Month: September 2018

8 Different Types of Cement Tests || Laboratory & Field Test

Different Types of Cement Tests

The quality of concrete depends on the quality of the cement. There are several types of cement available in the market. Therefore, it is very important to check the quality of cement before using it. Various tests on cement are conducted to ensure its quality. Cement tests Can be classified as follows:

a) Field Test.
b) Laboratory Test.

Different Types of Cement Test || Building Materials & Construction ||

Read More: – What is Cement

a) Field Test

The Purity and quality of cement can be judged by applying the following rough and ready field test of cement:

⇰ The color of the cement should normally be greenish-grey.

⇰ When the hand is inserted into a bag of cement, It should feel cool and not warm.

⇰ Any lump found in the cement bag should be powdered by pressing between the thumb and the fore finger. If it does not turn into powder form, the cement is considered to be spoiled by air setting.

⇰ It should give a smooth feeling when rubbed in between fingers.

⇰ A handful of cement thrown into a bucket of water should float for some time.

⇰ It should not feel oily when touched.

Read More – Concrete Slump Test

b) Physical / Laboratory Test

The following 8 Types of cement tests are usually conducted in the laboratory, this is also known as a physical test of cement:

1. Fineness Test.
2. Normal consistency test.
3. Initial and final setting time test.
4. Soundness test.
5. Compressive Strength Test.
6. Chemical composition test.
7. The heat of hydration test.
8. Tensile Strenght Test

1. Fineness Test

The object of this cement test is to check the proper grinding of cement. The fineness of cement is tested in two ways:

i) By Sieving.
ii) By Determining the specific surface.

i) Sieving

First of all, weight correctly 100 grams of cement and take it on a standard IS sieve no 9 (90 microns). Break down the air set lumps in the sample with fingers.

Continuously sieve the sample manually or mechanically for 15 minutes, Weigh the residue left on the sieve. This weigh shall not exceed 10% for ordinary cement & 5% for rapid hardening or low heat cement.

2. Normal Consistency Test

Normal Consistency test of cement is conducted to determine the quantity of water required to produce a cement paste of standard or normal consistency for use in other tests.

This test is performed with the help of Vicat’s Apparatus, Standard or normal consistency of a cement paste is that consistency which will permit the Vicat plunger (10 mm in diameter & 40-50 mm in length) to penetrate to a point 5 to 7 mm from the bottom of the Vicat mould.

To perform this test about 400 gm sieved cement is taken & 100 gm of water is added and mixed thoroughly for about 3 minutes. The paste is then filled into the Vicat mould, Making it level with the top of the mould.

The filled up mould is placed centrally below the movable rod fitted with a plunger. The bottom surface of the plunger is brought in contact with the surface of the cement paste and the reading of the scale is taken. The rod is then quickly released and the penetration is noted.

If the rod penetrates 5 to 7 mm from the bottom, the paste is said to be of normal consistency. Otherwise, the trial paste should be made with a varying quantity of water and the test is repeated as above till the desired penetration is obtained.

Let, W = Weight of cement taken.
W1 = Weight of water for desired penetration.

Then, the percentage of water for normal consistency P = (W1 / W)× 100

3. Initial and Final Setting Time Test

When cement is mixed with water is stiff and sticky paste is formed. This cement paste remains plastic for a short period. As the time lapses, the plasticity gradually disappears and the paste changes into a solid mass.

The phenomenon by virtue of which the cement paste changes from a plastic state to a solid-state is known as the setting of cement. The time to reach this stage is known as setting time.

The time is reckoned from the instant when water is added to the cement. The setting time is divided into two parts namely initial setting time and final setting time.

The time at which the cement paste loses its plasticity is termed the initial setting time. The time is taken to reach the stage when the paste becomes a hard mass is known as the final setting time.

The initial and final setting time test on cement is performed with the help of Vicat apparatus. The initial setting time of cement shall be the time from the period elapsing between the time when the water is added to the cement and the time at which the needle (1 mm square or 1.13 mm in dia and 40 to 50 mm in length) penetrate to a point 5 mm from the bottom of the Vicat mould.

To perform this test about 400 gm sieved cement is taken and water is added to it @ 0.85 P by weight of cement. Where P is the percentage of water required for normal consistency paste.

At the instant of adding water, the stopwatch is started. Water is mixed thoroughly for about 3 minutes. The paste is then filled into the Vicat mould, making it level with the top of the mould.

The filled up mould is placed centrally below the movable rod fitted with a needle. The bottom surface of the needle is brought in contact with the surface of the cement paste and the reading of the scale is taken. The rod is then quickly released and the penetration is noted.

The procedure is repeated until the needle fails to penetrate the flock for about 5 mm measured from the bottom of the mould. The time from the stopwatch is recorded which gives the initial setting time.

The cement shall be considered it finally set while applying final setting time needle gently, only an impression is marked on the top surface.

4. Soundness Test Of Cement

Soundness test of cement is performed to identify the presence of excess free lime and magnesia in the cement. This test is performed with the help of the Le-Chatelier apparatus.

Statement Of Problem: Two samples of cement are given, find out:

Which cement is unsound? and
Which cement is sound?

Theory

It is very important that the cement concrete is not so much as the change in its volume when it will be hardened. So it is necessary to control or reduce the quantity of the presence of free lime (CaO) and magnesia (MgO) in cement. So, the soundness test of cement is done to determine the quantity presence in cement.

During the manufacture of cement, free lime is produced. Free lime reacts with water and increases in volume considerably. Magnesia also has the same effect but its rate of reaction is slow.

A larger percentage of free lime and magnesia, if present, therefore, tends to increase the volume of the hardened concrete, thus causing disintegration. The cement is, therefore, said to be unsound when the percentage of free lime and magnesia is more than that specified by ISI (Table I). Unsoundness is measured with the help of the Le-Chatelier mould as explained in the procedure.

It must be specially mentioned here that in the event of the cement failing to comply with the above requirement, a further test should be made by the “Le-Chatelier Method” from another portion of the sample after aeration by spreading it out to a depth of 75 mm at relative humidity.

Test Procedure

Following are the procedure for Soundness Test of Cement:
a) Weigh accurately 100 gm of cement and place it on a standard IS Sieve 90 microns.

b) Break down any air set lumps in the sample with fingers, but do not rub on the sieve.

c) Continuously sieve the sample by holding the sieve in both hands and giving a gentle wrist motion or automatic sieve shaker may be used for this purpose. The sieving should be continuous for 15 minutes.

d) Weigh the residue left after 15 minutes sieving. This residue shall not exceed the specified limits.

e) For recording observations, use plate 4, in Part IV.

Precautions

a) The cleaning of the sieve should be done very gently with the help of a brush i.e. 25 mm or 40 mm bristle brush with 25 cm handle.

b) After sieving the cement must be removed from the bottom surface of the sieve gently.

c) Weighing machine should be checked before use.

d) Sieving must be carried out continuously.

5. Compressive Strength Test

To perform this test 200 gm of cement and 600 gm of standard sand are taken and mixed thoroughly. To this, water is added @ P/4 + 3% when standard sand is used and @ P/4 + 3.5 % when ordinary sand is used. Where ‘P’ is the percentage of water required for a paste of normal consistency.

It is mixed thoroughly to an even colour. The cube mould of size 7.06 cm is placed on a non-porous base plate and is oiled inside. The above mortar is put into the cube mould and is compacted for two minutes by the vibration machine. The top surface is smoothened off by a trowel.

Like this mould, six moulds are filled. The prepared cubes are kept at a temperature of 27° ± 2° C for 24 hours. After this period, mortar cubes are taken out of the moulds and submerged in clean and fresh water for curing.
Compressive strength test of cement is performed at the period mentioned below.

For ordinary cement, after 3 days and 7 days.
For rapid hardening cement, after 1 day and 3 days.
For low heat cement, after 3, 7 and 28 days.

The cube is tested by placing it under the Jaws of the compressive testing machine. The load is steadily and uniformly applied. The load at which the cube is fractured is noted in each case. The compressive strength is calculated by dividing this load by the cross-sectional area of the cube.

6. Chemical Composition Test.

As per IS: 269 – 1975 the chemical requirements of ordinary cement should be as follows

1. The ratio of the percentage of alumina to that of iron oxide should not be less than 0.66

2. The ratio of the percentage of lime to those of alumina, iron oxide and silica calculated with the following formula should not be less than 0.66 and it should not be greater than 1.02.

➤ The loss on ignition should not exceed 4 %.
➤ Total sulphur content as SO3 should not exceed 2.75 %.
➤ Weight of insoluble residue should not exceed 1.5 %.
➤ Weight of magnesia should not exceed 5 %.

7. The Heat of Hydration Test

The heat of hydration is defined as the chemical reaction between cement and water. during hydration of cement, sufficient heat is generated. The process of heat generation is quite rapid in the initial stage of the setting but its rate diminishes with the passage of time.

For mass concrete low heat cement should be used. As per IS: 4031 – 1968, the heat of hydration for low heat cement should be as follows:

After 7 days not more than 65 calories per gram and after 28 days not more than 75 calories per gram of cement.

8. Tensile Strenght Test

For evaluate the tensile strength of the cement, at first, six numbers of standard briquettes are made from cement mortar. All these briquettes are broken after 1 day, 3 days and 7 days of curing. The average strength of briquettes after 1, 3 and 7 days should be as follows:

Time of immersion( Curing period)	Ordinary cement	Rapid hardening cement
After 1 day	————	20 kg/cm² (2 N/mm²)
After 3 days	20 kg/cm² (2 N/mm²)	30 kg/cm² (3 N/mm²)
After 7 days	25 kg/cm² (2.5 N/mm² )	———-

Read Also:

Types of Cement

Bogue’s Compounds

TYPES OF RAILS – Double Headed, Bull Headed & Flat Footed Rails

Types of Rails

In railway engineering, there are 3 types of rails used in the construction of railway tracks which are discussed below:

Double Headed Rails.
Bull Headed Rails.
Flat Footed Rails.

Above three Types of rails are described below in detail:

TYPES OF RAILS - Double Headed, Bull Headed and Flat Footed Rails

1. Double Headed Rails

The rail sections, having their head and foot of same dimensions, are known as double headed or Dumb-bell rails. These rails have less strength and stiffness as compared to flat footed rails. These rails are not used nowadays on Indian Railway.

2. Bull Headed Rails (B.H Rails)

The rail section, having the head a little thicker and stronger(Bull size) than the lower part is known as Bull headed rails. These rails have less strength and stiffness as compared to flat footed rails. Bull headed rails are generally used for constructing points and crossings.

Advantages of Bull Headed Rails

1. They keep better alignment and give a more solid and smoother track.

2. The rails can be easily removed and replaced quickly. Hence renewal of the track is easy.

3. The heavy chair with a large bearing on sleepers gives longer life to the wooden sleepers and greater stability to the track.

4. These rails facilitate easy manufacturing of points and crossings.

Disadvantages of Bull Headed Rails

1. They require costly fastenings.

2. They have less strength and stiffness.

3. They require heavy maintenance costs.

3. Flat Footed Rails(F.F. Rails)

The rail sections, having a flat foot, are known as flat-footed rails. These rails have more strength and stiffness as compared to Double Headed Rails & Bull Headed Rails. Flat footed rails are most commonly used in India.

Advantages of Flat Footed Rails

1. These rails have more strength and stiffness.

2. Fitting of rails with sleepers is simpler so they can be easily laid and re-laid.

3. No chairs and keys are required as in case B.H. rails.

4. Maintenance of points and crossings made with these rails is easy.

5. They give better stability and longer life to the track and reduces maintenance cost.

6. These rails are less costly than other types of rails.

7. These rails require less number of fastenings.

Disadvantages of Flat Footed Rails

1. The fitting gets loosened more frequently.

2. The straightening of bent rails, replacing of rails, and de-hogging of battered rails are difficult.

3. These rails sink into the wooden sleepers under heavy trainloads. Hence they require a bearing plate to overcome this problem.

4. Manufacturing of points and crossing with these rails is difficult.

FAQs

How many types of rail sections are there?

There are three types of rail sections, they are 1. Double Headed Rail, 2. Bull Headed Rail and 3. Flat-Footed Rail section.

What is the meaning of the 25R, 35R, 45R, and 55R rail sections?

25R, 35R, 45R, and 55R means that the weight of the rail section per meter length is 25 Kg, 35 Kg, 45 Kg, and 55 Kg respectively.

Read More:

Functions Of Rails

Creep of Rails

Properties and Function of Bogue’s Compounds

Bogue’s Compounds

Following are the four compounds which are known as bogues compounds and their formula & abbreviated formula are described below:

Name of Bogues Compound	Abbreviated Formula	Formula
Tri-calcium silicate	C₃S	3 Cao.Sio₂
Di-calcium silicate	C₂S	2 Cao.Sio₂
Tri-calcium aluminate	C₃A	3 Cao.Al₂o₃
Tetra-calcium alumino-ferrite	C₄AF	4 Cao.Al₂o₃.Fe₂o₃

Properties and Function of Bogue’s Compounds

The Bogue’s compounds (basic compounds) of Ordinary Portland Cement and their function are given below:

Bogue’s Compounds	% by mass of cement	Properties & Function of bogue’s compounds
Tri-calcium silicate (C3S)	25-50	It hydrates at a faster rate and produces higher heat of hydration. It is responsible for rapid hardening with an early gain in strength & has less resistance to chemical attack.
Di-calcium silicate(C2S)	20-45	It hydrates & hardens slowly and produces less heat of hydration. It provides much of the ultimate strength & has greater resistance to chemical attack.
Tri-calcium aluminate(C3A)	5-12	It is the first compound which starts hydrating. It produces the highest heat of hydration & responsible for the setting of cement.
Tetra-calcium alumino-ferrite (C4AF)	6-12	It hydrates rapidly but its individual contribution to the overall strength of cement is insignificant.

Read More:

Cement Test

Chemical Composition of Cement

6 FUNCTIONS OF RAILS

Functions of Rails

The rolled steel sections laid end to end in two parallel lines over sleepers to form a railway track as known as rails. Rails in the railway track serve the following functions:

1) Rails provide a hard, smooth surface for passage of heavy moving loads with minimum tractive resistance.

2) Rails bear the stresses developed due to heavy vertical loads, lateral and braking forces and variation in temperature.

3) Rails provide a continuous level surface and as possible as a straight path for the movement of trains, which helps the traffic to travel comfortably.

4) Rails transmit the loads to sleepers and consequently reduce pressure on ballast and formation.

5) They assist as a lateral guide for the wheels of a train.

6) The rail material(high carbon steel) used is such that it can easily withstand wear and tear.

Read Also:

Railway gauge

Permanent Way In Railway

Requirements Of An Ideal Sleeper

Railway Gauge | Definition | Types | Factor Affecting | Advantages of Uniform Gauge

What is a Railway Gauge?

The clear horizontal distance between the inner faces of the two rails forming a track is known as a Railway Gauge. The distance between the inner faces of a pair of wheels is called the wheel gauge.

Railway Gauge | Definition | Types | Factor Affecting | Advantages of Uniform Gauge

Types of Gauges in India

In Indian railway, the following gauges are used:

a) Standard Gauge or Broad Gauge – Gauge width 1.676 m.
b) Metre/Meter Gauge (M.G) – Gauge width 1.000 m.
c) Narrow Gauge (N.G) – Gauge width 0.672 m.
d) Feeder Track Gauge or Light Gauge – Gauge width 0.610 m.

What is Broad Gauge?

When the clear distance between the inner faces of the two rails is 1.676m, then the gauge is called Broad Gauge. This is also known as the Standard Gauge.

What is a Metre Gauge?

If the horizontal distance between the inner faces of two rails is 1.0 m, the gauge is called a Meter Gauge.

What is the Narrow Gauge?

When the clear distance between the inner faces of the two rails is 0.762m, the gauge is called the Narrow Gauge. These gauges are mainly used for the hilly area and the place where traffic volume is low.

Gauges in Different Country

The railway gauges that are used in different countries are presented below:

S. NO	Types of Gauge	Width of Gauge(m)	Countries
1.	Broad Gauge	1.435 1.451	Canada, U.K, U.S.A., etc. Entire Europe except for Spain, Portugal, and Russia.
2.	Metre Gauge	1.0 1.069	Argentina, France, Switzerland, etc. Australia, Japan, South Africa, etc.
3.	Narrow Gauge	0.762 0.610	India and U.K South Africa and India

Factors Affecting Adopting of a Particular Gauge

The following factors govern the choice of different gauges:

1. Cost of construction and funds available for the railway project.

2. Volume and nature of traffic.

3. The intensity of the population.

4. Industrial and commercial development of the locality.

5. Prospects of future development of the area.

6. Topographical and geological features of the country.

7. Speed of movement required.

Advantages of Uniform Gauge

The use of a uniform gauge has the following advantages:

1. The delay cost and hardship in shifting passengers and goods from the vehicle of one gauge to the other are avoided.

2. Labour expenses of shifting are saved.

3. Breakage of goods due to shifting is avoided.

4. Possibility of thefts and misplacement during the shifting operation is eliminated.

5. Large sheds to store goods are not required.

6. Labour strikes etc. do not affect the service and operation of trains.

7. Wagons can be efficiently used on all the tracks if the gauge is uniform.

8. Locomotives can be effectively used on all the tracks if a uniform gauge is adopted.

9. During military movement, no time is wasted in shifting of personnel and equipment if the gauge is uniform.

10. Duplication of equipment such as platforms, sanitary arrangements, etc is avoided.

Read Also:

Permanent way

Factor Affecting Adoption of a Particular Gauge

FUNCTIONS OF RAILS

Permanent Way In Railway – Definition || Component Parts || Requirements

Permanent Way In Railway

What is(definition of) permanent way?
The railway track of permanent nature is called permanent way or permanent track.

In other words, a permanent way is the combination of rails, fitted on sleepers and resting on ballast and subgrade.

Purpose of Permanent Way

The purpose of the permanent way is to provide a permanent facility for safe and quick movements of normal commercial traffic between the starting and destination station.

Component Parts of a Permanent Way

The following are the component parts of a permanent way: a) Formation of sub-grade. b) Ballast. c) Sleepers. d) Rail. e) Fixtures and fastenings.

Requirements of an Ideal Permanent Way

The following are the principal requirements of an ideal permanent way:

1. The gauge should be correct and uniform.

2. The rail should be at a proper level. In the straight track, two rails must be at the same level. On curves, the outer rail should have proper superelevation.

3. The alignment should be correct.

4. The gradient should be uniform. Any change of gradient should be followed by a smooth vertical curve.

5. The tractive resistance of the track should be minimum.

6. The track should possess sufficient elasticity.

7. The track should be sufficiently strong against lateral forces.

8. The radius and superelevation on curves should be properly designed and maintained.

9. The drainage system of the track should be perfect.

10. It should be free from excessive rail joints. All joints including points and crossing should be properly designed and maintained.

11. All the components of track should fully satisfy the requirements for which they have been provided.

12. There should be adequate provision for easy renewals and repairs of any portion of the track.

13. The track structure should be strong.

14. The initial cost of construction, as well as the maintenance cost of the track, should be as minimum as possible.

Read Also:

FUNCTIONS OF RAILS

TYPES OF RAILS

Railway Gauge

Functions of Curves For a Railway Track

5 Major Difference Between Bridge And Culvert

Difference Between Bridge And Culvert

5 Component Parts of a Bridge

Field Measurement of Shear Strength of Cohesive Soil By Vane Shear Test

Vane Shear Test On Soil

Vane shear test is a simple and quick test, used either laboratory or in the field.

Aim of Vane shear test

To determine the undrained shear strength of cohesive soil.

Testing Equipment For vane shear Test

⇰ A vane shear testing equipment consists of four thin plates, called vanes, welded orthogonally to a steel rod.

⇰ A torque measuring arrangement, such as a calibrated torsion spring is attached to the rod. The steel rod is rotated by worm gear and worm wheel arrangement.

Field Measurement of Shear Strength of Cohesive Soil By Vane Shear Test

The procedure of Vane Shear Test

⇰ A pit is first of all made into the ground up to a depth at which the shear strength is to be tested.

⇰ The vane tester is then pushed or driven carefully into the soil below the bottom of the pit, to a depth somewhat greater than the length of the vane.

⇰ The torque rod is now rotated (usually 1° per minute). The rotation is continued till the soil falls, which will be indicated by the sudden decrease of torque without any back movement of torque wheel.

⇰ The maximum torque (T) given till failure is measured and recorded. The shear strength (𝛕f) is calculated by using the following equation;

𝛕f = 2T / πd²[ H + d/3]

Where, H = Height of the vane And, d = Diameter of the vane.

Consolidation Settlement Analysis of Soil

Comparison Between Conservancy System and Water Carriage System

Conservancy System

1. This system does not permit compact design of buildings.

2. This system is non-hygienic.

3. A large area is required for treatment and disposal.

4. Labour force required is much more

5. There are chances for the out break of epidemic.

6. Underground sources of water may be polluted.

7. It requires a small quantity of water.

8. It is cheap in initial cost.

9. No skilled labor and technical persons are required for the maintenance of this system.

10. This system is considered suitable for rural and undeveloped areas.

Water Carriage System

1. This system permits compact design of buildings.

2. This system is hygienic.

3. Less area is required for treatment and disposal.

4. Only a few labours are required.

5. The risk of outbreak of epidemic is greatly reduced.

6. There are no chances of nuisance on the streets.

7. It requires a large quantity of water.

8. The initial cost is very high.

9. Highly skilled labour and technical persons are required for the maintenance of this system.

10. This system is considered suitable for urban area.

Read Also:

Water Carriage System

Spillway

12 Factors Considering Selection of Site For a Bridge & Culvert construction

Factors considering Selection of Site For a Bridge & Culvert Construction

The selection of a site for bridges and culverts is an art and requires considerable investigation. A few points that deserve attention are given below.

1. A site which is on a straight reach of the drainage should be selected. The curved reach of drainage should be avoided as far as possible.

2. The stream at bridge side should have permanent, firm, straight and high banks.

3. The stream at the Bridge site should be well defined and as narrow as possible.

4. The site should be sufficiently away from the confluence point.

5. There should be no scouring and silting of the stream at the bridge site.

6. A site which offers a square crossing should be selected as far as possible.

7. The site which offers more advantageous foundation condition should be preferred.

8. A site which is sufficiently away from the landslides and subsidence should be preferred.

9. The site should not interfere adversely with any other bridges, weirs, regulators, dams, etc in the vicinity.

10. There should be a minimum obstruction to natural waterway at the bridge site.

11. The stream at the bridge site should be free from costly river training works.

12. The bridge should provide proximity to the direct alignment of the communication route to be served.

Read Also:

Spillway

Difference Between Bridge and Culvert

Bridge	Culvert

Large bridges are generally made of R.C.C. steel, pre-stressed concrete.	The Bridge has a total span up to 6m is called culvert.
All bridges are not culverts.	All culverts are bridges.
It is constructed where a drain or depression of any width crosses the roadway or railway.	It is constructed where a small drain or depression crosses the roadway or railway.
It may consist of the elaborate superstructure.	It consists of a minor structure.
Culverts are generally made of brick or stone masonry, plain or reinforced concrete, and Hume pipe.	Culverts are generally made of brick or stone masonry, plain or reinforced concrete, Hume pipe.