SOUNDNESS TEST OF CEMENT

SOUNDNESS

In this post we will discuss how to calculate the Soundness of cement paste

 

After reading this you will be able to answer,

1) what is Soundness?

2)How Soundness is caused?

3) How to calculate Soundness?

4) which apparatus used for calculating of Soundness

Hope you will enjoy 

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Introduction :---

 Soundness Test

Purpose of this test is to detect the change in volume of cement after setting. 
Unsoundness property is because of excess lime & excess magnesia content.

 These are 2 methods is detecting the unsoundness.
a) Le-Chattier Test
b) Autoclave

NOTE: Le- chattier detect the expansion due to excess lime whereas Autoclave Method detect the expansion due to Lime & Magnesia both.

APPARATUS

Le-chatelier apparatus

Soundness test of cement

Le chatelier test

It consists of a small split cylinder of brass metal. 

It’s dia is 30mm & height is 30mm.

Cement is mixed with water & the consistency is 0.78P. The mould is covered with glass plate at top & bottom. And measure the gap b/w indicator arms after 24 hours of mixing of water. Then submerged the mould in water & heat this water up to boiling point & place this mould for 3 hour. Then, remove the mould from water & let it cool down for half an hour. Then, again measure the gap b/w indicator arm.

The difference b/w these two measurement should be the expansion of cement

NOTE:-

i) For OPC, PPC, Low Heat cement, Rapid Hardening Cement, the expansion limit is 

10mm.

ii) For High Alumina Cement & Super sulphated cement, the expansion is 5mm.

Autoclave Test

A 25 × 25 × 250mm specimen is made by cement paste & place this specimen at 

open atmosphere for 24 hours. Then, measure the length of specimen.

Place this specimen in Autoclave & start steam saturation in rate of that absolute 

pressure 1.2N/mm2– 2.1 N/mm2 reaches at this level within 1/2hour. Then, remove the 

specimen from Autoclave & place it in water (90°C) for 1/2hour again. Then, again remove the mould from hot water & let it cool down. Measure the length of member once again.

The percentage length change should the expansion of cement.

For all type of cement, the expansion should not be more than 0.8%