STUDY ON COMPRESSIVE STRENGTH AND ELASTIC MODULUS OF PETROCHEMICAL CONTAMINATED CONCRETE

Abstract

Concrete is a major construction material for a wide variety of applications. It has been used since a century for the construction of structures which are in direct contact with petrochemicals. Their economic use in these structures justify the promotion of further research work into the use of concrete on a wider scale. Structural properties like compressive strength and Elastic modulus are employed as a functional material representative at the design stage, changes in the material behaviour at the microstructural level resulting from petrochemical interaction can be expected to translate into changes in mechanical properties of concrete. The important aspect of the present investigation is to monitor the Compressive strength and Elastic modulus of concrete which have been contaminated with petrochemicals. Petrochemicals used are High Speed Diesel oil and Kerosene oil. Non destructive test (NDT) study was also taken up to monitor the progressive changes in properties and quality of concrete. The major strength relating and economical NDT methods which are used in the investigation are the Schmidt's rebound hammer method and Ultrasonic pulse velocity test. Statistical regression models relating the corresponding NDT parameters and direct compressive strength were developed. The experimental programme was carried out with concrete which was contaminated with petrochemicals i.e. H.S.D. oil and Kerosene oil in different percentage (1% & 2%). For the purpose of comparison, tests were also conducted on non-contaminated concrete specimens at three different curing periods (7 days, 28 days and 3 months). It was observed that the percentage reduction in strength compared to uncontaminated concrete increased with time and the percentage of deterioration was 14% and 27% in H.S.D. oil and Kerosene oil respectively. IV The study was also taken up on concrete specimens which were soaked in petrochemicals i.e. H.S.D. oil and Kerosene. For comparison, tests were also conducted on specimens cured in water for 6 months and 1 year periods of exposure. From the previous experiment conducted on the same lines, 3,7,14, and 28 days data were collected and results were tabulated. It was observed that percentage reduction of strength compared to controlled environment increased upto 6 months and thereafter it reduced. To assist the study and interpretation of physical results, X-ray diffraction analysis was done. X-ray diffraction study reveals that although the chemical compounds formed in petrochemical contaminated concrete are same as those due to hydration of cement in concrete, their percentages differ significantly. The differences in relative amounts of weak and strong compounds formed help in explaining the behavioural changes of concrete.