Development of magnesium oxalate cements with recycled portland cement paste

İçınsel, Nesim
In search of lower-carbon-footprint alternatives to portland cement systems, magnesium-based cements are one of the most promising materials to investigate. Even though it is not possible to directly replace the calcium oxide in portland cement with magnesium oxide, magnesium oxide has its distinct mechanisms of forming binders with various materials. Some of the proven magnesium cements use acid-base reactions to create a binder by coupling an acid with magnesium oxide, such as the well-known magnesium phosphate cements. In this study, oxalic acid (an acid that can even be produced from carbon dioxide in the atmosphere) is coupled with magnesium oxide to form a cementitious system. In an effort to control this very reactive system, oxalic acid is blended with recycled portland cement paste. The development of an appropriate mixture design is attempted, and some experiments are carried out to investigate the possibility of forming a stable and serviceable binder. Then the developed binder (magnesium oxalate hydrate) is analyzed to elucidate the mechanism of formation and effects of raw materials, retarders, pozzolans, and mix design on the resulting system. The compressive strength development of the mortars is evaluated together with their mineralogy and microstructures using x-ray diffractometry, x-ray fluorescence spectroscopy, electron microscopy, and thermogravimetric analysis. A somewhat porous mortar, with low-to-medium strength but with a significantly lower carbon footprint than portland cement mortar could be obtained.


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An emerging alternative to Portland cement, oxalate cement is a promising candidate for reducing the carbon footprint of the construction industry. Oxalic acid (OA) can be produced via direct electrochemical CO2 reduction, making carbon-neutral cement with OA possible. This study investigates the development of the mechanical, mineralogical, and microstructural properties of clay oxalate cement (COC) made with OA salt and dead-burned magnesia (DBM). Methods to prepare clay oxalate (CO), the OA salt used in ...
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Magnesium potassium phosphate cements (MKPCs) have some promising properties to be considered as an alternative to ordinary Portland cement binders. The favorable properties of these cements are high early and ultimate strength. On the other hand, they have some problems like rapid setting, high heat of reaction, high cost and poor water stability. In this study, the effect of several factors like magnesium-to-phosphate molar ratio (M/P), water-to-binder ratio (W/B) and retarder (borax) content on propertie...
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Citation Formats
N. İçınsel, “Development of magnesium oxalate cements with recycled portland cement paste,” M.S. - Master of Science, Middle East Technical University, 2020.