How you know the initial setting time for any type of concrete ?

I agree with Mr. Ali in SI standard  but I  using BS EN standard and ASTM C standard  for more benefit 

the setting time of cement are measured using VICAT APPARATUS .

the test method is prescribed by BS EN196-3:2005.

for the determination of the initial set , a round needle with a diameter1.13+0.05 or -0.05 mm is used .this needle acting under a prescribed weight , is used to penetrate a paste of standard consistency placed in a special mould .

when the paste stiffens sufficiently for the needle to penetrate no deeper then to a point  5+1 mm or -1 mm from the bottom  initial set is said to have taken place .

initial set is expressed as the time of60 minutes is prescribed by BS EN197-1 :2000 for cements with strengths of42.5 MPa 

75 minutes for cement with strengths of52.5 MPa 

and45 minutes for cement with higher .

The initial setting time of high alumina cement is prescribed by BS NE915-2:1972  (1983) as between2 and6 hours.

FOR  American Standard ASTM  C150-09 prescribes a minimum time for the initial set of45 minutes , also using the VICAT APPARATUS prescribed in ASTM C191-08 .

Endorse the Experts Answers, Specially Mr. Ali and Sir Alex Al Yazouri.

The initial setting time for different types of cements is as follows:

For OPC (Ordinary Portland Cement)33 Grade as per IS269:1989  30 minutes

For OPC43 Grade as per IS8112:1989  30 minutes

For OPC53 Grade as per IS12269:1987  30 minutes

For PPC (Portland-Pozzolana Cement) as per IS1489:1991  30 minutes

For RHC (Rapid Hardening Cement) as per IS8041:1990  5 minutes

For LHC (Low Heat Cement) as per IS12600:1989  30 minutes

For PSC (Portland Slag Cement) as per IS455:1989  30 minutes

I hope you are useful answer and thank you

Admixtures which is are added to concrete batch immediately before or during mixing concrete. Concrete admixtures can improve concrete quality, manageability, acceleration or retardation of setting time among other properties that could be altered to get specific results. Many, not to say all, concrete mixes today contain one or more concrete admixtures.

i support Mr. Appi Reddy answer

sorry, I don't know. because this is not my specialty 

I support an answer of En.Alex Al Yazouri ..

Thanks..

We conduct the Initial Setting Time & Final Setting Time by using Vicat's Apparatus. This is a laboratory test. 

Initial Setting Time is calculated using the1mm needle in the Vicat's Instrument. Cement paste is made using85% of water requirement calculated in the normal consistency. The time t1 is noted. 

This paste is placed in the Vicat's mould. The1mm needle is brought to the surface (top) of mould. Then gently the needle is released to penetrate into cement paste. The depth of penetration is measured. This test is repeated at every2 minute interval till a value of penetration5mm above bottom of mould is happened. This time is recorded as t2 .

The time elapsed between the addition of water to cement and needle penetration into cement paste upto5mm from the bottom of the Vicat's mould. i.e. t2 - t1.

I am agree with Mr Ali........