Hydration of ternary cements elaborated with limestone filler and calcined kaolinitic clay

TIRONI A., SCIAN A.N., IRASSAR E.F.

Beijing

Congreso; 14th International congress on the chemistry of cement; 2015

The China Ceramic Soc., China Building Materials Acadey and State Key Lab. of Green Building Materials

This paper describes the performance of ternary blended cements made with calcined clays (CC),limestone filler (F), and two different Portland cements (PC). CC was obtained from kaolinitic clay(low grade of kaolinite, and quartz as main impurity) calcined at 750 ºC during 4 hours. Themetakaolinite containing in the CC (44%) has a high pozzolanic activity. Portland cements with lowand medium C3A-content were used. Ternary blended cements were prepared replacing CC (0 to 30%)and F (0 to 10 %) by mass in both PCs used.Pozzolanic activity of blended cements was measured using Frattini test and in terms of compressivestrength at 2, 7 and 28 days. The microstructural change was followed by XRD to determine theassembly of hydration products, the porosity determined by mercury intrusion porosimetry (MIP)The results of this study show that the pozzolanic activity of CC is more effective for low C3A-content inPC. The presence of limestone filler stimulates the pozzolanic reaction after 7 days for both PCs. Thelimestone filler in ternary blended cements has a large contribution to compressive strength when thePC used has medium C3A - content. The combination of CC and F increases the amount of AFmphases. At all ages, blended cements with 5% F and 15% CC present the best performance. The C3Acontentin the Portland cement is a significant variable to be considered for the formulation of blendedcements with CC and F. The coupled effect of CC and F increased when increased the C3A-content inPortland cement.OriginalityThe use of calcined clays providing