High-calcium fly ash from pulverised coal combustion as a component of expansive cements
O. M. SHARONOVA1, V. V. YUMASHEV1, S. S. DOBROSMYSLOV2,3
1Krasnoyarsk Scientific Centre SB RAS, Institute of Chemistry and Chemical Technology SB RAS, Krasnoyarsk, Russia
2Siberian Federal University, Krasnoyarsk, Russia
3Krasnoyarsk Scientific Centre SB RAS, Krasnoyarsk, Russia
Keywords: high-calcium fly ash, expanding effect, compressive strength, composite cement
Abstract
The use of high-calcium fly ash (HCFA) as an expanding component of cements contributes to an increase in the level of their utilisation and improvement of binding properties. The influence of HCFA fractions of different size and composition on the expanding effect of binders based on them is studied in the work. The binders based on 100 % of three industrial fractions of high-calcium fly ash of different dispersion and composition, sampled from the 1st, 2nd and 4th fields of the Krasnoyarsk TPP-2 electrostatic precipitators, were studied; the expanding effect of binders based on these fractions was determined with respect to Portland cement (PC) grade CEM I 42.5N. It was determined that an increase in the volume of hardening specimens is 6-19 and 6-42 % after hardening for 5 and 120 days, respectively. An increase in the volume of specimens correlates with the content of CaO and MgO oxide phases in the initial HCFA fractions and is accompanied by a decrease in the average density and compressive strength. The specimens of cement-fly ash compositions with the content of 50 % PC and 50 % HCFA, including a mixture of different fractions of FA, were studied. The positive effect of HCFA fractions on the properties of composite cement, including the regulation of the expansion effect and an increase in compressive strength, was determined.
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