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Soundness test on Cement – Procedure and Calculation

The soundness of the cement is the ability to resist volume changes after hardening. The soundness test on cement is significant because,using unsound cement leads to cracks and hamper the structural quality. A sound cement is one of the key materials used in construction. Therefore it is essential to determine its quality before using it in construction. 

Cement tests – Categories

Cement is one of the oldest and most used binding materials and an integral ingredient used in the construction sector. The quality, serviceability, and stability of a structure are directly related to the quality of cement used in it. Hence it is necessary to analyse the quality of cement before using it for works. The tests for determining cement quality are split into two major categories.

Field tests on Cement

The quality of cement is determined using some simple field tests. These tests do not require any sophisticated types of equipment and professional skills and get the results very quickly. By conducting these simple tests and analyzing the results we will get an idea about the cement quality and can immediately decide on accepting or rejecting it.

Following are the common field tests conducted to ensure the quality of cement

These are first look tests and the quality of cement is ensured by its smoothness to touch, the colour of cement, etc.

  • Checking manufacturing date
  • Visual checking of lumps
  • Feel test
  • Heat of cement
  • colour
  • Water float test
  • Setting test

These basic tests give an approximate characteristic of cement. These are easy and quick but not accurate, however help in concluding the acceptance of cement for works.

Laboratory tests for Cement

The laboratory tests defines the physical and chemical properties of cement. It is not possible to check all the cement properties at the site. The main laboratory tests conducted on cement is as follows.

Lab tests require time. But it provides accurate results. In this article, we are going to describe the Soundness test on cement.

Soundness test of cement

The soundness of the cement is the ability to resist volume changes after hardening. The soundness test on cement is significant because usage of unsound cement leads to cracks and hamper the structural quality.

The chemical composition of cement consists of lime. About 60 to 70% of cement is lime. The main function of lime is to help cement in the setting process. A good quality cement do not change its volume after hardening. Following are the reasons for the unsoundness of cement.

  • If the cement has an excess amount of lime, expansion or contraction in volume occurs after setting.
  • Another reason for unsoundness is the inadequate burning of cement. This leads to cracks, disintegration and a decrease in durability.
  • Improper grinding and mixing of raw materials during the manufacturing process of cement.
  • Due to the high proportion of magnesium content or sulphate content.

Therefore Soundness test is performed to determine whether the cement shows volume changes or not.

Relevant IS code for soundness test of cement

  • IS 4031 (Part 3)-1988
  • ASTM C 151-09
  • BS EN 196-3: 2005

Apparatus required

Soundness of cement is calculated by using Le-chatelier’s apparatus.

  • Le-Chatelier mould
  • Balance
  • Water bath
  • Vernier Calliper
  • Pan and trowel

Le-chatelier mould is made using brass. It consists of a spring-tensioned split cylinder and an indicating long arm in its either side. The internal diameter and height of the cylinder are 30mm and 30mm. The size of glass plates is 50mm x 50 mm. For each test, we need three such moulds. The test should be performed at a temperature of 27 ± 2°C and relative humidity of 50 to 80 per cent as per IS code.

Le-Chatliers for testing soundness of cement
Le-Chatliers for testing soundness of cement

Procedure for soundness test on Cement

Before Performing the test, calculate the standard consistency of cement to find out the water required to obtain the normal consistency(P).

  • Take about 100 gm of cement and add 0.78-times the water needed to make cement paste with normal consistency.
  • Then grease the glass plate and the Le-chatelier mould to avoid the sticking of cement on its surface.
  •  Fill the cement paste and strike out the excess cement using a trowel.
  • Cover the mould with another glass plate and place a weight above the glass plate.
  • Then immerse the whole assembly inside the water bath for 24 hours. 
  • After 24 hours, take out the mould from water and measure the distance between the indicators.
  • Note this measurement as L1. After that place, the assembly in the water bath 
  • Boil the water for 25 to 30 minutes and leave them for 3 hours.
  • After that, allow them to cool till it reaches the room temperature.
  • Now take out the assembly and measure the distance between the indicators and mark them as L2. 

Calculation

Volume expansion of cement = L1 – L2

L1 is the distance between the indicators after immersing in water for 24 hours

L2 is the distance between the indicators after immersing in water at boiling temperature for 3 hours

This value differs for different types of cement. The expansion of volume for Ordinary portland cement, portland pozzolanic cement, low heat cement and rapid hardening cement should not exceed 10mm. For high alumina cement, super sulphate cement, the volume expansion should not exceed 5mm. Because it contains excess lime or magnesium which is not suitable for construction.

Soundness test on Aggregate | Sample selection and procedure

Soundness test determines the disintegration of aggregates due to weathering. This includes freezing, thawing, marine condition etc. However, the weak and porous aggregate shows a change in weight during this soundness test.

Aggregates are the significant factor that contributes adequate strength to concrete.Therefore it is important to obtain the right quality aggregate for construction. 

Must Read : Bricks – 8 tests to ensure quality

Tests on Aggregate

For ensuring the quality of aggregates the following tests are conducted.

Soundness test for aggregates (IS-2386-PART-5)

Aggregate samples are submerged in sodium sulphate or magnesium sulphate solution repeatedly. This process causes salt deposits in the aggregate pores which tends to break the aggregates. After specified number of dipping & drying process the aggregates are sieved to determine the percentage loss of material.

Soundness test of aggregate
Soundness test of aggregate

Relevant IS code

  • IS: 2386 Part V

Sample selection for fine and coarse aggregates

  • The fine aggregate passing through the 10 mm IS sieve should be held as a sample for this test.
  • Then sieve the sample again through 10mm, 4.75 mm, 2.36 mm, 1.18 mm, 600 microns, 300 microns.
  • However, the sample should be decided in such a way that, it will not yield below 100g of given sizes. 
  • For coarse aggregate, sample remove aggregates finer than 4.75 mm. 
  • Then dry the sample and again sieve through 80mm, 63mm, 40mm, 20mm, 10mm IS sieves.
  • Choose the sample in such a way that, it will not yield below the given amount for the given sizes.
  • Weigh the samples separately and store them in different containers.

Apparatus for Soundness test

  • IS Sieves (80 mm, 63 mm, 40 mm, 31.5 mm, 25 mm, 20 mm, 16 mm, 12.5 mm, 10 mm, 8.0 mm, 4.75 mm, 4.0 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron, 150 micron)
  • Container
  • Weighing machine
  • Drying oven (105 to 110 degree)

Reagents used

  • Sodium sulphate solution
  • Magnesium sulphate solution

Test procedure of soundness test

  • After the selection of aggregate samples, wash them thoroughly on a 300 micron IS sieve.
  • Then dry them at 105 to 110-degree celsius in drying oven.
  • After that immerse the sample in a solution of sodium sulphate or magnesium sulphate for 16 to 18 hours. 
  • Cover the container for reducing evaporation and accidental addition of extraneous substances. 
  • The temperature of the solution should be 27 degree Celsius. 
  • After 18 hours, take out the sample and dry them at 105 to 110-degree celsius. 
  • Allow them to cool to room temperature and repeat this process.
  • After the final cycle, wash the sample and dry them again at 105 to 100-degree celsius.
  • Weigh them and sieve them through the same sieve we used before the test.
  • The percentage of finer sieve after the test and before the test is determined.
  • The percentage loss of weight indicates the soundness of aggregate.