Study of compressive strength of concrete of certain flyovers in Mumbai

Strength of concrete is ascertained by its compressive strength after 7 days and 28 days. As the hardened concrete from various components must satisfy the acceptance criteria given by IS 456. However, to conform this at the time of casting of these components of any structure, simultaneously 9 cubes are casted by the same concrete, which is used in the components. These cubes when tested after 7 days and 28 days give the information about strength of concrete, which has gone in that components. As voluminous data of strength of sample is available in any manufacturing unit, whereas in construction the cube test data is mandatory for every contractor to give these results either from Indian (or International) standard Certified laboratory or from their testing laboratory, tested in front of client's engineer. Such cube strength data was collected from 5 different flyovers with the help of Maharashtra State Road Development Corporation (MSRDC) Then the various statistical methods to analyse strength of concrete such as two-way analysis, split-plot technique, analysis of covariance are used. From the analysis it was confirmed that, the concrete strength comply with the required acceptance criteria as given by IS-456.It is observed that there is significant difference between component strength of concrete used in various components of the structure such as pile, pilecap, girder etc. As expected, it is observed that the cube strength results after 7 and 28 days of casting are significantly different. It has been seen that there is an interaction between strength of concrete and number of days casting.