Microstructure of Portland cement mortar amended by burnt kaolin sand

• Published in: Journal of thermal analysis and calorimetry 2010-06, Vol.100 (3), p.779-787
• Main Authors: Krajči, L’., Moujmdar, S. C., Kuliffayová, M., Janotka, I.
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Applied sciences; Buildings. Public works; Cement; Cement concrete constituents; Cements; Chemistry; Chemistry and Materials Science; Clay; Contact; Exact sciences and technology; Inorganic Chemistry; Kaolin; Materials; Measurement Science and Instrumentation; Mortars; Permeability; Physical Chemistry; Polymer blends; Polymer Sciences; Portland cements; Raw materials; Sand
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-010-0718-8

Two types of raw materials, original kaolin sand OKS I and OKS II were used for experiment. They were transformed (1 h at 650 °C with 10 °C/min temperature increase) to burnt kaolin sand (BKS I and BKS II) with pozzolanic properties. Contents of decisive mineral—metakaolinite—in BKSs are as follows: BKS I (fraction below 0.06 mm) 20%; BKS II (fraction below 0.06 mm) 36% and BKS II (fraction below 0.1 mm) 31% by mass. Mortars with blends of Portland cement (PC) and BKS were prepared announced as: MK I (0.06) with 5 and 10% cement substitution by metakaolinite; MK II (0.06) with 5 and 10% cement substitution by metakaolinite and MK II (0.1) with 5, 10, 15 and 20% cement substitution by metakaolinite. The reference mortar with 100% of PC was made for comparison. All mortars were adjusted on the constant workability 180 ± 5 mm flow. Besides significant increase in compressive strengths—the refinement of pore structure in mortars with BKS connected with decreases in permeability and Ca(OH) 2 content were revealed. The above facts confirm pozzolanic reaction of BKS in contact with hydrated PC and indicate perceptiveness of BKS for the use in cement-based systems as a pozzolanic addition.