Abstract
The aim of this work is to investigate the influence of selected alkaline activators on pozzolanic and hydraulic activities of fly ashes using thermal analysis (TG/DTG) and infrared spectroscopy (FTIR). Two types of fly ashes differing in chemical compositions, especially content of calcium components, were selected for investigations. The study was carried out for two types of samples: (1) fly ash–lime paste performed with low-calcium fly ash and (2) a paste performed with high-calcium fly ash and water without introduction of additional amount of Ca(OH)2. Chemical admixtures NaOH, Na2SO4, and Na2CO3 were added to both the types of samples. It was confirmed that influence of chemical activators on pozzolanic and hydraulic properties of fly ashes strictly depends on the kind of fly ash and availability of Ca(OH)2. For example, in case of high-calcium fly ash, the most active action was exhibited by NaOH solution.
Highlights
In recent years, more and more attention is paid to the necessity to reduce emission of CO2 to atmosphere.development of new binders which may be an alternative for traditional Portland cement becomes priority objective, and it is an ongoing research topic in theB
The study was carried out for two types of samples: (1) fly ash–lime paste performed with low-calcium fly ash and (2) a paste performed with high-calcium fly ash and water without introduction of additional amount of Ca(OH)2
It was confirmed that influence of chemical activators on pozzolanic and hydraulic properties of fly ashes strictly depends on the kind of fly ash and availability of Ca(OH)2
Summary
More and more attention is paid to the necessity to reduce emission of CO2 to atmosphere.development of new binders which may be an alternative for traditional Portland cement becomes priority objective, and it is an ongoing research topic in theB. Faculty of Civil Engineering, Mechanics and Petrochemistry, Institute of Chemistry, Warsaw University of Technology, Fly ashes are frequently used as cement replacements or components of geopolymers These waste materials exhibit the so-called pozzolanic activity. It means that they can react in the presence of water and available Ca(OH) at room temperature [13, 14]. Some kinds of fly ashes contain properly high amount of calcium compounds to exhibit self-cementing properties It means that they are able to hardening in the presence of water but without introduction of additional amount of. Silicate and aluminate ions move into solution where they may undergo further reactions Such activating action of NaOH is clearly confirmed by results obtained by thermal analysis Comparing with the results for PK activated with other admixtures, one may conclude that the action of
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