# COMPRESSIVE STRENGTH OF BUILDING LIME (IS:6932-Part 8-1973)

|# Objective

For** **determination compressive strength of building lime.** **

**Reference**** Standards**

IS: 6932(Part VII)-Method of tests for Building Limes (Determination of compressive and transverse strengths).

**Equipment & Apparatus**

- Oven (300
^{0}C) - Compression testing machine

**Test Sample Preparation**

- 500 gm of lime is mixed with 60 to 65 % of water for 5 minutes and then the resulting putty is passed twice through a mixer.
- 350 g of above putty is mixed with standard sand (mass equal to 3 times the mass of the dry lime i.e. 636 g to 656 g). The lime putty and sand is thoroughly mixed for 10 minutes continuously.

** ****Procedure**

- Twelve cubes with side 5 cm is prepared from standard lime-sand mortar using metallic moulds.
- The moulds is filled by hand, the mortar being pressed in with the thumb, lightly tamped, smoothed off with 2 or 3 strokes of the trowel. These cubes are then stored undisturbed in a container for a period of 72 hours in an atmosphere of at least 90 percent relative humidity and at a temperature of 27±2
^{0}C. - After 72 hours the specimens is taken out of the moulds and placed in the air in laboratory for 4 days.
- When 7 days old the specimen is immersed in clean water and left there until just prior to testing for its strength in the testing machine.
- After 7 days of storage in water 6 of the cubes is taken out of water, wiped surface-dry and tested for compressive strength in a compression testing machine. This gives strength at 14 days.The load is increased at a rate of 15kg/min.
- The remaining 6 test specimens is taken out after 21 days and similarly tested the determining the compressive strength at 28 days.

**Calculation**

The measured compressive strength of the cubes are to be calculated by dividing the maximum load applied to the cubes during the test by cross-sectional area, calculated from the mean dimensions of the section.** **

**Reports**

The average strength of the 6 specimens is taken as the compressive strength of mortar and the result is expressed kg/cm^{2}.** **

**Safety & Precautions**

- Use hand gloves while removing containers from oven after switching off the oven.
- To wear safety shoes & apron during the time of test.
- Before testing, machine should be checked.
- After test electric supply should be off.
- Equipment should be cleaned thoroughly before testing & after testing.
- Petroleum jelly should be applied to the mould.