Preparation and characterization of magnesium oxalate cement

Development of Magnesium/Calcium Oxalate Cements

“…FA:OxAc:water are mixed at 1.0:1.5:1.0 by mass as in (15). The resulting paste heats up and within minutes sets into a strong but water-soluble solid.…”

“…The mixture proportions in Table 2 were chosen to achieve a low estimated carbon footprint and adequate mechanical performance. The FAOx-to-alkaline binder ratio influences the strength and water resistance of oxalate binders and a ratio close to 2 is close to optimum when MgO1500 is used (15). The calcination of MgCO 3 to produce 1 g MgO emits ~1.1 g chemical CO 2 .…”

“…A carbon-neutral/negative yet practical binder needs to use a low-cost, powder with a low carbon footprint, to be able to trap large amounts of CO 2 , to be cast on site, and yield a reaction product with sufficient physical and mechanical properties. Recent studies (15)(16)(17)(18) have proposed magnesium oxalate cement (MgOx) as a new alternative to PC. MgOx is an acid-base cement, similar to the well-known magnesium phosphate cements (MPC) (19)(20)(21)(22).…”

“…Ca analogues of MgOx, such as those made with hydrated lime as the basic powder, can also set and harden, but high water demand and dimensional stability issues lead to high porosity and low strength. MgOx are rapid setting, can reach medium-to-high ultimate strength, and are water-resistant (15). However, like MPCs, they use dead-burned MgO.…”

“…However, like MPCs, they use dead-burned MgO. Since low-cost MgO is typically obtained by decarbonating MgCO 3 and burning MgO at ~1500 °C leads to significant fuel-related emissions, MgOx cements can be made low carbon but not carbon negative (15). Replacement of dead-burned MgO with a less carbon-intense waste or natural material is needed to further decrease the carbon footprint of oxalate cements.…”