CT Lab - Tests of Cement Consistency and Setting time

Concrete Laboratory

Tests of Cement consistency and setting time

Introduction:

Consistency means amount of water needed to prepare a plastic mix.

Consistency test is used to find the amount of water to be mixed with cement. It is necessary to find the consistency because amount of water present in the cement paste may affect the setting time

“More water, more time needed for setting”

Initial setting time is the time from mixing dry cement with water till the beginning of interlocking of the gel.

Final setting time is the time from mixing dry cement with water till the end of interlocking of the gel.

Knowing the initial setting time is important in estimating free time for transporting, placing, compaction and shaping of cement paste.

Sample Test Results

Normal consistency:

Trial #    Amount of cement         Amount of water             Depth of penetration

1              500 grams                            150 ml                   16 mm

2              500 grams                            155 ml                   9 mm

3              500 grams                           160 ml                   5 mm

Setting time measurement:

Time                      Penetration

5 min                     0

20 min                   1 mm

35 min                   3 mm

55 min                   4 mm

70 min                   5 mm

The initial setting time is 70 min (i.e. 1: Hour 10 Minutes)

The final setting time is 10 hours.

Conclusion:

·         To measure the setting times of cement, you have to do our tests on cement of standard Consistency.

·         Normal consistency of standard cement can be gained by using the W/C ratio and depending on 26%- 33%.

·         The higher rate of water the more initial setting time needed.