Why soundness test on cement?

RathnashikamaniStarred Page By Rathnashikamani, 20th Feb 2012 | Follow this author | RSS Feed | Short URL http://nut.bz/129sh0on/
Posted in Wikinut>Guides>Science>Materials And States

Cement is the most important construction material that binds the building blocks and extensively used in production of concrete.

Cement shall not undergo any appreciable change in volume after it sets within the specified time period.

Sound cement will not undergo change in its volume after its final setting. Here is an explanation why soundness test on cement is very important.

Soundness Test on Cement

It is very essential that the cement after setting shall not undergo any appreciable change in volume, because change in volume after setting of cement causes
cracks, undue expansion,and as a result disintegration of concrete
.

Soundness of cement is determined using the Le Chatelier apparatus. This apparatus consists of a split cylinder made of spring brass or other suitable metal.

The cylinder is 30 mm in diameter and 30 mm high. The cylinder has two indicator arms 165 mm long (measured from the center of the cylinder) with pointed ends on either side of the split.

The procedure for test is explained in the following reference links:

Soundness Test on Cement

Test to check soundness of cement

And the following video shows how the test is conducted.

Why soundness test is required to be carried out on cement?

Quality control during the manufacturing of cement influences its soundness. The unsoundness in cement is due to the following factors during its production:


    => If there is an excess of lime present in the cement.

    => If the cement would have undergone inadequate burning

    => Insufficiency in fineness of grinding or non-uniform mixing of raw materials.

    => If there is too high a proportion of magnesium content in the cement.

    => If there is too high calcium sulphate content in the cement.

As unsoundness in cement does not show up for a considarable period of time, accelerated tests are required to detect it before using the cement in the work.

How to achieve better soundness of cement?

To achieve better soundness properties of cement,

    => The magnesia content allowed in cement is limited to not more than 6 per cent.

    => Calcium sulphate (CaSO4) ie gypsum is added to the clinker while grinding to prevent flash set of cement.

    => The quantity of gypsum in cement manufacturing varies from 3 to 5 per cent depending upon Tricalcium Silicate (C3A) content.

What happens if gypsum is more in cement?


If gypsum (Calcium Sulphate) is more than that could be combined with C3A, excess quantity of this gypsum will remain in the cement in free state. This excess of gypsum causes expansion in cement when mixed with water and leads to disruption of the set cement paste.

* * *
Image credits:
Cement grains By Andrew R. Barron (http://cnx.org/content/m16445/latest/#grain) , via Wikimedia Commons

Cement bags By StaraBlazkova (Own work) , via Wikimedia Commons

Sound cement makes sound structures {Building at 10 Calle de Francisco Gervás (street) in Madrid, Spain}By -Merce- from Spain (Flickr) , via Wikimedia Commons

Gypsum By CFT at de.wikipedia (Original text : Carl 20:52, 2. Mai 2007 (CEST)) , from Wikimedia Commons

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Comments

author avatar Delicia Powers
14th Mar 2012 (#)

great information that will come in handy this spring as I need to replace a fence post in some new cement and this is very helpful information in that project, thank you...:0)

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author avatar Rathnashikamani
15th Mar 2012 (#)

Thank you Delicia.

I think you'll be able to get some good quality precast fence posts in your area, so you need not go into the process of casting it insitu.

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author avatar Buzz
14th Mar 2012 (#)

What a very useful info on building construction, among other things, dear friend. Nice you wrote an article from your profession as an engineer. Namaste!

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author avatar Rathnashikamani
15th Mar 2012 (#)

Namaste my friend.

I thought I must write something professional that makes my effort easy as I know the subject well.

And I hope Wikinut administration will create appropriate categories that would accommodate technical articles.

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author avatar Retired
14th Mar 2012 (#)

Very informative and well-researched. Great star page. *applause*

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author avatar Rathnashikamani
15th Mar 2012 (#)

Thank you rd-ji for the applause.
You're right, I've compiled this page with an effort to present it differently when compared to the already available similar kind of pages.

Namaste!

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author avatar Jules Castillo
14th Mar 2012 (#)

you must be an engineer my friend

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author avatar Rathnashikamani
15th Mar 2012 (#)

Yes my friend, thank you.

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author avatar Mikey.
14th Mar 2012 (#)

Hi Rhatna,I work in a quarry,We use a lot of cement in ready mixed concrete and the making of concrete blocks for building. I enjoyed reading your article very much.

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author avatar Rathnashikamani
15th Mar 2012 (#)

Thank you Mikey.
Nice to know that we have the same kind of tough work experiences at construction sites.

Hope to see you sharing your technical knowledge here at Wikinut.

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author avatar Songbird B
16th Mar 2012 (#)

Excellent and as always informative Star Page Rathna dear friend! I always learn so much from you..

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author avatar avery sandiego
17th Mar 2012 (#)

This is very helpful and informative article...Great work!

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author avatar Sivaramakrishnan A
18th Mar 2012 (#)

I become aware again that what we take for granted has not been achieved with ease. We need to take the basics seriously. Thanks Rathna, for the share - siva

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author avatar Don Rothra
18th Mar 2012 (#)

Great information, but I'm glad I'm retired from all the construction business. I remember having to have our foundations tested and inspected. I never had a test fail. (lucky)

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author avatar vpaulose
22nd Mar 2012 (#)

Shining star sounds in this slurry cement work. Thank you Rathna. I missed you for long.

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author avatar Denise O
27th Mar 2012 (#)

Rathna, just great information on cement that I never even thought of, good thing we have such intelligent folks like you, that do this work for us. Congrats on the star page, it is well deserved. As always, thank you for sharing.:)

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author avatar Ivyevelyn, R.S.A.
29th Mar 2012 (#)

Hello, Rathnashikamani:
I have fallen behind but I am pleased I have caught up with your cement page. I remember helping my father mix cement. Thank you for an interesting page. I have always wanted to put my hand into cement and know it will stay there for a long, long time.
Love, Ivyevelyn.

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author avatar 7979barb
12th Apr 2012 (#)

good article, not to be a conspiracy nut here but that being the case with cement how was it the twin towers and the cement used in them were turned to dust? I think explosives but that is just my opinion. Good article thanks

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author avatar sarosh
2nd May 2012 (#)

Nice info

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author avatar Naseer Ahmed
4th Jun 2014 (#)

this is good artcle. but i want to tell just one thing the acces of calcium sulphate reduce the striength of cement

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author avatar Deepak pawar
29th Mar 2017 (#)

Soudnes

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author avatar Deepak pawar
29th Mar 2017 (#)

Soundness test

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author avatar Ramesh Ranjan
17th Nov 2017 (#)

Excellent

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