Overview

Initial setting time is that time period between the time water is added to cement and time at which 1 mm square section needle fails to penetrate the cement paste, placed in the Vicat’s mould 5 mm to 7 mm from the bottom of the mould.

Final setting time is that time period between the time water is added to cement and the time at which 1 mm needle makes an impression on the paste in the mould but 5 mm attachment does not make any impression.

Apparatus

Measuring instruments

NAME	CAPACITY / RANGE / SIZE	ACCURACY / LEAST COUNT
Vicat apparatus	Should be made as per IS:5513	—
Balance	1000 g	1 g
Measuring cylinder	100 ml	1 ml
Stop watch	30 min.	0.2 sec

Other apparatus

Glass plate, enamel tray, trowel

Environmental Condition

Temperature	27 ± 20 C
Relative Humidity	90 % (min)

Procedure

(a)Test Block Preparation

1. Before commencing setting time test, do the consistency test to obtain the water required to give the paste normal consistency (P).
2. Take 400 g of cement and prepare a neat cement paste with 0.85P of water by weight of cement.
3. Gauge time is kept between 3 to 5 minutes. Start the stop watch at the instant when the water is added to the cement. Record this time (t₁).
4. Fill the Vicat mould, resting on a glass plate, with the cement paste gauged as above. Fill the mould completely and smooth off the surface of the paste making it level with the top of the mould. The cement block thus prepared is called test block.

(b)Initial Setting Time

1. Place the test block confined in the mould and resting on the non-porous plate, under the rod bearing the needle.
2. Lower the needle gently until it comes in contact with the surface of test block and quick release, allowing it to penetrate into the test block.
3. In the beginning the needle completely pierces the test block. Repeat this procedure i.e. quickly releasing the needle after every 2 minutes till the needle fails to pierce the block for about 5 mm measured from the bottom of the mould. Note this time (t₂).

(c)Final Setting Time

1. For determining the final setting time, replace the needle of the Vicat’s apparatus by the needle with an annular attachment.
2. The cement is considered finally set when upon applying the final setting needle gently to the surface of the test block; the needle makes an impression thereon, while the attachment fails to do so. Record this time (t₃).

Calculation

Initial setting time=t₂-t₁

Final setting time=t₃-t₁,

Where,

t₁=Time at which water is first added to cement

t₂=Time when needle fails to penetrate 5 mm to 7 mm from bottom of the mould

t₃=Time when the needle makes an impression but the attachment fails to do so.

Precautions

• Release the initial and final setting time needles gently.
• The experiment should be performed away from vibration and other disturbances.
• Needle should be cleaned every time it is used.
• Position of the mould should be shifted slightly after each penetration to avoid penetration at the same place.
• Test should be performed at the specified environmental conditions.

Standard Specification

Type/Name Of Cement	Referenced Indian Stanadard	Initial Setting Time, mints (min.)	Final Setting Time, mints (max.)
OPC(33)	IS:269	30	600
OPC(43)	IS:8112	30	600
OPC(53)	IS:12269	30	600
SRC	IS:12330	30	600
PPC	IS:1489,P1	30	600
RHPC	IS:8041	30	600
PSC	IS:455	30	600
High alumina	IS:6452	30	600
Super sulphated	IS:6909	30	600
Low heat	IS:12600	60	600
Masonry cement	IS:3466	90	1440
IRS-T-40	Railway	60	600

Technical Discussion

• It is essential that cement set neither too rapidly nor too slowly. In the first case there might be insufficient time to transport and place the concrete before it becomes too rigid. In the second case too long a setting period tends to slow up the work unduly, also it might postpone the actual use of the structure because of inadequate strength at the desired age.
• Setting should not be confused with hardening, which refers to the gain in mechanical strength after the certain degree of resistance to the penetration of a special attachment pressed into it.
• Setting time is the time required for stiffening of cement paste to a defined consistency.
• Indirectly related to the initial chemical reaction of cement with water to form aluminum-silicate compound.
• Initial setting time is the time when the paste starts losing its plasticity.
• Initial setting time test is important for transportation, placing and compaction of cement concrete.
• Initial setting time duration is required to delay the process of hydration or hardening.
• Final setting time is the time when the paste completely loses its plasticity.
• It is the time taken for the cement paste or cement concrete to harden sufficiently and attain the shape of the mould in which it is cast.
• Determination of final setting time period facilitates safe removal of scaffolding or form.
• During this period of time primary chemical reaction of cement with water is almost completed.

Test Standard Reference

• IS:4031(Part 5):1988-Methods of physical tests for hydraulic cement (Determination of initial and final setting times)