Obtaining of Composite Cements with Addition of Fly Ash
Rakhimova G. Syndarbekova G. Zhanikulov N. Yerkebayeva B. Potapova E. Rakhimov M.
October 2025Multidisciplinary Digital Publishing Institute (MDPI)
Buildings
2025#15Issue 19
The potential for creating composite cements by incorporating fly ash is demonstrated. Analysis revealed that the fly ash examined consists of 69.66 wt. % silicon oxide, 21.34 wt. % aluminum oxide, 1.57 wt. % calcium oxide and 2.78 wt. % iron oxide. Fly ash mainly consists of quartz (SiO2), goethite (FeO(OH)) and mullite (3Al2O3·2SiO2). The properties of the cement composition containing 5 to 25 wt. % fly ash were studied. Incorporating fly ash enhances system dispersion, promotes mixture uniformity, and stimulates the pozzolanic reaction. Compositions of composite cements consisting of 90% CEM I 42.5 and 10% fly ash were developed. The cement stone based on the obtained composite cement had a compacted structure with a density of 2.160 g/cm3, which is 9.4% higher than the control sample. It is shown that when composite cement containing 10% fly ash interacts with water, hydration reactions of cement minerals (C3S, C2S, C3A and C4AF) begin first. This is accompanied by the formation of hydrate neoplasms, such as calcium hydroxide (Ca(OH)2) and calcium hydrosilicates (C-S-H). Fly ash particles containing amorphous silica progressively participate in a pozzolanic reaction with Ca(OH)2, leading to the formation of additional calcium hydrosilicates phases. This process enhances structural densification and reduces the porosity of the cement matrix. After 28 days of curing, the compressive strength of the resulting composite cements ranged from 42.1 to 54.2 MPa, aligning with the strength classes 32.5 and 42.5 as specified by GOST 31108-2020.
additive , cement stone , composite cement , fly ash , physical and mechanical properties , pozzolanic properties
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Department of Building Materials and Technologies, Abylkas Saginov Karaganda Technical University, Qaraghandy Region, Karaganda, 100000, Kazakhstan
Department of Inorganic and Technical Chemistry, E.A. Buketov Karaganda University, Qaraghandy Region, Karaganda, 100028, Kazakhstan
Department of General Technical Disciplines, Non-State Educational Institution Kazakhstan University of Economic and Telecommunication Systems, West Kazakhstan Region, Uralsk, 090006, Kazakhstan
Department of Chemical Technology of Composite and Binding Materials, D. Mendeleev University of Chemical Technology of Russia, Moscow, 125047, Russian Federation
Research Institute “Environmental Industrial Policy Centre”, Moscow, 115054, Russian Federation
Department of Building Materials and Technologies
Department of Inorganic and Technical Chemistry
Department of General Technical Disciplines
Department of Chemical Technology of Composite and Binding Materials
Research Institute “Environmental Industrial Policy Centre”
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