WHY WE TEST CONCRETE SRTRENGTH AFTER 28 DAYS?
Why do we test concrete compressive strength after 28 days?
The table below shows the compressive strength gained by concrete after 1, 3, 7, 14 and 28 days with respect to the grade of concrete we use.
Age | Strength per cent |
1 day | 16% |
3 days | 40% |
7 days | 65% |
14 days | 90% |
28 days | 99% |
From above table, we see that, concrete gains 16 percent strength in one day, 40 percent in 3 days, 65% in 7 days, 90% in 14 days and 99% strength in 28 days. Thus, it is clear that concrete gains its strength rapidly in the initial days after casting, i.e. 90% in only 14 days. When, its strength have reached 99% in 28 days, still concrete continues to gain strength after that period, but that rate of gain in compressive strength is very less compared to that in 28 days.
After 14 days of casting concrete, concrete gains only 9% in next 14 days. So, rate of gain of strength decreases. We have no clear idea upto when the concrete gains the strength, 1 year or 2 year, but it is assumed that concrete may gain its final strength after 1 year. So, since the concrete strength is 99% at 28 days, its almost close to its final strength, thus we rely upon the results of compressive strength test after 28 days and use this strength as the base for our design and evaluation.
Though there are also some rapid method of testing concrete compressive strength which gives relation between rapid test methods and 28 day strength. This rapid test is done where time is limited for construction and strength of structural member must be known to carry out further construction work.
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Concrete after 100 years? %
100 Years Durability Possible in Prestressed Concrete Products, for Ex. Prestressed Concrete Spun Poles.
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what if the cube set failed in test? will you demolish the whole structure? but you can't wait for 28 days after casting you have to do simultaneously the other casting also.
you do not have to demolish the structure before carrying out a core test to determine the insitu strength of the dried concrete
what is the formula as per is code to test concrete after 30 days and what percentage difference do we get?
varun im raju kc from nepal plz contg me
For required strength concrete must be mixed properly & ratio of cement & water cement ratio be maintained, curing should be done atleast for seven days
helpful data….
AFTER HOW MANY DAYS OF CASTING CONCRETE IS TREATED AS OLD CONCRETE
because its necessity of now days .and we check the quality of mixing concrete
What is the importance of NDT test???? And what is the latest technology of NDT to make easy and simple?
The knowledge of:
WHY WE TEST CONCRETE SRTRENGTH AFTER 28 DAYS?
Tankx for your agkwn……
May be every er. Knows!
But simple explanation. That's Why I like Constructor.org very much since long before. Thanks for your valuable articles!
Actually modern day concrete give more strength in early age. As an example I have experienced 80% of strength achieving within 7days without any admixtures.
How about accelerated curing/steam curing and the testing details? Please throw light on this.
thanks for this information but i have a question on the plot that consists salt what what precaution shall i take for better design and sustainable building structure
We test the concrete after 7 days or 14 days and mostly 28 days, if test results are negative then what?
u r right
helpful data..
(Y)
and last 1% …?????
It is mostly useful to all field engineers and helps them
but it totally depend upon curing
how about for non load bearing material that use some cement e.g wood wool cement board. Do we need to wait until day 28 for test? TQ
I really appreciate this information, I will like to have more
right
Do these tabulated data belong to any references or any recommendations by codes?
sir thanks for your information but percentage you are given it have any reference or any recommendation by ASTM standard