Materiales de Construcción, Vol 68, No 332 (2018)

Evaluation of cements obtained by alkali-activated coal ash with NaOH cured at low temperatures

A. A. Hoyos-Montilla
Cement and Building Materials Group, Department of Materials and Minerals, Faculty of Mines, Universidad Nacional de Colombia, Colombia

Y. P. Arias-Jaramillo
Cement and Building Materials Group, Department of Materials and Minerals, Faculty of Mines, Universidad Nacional de Colombia, Colombia

J. I. Tobón
Cement and Building Materials Group, Department of Materials and Minerals, Faculty of Mines, Universidad Nacional de Colombia, Colombia


The temperature at which the alkaline activation process takes place is a significant factor in the evolution of the mechanical properties of coal ash cementitious base material. In this work, the influence of temperature (8 a 38 °C) and curing time (3 and 28 days) on the mechanical properties of the alkaline synthesis of two coal ashes was evaluated through the study of the mineralogical evolution of the cementitious phases by XRD and FTIR. We found that the type of zeolite, a synthesis product, depends on the study factors. For values above 28 °C and at least 7 days, alkalinely activated cements with compressive strength above 20 MPa were achieved. Other parameters, such as SiO2/Al2O3 ratio, percentage of unburned coal and particle-size distribution, should be taken into account in the variation of mechanical performance.


Fly ash; Temperature; Alkali-activated cement; Particles size distribution; Compressive strength

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