Civil Researchers

Principal Investigator :  Dr. S. P.  Patil

Title: Strength estimation for high strength concrete incorporating metakaolin and strain measurement in prestressed high strength concrete beam with prestress losses estimation by using time step method
Date of Commencement and Period of funding:  11.05.2009
Amount (Rs.)  : 1,50,000
Funding Agency :  University Of Pune

In this research work, an attempt has been made to study the effects of mineral admixtures by partial replacement to cement in terms of improved performance in compressive strength and durability of prestressed concrete. Apart from this, the strain produced in pre tensioned wire is measured with the help of strain gauges to analyze the behavior of pre stressed concrete such as prestress losses etc. In brief, an attempt is to be made to produce high performing prestressed concrete for different grades as per IS: 1343 with minimum cement content.

Mix design of M30 grade concrete is made of different groups such as:- 1) Mix design with Ordinary Portland Cement 2) Mix design with OPC + Metakaolin 3) Mix design with OPC + Fly Ash etc. For these mix designs of concrete, pretensioned beams (designed section) and cubes are caste in moulds and which will be further tested, analyzed for the said purpose. Apart from this computer program is developed for quick estimation of prestress losses.
Apart from this, prestressing yard is prepared by an assembly of 4 M.S. channels (Every two channels facing each other from 12.95 m apart) and embedded in M20 grade concrete as Prestressing abutments. Each channel is drilled at 3 different locations for passing the pretensioned cables/wires through these holes for maintaining eccentricity in prestressing beams. These cables are anchored at their ends and tensioned with the help of prestressing monostrand hydraulic jack. Now strain produced in these cable is monitored with help of strain gauges and strain indicator by casting prestressed concrete beams as per designed section and different mix design. The strain results are represented in cumulative prestress losses to study the effect on compressive strength of prestressed pozzolanic concrete.

The aim of the dissertation work is to initiate and providing platform for further studies on following issues :

    • To provide high performance prestressed concrete as economically as possible by incorporating mineral admixtures by means of suitable mix design for different grades of concrete as per IS 1343:1980 (1999).
    • To correlate strain analysis with compressive strength of concrete by means of prestress losses.
    • To assess health monitoring of member by means of calibration devices and create a technical database for predicting serviceability of the member before its failure. This database can be useful on macro basis for large structures such as prestressed concrete bridges etc.
    • The results obtained after actual work will be submitted to Bureau of Indian Standards, New Delhi further recommendations.