was chosen must be straight in nature.

2. Tunnel should have a grade, which is less than the outside. It is observed that in the railway tunnels, constant slipping of the wheels takes place due to the wetness of the rails. This reduces the hauling capacity of the locomotives.

3. Gradient of 0.2% must be provided to ensure proper drainage.

4. When it comes to long tunnels, two grades at either ends must be provided.

Advantages of Tunnels:

• a) Tunnels are more economical than open cuts beyond certain depths.

• b) Tunnels avoid disturbing or interfering with surface life and traffic during construction.

• c) Tunnels prove to be cheaper than bridges or open cuts to carry public utility services like water, sewer, gas, electricity and telephone lines.

• d) There is an overall reduction in cost because of shortening the distance as compared to bridges or open cuts.

• e) Tunnels avoid interference with surface and air rights.

• f) Its maintenance cost is low.

Disadvantages of Tunnels:

• a) The initial cost of construction of a tunnel is high as compared to an open cut.

• b) It is necessary to have skilled labour and technical supervision of high order for the construction of a tunnel.

• c) It takes a long time for the successful completion of a tunnel under normal conditions.

• d) The construction of the tunnel requires specialized and sophisticated equipment.

Various Methods for tunnelling through the rocks are as follows:

• i) Full face method
• ii) Heading and bench Method
• iii) Cantilever car dump Method
• iv) Drift system
• v) Pilot tunnel Method

Various Methods for tunnelling through the soft ground are as follows:

• i) Forepoling Method
• ii) Needle beam Method
• iii) Five-piece set Method
• iv) Liner plates Method
• v) Casing Method
• vi) Square set and lagging Method
• vii) Horse cups Method

Tunnel Jacking:

• Tunnel jacking is the process of making a tunnel in already existing bodies such as road and railway area

Immersed Tunnel:

• These types of tunnels are partly or wholly under water.

Tunnel Lining:

• Tunnel lining is the wall of the tunnel.
• It is usually in the form of a ring of a precast concrete segment.

Shield Tunneling:

• A shield tunnelling is a protective structure and trailing support mechanism.

Grouting:

• It is a method of providing additional support to the drilled mine.

Methods of tunnelling in hard rock	Methods of tunnelling in soft soil
Drift Method	Fore-poling method
Heading and benching method	Needle beam method
Full face method	Army method or case method
Cantilever car dump method	American method
Pilot tunnel method	English method
Perimeter method or German method	Belgian method
	Shied tunnelling method
	Linear plates method

Most suitable shape of the tunnel for noncohesive soils is a circular section.

• The circular section of a tunnel offers greater resistance to external pressure caused by water, water-bearing soils or soft grounds.

Advantages of Circular section:

• i) It is the best theoretical section for resisting internal and external section.
• ii) It provides the greatest cross-sectional area for the least perimeter.
• iii) It is the best suited for noncohesive soils.
• iv) It is most suitable for sewers and water carrying purposes.

Disadvantages of Circular section:

• i) Not suitable for roadways or railways as more filling is required.
• ii) The shape is more difficult for the concrete lining.

California Bearing Ratio (CBR) test:

California Bearing Ratio (CBR) test is a method of classifying and evaluating soil-subgrade and base course materials for flexible pavements.

CBR test, an empirical test, has been used to determine the material properties for pavement design.

This test measures the strength of the material and is not a true representation of the resilient modulus.

It is a penetration test wherein a standard piston, having an area of 3 in 2 (or 50 mm diameter), is used to penetrate the soil at a standard rate of 1.25 mm/minute.

The pressure up to penetration of 12.5 mm and it’s ratio to the bearing value of a standard crushed rock is termed as the CBR.

Types of Explosive

Type of Explosive	Suitability
Blasting Powder	In large quarrying blocks
Dynamite	Small boreholes and quarries
Cordite and Gelignite	Under water
Lithofracteor	Tunnels

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