Concrete using Siliceous Fly ash at very High Levels of Cement Replacement: Influence of Lime Content and Temperature

Singh, G V P B and K V L, Subramaniam (2016) Concrete using Siliceous Fly ash at very High Levels of Cement Replacement: Influence of Lime Content and Temperature. In: 2nd RN Raikar Memorial International Conference & Banthia-Basheer International Symposium on Advances in Science & Technology of Concrete, 18-19 December, 2015, The Lalit, Mumbai.

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Potential for producing viable binders at very high levels of cement replacement (60% and above) with fly ash is explored. The role of lime content and temperature on the efficiency of fly ash in contributing to strength gain is investigated using quantitative X-ray diffraction (XRD) analysis. Results of fly ash characterization are presented using quantitative X-ray diffraction (XRD) to identify its reactive potential associated with the amorphous silica content. A new method for quantitative phase analysis of the amorphous phase contributions in the XRD spectrum is presented. A strength-based efficiency factor which provides a measure of the contriubtion of fly ash is introduced. Temperature is shown to increase the efficiency of fly ash by accelerating the dissolution of the reactive amorphous content. Efficiency of fly ash in the binary high volume fly ash-cement blend is limited by the availability of lime. Increasing the lime content in the system provides significant enhancement in strength, but it does not influence the dissolution of fly ash With the availability of lime, the efficiency is limited by the rate of contribution of reactive Silica from fly ash, which is influenced strongly by temperature. Concrete strengths of 30 MPa and higher were achieved with 65% replacement of cement with fly ash and total cement content of 100 kg/m3. The strength gain in concrete is shown to be related to the depletion of lime in the system, formation of amorphous hydration products and the depletion of Si/Al content from fly ash. An investigation of the underlying mechanisms reveals the potential for further strength enhancement by effectively engaging all the reactive components of fly ash.

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IITH Creators:
IITH CreatorsORCiD
K V L, Subramaniam
Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Fly ash, Quick lime, Rietveld refinement, Efficiency factor, Si/Al dissolution, Amorphous product content.
Subjects: Civil Engineering > Soil Structure Interaction
Divisions: Department of Civil Engineering
Depositing User: Team Library
Date Deposited: 23 May 2016 03:54
Last Modified: 05 Jul 2017 10:10
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