ICMR- National Institute for Research in
Tuberculosis Chennai invites the application
forms to the post of Technical Assistant through
direct recruitment.
TOTAL POST: 81
POST NAME:
Technical Assistant
PAY SCALE
Pay Scale level-6
Rs 35400-112400 Rs
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From: 12/07/2023
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| 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 particlesand make brick brittle |
| Alumina | 20-30% | plasticity to brick | weak and warp ondrying of brick |
| Lime | 10% | prevent shrinkage on drying | melt and brick loose its shape |
| Iron Oxide | <7% | gives red colorhelps lime to fuse with sand | dark blue color |
| manganese oxide | <1% | yellow tint colordecrease shrinkage | decay of brick |
| sulphur oxide carbon dioxide | very small | spongy, swollen structure in the brickdecolored by white blotches | |
water | very small | ||
| Note | good clay for making the brick is weathered clay. | ||
| Alkalies | very small | melt and loosetheir shape | |
| Organic matter | none | after burning leaving pores and make brickporous | |
| Pebbles, Gravels, Grits | lesser | weak and porousnot give uniformity during mixture | |
Following test conducted on soil for determination of water content or Moisture
1 Oven Drying Method 2 Sand Bath Method 3 Alcohol Method 4 Calcium Carbide Method 5 Pycnometer test 6 Radiation Method 7 Torsion Balance MethodOven Drying Method
Oven drying method is the most accurate and simplest method for water content determination. In this method complete drying of soil sample occur and water content in sample is calculated accurately by a maintained temperature in the oven ( 105° C to 110° C) for 24 hours. Note: For highly organic soils a low temperature of about 60° C is preferable. If Gypsum is present, the temperature should not be more than 80° C but for a long time.
Table of Contents
The Oven Drying Method is used to determine the water content in a specific soil.
This method is necessary to understand the bearing capacity as well as the probable settlement of the soil. It is carried out in the laboratory itself.
i. Thermostatically controlled oven maintained at a temperature of 110 ± 5oC
ii. Weighing balance, with an accuracy of 0.04% of the weight of the soil taken
iii. Air-tight container made of non-corrodible material with a lid
iv. Tongs
| Size of particles more than 90% of passing | Minimum Quantity ( grams) |
| 425-micron sieve | 25 |
| 2 mm sieve | 50 |
| 4.25 mm sieve | 200 |
| 10 mm sieve | 300 |
| 20 mm sieve | 500 |
| 40 mm sieve | 1000 |
The procedure for the oven drying method can be listed as follows:
i. The air-tight container along with its lid must be first weighed(W1).
ii. The specimen sample is then taken in the container, and the weight of a container along with the lid and sample is taken, say W2.
iii. Then, the container is left in the oven. The specimen is dried to a constant weight at temperatures ranging from 105 to 110 degrees Celsius for about 16 to 24 hours.
iv. The container, along with the lid and the dried sample, are finally weighed(W3).
v. The moisture content is then calculated using the following formula:
W= [ (W2-W3) / (W3-W1) ] * 100
Where,
W1= Weight of the container with a lid in grams
W2= Weight of the container with lid and wet sample in grams
W3= Weight of the container with lid and dry sample in grams
Note: To get an accurate value, a minimum of three soil samples should be taken to test, and average water content should be taken as a result.
| Sl. No. | Observations and Calculations | Determination No. | ||
| 1 | 2 | 3 | ||
| Observation | ||||
| 1 | Container No. | |||
| 2 | Weight of empty container (W1) | |||
| 3 | Weight of container + soil (W2) | |||
| 4 | Weight of container + dry soil (W3) | |||
| Calculations | ||||
| 5 | Weight of water Mw= M2 – M3 | |||
| 6 | Weight of solids, Ms= M3 – M1 | |||
| 7 | Water content= (5)/(6)x100 | |||
Water content of the given soil sample = ______%
a. Temperature of the oven should be maintained between (105°-110°)C.
b. Wait to cool for the dry soil in a container to remove from the oven ( or use tongs).
c. For accurate calibration, the thermostat should be kept on checking regularly.
#Opportunities
Dear Students
Institute of Banking Personnel Selection (IBPS)
invites the application forms through Common
Recruitment Process for recruitment of clerks in
participating banks (CRP Clerks-XIII for
vacancies of 2024-25)
TOTAL POST: 4045
POST NAME:
1. CRP Clerks-XIII for vacancies of 2024-25
EDUCATIONAL QUALIFICATIONS:
As on 21-07-2023
Bachelor Degree in Any Stream from
Recognized University in India
AGE LIMIT
As on 01-07-2023
20- 28 Years
Age relaxation as per Norms
SELECTION PROCESS
Written Exam:
1. Prelims Exam
2. Mains Exam
HOW TO APPLY
Mode: Online
Start date: 01-07-2023
Last date: 21-07-2023
1. Online Examination – Preliminary August/
September 2023
2. Online Examination – Main October 2023
APPLICATION FEES:
Rs. 175/- : SC/ST/PwBD/EXSM candidates.
Rs. 850/- : for all others
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#Opportunitie and Jobs
Dear Students
Union Public Service Commission invites
online recruitment applications for recruitment
of various Posts.
TOTAL POSTS: 257
POST NAME:
1. Air Worthiness Officer
2. Air Safety Officer
3. Livestock Office
4. Junior Scientific Officer
5. Public Prosecutor
6. Junior Translation Officer
7. Assistant Engineer Grade-I
8. Assistant Survey Officer
9. Principal Officer
10. Senior Lecturer
EDUCATIONAL QUALIFICATION
Degree in relevant discipline and post
qualified experiences as per post
AGE LIMIT
Upper Age limit 30/35/50 Years as per Post
HOW TO APPLY
Start date: 24-06-2023
Last date: 13-07-2023
APPLICATION FEES:
For SC/ ST/ PWD & Women candidates: 0 Rs
General: 25 Rs
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Dear Students
Rajasthan Public Service Commission (RPSC) Rajasthan RPSC State and Sub. Services Combined Competitive Exam 2023
TOTAL POST: 905
POST NAME:
1. Rajasthan State Service Exam
2. Rajasthan Subordinate Service
EDUCATIONAL QUALIFICATIONS:
Bachelor Degree in Any Stream from
Recognized University in India
AGE LIMIT
21- 40 Years
Age relaxation as per Norms
SELECTION PROCESS
Written Exam:
1. Prelims Exam
2. Mains Exam
HOW TO APPLY
Mode: Online
Start date: 01-07-2023
Last date: 31-07-2023
APPLICATION FEES:
General: 600/-
OBC / BC / EWS/ SC / ST: 400/-
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| 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.
#Opportunities and Jobs
Dear Student
Kerala Public Service Commission (KPSC)
invites the application Online Form for various
recruitment
TOTAL POST: 114
POST NAME:
Assistant Engineer/Head Draftsman
DISCPLINE
1. Civil Engineering
EDUCATIONAL QUALIFICATIONS:
Degree in Engineering from a Recognized
University in India on Regular Basis.
PAY SCALE
Scale pay of Rs.55, 200-1, 15,300/-
HOW TO APPLY
Mode: Online
Start Date: 15-06-2023
Last date: 19-07-2023
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