In part I, you gonna find workability of concrete.
While referring curing & strength development only age of concrete was considered. But temperature during the early period also influence the rate of gain of strength. Since strength of concrete depends on the both time & temperature, It can be said to be function of summation of product of time and temperature of curing.
The temperature considered for reference is in between (-12oC to -10oC) in general -11oC i.e. temperature up to which hydration takes place. Maturity is measured in oC-hr or oC-day. A sample of concrete cured at 18oC for 28 days is taken as fully matured concrete.
M= 28 x 24 [18-(-11oC)]=19488oC-hr
However, the standard calculation done on the basis of maturity of concrete taken as 19800oC-hr.
Maturity concept is useful for estimating the strength of concrete at any other maturity as percentage of strength of concrete of maturity as follows:
Here, the value of constant A and B depends upon strength of concrete.
If strength at given maturity is known then the number of days required to reach same strength at any temperature is given by,
Problem: A strength of a sample of fully matured concrete is found to be 32.8Mpa. Find the strength of identical concrete at the age of 7 days when cured at an average temperature during day at 20oC & high 10oC.
Use of angular or cubical aggregates from strong concrete.
Rough textured aggregate leads to formation of strong concrete.
Use of Plasticizer & Super plasticizer increase the strength of concrete.
Properly mixing, properly compaction and curing of concrete in proper way may leads to increase the strength of concrete.
Smaller size aggregate gives strong concrete (because it has more bond strength).
Well Graded aggregate increase the strength.
