Mechanical Strength of Trass as Supplementary Cementing ... - USM

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Normalized Heat (J g –1 ) 70 60 50 40 30 20 10 0 0 24 48 72 96 120 144 168 Hydration time (h) 8218 5344 2462 Figure 5: Heat release of trass–lime reaction with addition of 2.71 wt. % Na2SO4 on different finenesses of trass. Normalized Heat (J g –1 ) 70 60 50 40 30 20 10 0 0 24 48 72 96 120 144 168 Hydration time (h) Figure 6: Linear and exponential correlations of heat flow versus hydration time for different mixture.
Journal of Physical Science, Vol. 19(2), 51–59, 2008 59 other hand, samples treated by Na2SO4 showed an exponential correlation, with the exception of sample at low Blaine. This also supported by strength development from 2 up to 28 days of samples with high Blaine treated by chemical activation. 4. CONCLUSION Mechanical strength gained from the mechanical and chemical activations of trass explains and proves that trass could be used as a supplementary cementing material in blended cement. The increase of mechanical strength was also explained by an increase of heat released during pozzolanic reaction. Exponential correlation between the heat release and the reaction time explains the effective activation of trass by means of chemical activation at finenesses above 2500 cm 2 g –1 Blaine. Trass of fineness of 9190 cm 2 g –1 Blaine at trass–lime system (2:1) gives maximum strength of 124 kg cm –2 at 28 days with addition of 2.71 wt. % Na2SO4. 5. REFERENCES 1. Muller, C.J. (2005). Pozzolanic activity of natural clay minerals with respect to environmental geotechnics. Dissertation, Swiss Federal Institute of Technology Zurich, Switzerland. 2. Rahhal, V. & Talero, R. (2005). Early hydration of Portland cement with crystalline mineral additions. Cement and Concrete Research, 35, 1285–1291. 3. Chen, W. (2007). Hydration of slag cement. Ph. D. Thesis, University of Twente, Netherland. 4. Bao-min, W. & Li-jiu, W. (2004). Development of studies and applications of activation of fly ash. Proceedings of the International Workshop on Sustainable Development and Concrete Technology, Beijing, China, 20–21 May, 159–169. 5. Arjunan, P., Silsbee, M.R. & Roy, D.M. (2001). Chemical activation of low calcium fly ash. Part I : Identification of suitable activators and their dosage. Proceedings of the International Ash Utilization Symposium, Center for Applied Energy Research, University of Kentucky, 22–24 October, Paper #105. 6. Allahverdi, A. & Ghorbani, J. (2006). Chemical activation and set acceleration of lime–natural pozzolan cement. Ceramics-Silikaty, 50(4), 193–199.
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