It means, time elapsed between when the water is added into the cement & when the cement paste begins to lose its fluidity.
It may also be defined as, the time when water is added into the cement & the Vicat square needle penetrating to a depth of 33-35 mm from the top or 5 to 7 mm from the bottom of the Vicat Apparatus’s mould.
Final Setting Time (FST) of Cement :
In a simple word, Final Setting Time (FST) of Cement means the interval between when water is added mixed into the cement & when the cement paste has totally lost its fluidity.
Here are the list of all the Apparatus required for the Initial and Final Setting Time of Cement are :
1. Weighing Balance – The permissible variationat a load of 1000g shallbe ± 1.0 g.
2. Vicat Apparatus – these appratus should be confirm to IS 5513-1976.
1.Before starting of these test of Initial and Final Setting Time of Cement. First of all we perform test of Consistency of cement, it meansa test to find out % of the water required by the weight of cement as normal consistency of cement (P).
2.For the Consistency of cement test, we have to take about 400 gm of cement & then we have to add water about 0.85x P(P is % water required for normal consistency of cement)
3.Now we have to Mix the water in the cementforabout3-5 min.
4.We have to Start the stopwatch when the water is added to the cement. Record this time, denote it as (T1).
5.Now we have to put this prepared cement paste in to the Vicat apparatusmould. Which having a diameter of 80 mm & height of 50 mm, we have to rest the appratus on a non–porous glass plate.
6.After Properly filling the cement paste in appratus, we have to make smooth the top surface of mould and level it.
I. Procedure of Initial Setting Time of Cement
1.For determining the IST of cement, we have to filled this mould with cement pastebelow the Vicat apparatus.
2.After that we have to fix the needle which we have to be used for testing of the initial setting time.
3.In the next step, we have to Lower the bottom of the needle such that it just touches the top of cement paste which we have filled in mould.
4.After completing the above steps, now we have to Remove the locking pin from the top & it will quickly release the needle, we have to just allowing it to penetrate into the cement paste.
5.We will observe that the needle penetrates &touches the bottom of mould.
6.After that We have to Repeat this process quickly by just releasing the needle after every 2 minutes till the needle fails to penetrate the cement paste for about 5 mmfrom the bottom of the mould.
5.We have to Note Time (T2) when needle fails to penetrate5 mm from the bottom of mould.
II. Procedure of Final Setting Time of Cement
1.For determiningthe Final setting time of cement (FST), we have to change the needle with the needle which having an angular ring attachment.
2.After changing of needle, we have to slightly release this needle on the surface of the cement paste.
3.Atlast, we have to observe that the needle or ring is making any impression on the surface or not.
4.We have to then note the time, when need fails to make an impression on the surface of cement paste (T2).
Calculation of Initial and Final Time
1.Initial setting time (IST)= Time when needle fails to penetrate 5 mm from the bottom of mould (T2) – time when added to cement (T1)
2.Final setting time of cement = Time when angular need ring impression stop on cement paste (T3) – Time when water added to cement (T1)
IS Code for Initial & Final Setting Time of Cement :
Take an example, Consistency of cement (P) = 30% and Weight of cement = 400 kg
Water to be added in cement = (0.85 x P ) x 400 = (0.85 x 30%) x 400 = 102 ml
The time when water added to cement = 8:00 am
Time, when needle fails to penetrate less than 5 mm from the bottom of mould = 10: 00am
Initial Setting Time of Cement = 10 : 00am – 10 : 45 am = 45 min.
Time When angular ring needle fails to make impression on the surface of cement paste = 4 : 00 pm
Final setting Time of Cement : 5 hr - 300 min.
Standard Values for the IST & FST for different types of Cement :
In construction industry, there are various types of cements we used which dependson the types of cement as well as theadmixture used in the manufacturing of cement.
Due to these reasons, setting time may varies fordifferent cement. The standard–setting time for different types of cement is given below.
Name of Cement
Ref. IS Code
Initial Setting Time(min)
Final Setting Time(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 Sulphate
IS: 6909
30
600
Low Heat
IS: 12600
60
600
Masonry Cement
IS: 3466
90
1440
IRS – T -40
Railway
60
600
Here is the video of Initial and Final Setting time of cement :
1. What is Initial & final setting time of cement ?
FAQs:
1.Initial Setting of Cement
In a simple words, it means the time elapsed between when the water is added into the cement & when the cement paste begins to lose its fluidity. It should not be less than30 min for OPC cement.
2.Final Setting Time of Cement
Final Setting Time of Cement means, the time between the water is added to the cement & the time when the cement paste loses its plasticity completely & should be able to resistcertain definite pressure. Final Setting Time of Cement should not be more than 600 min for OPC cement.
3.Initial and Final Setting Time of OPC Cement?
For OPC cement, the Minimum setting initial setting is 30 min as well as the maximum final setting time is 600 min.
4.What is the Initial setting time of Portland Pozzolona cement (PPC) ?
The Min. initial setting time for PPC type of cement is 30 min.
5.Setting Time of Cement
Basically, The initial setting time of cement gives an idea about how fast cement can start losing its plasticity.
As well as the final setting time of cement gives an idea about how much cement takes to lose its full plasticity & gain some strength to resist pressure.
0 Comments