Soundness Test of Cement

Introduction

     Soundness means the ability to resist volume expansion. In the soundness test, a specimen of hardened cement paste is boiled for a fixed time so that any tendency to expand is speeded up and can be detected. Le-Chatelier’s apparatus is used for this test. This apparatus measures the excess lime in the cement.

Objective(s) of the Experiment

     The test is carried out to determine the soundness of cement using Le-Chatelier’s apparatus.

Equipments Needed

1. Le-Chatelier apparatus
2. Water bath
3. Caliper or Ruler
4. Measuring cylinder
5. Balance
6. 2 Glass plates
7. Trowel

Procedures

1. Before commencing setting time test, do the Consistency Test to obtain the water required to give the paste normal consistency (P).
2. Prepare a paste by adding 0.78 times the water required to give a paste of Standard Consistency (i.e. 0.78P).
3. Lightly oil the Le-chatelier mould and place it on a lightly oiled glass plate.
4. Fill the mould with the prepared cement paste. In the process of filling the mould keep the edge of the mould gently together.
5. Cover the mould with another piece of lightly oiled glass plate, place a small weight on this covering glass plate.
6. Submerge the whole assembly in water at a temperature of 27 ± 2^oC and keep there for 24 hours.
7. Remove the whole assembly from water bath and measure the distance separating the indicator points to the nearest 0.5 mm (L₁) as shown in the figure below.
8. Again submerge the whole assembly in water bath and bring the temperature of water bath to boiling temperature in 25 to 30 minutes. Keep it at boiling temperature for a period of 3 hours.
9. After completion of 3 hours, allow the temperature of the water bath to cool down to room temperature and remove the whole assembly from the water bath.
10. Measure the distance between the two indicator points to the nearest 0.5 mm (L₂) as shown.

Result and Calculation

Soundness/expansion of cement = L₁ – L₂
Where:
L₁=Measurement taken after 24 hours of immersion in water at a temperature of 27 ± 2^oC
L₂=Measurement taken after 3 hours of immersion in water at boiling temperature.

Discussion and Conclusion

Le-chatelier method can be used to find out the presence of unburnt lime (CaO).Presence of unburnt lime may develop cracks in the cement because of increase in volume. The standard specifications for different types of cement are shown below

Standard Specifications

References

1. CivilBlog. ‘Soundness of Cement by Le-Chateliers Method (IS: 4031 – Part 3-1998)’ http//www.civilblog.com/2017/10/12/soundness-of-cement/ Assessed on March 6, 2018.

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