Short answer
What are the initial and final setting times of cement? Initial setting time is the time from adding water until the Vicat needle stops at 5.0 ± 0.5 mm from the bottom of the paste mould. Final setting time is the time until the needle leaves an impression and its annular attachment does not. IS 4031 Part 5 reports both in minutes, to the nearest five. They are lab results, and not the time you have on site.
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Setting time is one of the most quoted and most misunderstood numbers about cement. It is the time a cement paste takes to stiffen in a standard laboratory test. It is not the time you have to place concrete, it is not the time at which the concrete is strong, and it is not the time to strike the formwork. This page explains what the two times are, how the standard measures them and what limits apply. For the other cement tests, see checking cement on site.
What are the initial and final setting times?
IS 4031 (Part 5) does not define “setting” in general. It defines the two times by what the Vicat needle does. The initial setting time is “the period elapsing between the time when water is added to the cement and the time at which the needle fails to pierce the test block to a point 5.0 ± 0.5 mm measured from the bottom of the mould” (clause 5.2). The final setting time is the period from adding water to “the time at which the needle makes an impression on the surface of test block while the attachment fails to do so” (clause 5.3).
In plain terms, initial setting is when the paste has started to stiffen, and final setting is when the paste has hardened to the point where the needle still makes an impression but the annular attachment no longer does. Setting is not hardening in the sense of strength, and Part 5 does not link it to strength.
How is the Vicat test done?
The standard’s own steps, in order, are these. They are laboratory steps, and not an exercise for site.
- The moulding room, the dry materials and the water are held at 27 ± 2 °C, and the laboratory humidity at 65 ± 5 percent (clause 3.1). The moist closet is held at 27 ± 2 °C and not less than 90 percent humidity (3.2).
- A representative sample of cement is taken and mixed thoroughly (2.1).
- A neat paste is prepared by gauging the cement with 0.85 times the water that gives a paste of standard consistency, as found by IS 4031 (Part 4) (5.1).
- A stop-watch is started at the instant water is added to the cement (5.1).
- The Vicat mould, resting on a non-porous plate, is filled completely and the top is smoothed level. This is the test block (5.1).
- The block is placed at once in the moist closet and left there except when the setting time is being determined (5.1.1).
- For the initial time, the needle (C) is lowered gently to the surface, released, and the step is repeated. At first it pierces the block completely. The initial setting time is reached when it stops at 5.0 ± 0.5 mm from the bottom of the mould (5.2).
- For the final time, the needle is replaced by the needle with an annular attachment (F). The final setting time is reached when the needle leaves an impression and the attachment does not. If a scum forms on the surface, the underside of the block is used (5.3).
- The results are reported to the nearest five minutes (6.1).
The standard adds three precautions: use clean appliances, keep the apparatus free from vibration, and keep the needle straight. The apparatus itself, the Vicat apparatus, is described in IS 5513, which we did not read, and the standard gives no reading interval.
What are the limits?
The cement product standards set the limits that the result is checked against. For Portland pozzolana cement, IS 1489 (Part 1):2015 Table 2 gives an initial setting time of at least 30 minutes and a final setting time of at most 600 minutes, tested by IS 4031 (Part 5): a minimum for the initial setting time and a maximum for the final. CPWD Specifications 2019 (clause 3.1.2.4) gives the same two limits for “cement of any type of any grade” for its own works. IS 269:2015 for ordinary Portland cement is in force, but we could not read its text, so we do not quote its table. The earlier OPC editions have been withdrawn. Check the current edition of the product standard for your cement.
| Where it appears | Initial setting time | Final setting time |
|---|---|---|
| IS 1489 (Part 1):2015, Table 2 (fly ash based PPC) | At least 30 minutes | At most 600 minutes |
| CPWD Specifications 2019, clause 3.1.2.4 (cement of any type and grade, for CPWD works) | Not less than 30 minutes | Not more than 600 minutes |
| IS 269:2015 (OPC) | In force; text not read | In force; text not read |
In practice, a cement with too short an initial setting time gives little time to mix, carry and place, and one with too long a final setting time delays the work.
Why does initial setting time matter on site?
IS 456 says concrete “shall be placed and compacted before initial setting of concrete commences and should not be subsequently disturbed” (clause 13.2), and that it should be transported “as rapidly as possible” in ways that prevent segregation and keep the required workability (13.1). That is where the laboratory number connects to site work.
The laboratory result is for cement paste at standard consistency, under standard conditions. Concrete on site has aggregate, a different water content, admixtures perhaps, heat or cold, and wind. It can stiffen sooner or later than the paste test suggests. So the 30 minutes in the limit is a minimum for the cement paste in the laboratory, and it is not a placing time limit. How long a mix stays workable is decided by the mix, the weather and the supplier or engineer, and a placing time limit comes from the specification or the engineer for your work.
What affects it is practice, not a standard. Heat shortens the time and cold lengthens it, as described on hot weather concreting and cold weather concreting. The type of cement matters: see OPC vs PPC vs PSC. Old or damp stock should be tested: see cement shelf life and storage.
What should I do about it on site?
This is practice, not a standard.
- Have labour, equipment and the formwork ready before concrete arrives, and place and compact it soon: see compacting concrete with a needle vibrator.
- Do not add water to concrete that has started to stiffen. See water-cement ratio.
- Ask the supplier or engineer for the time limit for each load: see ready-mix vs site-mix concrete.
- Do not use the laboratory setting time to decide when to remove formwork or to start curing. The engineer decides: see shuttering vs centering vs staging.
- If the cement is old or doubtful, ask the engineer to have it tested in a laboratory.
Can I check setting time at site?
Not by a standard method. IS 4031 (Part 5) needs a Vicat apparatus and controlled conditions. Pressing cement paste with a thumb or hand does not measure initial or final setting time.
What mistakes should I avoid?
These are practice, not code rules.
- Reading the final setting time as the time when concrete is strong or the formwork can come off.
- Treating the laboratory figure as the time available on site.
- Adding water to stiffening concrete to restore workability.
- Confusing setting with curing: curing is keeping the concrete moist for strength, and it starts after setting.
- Assuming a longer setting time is better.
- Using old, stiff or lumpy cement.
- Re-mixing concrete after it has begun to set.
Frequently asked questions
What is initial setting time?
The time from adding water until the Vicat needle stops 5.0 ± 0.5 mm from the bottom of the mould (IS 4031 Part 5, clause 5.2).
What is final setting time?
The time from adding water until the needle leaves an impression and the annular attachment does not (clause 5.3).
What is the limit on setting time?
IS 1489 (Part 1):2015 asks for an initial setting time of at least 30 minutes and a final setting time of at most 600 minutes for fly ash based PPC. CPWD 2019 asks the same for cement of any type and grade. Check the product standard for your cement.
Is setting time the same as curing?
No. Setting is the stiffening of the paste. Curing is keeping the concrete moist afterwards so that it gains strength.
Is final setting time the time to remove shuttering?
No. Formwork removal is decided by the engineer from the strength and the loads.
Related guides
- Checking cement on site: bag marks, licence and lab tests
- Hot weather concreting in an Indian summer
- Compacting concrete with a needle vibrator: method and mistakes
This guide is general information. Read the disclaimer. Your engineer decides the cement, the time limits and the formwork removal for your work.
Sources
- IS 4031 (Part 5):1988, Methods of Physical Tests for Hydraulic Cement, Part 5 Determination of Initial and Final Setting Times (edition 2.1, incorporating amendment 1): clauses 1.1, 2.1, 3.1, 3.2, 4.1, 5.1, 5.1.1, 5.2, 5.3 and 6.1 (page images read; the standard is two pages long).
- IS 1489 (Part 1):2015, Portland Pozzolana Cement, Part 1 Fly Ash Based (fourth revision): Table 2, setting time rows (page image read). BIS lists it as in force, valid to 2030-12-31.
- IS 456:2000, Plain and Reinforced Concrete, Code of Practice (fourth revision): clauses 13.1 and 13.2 (page image read).
- CPWD Specifications 2019 Vol 1 (Central Public Works Department), clause 3.1.2.4 on setting time of cement (page image read; a purchaser's specification, not the BIS text). IS 269:2015, Ordinary Portland Cement, is in force per BIS but its text could not be read.
General information only. It is not a structural design or professional advice. Ask a licensed structural engineer or architect to check your plans and site.