## SOUNDNESS TEST OF CEMENT BY LE – CHATELIER METHOD

A cement is said to be unsound if the hydration of a hardened paste of it is eventually accompanied by excessive expansion, causing cracking and reduction in strength.
Accelerated hydration procedures are used routinely in cement production to check that it does not possess this property. The simple apparatus devised by Le Chatelier  is used to indicate the expansion of a paste.Here we will discuss about the practical of soundness test of cement

Standard Used

IS 4031 PART 3

Objective

• To determine the soundness of cement.

Equipment

• The apparatus for conducting Le-Chatter test shall conform to IS: 5514 – 1969.
• Balance of capacity 500 grams and sensitivity 0.01gms.
• Water bath capable of raising the temperature from 27+ 20C to boiling point in 27 + 3 minutes.

Procedure

• Take representative sample of cement and mix with 0.78 times the water required to give a paste of standard consistency as per IS: 4031 (Part 4) 1988.
• Place a lightly oiled mould on a lightly oiled glass and fill it with this cement paste.
• Prepare the paste in a manner and under the conditions all as per IS: 4031 (Part 4) 1988.
• Keep the edges of the mould gently together during this operation.
• Cover the mould with another piece of lightly oiled glass sheet and place a small weight.
• Immediately submerge the whole assembly in water bath maintained at a temperature of27 + 20C and keep there for 24 hours.
• After 24 hours remove the mould from the water bath and measure the distance separating the indicator points (E1).
• Again submerge the whole assembly in water bath at a temperature of 27 + 20C and bring the water to boiling in 27 + 3 minutes and keep it for 3 hours.
• Remove the mould from the water bath, allow it to cool and measure the distance between the indicator points (E2).
• The distance between the two measurements indicates the expansion of the cement.
• Make at least two determinations for each test.

Calculation

• Calculate the Soundness of cement from the equation given below

Soundness = E2 – E1

E1= Initial distance between the indicator points.

E2= Final distance between the indicator points.

Report

Report the individual and the mean results to the nearest 0.5mm.

Precaution

• Take care to maintain the temperature of the moulding room, dry material and water within 27 + 20C and the humidity of the laboratory within 65 + 5%.

## COMPRESSIVE STRENGTH TEST OF CEMENT MORTAR CUBE AS PER IS 4031 PART 6

###### 1.SCOPE

1.1 This standard IS 4031  ( Part 6 ) covers the procedure of finding out compressive strength of cement: The strength of cement is determined by compressive strength tests, on 70.6 mm mortar cubes, made with specified cement , sand & water mixed & compacted manually with a compacting bar  as well as with vibrating machine.

###### 2. SAMPLING AND SELECTION OF TEST SPECIMEN

2.1 . The representative sample of the cement selected as above shall be thoroughly mixed before testing requirements of different equipment used for testing of cement.

###### 3. TEMPERATURE AND HUMIDITY

3.1 The temperature of the testing room, dry material ingredient and water should be maintained at 27 ± 2°C & relative humidity of the chamber or room should be maintained at 65 ± 5 percent.

3.2 The curing tank or box temperature & relative humidity should be maintained at 27 ± 2°C and more than 90 percent respectively

###### 4. GENERAL

4.1 Standard Sand.- The standard sand which is to be used in the test shall confirm to IS: 650 -1966·

###### 5. APPARATUS

5.1 Vibration Machine – Vibration machine conforming to IS : 10080-1982.

5.2 Poking Rod – Poking rod conforming to IS: 10080-1982.

5.3 Cube Mould- The. mould should have a size of 70.6 mm x 70.6 mm x 70.6 size conforming to IS : 10080-1982.

5.4 Gauging Trowel – Gauging trowel  having steel blade 100 to 150 mm in length with straight edges weighing 210 ± 10 g.

5.5 Balance – Electronic balance with 1 gm accuracy shall be used.

5.6 Graduated Glass Cylinders – Graduated glass cylinders with capacity of 150 to 200 ml .

###### 6. PREPARATION OF TEST SPECIMENS

6.1 Mix Proportions and Mixing

6.1.1 The temperature of water & test room at the time of mixing operations shall be maintained at 27 ± 2°C. Use Potable water for preparing the cubes.

6.1.2 The cement , standard sand & water for each cube shall be taken as per below mentioned standard :

a.Cement 200 g

b.Standard Sand 600 g ( 200 gm of each grading)

c.Water ( P/4+ 3.0) percent of combined mass of cement and sand, where P is the normal consistency of cement.

If normal consistency of cement  is 29.5 (assumed)  calculation of water will be done as below:

( P/4+ 3.0) x  1/100 x 800 = ( 29.5/4+ 3.0) x 1/100 x 800 = 83 gram.

6.1.3 Place on a nonporous plate, a mixture of cement and standard sand, Mix it dry with a trowel for one minute and then with water until’ the mixture is of uniform colour. The quantity of water shall be used as calculated from above equation. The mixing time shall  be in between 3  to 4 minutes, the mixture shall be rejected  if the time is less than 3 minutes and more than 4 minutes and the operation should be repeated with a fresh quantity of cement, sand and water.

###### 6.2 Moulding Specimens

6.2.1 In assembling the moulds ready for use, the sides of the mould shall be made from ferrous metal. All parts shall be robust enough to prevent distortion & the joints between the sides of the mould and between the sides and the base plate shall be  coated with oil or grease to prevent leakage of water from mould .

6.2.2 Place the assembled mould on the vibrating table machine vibration by proper holding in position by suitable clamp  & shall not be removed until the completion of the vibration period.

6.2.3 Immediately after mixing the mortar properly , place the mortar in the cube mould and rodded with the rod specified rod. The mortar shall be rodded 20 times in about 8 second to eliminate entrained air . Pour the remaining quantity of  cement mortar into the hopper of the cube mould and rodded again as done previously for the first layer and then compact the mortar by vibration.

6.2.4 Keep the period of vibration 2 minutes at the  speed of 12000 ± 400 vibration per minute.

6.2.5 After the end of vibration, remove the mould with base plate from the machine and make proper smooth finish top surface of the cube mould with the blade of a trowel.

###### 6.3 Curing of Specimen

Keep the prepared cube mould filled in moist closet or moist room or curing tank  for 24 hours . After completion of 24 hours , remove the mould form cube and immediately keep in clean fresh water . The water in which the cubes are kept shall be changed after every 7 days and keep on maintaining temperature 27 ± 2°C.

###### 7. Testing

7.1 Take out the three test cubes each for 3 , 7 & 28 days respectively for testing of  compressive strength  after completion of test age  for different cements.

7.1.1 Place the test cube in center of cube testing machine without any packing and apply the load steadily and uniformly , starting from zero at a rate of 35 N/mm²/min.

###### 8. Calculation

8.1 Calculate compressive strength of cement by dividing the maximum load applied to the cubes during the test by the cross-sectional area, calculated from the mean dimensions of the section and shall be expressed to the nearest 0.5 N/mm².For more detail see my video in you tube.

## INITIAL SETTING TIME AND FINAL SETTING TIME OF CONCRETE

SCOPE:

In this test we will cover the determination of Setting time of cement by means of the Vicat Needle Apparatus.

APPARATUS :

a. Vicat Apparatus .

b.Weighing Device.

c.Graduated glass jar 200 ml capacity.

d.A trowel and containers.

1) Weigh 300 gram of the sample of the cement on a nonporous  and platform and make it into a heap with a depression at the center.

2) Calculate the amount of water required for making paste as 0.85 of the amount of water required to make a paste of standard or normal consistency.Add the calculated quantity of water and simultaneously  start the stop  watch.

3) Mix the cement and water together & filled in such a manner that the  mould is completely filled.Strike off the top level of the mold with the trowel and slightly tap the mold so as to expel out all entrapped air.

4) Place the mould just below Vicat needle apparatus & keep  1 mm square needle in exact position.Now  release the moving rod and note the reading . Now raise the moving rod & clear off all the cement paste and wipe off the needle clear.

5) Repeat the step no:4 above at regular interval of ½ minute till the reading  becomes 5 mm exactly.

6) Note down the time between adding water to dry  cement to the moment when the reading is 5 mm.

7) Now remove the 1 mm needle from the rod and replace it by another needle for determining the final set.

8) As before allow the moving rod to travel downwards at every 2 minutes interval.When the needle makes a move but the metal attachment fails to do so note the total time elapsed.

9) Remove the needle, clean the apparatus with water .

RESULT:

Initial setting time of cement is ____________________

Final setting time of cement is ____________________