Recycling and reuse of reactive MgO cements – A feasibility study

Sonat, Cem; Lim, C.H.; Líška, Martin; Unluer, Cise

doi:10.1016/j.conbuildmat.2017.09.068

Cited by 64 publications

(14 citation statements)

References 43 publications

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“…The compressive strength of the specimens that were submitted to CP3 and CP4 was The specimen TMWM00C suggests that the MRP reacts with the water present in the mix and also with the CO 2 . Such behaviour was already expected since the MgO present on MRP reacts with water forming magnesium hydroxide (Mg(OH) 2 ), which reacts with dissolved CO 2 on the water forming hydrated magnesium carbonates (HMCs) [4]. The excess of water content does not collaborate with the gain of strength since the specimens which received the WI step and were not followed by the DS (CP3 and CP4),…”

Section: Compressive Strengthmentioning

confidence: 92%

“…In this scope, one of the main types of magnesiumbased cement is the reactive magnesia cement (RMC), which the literature describes as a blend of reactive MgO powder with conventional PC systems [3]. Such cement class is based on the carbonation cure for compressive strength gain, where the magnesium oxide (MgO) hydrates forming brucite, which is subsequently carbonated turning into hydrated magnesium carbonates (HCM), such as nesquehonite, hydromagnesite, and dypingite [4]. Some MgO-based cements have many properties that are superior to those of ordinary Portland cement (OPC), such as: good resistance to fire; high early strength; match very well to a wide variety of inorganic and organic aggregates, like gravel, marble flour, sand, sawdust [5], asbestos, wood particles and expanded clays [6].…”

Section: Introductionmentioning

confidence: 99%

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Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud

Soares¹,

Castro-Gomes²

2020

KEG

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In this preliminary study, the effect of the pre-drying stage, water immersion, carbonation curing cycles, and/or drying stage on carbonation curing of magnesium oxide-rich powder (MRP) was investigated. In addition, a blend of tungsten mining waste mud (TMWM) with MRP was also evaluated. The MRP and TMWM used have maximum grain sizes of 125 μm. The cement pastes were produced with 0 and 50 of TMWM weight percentage. The specimens were compacted into cylindric moulds (∅ = 20 mm; h = 40 mm) under 30 MPa and, subsequently, submitted to five different processes of curing involving a pre-drying stage before carbonation, rapid water immersion cycles, additional drying periods, and different carbonation curing periods. The atmosphere of the pressurized carbonation curing chamber was controlled to provide a CO2 concentration of > 99%, the partial pressure of 1 bar and temperature of 60°C. The influence of the curing processes on the compressive strength of each mix was determined 12 hours after the carbonation curing period. This study demonstrates that the water content during the curing process plays an important role in the increase of the hardening process and on the compressive strength. Keywords: Carbonation curing, magnesium oxide, mining waste, curing processes, magnesium-based cement

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Section: Compressive Strengthmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud

Soares¹,

Castro-Gomes²

2020

KEG

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“…Sonat el al. 25 . calcined the MgO at temperatures between 700 °C and 1100 °C, and found that the calcination temperature had a significant effect on the strength values for shorter residence times (2 h), whereas the strength of samples subjected to 6 h of calcination did not change significantly between the temperature range of 700 ºC to 900 ºC.…”

Section: Magnesium Oxidementioning

confidence: 99%

Effect of Water Content and MgO / ADP Ratio on the Properties of Magnesium Phosphate Cement

2020

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Materials such as magnesium phosphate cement (MPC) have attracted significant attention of researchers, therefore, understanding the effects of dosage parameters, such as water content and MgO/ NH 4 H 2 PO 4 ratio on phase formation is essential for obtaining cementitious matrices with improved performance. In the present work MgO was sintered at 900 °C and 1110 °C in a conventional oven, and the effect of water concentration and MgO/NH 4 H 2 PO 4 (or ADP) ratio on the properties of MPC was evaluated in terms of phase formation by X-ray diffraction, pore size distribution, mechanical properties, and microstructure. For less-reactive MgO (calcined at 1100 °C) with a high MgO/ADP ratio, increased water content did not cause additional solubilization of ADP or formation of more hydrated phases, although the cement porosity increased. Compositions with more reactive MgO (calcined up to 900 °C) formed dittmarite (NH 4 MgPO 4 .H 2 O) independent of water content. Higher water content and MgO calcination temperature were associated with increased MPC setting time and decreased mechanical strength due to higher porosity.

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“…When compared to Portland cement (PC), reactive MgO cement (RMC) presents lower calcination temperatures and ability to be fully recycled [1][2][3][4]. While a ton of RMC results in the emission of 1100 kg of CO 2 (in comparison to 866 kg of CO 2 per ton of PC) [5], its ability to absorb CO 2 permanently could reduce RMC's net emissions and enable it to be considered as a sustainable binder [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Advances in the hydration of reactive MgO cement blends incorporating different magnesium carbonates

Dũng

Unluer

2021

Construction and Building Materials

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h i g h l i g h t sMg(OH) 2 surface-layers limit the further hydration of reactive MgO cement (RMC). Use of magnesium acetate (MA), hydromagnesite (H) and magnesite (M) improved RMC hydration. MA and M enhanced the morphology of hydration products. Simultaneous use of MA and M improved the compressive strength by 240%. Low-crystallinity Mg(OH) 2 with a bird nest-like structure was observed in RMC-H samples.

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Recycling and reuse of reactive MgO cements – A feasibility study

Cited by 64 publications

References 43 publications

Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud

Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud

Effect of Water Content and MgO / ADP Ratio on the Properties of Magnesium Phosphate Cement

Advances in the hydration of reactive MgO cement blends incorporating different magnesium carbonates

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