Browsing by Author "Somaratna, N."

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Correlation of compressive strength and flexural tensile strength of blended cement concrete
(SLIIT, Faculty of Engineering, 2024-10) Kulathilaka, U. G. D. U.; Somaratna, N.
Eurocodes for structural designs have been adopted for Sri Lanka. Hence in Sri Lanka, concrete designs need to be in compliance with the relevant Eurocodes – mainly EN1992 (EC2). In EC2, concrete is categorized by its compressive strength. The other strength parameters are derived from the compressive strength using correlations based on empirical data. A recent trend has been the increasing use of blended cement for concrete in certain applications. But the correlations specified in EC2 are based on data probably related to Ordinary Portland Cement (OPC) concrete. It is important to examine whether the correlations listed in EC2 are applicable to blended cement concrete too. The present study was performed to experimentally examine the correlation of compressive strength and flexural tensile strength of blended cement concrete. A parallel study was conducted for OPC concrete to serve as a baseline reference. Standard beam and cylinder specimens of concrete were cast, cured, and tested for flexural tensile strength and compressive strength. Three different mix ratios were used. Each mix was tested twice. The same series of tests were conducted for blended cement (Portland Composite Cement – PCC) and for OPC. Experimentally measured values of flexural tensile strength were compared against their estimated values derived from the experimentally measured compressive strengths, using EC2 listed relationships. The analysis showed that in the case of both OPC as well as PCC, the measured values of the flexural tensile strength exceeded their estimated values based on EC2 relationships. But the testing conducted has been limited in the number of tests performed, the range of mix ratios, and the types of aggregate used. In order to affirm the general applicability of Eurocode 2 relationships for blended cement concrete also, additional more comprehensive testing is warranted across a wider span of mix ratios and aggregate types.
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Experimental Investigation of Some Strength Parameter Correlation in Blended Cement Concrete
(SLIIT, Faculty of Engineering, 2024-10) Chularathna, P. K. G. O. T.; Somaratna, N.
Sri Lanka has adopted Eurocodes for structural designs. Accordingly, the design of concrete structures should adhere to EN1992 (Eurocode 2). The strength parameters of concrete essential for designs are classified in Eurocode 2 based on the compressive strength of concrete. Most of the other relevant strength parameters are derived using correlations with compressive strength. These correlations based on past empirical test results would typically be valid for concrete made using ordinary Portland cement (OPC). Recently there has been a tendency to use blended cements for concrete. To develop economical and safe designs in such cases the correlations among strength parameters used in EN 1992 should be verified as being applicable to blended cement concrete too. The study presented here was aimed at investigating the applicability of EN 1992 correlation between compressive strength and split cylinder tensile strength to blended cement concretes. Test specimens of concrete made using a blended cement – Portland Composite Cement (PCC) – were cast, cured, and tested under standard conditions for their compressive strength and split cylinder tensile strength. These tests were repeated for greater reliability. For comparison, similar tests were performed on concrete made using OPC also. The measured compressive strengths were used to produce estimated values of corresponding tensile strengths following the EN1992 correlations. Comparisons were made, in graphical form, between the measured tensile strengths and the estimated tensile strengths. Separately for each cement type. They revealed that the test results for OPC concrete, as expected, aligned with EN1992 correlations with a significant margin of safety while those related to blended cement, though complying with EN1992 correlations, provided only a narrow margin of safety. This indicates a need for a higher level of quality assurance for blended cement concrete. As these observations are based on a limited number of tests it is recommended to conduct further comprehensive studies.