SOUNDNESS OF CEMENT BY LE-CHATELIERS METHOD

SOUNDNESS OF CEMENT BY LE-CHATELIERS METHOD (IS:4031-PART 3-1988)

OVERVIEW

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. Soundness means the ability to resist volume expansion.

APPARATUS

MEASURING INSTRUMENTS

NAME	CAPACITY / RANGE / SIZE	ACCURACY / LEAST COUNT
Le-chatelier apparatus	Should be made as per IS:5514
Water bath	1000C (min)	10C
Caliper	30 cm	0.5 mm
Measuring cylinder	100 ml	1 ml
Balance	100 g	1 g

OTHER APPARATUS

Glass sheets (2 nos), Enamel tray, trowel

Le chatelier Apparatus

ENVIRONMENTAL CONDITIONS

Temperature	27 ± 20 C
Humidity	65 ± 5 %

PROCEDURE

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 sheet.
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 sheet, place a small weight on this covering glass sheet.
6. Submerge the whole assembly in water at a temperature of 27 ± 20 C 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).
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).

CALCULATIONS

Soundness/expansion of cement = L1-L2

L1=Measurement taken after 24 hours of immersion in water at a temp. of 27 ± 20 C

L2=Measurement taken after 3 hours of immersion in water at boiling temperature.

Calculate the mean of two values to the nearest 0.5 mm.

• Note::In the event of cement failing to comply with the specified requirements, a further test should be made from another portion of the same sample in manner described above, but after aeration (done by spreading out to a depth of 75 mm at a relative humidity of 50 to 80% for a total period of 7 days).

PRECAUTIONS

• All the measurements should be done accurately.
• Do not apply extra pressure while filling the moulds.
• During boiling water level should not fall below the height of the mould.

STANDARD SPECIFICATIONS

Type/Name of cement	Reference Indian standard	Expansion (max.)
OPC (33)	IS:269-1989	10 mm
OPC (43)	IS:8112-1989	10 mm
OPC (53)	IS:12269-1987	10 mm
Rapid hardening	IS:8041-1990	10 mm
Low heat cement	IS:12600-1989	10 mm
Super sulphated	IS:6909-1990	5 mm
Portland pozzolana	IS:1489-1991(part 1)	10 mm
PSC	IS:455-1976	10 mm
High alumina cement	IS:6452-1989	5 mm
SRC	IS:12330-1988	10 mm
Masonry cement	IS:3466-1988	10 mm
IRS-T-40	Railway standards	5 mm

TECHNICAL DISCUSSION

• Volume expansion in cement mortar or in cement concrete is caused by the presence of unburnt lime (CaO), dead burnt MgO and also CaSO4.
• By Le-chatelier method we can only find out presence of unburnt lime (CaO).
• Presence of unburnt lime may develop cracks in the cement because of increase in volume.
• Free lime (CaO) and magnesia (MgO) are known to react with water very slowly and increase in volume considerably, which result in cracking, distortion and disintegration.

TEST STANDARD REFERENCE

• IS:4031(Part 3):1988-Methods of physical tests for hydraulic cement (Determination of soundness)