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INSIDE WIRE OF CRACKING THE INTERVIEW

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Masterbuilder in collaboration with Baton Consultants is starting a series for students. The articles in this series are for students. They are written towards improving the thought process & making the students ready for the real world.

The real world, what is so different about the real world?

At the college level, many students do not get enough exposure to material, equipment & projects. There are several gaps between the curriculum and the actual working. In fact, I will not mince my words in calling the real world a cruel person, who expects civil engineers & architects to be well prepared & knowledgeable from day one.

CONCRETE – AN IMPORTANT MATERIAL IN CONSTRUCTION

What is it that I need to know about Concrete?

To give a concrete example,

Concrete is a multiphase material which is in a liquid state when fresh, can be poured into moulds of any shape and it is like the stone when sets and hardens which can take the huge compressive load. It is the magical substance which is used to build any building, structure, road or any other infrastructure project.

The secret behind concrete is the formulation of the mix proportion. Mix proportion will decide what material will go in what proportion to get concrete of required properties. A Column, beam, road, dam, tower etc., will need different strengths. The mix proportion is the main answers all their query.

 

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The four basic elements included in the recipe are cement, sand, aggregate & water. These are mixed along with some special admixtures to make the finest concrete. The fundamental source is mother nature. Cement is made from processing limestone which is mined. Sand used is either natural, which is dredged from river beds or manufactured from crushing rock. Aggregates are made from crushing rock which is mined from quarries by drilling & blasting. Therefore all the elements are coming from the earth. Human beings have successfully mastered the technique of converting earth into buildings, roads, dams, bridges, etc.

There have been examples of concrete like material, been used before the invention of modern cement by Joseph Aspdin in the year 1824. In 3000 BC, the Egyptians were using early forms of concrete to build pyramids. They mixed mud, stone, straw & some more materials to form huge blocks. These blocks were then glued together by using mortar made of gypsum and lime. In 300 BC to 476, the ancient Romans used a Volcanic ash a material that is remarkably close to modern cement to build many of their architectural marvels, such as the Colosseum, and the Pantheon. The Romans also used animal products in their cement as an early form of admixtures.

For making concrete on the large scale we require a large kitchen. This kitchen is called a batching plant. The batching plant holds the raw material in large storage bins called silos or on ground in stockpiles. Cement is stored in silo, aggregates & sand are in stockpiles. All the material is conveyed to reach the main hopper. Each item is carefully weighed online using a device called load cell.

All the precisely weighed material is mixed in an industrial mixer for a few minutes along with water to make a homogeneous mix. This mix is then transferred to the site by transit mixers and taken to higher levels manual or pumps. The process has to ensure that the mix does not solidify till it reaches the mould.

Trapped air is an enemy. Trapped air can cause major issues. Honeycombing in structures happens because bad proportions which do not allow the concrete to uniformly cover the entire space. Therefore the moulds have to be vibrated externally or internally to ensure that all the trapped air is removed & the concrete is evenly distributed in the entire mould.

 

 

The concrete admixture is a large subject by itself. These are the chemicals which have the capability to change the mood of the concrete. They can make it more workable or stay in liquid state for a longer time or increase the setting time or help it flow through pipes etc.

Concrete needs to be tested for its Density, Compressive strength, Flexural strength, Permeability, etc. Please ensure that you study all of them before appearing for your interview. These are the favourite questions of all interviewers.

The ready mix is a very popular concept. In concrete, we have two types of ready mix products, one that is ready to use & other that needs to be mixed at the site by addition of water in the right proportion. Ready to mix concrete is also sold in bags for minor works. However, the usual requirement is in masses & here the first option is preferred.

There is a good amount of research happening in the subject of recycling of concrete wherein older structures, which are demolished, can be crushed & the concrete could be recycled. The cement which is not completely hydrated also can be reused. Aggregates can also be re-used. This technology will help the environment & considerably reduce the mining activity.

Decorative Concrete is the latest trend. Designers are looking at different ways to create something that is unique & can be achieved at an optimal cost. The transformation of concrete into decorative concrete is achieved through the use of a variety of materials that may be applied during the pouring process or after the concrete is cured, these materials and/or systems include but are not limited to stamped concrete, acid staining, decorative overlays, polished concrete, concrete countertops, vertical overlays and as much as you can imagine.

Let your imagination run over ideas in concrete but do not forget your fundamentals which are based on the theory of concrete.

The Open Book Contest

This contest allows you to read books or search the internet for answers. What we are looking for is the writing style specially the explanation part which needs to be crisp & smart. Please take part in this contest. It will give you a chance to interact with the author as well as help brush up your knowledge for that special interview & get your dream job.
Author’s Bio

 

 

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Mandar Chitre, Consultant, Trainer & Writer

Mandar Chitre is a Consultant, Trainer & Writer. He comes with a 20 years of ex-perience in the construction & building material industry. Mandar is an engineering graduate with masters in marketing. He also holds a diploma in business management & indirect tax. He is one of the very few marketing professionals who also holds a diploma in corporate laws. Mandar has a completely diversified portfolio ranging from multinational to owner driven companies & sales to supply chain. As a writer, he has won a few national prizes.

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