Field test of brick, cement, sand and stone chips are very much essential as they are the most common construction materials which are used in almost all of the civil engineering construction from brickwork to floor finishing everywhere. As a civil engineer, working in a site is the challenging one, as on the site engineer all the responsibility and liabilities depends upon for good quality construction.But alone a good supervision is not enough for a good construction having required properties and durability. A proper quality control is essential at all the stages, specially at the very start , where we have to select right materials for a type of construction, as the materials are the cell of each structure. A Civil Engineer may not always have the facility of laboratory at the site for the testing of materials so as to ascertain the quality of a material weather it is bad or good, suitable or not. So a civil engineer should be able to judge the quality of the basic construction materials such as Brick, Cement, Sand and Stone Chips by means of Visual Inspection of those materials, which can be done by doing the Field Test on those materials. Here I’ve listed the different field tests for basic construction materials which becomes necessary in day to day work.
How To Check If A Brick Is Good? ==>
The following field tests are to be performed in order to determine if a Brick is good :-
A good brick should be of proper shape and standard specified size, the edges of it should be sharp, there should not be any cracks and fissures on the brick.
The colour of a good brick should be copper red colour. A yellowish tint on brick indicates that it is under burnt and hence possessing of lower strength, and if a brick is of dark blackish blue colour then it indicates the brick is over burnt and is brittle in nature.
When a brick is struck by a hammer or against another brick, it should emit a clear metallic ringing sound, it should not be dull.
A freshly fractured brick should show a homogeneous compact structure without any lumps.
If a brick is dropped from about a height of 1m on a hard ground or on another brick, it should not break.
When a brick is scratched with finger nail it should not leave any impression on the brick.
A good brick (1st Class) should not absorb water by not more than 20% of its own Dry weight when immersed in water for a period of 24 Hours.
How To Check If Cement Is Good? ==>
The following field tests should be performed to determine if the cement is of good quality :-
The cement should be of Greenish Gray colour for Ordinary Portland Cement, and Blackish Gray colour for Portland Pozzulana Cement and Whitish Gray colour for Portland Slag Cement.
There should not be any hard lumps on cement, the cement should be finely powdered. If cement contains hard lumps, then it must be rejected.
The cement when rubbed between fingers should feel smooth, it should not feel granular. If it is granular then it means adulteration with sand.
A cement paste should feel sticky in between fingers.
When hand is dipped into a heap or into a bag of cement, it should feel cool, not warm.
If a hand full of cement is thrown into a bucket of water, the cement should sink, not float as the Specific Gravity of Cement is greater than that of Water.
If a thick cement paste made on a glass and immersed in water should set, not crack.
How To Check If Sand Is Good? ==>
GOLDEN YELLOW SAND, A SIGN OF GOOD QUALITY SAND
The following tests should be performed to determine the quality of Sand :-
The Sand should be free from organic impurities and mineral salts, The maximum permissible quantity of organic impurities should be restricted to 5%.
The Sand should be of Golden Yellow colour.
The Sand particles should be sharp and angular to increase the interlocking property between the sand particles.
The sand should coarse for Concreting and medium sand may be allowed in brickwork and is preferable for plastering works.
How To Check If Stone Chips Are Good? ==>
STONE CHIPS STACK
The visual tests or field tests for Coarse aggregate, that is stone chips are very limited though there are many laboratory tests are available. Mainly the following things are observed as for Field Test :-
The Stone Chips are to be well graded to increase the mechanical interlocking between them.
Stone Chips should be Angular as far as possible and be porous.
The Stone Chips should not be flaky and elongated.
The Stone Chips should not contain organic and other impurities, as only 5% clay content in concrete can reduce the strength of the concrete as much as 20%.
I hope this article will help you in your day to day work, as a Civil Engineer I feel these small little things are very much important as a good material is inevitably necessary to produce good construction. Taking care of these small things can turn out great results, which otherwise may not be achieved by higher designing standards. Quality control is the key to the construction, as the Ingredient of good quality will surely produce better taste isn’t it?.
In my next article I will discuss about the Top 10 Faults which are done by mason, and which are mostly ignored by the engineers but which may cause disastrous results in the ultimate structure.
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Academically a Civil Engineer (DCE, 1st Class with Distinction 90%), pursuing A.M.I.E. with specialization in Structural Engineering. Er. Chakraborty by profession is a Government Civil Engineer Officer, WBSSE(C) (Group - A, Gazetted). He is a Passionate Blogger in his field of excellence. He writes for upholding the ethics of this Nobel Profession and to share his experience to all Practicing Civil Engineers & Civil Engineering Students for the betterment of the Engineering fraternity.