CONCRETE, Stone

Stones || Quality tests on stones ||Types and procedures

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Stones are the form of rocks from the earth’s crust. They find their application in the construction of residential and public buildings, dams, harbours, face-work of structures, road metal, and railway ballast. Besides, stones have good strength and durability.

Quality tests on stones are crucial for construction projects. Testing stone ensures that it meets the necessary standards for strength and durability. There are various tests for stones that assess different properties. These tests for stones include crushing strength, water absorption, and abrasion resistance. By performing these tests, engineers can decide the suitability of the stone for specific uses. Properly testing stone helps prevent structural failures and ensures long-lasting constructions. In this blog, we will explore the different types of stones and the procedures for each quality test. This information is essential for anyone involved in construction and material choice.

  1. Types of Stones Used in Construction
  2. Acid test
  3. Attrition test on stones
  4. Crushing test on stones
  5. Stone Crystalline test
  6. Freezing and Thawing Test
  7. Hardness Test
  8. Impact test
  9. Water absorption test
  10. Microscopic tests on stones
  11. Smiths tests

Types of Stones Used in Construction

Granite is a hard, durable stone, ideal for high-stress applications. Tests on stones, like crushing strength tests, highlight its robustness. Limestone is versatile but porous, requiring water absorption tests. Marble is prized for aesthetics, with abrasion resistance tests ensuring durability. Sandstone, used in paving and walls, needs strength and porosity tests. Slate, known for durability, is tested for impact resistance and is used in roofing and flooring. Proper testing stone ensures suitability for construction.

Qualities of Good Stone

We consider good-quality stones for the construction of important engineering structures. The next are the prime requirements of good-quality stones.

Also read : 9 lab tests for flexible pavements

  • The heavy stones have less porosity and high compactness. Thus the specific gravity of stones should be high.
  • Uniform and appealing colour stones are employed for decorative works.
  • Should have a homogeneous composition and should have less water absorption.
  • It should have the ability to get good polish.
  • Moreover, it should be free from iron oxides and calcium carbonate to resist fire.
  • The dense compaction of rocks can withstand the consequences of external agencies.
  • A good stone must be free from quarry sap.
Stones : Quality tests
Stones - Quality tests

Test on stones

Testing stone is essential to make sure durability and strength in construction. These tests for stones assess various properties. Proper tests on stones prevent structural issues.To conclude the strength, durability and other engineering properties of the stone, the following tests are performed. 

  • Acid test
  • Attrition test
  • Crushing test
  • Crystalline test
  • Freezing and thawing test
  • Hardness Test
  • Impact test
  • Water absorption test
  • Microscopic Test
  • Smith’s Test

Acid test

The acid test is a crucial procedure in testing stone for quality. Tests on stones help to determine the durability and suitability. Proper tests for stones ensure reliable construction materials.The acid tests determine the presence of calcium carbonate in rocks. The test method is as follows,

  • Take some 50 to 100g specimen randomly.
  • Then place them in the solution of sulphuric acid and hydrochloric acid having 1% strength for about one week.
  • Frequently mix the solution and immerse the specimen fully.
  • Subsequently, observe the specimen. 
  • Specimen with high lime content causes efflorescence due to the presence of an acid solution.
Quality tests on stones -Acid test

Attrition test on stones

The attrition test indicates the rate of wear of the stone under the sudden impact of loads. Another name of the attrition test is the abrasion test. The apparatus for the attrition test is Devel’s testing machine.

  • Take some sample specimen and break them into small pieces having 60mm size.
  • Now take 50N of stones and place them in the cylinder of the testing machine. 
  • Then close the cylinder and rotate them for 5 hours at a rate of 30 rpm. 
  • After 5 hours, take the samples outside and sieve them through a 1.5 mm mesh.
  • Weigh the amount of material retained in the sieve and calculate the percentage of wear using the following formula.

Percentage of wear = ( Loss in weight / Initial weight ) x 100

Thus, we get the percentage of wear.

Attrition test on stones
Stones

Crushing test on stones

The crushing test gives the strength of the stones. These tests are performed for stones to be used at the bottom of heavy structures.

  • For this test, cut the stone specimens into 40mm x40mmx 40mm and dress the sides.
  • Minimum of three specimens are needed for this test.
  • Before starting, place the specimen in water for 72 hours.
  • Then cover the load-bearing surface of the specimen with a plywood layer.
  • Now place the specimen in the testing machine.
  • Simultaneously, apply load axially at a rate of 13.7 N/mm2 per minute.
  • Note down the load at which the stone breaks. Calculate the strength using the following formula.

Crushing strength = Maximum load at which stone breaks / Loaded area 

However even weak stone possess high compression strength. For example, the crushing strength of stone for ordinary building works should not exceed 1N/mm^2. 

Stone Crystalline test

This test defines the weathering nature of stones. To conduct this test we need at least 4 cubes with 40mm size. The crystallisation of Calcium sulphate causes eroding of stones

  • To start with first, immerse the samples in a solution of sodium sulphate at normal room temperature.
  • After that dry them at 100 degree Celsius and repeat these steps 5 times.
  • Then note down their difference in weight in the percentage of the original weight.
  • The difference in weight shows the weathering quality of the stones. 

Freezing and Thawing Test

As stones in the construction work are exposed to sunlight, wind, rain etc. This test is necessary to carefully study the behaviour of stone. The test procedure is as follows.

  • Take the specimen and immerse it in water for 24 hours.
  • Then place it in a freezing mixture at 12 degree Celsius for 24 hours.
  • Frequently repeat the above two steps and observe the stone quality. 

Besides, perform this test only in the shade to prevent the consequences of rain, sunlight, etc.

Hardness Test

The hardness of the stone is its ability to resist scratch or rebound.

  • For this test, we use a penknife. This can not make a scratch on pard stones like granite.
  • Moh’s scale value determines the hardness of the specimen.
  • For example, Moh’s scale value is 1. Since it is easily scratchable.
  • Likewise for Quartz, Moh’s scale value is 7. Since it cannot be scratched with a knife.

Impact test

The impact test determines the toughness of the stone. The impact testing machine is the apparatus used for this test. The test procedure is as follows.

  • Take a specimen in a cylindrical shape with 25mm diameter and 25mm height. 
  • Then place it on the cast iron anvil of the machine
  • After that, allow a steel hammer of 20N to fall vertically over the specimen
  • The first blow height is at 1cm. For the second blow height, it is 2cm and so on. 
  • Gradually increase the height of the blow. Finally, note down the height at which the specimen breaks. 
  • The height at which the specimen breaks is the toughness index.

Water absorption test

Through this test, we can determine the porosity as well as moisture content. The water absorption test is as follows

  • Prepare a stone sample and record its weight asW1
  • Then immerse the cube in distilled water for 24 hours. 
  • After that wipe the water with a damp piece of cloth. Again weigh the sample as W2.
  • Now suspend the cube freely in water and record its weight as W3.
  • Subsequently, place the cube in boiling water for five hours. Again weigh the cube and record its weight as W4.
  • From the above data, we can also calculate the percentage absorption of water and saturation coefficient using the formula.

Percentage absorption by weight after 24 hours = (W2- W1)/ W * 100

Percentage absorption by volume after 24 hours = (W2 – W1)/( W2 – W1) * 100

Saturation coefficient = Water absorption / Total porosity = (W2- W1) – ( W4- W1)

Microscopic tests on stones

This test helps to study the geology of the stone. The sample is placed for microscopic examination to analyse the below properties.

  • Mineral components
  • Texture and nature of stones
  • Presence of malicious substance
  • Determining defects and pores
  • Size calculation, etc.

Smiths tests

Smith’s test calculates indicates the presence of earth matter in stones. 

  • In this test firstly, break the specimen into small pieces.
  • Then take a test tube with clear water and place these pieces in it.
  • Vigorously shake the test tube. The muddy colour of the water shows the presence of earthy matter.

Key Takeaways

Quality tests on stones are essential for ensuring their suitability in construction projects. Testing stone involves various tests, including crushing strength, water absorption, and abrasion resistance. Each test stone procedure is designed to assess specific properties, such as strength, durability, and weather resistance. Granite, limestone, marble, sandstone, and slate are commonly used stones that undergo these tests for stones. Procedures like the acid test, attrition test, and freezing and thawing test help determine the stone’s durability and resistance to environmental factors. Proper tests on stones prevent structural issues and ensure long-lasting constructions. Understanding these tests for stones is crucial for anyone involved in construction and material selection.

Conclusion

In conclusion, performing quality tests on stones is a fundamental step in construction to ensure the materials’ strength and durability. Testing stone through various procedures, such as crushing strength, water absorption, and impact tests, provides critical information about the stone’s properties. These tests for stones help in selecting the right material for different construction purposes, ensuring safety and longevity. Types of stones like granite, limestone, marble, sandstone, and slate each require specific testing methods. Therefore, incorporating these tests on stones into the construction process is vital for achieving reliable and robust structures. Properly testing stone materials guarantees their performance and enhances the overall quality of construction projects.

water conservation

Wastewater Treatment- Stages and Process full details

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Wastewater treatment is an area where a lot of experts have carried out in-depth research. According to The United Nations World Water Development Report (WWDR), about 80% of wastewater is released into the water bodies without proper treatment on a global scale.

In the previous blog, I showed you some innovative ways to conserve water. Today we are going to dig deeper into the journey of wastewater through a wastewater treatment plant.

In the first section, let me introduce you to the wastewater treatment process.

Wastewater Treatment Process

The method of removing pollutants from wastewater or sewage and converting it into an effluent that can be added to the water cycle is known as wastewater treatment. In wastewater treatment plants, pollutants in wastewater are reduced to a degree that nature can accommodate.

Here’s a step-by-step guide to explain what happens at each point of the treatment process and how contaminants are neutralised or removed to help keep our rivers and streams safe. 

Also check out some rainwater harvesting methods.

Wastewater Treatment Stages

Wastewater Treatment Process
Wastewater Treatment Process

As shown in the diagram, the three main stages in the treatment of wastewater are:

  • Primary Treatment
  • Secondary Treatment
  • Tertiary Treatment

Let’s analyse what happens in each of the stages in detail.

Primary Treatment of Wastewater

Wastewater reaching a treatment plant through pipes first undergoes primary treatment irrespective of its source. About 60% of the suspended solids are removed from the wastewater during primary treatment along with aeration or stirring in the water to put oxygen back. It includes the following steps:

1. Screening

  • The majority of the floating materials are removed from the wastewater using screens of 10 mm openings and settling tanks.
  • The floating materials include stone, rocks, sticks and even dead animals. Solid materials make up about a third of the wastewater. 
  • As a result, eliminating solid waste at the initial stage makes subsequent treatment procedures easier. Also, they may cause problems later in the treatment process if they are not removed.
  • Solid waste is collected and disposed of in landfills after the screening process.

2. Sedimentation

  • The sewage then flows through the grit trap or grit chamber which collects sand, cinders, and small stones at the bottom.
  • The wastewater is then directed to sedimentation ponds, settling tanks, or clarifiers after the settled grit have been removed.
  • Organic and inorganic matter, as well as suspended solids, are removed in this process.
  • The suspended particles begin to fall to the bottom and form a solid mass known as sludge.

3. Sludge Removal

  • In the sedimentation tanks, sludge (the organic solid component of the sewage) settles out of the wastewater.
  • Mechanical scrapers in the tank’s base continuously move accumulated sludge to a hopper, where it is pumped to sludge treatment facilities.
  • The thickening step removes some of the water before the sludge is processed in digesters.

4. Scum Removal

  • Lighter materials rise to the surface as sludge settles to the bottom of the sedimentation tanks.
  • Grease, oils, plastics, and soap are among the ‘scum.’
  • Scum is skimmed off the surface of the wastewater by slow-moving rakes.
  • Scum is thickened before being poured into the digesters with the sludge.

Around 90% of suspended solids, 55% of faecal coliforms, and 50% of biological oxygen demand are removed during the primary treatment process. The waste must be subjected to secondary treatment in order to be completely free of toxic substances. Let’s see how to do that.

Wastewater Treatment Stages
Source: researchgate.net

Secondary Treatment of Wastewater

  • Secondary wastewater treatment is designed to significantly degrade the biological content of the waste by aerobic biological processes, and it operates at a deeper level than primary treatment.
  • During secondary wastewater treatment, about 85% of the organic matter in sewage is eliminated.
  • The method entails combining the wastewater with bacteria and oxygen at high pressures.
  • Bacteria digest organic matter with the aid of oxygen.

Secondary wastewater treatment reduces common biodegradable pollutants to acceptable levels, allowing for cleaner release into the nearby water bodies. It is done in one of three ways:

1. Biofiltration

Sand filters, contact filters, and trickling filters are used in biofiltration to ensure that any excess sediment is extracted from the wastewater.

  • A trickling filter consists of a bed of stones that is about 6 feet tall.
  • Sewage coming out of the sedimentation tank is permitted to pass through this stone sheet.
  •  The bacteria congregate on these stones and begin to multiply and evolve until all of the organic matter in the sewage has been consumed.
  • Following the process, the clean water is piped out and directed to another sedimentation tank.

2. Oxidation Ponds

  • Oxidation ponds, also known as lagoons or stabilisation ponds, are large, shallow ponds that use the interaction of sunlight, bacteria, and algae to treat wastewater.
  • Algae use the sun’s energy, as well as carbon dioxide and inorganic compounds released by bacteria in the water, to grow.
  • During photosynthesis, algae release oxygen, which is needed by aerobic bacteria. 
  • Mechanical aerators are often used to provide even more oxygen, reducing the size of the pond needed.
  • Dredging is needed to remove sludge deposits in the pond.
  • Filtration or a combination of chemical treatment and settling will kill any residual algae in the pond effluent.

3. Activated Sludge Process

  • The air and sludge are allowed to come into close contact with the bacteria during this process and then passed into the settling tank.
  •  The sewage from the settling tank is first sent to an aeration tank, where bacteria are added to the air and sludge.
  • The entire setup is left alone for several hours, during which time the bacteria decompose the organic matter into toxic by-products. 
  • The sludge, which has been activated by billions of bacteria, is returned to the aeration tank to handle fresh sewage.
  • The previously treated wastewater is pumped to the sedimentation tank, which filters out any bacteria.

We have seen the primary and secondary treatment of wastewater. Now it’s time to see what happens in the tertiary treatment of wastewater.

Tertiary Treatment of Wastewater

The aim of tertiary wastewater treatment is to improve the water’s quality to meet domestic and industrial standards, as well as to meet specific criteria for water discharge safety. It can be done by ion exchange, reverse osmosis, chemical precipitation, membrane filtration etc. In the case of municipally treated water, the tertiary treatment also includes the elimination of bacteria, ensuring that the water is safe to drink.

In some cases, quaternary treatment is also done. This stage deals with contamination levels of a few parts per million to billions of parts per billion, and it often includes oxidation or fine filtration.

Wastewater Treatment
Wastewater Treatment

Shall we wrap up?

Conclusion

Wastewater treatment refers to the purification of sewage from various sources and converting it into a reusable form. It involves mainly 3 stages namely primary, secondary and tertiary.

Primary treatment involves screening, sedimentation, sludge and scum removal. Secondary treatment deals with the removal of biological contaminants using oxidation ponds, trickling filters or activated sludge process. Finally, the Tertiary treatment converts water into a reusable form.

The management of wastewater is inextricably related to the availability of clean and adequate water sources. Far from being anything to discard or neglect, wastewater will play an important role in meeting the increasing water demand in rapidly expanding cities, improving energy production and industrial growth, and promoting sustainable agriculture.

Also see : Concepts of green building – 4 comprehensive concepts explained.

civil engineering, Earthquake Engineering

Earthquake Engineering- A Comprehensive Guide

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Earthquake Engineering though not a mainstream engineering branch, is a widely researched topic now. Though all of us wouldn’t have experienced an earthquake most of us must have seen news and videos about the tremendous loss it causes. Looks scary, right? That’s exactly what makes Earthquake Engineering a subject of immense possibilities and research.

In this blog let me walk you through what is Earthquake Engineering and the relevant topics in Earthquake Engineering.

What is Earthquake Engineering?

Earthquake engineering is a branch of civil engineering that considers the impacts of earthquakes while designing and analysing engineering structures. The ultimate aim is to make such structures more earthquake resistant. 

In a major earthquake, an earthquake (or seismic) engineer attempts to construct structures that will not be affected by slight shaking and will prevent significant damage or failure. Earthquake engineering is a scientific area concerned with reducing seismic risk to appropriate socioeconomic levels to protect society, the natural environment, and the built environment from earthquakes.

Also See : Prefabrication in construction – Advantages – Disadvantages

Also See : Cellular light weight concrete -Manufacturing process – Properties

Earthquake Engineering Objectives

The main objectives of earthquake engineering include:

  • Anticipate the effects of powerful earthquakes on urban areas and civil infrastructure.
  • Design, construct and maintain structures so that they function as expected and per building codes when exposed to earthquakes.

Isn’t it amazing that a properly designed structure need not be extremely strong or costly? Instead, it just has to be carefully designed to withstand seismic forces while sustaining a minimum amount of damage. In this blog, I will show you how exactly this can be done.

Earthquake Engineering Relevant Topics

Let me give you a brief description of earthquake engineering’s relevant topics.

  • Seismic Performance in Earthquake Engineering
  • Seismic Vibration Control in Earthquake Engineering

Earthquake Engineering- Seismic Performance

The ability of a structure to maintain its key functions, such as protection and serviceability, during and after an earthquake exposure is referred to as earthquake or seismic performance. If a structure does not threaten the lives and well-being of those in or around it by partially or fully collapsing, it is considered secure.

Earthquake Engineering- Seismic Vibration Control

The term “seismic vibration control” in Earthquake Engineering refers to a range of technological methods for reducing seismic vibrations in both building and non-building structures. There are three types of seismic vibration control devices: passive, active, and hybrid.

  • Passive control devices have no feedback capability between them, structural elements and the ground
  • Active control devices incorporate real-time recording instrumentation on the ground coupled with earthquake input processing equipment and actuators inside the structure.
  • Hybrid control devices combine the functionality of active and passive control systems.

Due to reflections, as ground seismic waves reach up and begin to penetrate a building’s foundation, their energy flow density drops dramatically: usually by up to 90%. The residual portions of the incident waves after a major earthquake, on the other hand, also have significant destructive potential.

There are a variety of ways to monitor seismic waves once they reach a superstructure to mitigate their damaging effects and increase the building’s seismic efficiency, for example:

  • Dissipating wave energy within a superstructure using properly designed dampers.
  • To spread wave energy over a wider frequency range.
  • By absorbing the resonant portions of the entire wave frequencies band with mass dampers.
Earthquake Engineering
Losses due to Earthquake

Let’s see how to apply these principles in the construction field.

Earthquake Resistant Construction

Earthquake resistant construction refers to the use of seismic design to ensure that buildings and non-built structures withstand earthquakes to the best of their abilities and in accordance with relevant building codes.

Detailing of the members and their relations should be as straightforward as possible to achieve good workmanship. Earthquake design, like any other form of construction, entails the construction, retrofitting, or assembling of infrastructure using the materials available.

  • Adobe Structures
  • Timber frame structures
  • Light frame structures
  • Reinforced Masonry Structures
  • Reinforced concrete structures

Adobe Structures

  • About a third of the world’s population lives or works in Adobe structures.
  • Adobe mud bricks are one of the most popular and oldest building materials.
  • Adobe is widely used in some of the world’s most vulnerable areas, including the Indian subcontinent, and other parts of Asia.

The following are important factors to consider when improving the seismic efficiency of adobe construction:

  • Construction quality.
  • Box-like and compact layout.
  • Seismic reassurance.

Timber frame structures

  • Timber framing has been used in many parts of the world for thousands of years.
  • The use of timber framing in buildings provides the building’s full skeletal framing, which has structural advantages because the timber frame if properly designed, lends itself to better seismic survivability.
Timber framed structure
Timber framed structure

Light Frame Structures

  • Rigid plywood shear walls and wood structural panel diaphragms provide seismic resistance to light-frame structures.
  • For all engineered wood structures, special provisions for seismic load-resisting systems include consideration of diaphragm ratios, horizontal and vertical diaphragm shears, and connector/fastener values.
  • Collectors, or drag struts, are often used to distribute shear along a diaphragm length.

Reinforced masonry structures

  • Reinforced masonry is a building method in which steel reinforcement is inserted in masonry mortar joints or put in holes and then filled with concrete or grout.
  • This can be achieved using a variety of methods and techniques in which the reinforced hollow unit masonry is the most common form.
  • The shear strength of the wall must be greater than the flexural strength to achieve ductile action in masonry.
Reinforced Masonry structures
Reinforced Masonry structures

Reinforced concrete structures

Steel reinforcement bars (rebars) or fibres are inserted into reinforced concrete to strengthen a brittle composite. It can be used to make beams, columns, floors, and bridges, among other things.

Prestressed concrete is a form of reinforced concrete that is used to overcome the natural weakness of concrete in strain. It can be used for beams, floors, and bridges with longer spans than ordinary reinforced concrete allows. 

Post Tension - slabs
Post Tension – slabs

Prestressing tendons are used to apply a clamping load to the concrete compression member, resulting in compressive stress that compensates for the tensile stress that would otherwise be applied by a bending load. A typical reinforced concrete frame should have ductile joints to avoid catastrophic failure in response to earth-shaking.

Now you have seen the basic aspects of Earthquake Engineering. How do you feel about it? Let’s know in comments.

green building

Green Airport Concept, Features and Examples Full Guide

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Green Airport has been in the news for quite some time as more and more airports are going green. According to studies by ATAG, the global aviation industry produces 2% of all anthropogenic carbon dioxide emissions. When it comes to climate change, the aviation industry is under increasing pressure to clean up its act, but gas-guzzling planes aren’t the only culprits. 

As airports grow, so does their carbon footprint and emissions. As new terminals, ground transportation vehicles, and facilities are built, the energy demand increases. 

As a result, many airports around the world have incorporated greener elements into their designs and operations strategies, as well as pledged to support environmentally sustainable initiatives thereby transforming  into green airports. Before we dig into the details about various green airports around the globe I will show you what exactly a green airport is.

What is the Green Airport concept?

Green airport is an airport that complies with the latest sustainability criteria, reduces the effects of airport activities on the environment, and mitigates the impact of climate change on related facilities and operations.

In this blog let me take you on a trip to various green airports in the world and we will analyse the key features that make each one a green airport.

Green Airports in the world

A number of airports around the world have begun to implement “green” programmes in order to make their buildings greener and more environmentally friendly. Here are 5 such airports that have earned international recognition for their sustainable and green initiatives.

1. Boston Logan International Airport, US

  • The world’s first air terminal to receive the Leadership in Energy and Environmental Design accreditation is located at Boston Logan International Airport. 
  • Its Terminal A has heat-reflective roofing and pavement surfaces, as well as water-saving low-flow bathroom fixtures.
  • One of the airport’s runways was resurfaced with environmentally friendly asphalt that could be heated at a lower temperature during the construction process which would result in a 2,000t reduction in carbon emissions over the lifetime of the project. 
  • The airport’s offices are topped with a fleet of 6ft tall wind turbines that generate about 3% of the energy required for operations.

Seems like Boston Airport is pacing really fast towards being a green airport, right? Let’s look at the other ones which are turning into green airports.

2. Galapagos Ecological Airport, Galapagos Islands – World’s first completely Green Airport. 

  • Built to operate entirely on solar and wind energy, with windmills providing 65% of total energy and photovoltaic panels on walkways providing 35%
  • Steel pipes taken from oil extraction fields were used to build 80% of the infrastructure.
  •  Wood and metal structures from the airport’s previous home, Seymour, were reused, and furniture was made with environmentally friendly materials.
  • A desalination plant is also present at the airport, which collects seawater and purifies it for use in the terminal. 
  • The wastewater is then pumped back into the treatment facility for future use by travellers.
Green Airport
Green Airport

3. Singapore Changi Airport, Singapore

Singapore’s Changi Airport is not only one of the best in the world, but it also has a reputation for being environmentally friendly.

  • With skylights to enhance natural light, air conditioners located closer to the floor, and an abundance of greenery.
  • The recently opened Terminal 4 features a green wall with over 20,000 plant species, which lowers the temperature of the airport and increase air quality.
  • Energy-efficient motion sensors and lighting, water-efficient fittings, and roof-mounted solar panels are among the other features installed at Changi.

4. Stockholm Arlanda Airport, Sweden- First Green Airport to achieve carbon neutrality

  • The only airport in the world with an environmental permit that includes a limit on carbon dioxide emissions.
  • In this green airport, hangars and airfield buildings are heated with a special biofuel system to conserve energy. 
  • A collection of wells connected to an underground aquifer collect water and sends it to the terminal’s air conditioning system in the summer.
  •  This approach is often used to heat cement pads near the airport’s hangars, preventing ice from forming on the doors and ramps.

5. Delhi Indira Gandhi Airport, India

  • The 5.4 million-square-foot Terminal 3 at the airport features well-lit departure lounges, 1,200 low-power LCD displays, 300 rainwater harvesting stations, and erosion-control storm drains. 
  • Passengers are transported between terminals and baggage claim using battery-powered vehicles.
  • Indira Gandhi Airport recently received two awards for its environmental stewardship,     
  1. Wings India Award for the ‘Most Sustainable and Green Airport,’ 
  2. ACI’s designation as the world’s best airport with over 40 million passengers a year.

Through this blog, we have taken a closer look at some green airports that are setting a precedent for other aviation hubs to emulate by sustainable practices and the use of renewable fuel sources. What do you think of these features and what other energy-saving measures and sustainable practices can be adopted to uplift our airports to the status of a green airport? Let me know in the comments.

Best Engineering colleges, civil engineering

Best Engineering Colleges in India- 10 Best Colleges Full Details

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Best Engineering Colleges in India is a topic that every engineering aspirant would love to know. One of the most prestigious and sought-after courses pursued by students in India would be Engineering. Many engineering colleges in India offer undergraduate and postgraduate engineering programs across various disciplines.

Students worldwide study at India’s top-ranked engineering colleges and institutes, which annually produce more engineers than most other countries. In this blog let’s have a look at the 10 best Engineering Colleges across the country.

Let me show you what Engineering is and which are the popular Engineering Colleges in India opted by students.

In layman’s terms, Engineering can be defined as the application of basic scientific principles and maths to find solutions to the problems faced by society.

Top 15 Engineering Colleges
Best 10 Engineering Colleges
CollegeDetailsLocationStateScore out of 100NIRF Rank
IIT MadrasMore DetailsChennaiTamil Nadu89.931
IIT  DelhiMore DetailsNew DelhiDelhi88.082
IIT BombayMore DetailsMumbaiMaharashtra85.083
IIT KanpurMore DetailsKanpurUttar Pradesh82.184
IIT KharagpurMore DetailsKharagpurWest Bengal80.565
IIT RoorkeeMore DetailsRoorkeeUttarakhand76.296
IIT GuwahatiMore DetailsGuwahatiAssam74.907
IIT HyderabadMore DetailsHyderabadTelangana66.448
NIT TiruchirappalliMore DetailsTiruchirappalliTamil Nadu64.109
IIT IndoreMore DetailsIndoreMadhya Pradesh62.8810
IIT (BHU) VaranasiMore DetailsVaranasiUttar Pradesh62.5411
IIT (ISM) DhanbadMore DetailsDhanbadJharkhand62.0612
NIT SurathkalMore DetailsSurathkalKarnataka61.3013
Anna UniversityMore DetailsChennaiTamil Nadu59.8914
Vellore Institute Of TechnologyMore DetailsVelloreTamil Nadu59.3215

Now let’s have a closer look at the best 10 Colleges

Best Engineering Colleges in India

1. IIT Madras- One of the best Engineering Colleges in India for 5 years in a row

IIT Madras boasts of a vibrant residential campus situated in Chennai, which provides an unparallel environment for the personal and professional growth of students. 

  • Ranked as the top engineering institute in India for 5 years in a row (2016-2020) by the NIRF.
  • Has a deep technology startup ecosystem, excellent campus infrastructure, generous alumni support, and involvement
  • Offers UG and PG degree programs, M.S. and Ph.D. research programs across 16 departments.
  • Placements: Average – Rs. 8 L.P.A/- Highest – Rs. 95.8 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

Also read: BE Civil engineering subjects semester wise complete details.

2. IIT Delhi

Situated in Delhi, the capital of India, it is one of the finest institutions in India.

  • Offers various disciplines including Engineering, Physical Sciences, Management, and Humanities & Social Sciences.
  • Placements: Average – Rs. 17.53 L.P.A/- Highest – Rs. 27.07 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

3. IIT Bombay- Best Engineering Colleges in India (QS Ranking)

Located in Powai, Mumbai the strategic location offers the advantage of being in the financial capital of the country while enjoying the serene natural beauty of the campus which shares borders with the Sanjay Gandhi National Park.

  • With an overall score of 79.9, it was Ranked 1st in India and 49th globally in Engineering and Technology in the Quacquarelli Symonds (QS) World University Rankings.
  • Placements: Average – Rs. 10 L.P.A/- Highest – Rs. 182 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

If you wish to dig into your ideas in the lap of nature like Newton did once, then IIT Bombay is your place.

4. IIT Kanpur

A premier institute located in the city of Kanpur with the motto of creating, disseminating, and translating knowledge in science, engineering, and allied disciplines.

  • IIT Kanpur has some of the unique innovations to its credit including the first solar-powered Indian-made UAV and India’s first nanosatellite Jugnu.
  • Offers a host of interdisciplinary programs like Cognitive Science, Nanotechnology, Nuclear Engineering, etc.
  • Placements: Average – Rs. 10 L.P.A/- Highest – Rs. 100 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

Also read: Civil engineering subjects; Skills mastered and Applications.

5. IIT Kharagpur

Spread over 2100 acres of campus at Kharagpur, this premier institute welcomes its students not only with libraries and classrooms but also with lush greenery, lakes, lawns, stadiums, tennis courts, hockey, football, and cricket grounds, as well as a gym and a swimming pool.

  • Offers about 30 micro-specialisation courses including intellectual property rights, quality engineering, management, law, social science, and foreign languages.
  • At the end of your B.Tech, the institute molds you into something more than a techie.
  • It boasts of notable alumni like Sundar Pichai
  • Placements: Average – Rs. 10 L.P.A/- Highest – Rs. 42 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

6. IIT Roorkee-Oldest among best engineering colleges in India

With 174 years of rich heritage, IIT Roorkee is the oldest technical institution in Asia. It is located at Roorkee in Uttarakhand.

  • Has 21 academic departments which cover engineering, applied sciences, humanities & social sciences, and management programs.
  • Also ranked 12th among management schools in India by the National Institutional Ranking Framework in 2020
  • Placements: Average – Rs. 10 L.P.A/- Highest – Rs. 80 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

7. IIT Guwahati

With the mighty Brahmaputra river flowing on one side and hills on the other, IIT Guwahati has probably the most beautiful campus in India.

  • Hosts Param-Ishan which is the fastest and most powerful supercomputer in northeastern, eastern, and southern regions of the country.
  • Offers B.Tech, B.Des, M.Tech., M.Des., MA, M.sc., and Ph.D. programs over 11 departments.
  • Placements: Average – Rs. 14.6 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

8. IIT Hyderabad

Located in Hyderabad, it is the first institute to launch an executive MTech Programme in Data Science for working executives and professionals.

  • Offers courses in liberal arts and creative arts including macroeconomics, introductory psychology, Japanese, French, German language, etc.
  • Placements: Average – Rs. 10 L.P.A/- Highest – Rs. 35 L.P.A/-
  • Admission/ Entrance Exam: JEE Advanced and GATE

9. NIT Tiruchirappalli

Located at Trichy, Tamil Nadu the 800 acres campus of NIT Trichy is one of the largest academic campuses in India.

  • Has been retaining its No.1 position among all NITs for 5 years in a row in the “India Rankings 2020” released by NIRF.
  • Best among all NITs.
  • Bagged the  “University of the Year” award in the Federation of Indian Chambers of Commerce and Industry awards in 2017
  • Placements: Average – Rs. 9 L.P.A/- Highest – Rs. 70 L.P.A/-
  • Admission/ Entrance Exam:  JEE Mains and GATE

10. IIT Indore 

It is located in Indore, Madhya Pradesh, and is one of the newly established IITs.

  • Despite being a relatively young IIT, it has proved its stature with higher rankings, 98% placement rate, 100% Ph.D. holding faculty, and 8.19% surge in the graduation rate.
  • Placements: Average – Rs. 16 L.P.A/- Highest – Rs. 36.48 L.P.A/-
  • Admission/ Entrance Exam:  JEE Advanced and GATE

Also see: Basics of civil Engineering -Simple and in depth guide.

So you have got an idea about the best colleges in India. Let me know which is your dream college and why you wish to study in that particular college. Comment below.

CONCRETE, quality tests on concrete

Compaction factor test – Workability of concrete-Test procedure

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Compaction factor test is a practical and reliable method used to assess the workability of concrete, especially when the mix is stiff and does not show clear results in a slump test. The compaction factor test for workability of concrete evaluates how easily concrete flows under gravity. It also assesses how it compacts by comparing partially compacted concrete with fully compacted concrete. In the workability of concrete compaction factor test, engineers gain a more accurate understanding of concrete consistency for low to medium workability mixes. Following the compaction factor test procedure helps achieve consistent results during laboratory testing. The compaction factor test of concrete is commonly applied in mix design and quality control and remains one of the dependable tests for workability of concrete used in practice. Compaction factor test is a lab test and is generally conducted on concrete samples having very low workability.

This article explains the compaction factor test, covering its principle, procedure, significance, advantages, limitations, and role in accurately evaluating the workability of concrete.

  1. Significance of Quality tests on concrete
  2. Production stage quality tests on fresh concrete
  3. Significance of compaction factor test
  4. Compaction factor test for workability of concrete
    1. Compaction Factor Test – Relevant codes
    2. Apparatus used
    3. Compaction factor test procedure
  5. Key Takeaways
  6. Conclusion

Significance of Quality tests on concrete

Quality tests on concrete are essential for ensuring strength, durability, and performance in construction. These tests help engineers assess the workability of fresh concrete and the quality of hardened concrete. Common quality tests on concrete include checks during the production stage (on fresh concrete before placing), tests on hardened concrete specimens, and evaluations performed directly on finished structures. Including tests like the flow table test for concrete ensures reliable results and consistent quality throughout a project.

A construction worker wearing a hard hat and safety vest examines concrete samples on a workbench, including a concrete compression testing machine and molds.
A civil engineer in a safety helmet and reflective vest analyzing concrete test specimens in a lab, showcasing the importance of quality control in concrete workability tests.

Following are the stages of quality tests

  • Production stage quality tests ( On fresh concrete before placing)
  • Hardened stage quality tests ( hardened concrete specimens)
  • On structures ( tests done on the structures )

Production stage quality tests on fresh concrete

Production stage quality tests on fresh concrete are crucial for ensuring the right workability and consistency before placement. These tests help engineers select the best mix for construction and maintain quality control. Key tests include the slump test, compaction factor test, Vee-Bee test, Kelly ball test, and the flow table test for concrete.

This article focuses on the Compaction factor test, explaining its procedure, importance, and how it compares with other workability tests like the slump test and other tests

Significance of compaction factor test

The compaction factor test is significant because it accurately measures the workability of concrete. This is especially true for stiff and low-slump mixes. This test provides more precise results than the slump test. It supports effective mix design. It also ensures consistent concrete quality through reliable laboratory-based workability assessment.

Compaction factor test for workability of concrete

The compaction factor test is used to determine the workability of concrete. Workability refers to the ease and uniformity with which freshly mixed concrete can be mixed, placed, compacted, and finished. Workability also represents the internal effort required to achieve full compaction. The compaction factor test of concrete was developed by the Road Research Laboratory, UK. It provides more precise and accurate results than the slump test. This test is especially suitable for stiff concrete mixes that do not slump and require vibration for compaction. The compaction factor test measures the degree of compaction under controlled conditions. It offers a reliable method for assessing concrete consistency in laboratory and quality control applications.

Also read : Bitumen – 9 lab tests on bitumen for flexible pavements.

Also read : Timber – Five important quality tests

Compaction Factor Test – Relevant codes

  • IS 1199 (Part 2): 2018 – Methods of Sampling and Analysis of Concrete – Workability
  • BS 1881 (Part 103) – Testing Concrete – Method for Determination of Compaction Factor
  • ASTM C1170 / C1170M – Workability of Fresh Concrete by Compaction Factor Method (Reference use)
  • DIN 1048 – Testing Methods for Fresh Concrete

These codes provide standardized procedures for conducting the Compaction Factor Test and ensure reliable evaluation of concrete workability.

The Compaction Factor Test method followed in IS 1199 (Part 2) is fundamentally the same as those in British standards. It is also similar to other international standards. All codes measure workability by comparing partially compacted concrete with fully compacted concrete.

  • Principle: Same across all standards
  • Apparatus: Same (two hoppers + cylinder)
  • Calculation: Same compaction factor ratio
  • Differences: Minor variations in dimensions, tolerances, and wording

Apparatus used

A female laboratory technician in a white lab coat and protective goggles is pouring a substance from a can into a blue funnel system, while a male colleague works in the background in a modern laboratory setting.
Laboratory setup for conducting the compaction factor test on concrete, demonstrating the apparatus used to measure workability.
  • Compacting factor apparatus
  • Cylindrical mould 
  • Hand scoop 
  • Trowel
  • Weighing machine
A blue civil engineering apparatus featuring two hoppers and a collecting bucket, designed for material testing.
Apparatus used for the Compaction Factor Test, designed to accurately measure concrete workability.

The figure shows the dimension of the hopper and the mould. The inside area of the hopper should be smooth. The apparatus is made of bronze or cast brass. At the lower ends of the hopper, there is a trap door with a 3mm thickness. A rigid frame attaches the hoppers and cylinder. After the completion of mixing, the test is conducted at a constant time interval. 

Compaction factor test procedure

  • Place the sample in the upper hopper of the apparatus using a hand scoop.
  • Fill the hopper with its brim level and open the trap door.
  • Then allow the concrete to fall into the lower hopper.
  • Immediately after the concrete rests, uncover the cylinder and open the lower trap door.
  • Cut off the excess amount of concrete above the cylinder using the trowel.
  • Then weigh the concrete in the cylinder nearest to 10g. This is the weight of partially compacted concrete.
  • Refill the cylinder with the same sample in the layers and the layer is heavily rammed or vibrated for full compaction.
  • Then weigh the fully compacted concrete and the weight of the empty cylinder.
  • Finally, Compute the compaction factor using the formula.

The compaction factor is the ratio of partially compacted concrete to fully compacted concrete.

Compaction factor = (W1 – W) / (W2 – W)

The compaction factor value varies from 0.7 to 0.95.

Key Takeaways

  • The Compaction Factor Test is used to evaluate the workability of concrete, especially stiff mixes.
  • It is more sensitive and accurate than the slump test for low-workability concrete.
  • The compaction factor test for workability of concrete measures ease of compaction under gravity.
  • It is best suited for laboratory-controlled conditions.
  • The workability of concrete compaction factor test helps compare different mix designs.
  • The test uses two hoppers and a cylindrical mould.
  • Following the compaction factor test procedure ensures consistent results.
  • The compaction factor test of concrete minimizes subjective judgment.
  • It supports quality control and mix optimization.
  • It is one of the reliable tests for workability of concrete.

Conclusion

The Compaction Factor Test remains an important method for assessing the workability of concrete. This is particularly true for mixes that show little or no slump. By measuring the ratio of partially compacted to fully compacted concrete, the compaction factor test for workability of concrete provides a clear and quantitative indication of consistency. When engineers follow the standard compaction factor test procedure, the results help in evaluating mix performance and maintaining uniform quality. The workability of concrete compaction factor test is especially useful in laboratory testing and mix design studies. As one of the established tests for workability of concrete, the compaction factor test of concrete continues to support accurate quality control and better construction outcomes.

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