Comparison of Physical and Chemical Properties of Micro-Silica and Locally Produced Metakaolin and Effect on the Properties of Concrete
The properties of locally produced metakaolin (MK) as cement replacing material and the comparison of reactivity with commercially available micro-silica have been investigated. Compressive strength, splitting tensile strength, and load-deflection behaviour under bending are the properties that have been studied. The amorphous phase of MK with micro-silica was compared through X-ray diffraction (XRD) pattern. Further, interfacial transition zone of concrete with micro-silica and MK was observed through Field Emission Scanning Electron Microscopy (FESEM). Three mixes of concrete were prepared. One of the mix is without cement replacement as control mix, and the remaining two mixes are 10% cement replacement with micro-silica and MK. It has been found that MK, due to its irregular structure and amorphous phase, has high reactivity with portlandite in concrete. The compressive strength at early age is higher with MK as compared to micro-silica. MK concrete showed higher splitting tensile strength and higher load carrying capacity as compared to control and micro-silica concrete at all ages respectively.
 J. B. Newman, Advanced Concrete Technology: Constituent Materials. Butterworth-Heinemann, 2003.
 ACI Committee 363, "State of the art report on high-strength concrete," in ACI J. Proc., 1984.
 S. J. Martin, "The use of metakaolin in high strength concrete." RMC Readymix Limited., Tech. Rep. Laboratory Report 78, 1995.
 J. Ding and Z. Li, "Effects of metakaolin and silica fume on properties of concrete," ACI Mater. J., vol. 99, pp. 393-398, 2002.
 C. Poon, S. Kou and L. Lam, "Compressive strength, chloride diffusivity and pore structure of high performance metakaolin and silica fume concrete," Constr. Build. Mater., vol. 20, pp. 858-865, 2006.
 P. Duan, Z. Shui, W. Chen and C. Shen, "Effects of metakaolin, silica fume and slag on pore structure, interfacial transition zone and compressive strength of concrete," Constr. Build. Mater., vol. 44, pp. 1-6, 2013.
 H. Baioumy and A. R. Ibrahim, "Mineralogical Variations among the Kaolin Deposits in Malaysia,”.
 http://malaysianminerals.com/kaolin.html. Accessed on 02/02/2014.
 O. C. HUAT, "Performance of Concrete containing Metakaolin as Cement Replacement Material," 2006.
 S. A. Speakman, "Basics of X-ray powder diffraction," the Center for Materials Science and Engineering at MIT, Tech. Rep. Massachusetts-USA, 2011.
 S. U. Khan, M. F. Nuruddin, T. Ayub and N. Shafiq, "Effect of Different Mineral Admixtures on the properties of Fresh Concrete." The Scientific World J., vol. 2014, pp. 11, 2014.
 A. Shvarzman, K. Kovler, G. Grader and G. Shter, "The effect of dehydroxylation/amorphization degree on pozzolanic activity of kaolinite," Cem. Concr. Res., vol. 33, pp. 405-416, 2003.
 G. Kakali, T. Perraki, S. Tsivilis and E. Badogiannis, "Thermal treatment of kaolin: the effect of mineralogy on the pozzolanic activity," Appl. Clay. Sci., vol. 20, pp. 73-80, 2001.
 R. Siddique and J. Klaus, "Influence of metakaolin on the properties of mortar and concrete: A review," Appl. Clay. Sci., vol. 43, pp. 392-400, 2009.
 J. Justice, L. Kennison, B. Mohr, S. Beckwith, L. McCormick, B. Wiggins, Z. Zhang and K. Kurtis, "Comparison of two metakaolins and a silica fume used as supplementary cementitious materials," in Proc. Seventh International Symposium on Utilization of High-Strength/High Performance Concrete, 2005.