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Soundness Test on Cement | By Lechatliers Apparatus

“The first step toward success is taken when you refuse to be a captive of the environment in which you first find yourself.”

It is necessary that Cement after hardening should not undergo any kind of change in volume. Certain cements are found to undergo large expansion on Hardening. This may cause serious problems in the durability of the structure. Testing of Cement for Soundness is done to ensure that the Cement does not show any appreciable subsequent expansion.

Unsoundness is due to the presence of an excess of Lime, Magnesia, Sulphates, and gypsum. Expansion is also due to Inadequate Burning, Insufficiency in Fineness, Insufficient Mixing.

What is the Soundness of Cement?

What is mean by soundness of cement? This is what soundness definition in civil engineering says “The ability of cement to resist the expansion and retain its original volume is called Soundness of Cement.” This indicates that a perfectly sound cement will undergo minimum volume change.

What is the soundness test?

The soundness test measures the change in volume due to expansion. This expansion should not exceed 10 mm for OPC, rapid hardening cement and low heat Portland cements. If the expansion goes more than 10 mm on testing, the cement is said to be unsound.

The soundness test can be conducted by Le-chatelier method and Autoclave Method. Le-chatelier test detects unsoundness due to free lime only.

Cement having a magnesia content of more than 3 percent shall be tested for soundness by Autoclave test which is sensitive to both free magnesia and free lime.

Why is soundness test done for Cement?

Unsoundness in cement is due to excess of lime, excess of magnesia or excessive proportion of sulphates.
Unsoundness in cement does not come to the surface for a considerable period of time. Therefore, accelerated tests are required to detect it.

Significance of Soundness Test on Cement

The Le Chatelier test detects unsoundness due to free lime only. Le-Chatlier’s method of testing does not indicate the presence and after effect of the excess of magnesia. Indian Standard Specification specifies that a cement having a magnesia content of more than 3 percent shall be tested for soundness by Autoclave test which is sensitive to both free magnesia and free lime.

There is no satisfactory test is available for the deduction of unsoundness due to an excess of calcium sulphate. But its content can be easily determined by chemical analysis



Determination of Soundness of Cement by Le-Chatelier’s Apparatus

Aim:

To determine Soundness of cement by Le-Chateliers apparatus.

Apparatus :

  1. Weighing Balance
  2. Specific Gravity Bottle
  3. Le-Chatliers Apparatus
  4. Water Bath
  5. Measuring Cylinder

Procedure :

  1. Before conducting test Oil the mould and glass plate.
  2. Now fill the mould with gauging Cement paste made with 0.78 times water required to give paste of standard Consistency.
  3. Cover the surface by any kind of Oiled sheet.
  4. Place a small weight on the sheet and allow the whole assembly to submerge into water immediately with normal room temperature for 24 hrs.
  5. Remove the assembly after 24hrs and measure the distance separating the indicator points and submerge the mould again.
  6. Bring the water Boiling with mould kept in it to 20 to 30 min then keep it boiling for 3 hrs.
  7. Now remove the mould allow it to cool and then measure distance between indicator points.
  8. The difference between two measurements indicates the expansion in the Cement. This must not exceed 10mm otherwise Cement is said to be unsound.

Precautions:

  • In weighting balance, the permissible variation at a load of 1000 g shall be ± 1.0 g. The permissible variation on new balance shall be one-half of this value. The sensibility reciprocal shall be not greater than twice the permissible variation.
  • Le- Chatelier apparatus conforming to 5.0 of IS: 4031 ( Part 3 ) – 1988.
  • Water bath should be capable of containing immersed Le-Chatelier moulds with specimens and of raising their temperature from 27±2°C to boiling in 27±3 minutes.
  • Vernier Calliper should be able to measure upto 30 mm with least count of 0.1 mm
  • Filling of moulds must not be done by applying extra pressure.
  • During the process of boiling, the water level must not go below the height of the mould.

Figure:

Observation Table:

Sr.No.Difference between the indicator after submerging for 24hrs at room temperature (L1)Difference between the indicator after boiling for 3 hrs (L2)Difference between two readings (L1-L2)
1
2
3

Calculations:

Formula for Soundness Test on Cement:

Expansion= L1 – L2

Here,

L1= Difference between the indicator after submerging for 24hrs at room temperature (L1)

L2= Difference between the indicator after boiling for 3 hrs (L2)

Results:

Average expansion of cement is=_ _ _ _ _ _

Conclusion:

The expansion should not exceed 10 mm for OPC, rapid hardening cement and low heat Portland cements. If the expansion goes more than 10 mm on testing, the cement is said to be unsound.

Le-Chatliers Apparatus helps us to find excess Lime present in Cement. Presence of unburnt lime may develop cracks in the cement because of increase in volume.


Expansion Limits of Different Types of Cement

Types of CementExpansion Limits
Ordinary Portland cement [OPC] 33 Grade, 43 Grade, 53 grade10mm
Portland Pozzolona Cement [PPC]10mm
Rapid Hardening cement10mm
Low heat cement10mm
Super sulphated cement5mm

Video Explanation on Soundness Test on Cement


FAQs Soundness Test on Cement

What is sound cement?

Perfectly sound cement will undergo minimum volume change on hardening but does not cause any damage to the structure. Ideally perfectly sound cement must not undergo any volume changes.
Practically every cement type undergoes volume changes but it should be in permissible limits as specified above.

What is unsound cement?

Unsound cement will undergo volume change on hardening this will allow the cement to expand or contract and can result in the formation of cracks on surface.

What is the importance of soundness of cement?

As we discussed earlier soundness is the ability of cement to retain its volume as soon as it hardens or solidified. Unsound cement will undergo volume change on hardening this will allow the cement to expand or contract and can result in the formation of cracks on surface.
Sound cement will undergo minimum volume change and ultimately result in no formation of cracks.

Is code for soundness test of cement?

The soundness of cement may be determined by two methods, namely Le-Chatelier method and the autoclave method as described in 5.0 and 6.0 of IS: 4031 ( Part 3 ) – 1988.


Soundness Test on Cement PPT


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