Magnesia Cement Research Articles

Fast removal of methylene blue by modified sorel cement using manganese(VII) as an additive: kinetics, thermodynamics, and equilibrium studies

ABSTRACT In this study, Sorel cement (SC) was doped with Mn7+ to develop a cost-effective adsorbent that can quickly remove methylene blue (MB) dye from aqueous solutions. The characteristics of the prepared adsorbents were examined using X-ray diffraction, atomic force microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The examinations confirmed the formation of SC and the successful doping of manganese. Batch adsorption experiments were also performed to investigate and to optimise the operational parameters such as Mn7+ ion concentration, contact time, dosage, MB concentration, pH, and temperature. The modified adsorbent revealed a significant adsorption improvement when compared with pure SC. A small addition of 0.01 g of Mn7+ exhibited 100% removal efficiency up to a dye concentration of about 100 mg/L, whereas about 64% removal efficiency was obtained with pure SC using 36.5 mg/L of the MB solution. Furthermore, the modified adsorbent revealed rapid equilibrium times of around 1 and 3 minutes using 36.5 and 100 mg/L of the MB solution, respectively. An experimental adsorption capacity of up to 246 mg/g was obtained, and the equilibrium data were consistent with the Freundlich isotherm and were well fitted with a pseudo-second-order kinetic model. The thermodynamic values indicated a physisorption, exothermic (ΔH° = −7.7 kJ/mol), and spontaneous (ΔG° = −9.4 kJ/mol) nature of the adsorption process with enhanced feasibility and comparable regeneration efficiency for up to five cycles. Therefore, the results indicate that the modified sorbent can possibly be utilised as a potential fast method for the removal of MB dye from wastewater.

Enhancing carbonation and strength of MgO cement through 3D printing

Magnesium oxide (MgO), which develops physical strength through carbonation, is a potential alternative to carbon intensive Portland cement. In this paper, we examined whether 3D printing could improve carbonation and compressive strength. The rheology of MgO paste was modified using mixtures of nanoclays and methylcellulose to produce cylinders with exposed open-to-air and closed (solid) infills. The results showed significant increases in strength at 3 and 28 days compared to conventionally cast specimens. This was attributed to higher exposed surface area and increase in porosity caused by high early water evaporation, both of which led to higher CO2 intake.

Effect of Value Added Admixture Zeolite on Setting Time and Compressive Strength of Magnesia Cement

In 1867,S. T. Sorel discovered Magnesia Cement in an aqueous solution by reacting magnesium chloride with magnesia. In comparison to Portland cement, this has versatile cementing characteristics. As an inert filler to absorb the heat evolved during the exothermic formations of magnesia cement Dolomite is used. Authors in this research paper have prepared Dry-mixes composition of magnesia and dolomite (inert filler) in the ratios of (1s And then these are gauged with 24oBegauging -solutions MgCl2 and the impact of admixture on their setting time -initial and final and compressive strength can be found. The initial and final setting time was observed to be increasing remarkably. With increase in percentage of admixture (zeolite) time of the cement blocks increased in the initial and final setting time also ratio of inert filler (dolomite) in the each dry-mix composition was observed and recorded. In the results it was found that to the percentage composition of admixture (zeolite) both initial and final setting time of cement blocks and also the ratio of inert filler in the dry-mix composition itis directly proportional. Quantity of magnesia cement drastically increases with Incorporation of zeolite and this further remarkably increases and improves strength of the cement. Magnesia cement could in fact act as carbon sinks, acting to favorably reduce greenhouse gas emissions. It is eco friendly cement.

Preparation of building materials from Bayer red mud with magnesium cement

In this paper, influences of red mud on the properties of magnesium oxychloride cement (MOC) and magnesium oxysulfate cement (MOS) were studied with a 200 day time scale.The results showed that the addition of red mud greatly enhanced the 28d water resistance of MOC cement from 0.84 to 1.10, of MOC cement, significantly increased the compressive strength of MOS cement from 24.12 MPa to 33.31 MPa and water resistance from 0.48 to 0.68. At 200d, the addition of red mud had little effect on MOC cement but greatly increased compressive strength and water resistance of MOS cement. The red mud and magnesium cement produced an amorphous gel, which made the matrix more compact.Meanwhile, magnesium cement played the role of solidification soluble salt in red mud and only slight frosting appeared.The research results show the potential of red mud as a modifier of magnesium cement and its application potential as a building material.

Feasibility for co-utilisation of Carbonated Reactive Magnesia Cement (CRMC) and industrial wastes in circular economy and CO2 mineralisation

The increased concern about climate change is leading to the growth of research interest in alternatives to mitigate its effect. Such trend is also observed in the materials and building technologies field, where among the many possible alternatives. Cementitious composites with a lower CO2 footprint have been recently developed to incorporate waste in their composition, with the capability to adsorb CO2. This study evaluates the feasibility of incorporating seven different wastes sources as filler and/or magnesia replacement in Carbonated Reactive Magnesia Cement (CRMC)-based mortars. CRMC-based mortars were designed to incorporate reactive magnesia and waste powders, by the volume ratio of three to one (sand to paste). The mortar specimens were cast by static compaction pressure and cured through accelerated carbonation curing for 24 h at controlled conditions. The performance of CRMC-based mortars was evaluated by compressive strength and microstructural examination. TG-DTG and FT-IR analysis were used to investigate the carbonation effectiveness through the specimens' volume. The results showed that the designed mortars embodying waste have achieved strength values of 8.5 to 14.6 MPa and the carbonation took place at the whole volume independently of the waste-based material used. The compressive strength results were found to be influenced by the pH of the raw materials. The study demonstrated that CRMC-based mortars have good binding properties with the different wastes investigated with the capability of adsorbing CO2 the surrounding environment into the cementitious matrix. It provides innovative solutions for the circular economy in the construction sector aside to sequestrate carbon within the built environment.

Incorporating hollow natural fiber (HNF) to enhance CO2 sequestration and mechanical properties of reactive magnesia cement (RMC)-based composites: Feasibility study

Reactive magnesia cement (RMC) hydrates and carbonates to harden, which can sequestrate CO2 from ambient air. However, the application of RMC-based composites in construction material is still limited by the inadequate CO2 diffusion through the dense microstructure of MgO carbonates. This work for the first time investigates and demonstrates the feasibility of utilizing hollow natural fibers (HNFs) to enhance the carbonation and mechanical properties of RMC. In this study, 2 vol.% sisal or PVA microfibers were added RMC-based matrix to make fiber-reinforced composites. The compressive test shows that addition of sisal fibers significantly enhanced the 14-day compressive strength (10 % CO2 curing) from 20.9 MPa to 39.3 MPa, while PVA fibers only marginally enhanced the strength to 25.0 MPa; the carbonation test of the composites, e.g., phenolphthalein color indication, FTIR, and XPS, shows that the lumens in the natural fibers served as the pathway for CO2 penetration, which significantly increased the carbonation depeth and degree and thus the material strength. The tensile strength of sisal fibers were tested after conditioning in oversaturated Mg(OH)2 or Ca(OH)2 solution, the result shows that the fibers deterioration in RMC-based matrix is minimal, almost neglible compared to that in Portland cement (PC)-based composites. Collectively, these experimental results indicate that RMC and HNF are complementary to each other and can potentially make a new class of sustainable building materials.

Магнезиальное вяжущее на основе техногенного сырья

The data of the research on the possibility of using technogenic raw materials (refractory waste of metallurgical furnaces) in the technology of building materials are presented. The authors propose a basic technological scheme for processing the refractory waste so as to obtain a binding material, namely, magnesia cement. The data of the laboratory studies of the chemical and mineral composition of technogenic raw materials are presented. There was performed a laboratory approbation of the technological process, during which a sample of magnesia cement was obtained. There were made standard samples of the solution based on the synthesized binder. The strength parameters of the solution were evaluated.

Fresh state properties and compressive strength development of reactive MgO-based systems

In this study, flowability, setting time, and strength gain of mortars containing reactive magnesium oxide cement (RMC) and a combination of micro-silica (MS), nano-silica (NS), slag, and fly ash (FA) as precursors without employing accelerated carbonation have been investigated. To increase the flowability and hydration degree, sodium hexametaphosphate (SHMP) was incorporated. The series containing RMC and MS simultaneously, had the greatest 3-day compressive strength value of about 25 MPa, whereas further strength gains in all the mixtures until the 7th day was minimal, which establishes that strength gains were due to hydration degree, not carbonation. RMC and MS simultaneously in a series, a combination of extremely high fineness materials dropped the flowability; the presence of slag and FA, on the other hand, enhanced it. The inclusion of NS in the mix didn’t demonstrate a perceptible change in any of the properties measured in this study; its inertness could be attributed to the unsuitable dispersion method. Setting time of reference mix was the shortest, which was in conformity with its fast initial strength gain. Replacement of RMC with any other binder extended both the initial and final setting time. It was hypothesized that a major difference in this study is the use of SHMP as a dispersant and hydration agent. The outcomes of this study confirm that RMC can be a potential binder material to be used in mortar productions.

Impact of varying proportions of dolomite powder filler on setting period and compressive strength of magnesia Cement an eco-friendly cement

A parametric study was conducted by authors to investigate the impact of varying proportions of dolomite as filler on cementing properties (standard consistency, setting time and compressive strength) of magnesia cement. For this purpose, dry-mix compositions were prepared by mixing magnesia and dolomite in the ratio 1:0, 1:1, 1:2, 1:3, 1:4, 1:5 and 1:6 by their weight and gauged with 24oBe and 28oBe densities of gauging solution. It was observed that initial and final both setting times were increasing remarkably. It has also been recorded that initial and final setting time of cement blocks increased with increasing concentration of gauging solution (24oBe and 28oBe) in the each dry-mix composition. Results show that both setting time of cement blocks are directly proportional to the ratio of inert filler in the dry-mix composition but compressive strength is decreased with varying dry-mixes ratio.

Potential of application of Rice Husk Ash (RHA) on magnesia cements for abrasive tools production

RESUMO O polimento e desbaste de rochas ornamentais ou revestimentos cerâmicos como o porcelanato, tem por finalidade promover, por meio de ferramentas abrasivas, melhor acabamento superficial nestes produtos. Neste contexto, verifica-se o uso de matrizes magnesianas para produção de compósitos à base de carbeto de silício (SiC) que podem ser usados pela indústria em rebolos ou coroas abrasivas. Outra opção, são as matrizes poliméricas que fazem uso do diamante sintético como abrasivo. Neste sentido, apesar das matrizes magnesianas serem de baixo custo comparativamente às matrizes poliméricas, observa-se a necessidade de aprimoramento desta tecnologia por meio do uso de adições, como a sílica da casca do arroz (SCA) estudada neste trabalho, em vista de melhorias no polimento e maior durabilidade destes compósitos. No Brasil, o emprego desta sílica pode representar uma alternativa de menor custo e, assim, colaborar no desenvolvimento de matrizes abrasivas à base de óxido de magnésio. Nesta pesquisa foi resgatada a tecnologia do cimento magnesiano e buscou-se implementar a adição da SCA para atendimento não somente dos requisitos técnicos para sua aplicação em rebolos abrasivos, mas, também, colaborar em soluções mais sustentáveis pelo emprego de uma sílica proveniente de fontes renováveis. Dessa forma, as matrizes desenvolvidas foram analisadas aos esforços de compressão, tração na flexão, dureza Mohs e estabilidade dimensional, para verificação de seu desempenho mecânico e durabilidade. Adicionalmente, análises de Difratometria de Raios-X (DRX) e Microscopia Eletrônica de Varredura (MEV) complementaram o estudo para identificação das fases formadas e verificação da viabilidade de aplicação destes compostos na produção de matrizes para rebolos abrasivos.

Effect of Hollow Natural Fiber (Hnf) Fraction on the Carbonation and Strength Development of Reactive Magnesium Cement (Rmc)-Based Composites

Effect of Hollow Natural Fiber (Hnf) Fraction on the Carbonation and Strength Development of Reactive Magnesium Cement (Rmc)-Based Composites

High-performance Reactive Magnesium Cement Incorporating Hollow Natural Fiber and Silica Sand

Global warming caused by CO2 emissions makes reactive magnesium cement (RMC) increasingly attractive due to its ability to sequester CO2, however, the diffusion of CO2 in RMC is severely limited by the dense hydrated magnesium carbonates (HMCs) formed on the outer layer. This work utilizes hollow natural fiber (e.g., sisal fiber) to facilitate the diffusion of CO2 into the deep part of the RMC specimen. Combining with adding silica sand as a filling agent, the mechanical strength can be enhanced from 42.4 MPa of the control group to 92.6 MPa of the specimen with 2 vol.% sisal fiber, this is attributed to that the addition of sisal fiber significantly enhances the carbonation depth. FTIR and XPS results further prove that the addition of 2 vol.% or more sisal fiber can improve the carbonation degree by over 200%, leading to a sharp reduction of CO2 emission from 37 kg/(m3>MPa) of the control group to 12.1 kg/(m3∘MPa) of the specimen with 2 vol.% sisal fiber. Therefore, adding hollow natural fiber and silica sand to RMC can be a promising approach to make RMC stronger and more sustainable.

Investigation of Mechanical and Insulation Properties of Sorel Cement Lightweight Samples

Bu çalışmada, Sorel çimentolu hafif betonların (SÇ) bazı mekanik ve yalıtım özellikleri incelenmiştir. SÇ numunelerinin yalıtım özelliklerinde iyileştirmeler yapabilmek için SÇ karışımları içerisine; hava sürükleyici katkı (HSK), ahşap talaşı (AT), mısır koçanı talaşı (MT), Puzolanlı madde (P), Afşin-Elbistan Termik Santral uçucu külü (AEUK) katkıları ayrı ayrı ikame edilerek numuneler üretilmiştir. Numuneler, bazı mekanik testlere ve yalıtım testlerine tabi tutulmuştur. Ayrıca referans numunelerin (R) farklı ortam koşullarına karşı dirençleri incelenmiştir. Numune dayanım değerlerinin yüksekten düşüğe sırasıyla SÇ, SÇ+HSK, SÇ+P, SÇ+AEUK, SÇ+AT ve SÇ+MT olduğu tespit edilmiştir. SÇ+AEUK numunelerinin çatlaması nedeniyle SÇ ve AEUK malzemelerinin birlikte kullanılmalarının uygun olmadığı gözlemlenmiştir. Suda bekletilen SÇ numunelerinin dayanımlarının zamanla düştüğü saptanmıştır. Ortam sıcaklık artışının R numunelerinin dayanımlarında 100 C’de artış, 500 C ve sonrasında düşüşe neden olduğu görülmüştür.
 Sonuç olarak katkı kullanılan numunelerin R numuneye göre dayanımlarında düşüş, yalıtım özelliklerinde ise bazı iyileşmelerin olduğu gözlemlenmiştir. Saptanan değerler kullanılan katkıların türüne ve oranına göre farklılık göstermiştir.

Potential additives for magnesia-based concrete with enhanced performance and propensity for CO2 sequestration

This study focuses on the development of carbonated reactive magnesia cement (RMC) concrete formulations involving hydromagnesite (H), magnesite (M) and hydration agent (HA). Partial replacement of RMC by H and M stimulated the formation of hydrate and carbonate phases. Use of H increased the rate and degree of hydration, resulting in the formation of a bird nest-like structure containing poorly-crystalline brucite. The higher propensity of this poorly-crystalline phase for carbonation increased the utilisation of RMC as a binder and facilitated its conversion into strength-providing HMCs. Synergistic combination of M and HA led to significant strength gain via increased carbonate content and reduced w/b ratio. Presence of M provided micro-aggregates that facilitated the enhanced formation of large carbonate crystals with improved morphologies, resulting in microstructure densification and 113 % strength increase. Furthermore, partial replacement of RMC with M enabled reduction of natural resources, CO2 emissions and energy consumption associated with RMC production.

Cement as a component of the multi-barrier system: radionuclide retention in cementitious environments

Abstract. Safety concepts regarding nuclear waste disposal in underground repositories generally rely on a combination of engineered and geological barriers, which minimize the potential release of radionuclides from the containment-providing rock zone or even their transport into the biosphere. Cementitious materials are used for conditioning of certain nuclear waste types, as components of waste containers and overpacks, as well as being constituents of structural materials at the interface between backfilling and host rock in some repository concepts. For instance, the preferred option for the disposal of high-level waste (HLW) in Belgium is based on the supercontainer design, which consists of a carbon steel overpack surrounded by a thick concrete buffer (Bel et al., 2006). In the event of formation water interacting with cementitious materials, pore water solutions characterized by (highly) alkaline pH conditions will form. These boundary conditions define the chemical response of the radionuclides, but also influence the behaviour of neighbouring components of the multi-barrier system, e.g. bentonitic or argillaceous backfilling and host rock. Hardened cement paste or Sorel cement are considered to be main sorbing materials present in the near field of repositories for low- and intermediate-level waste (L/ILW). Hence, interactions of radionuclides with cementitious materials represent a very important mechanism retarding their mobility and potential migration from the near field (Wieland, 2014; Ochs et al., 2016). While the quantitative description of the sorption processes (usually in terms of sorption coefficients, i.e. Kd values) is a key input in the safety analysis of nuclear waste repositories, detailed mechanistic analysis and understanding of sorption phenomena provide additional scientific arguments and important process understanding, and thus enhance both the quality of safety arguments and the overall confidence in the safety assessment process. Research at KIT-INE dedicated to the interaction of cementitious materials with radionuclides is conducted in the context of different repository concepts, including clay (low- and high-ionic strength conditions), crystalline rock or rock salt. Experimental and theoretical studies are performed within the framework of national (GRAZ, BMWi) and international (CEBAMA and EURAD-CORI, EU Horizon 2020 Programme) projects, extending to third-party projects with several waste management organizations in Europe, e.g. SKB (Sweden), ONDRAF-NIRAS (Belgium) or BGE (Germany). The combination of classical experimental (wet chemistry) methods, advanced spectroscopic techniques and theoretical calculations provides both an accurate quantitative evaluation and a fundamental understanding of the sorption processes. Examples of recent studies at KIT-INE on radionuclide behaviour in cementitious systems in the context of both L/ILW and HLW will be presented in this contribution to explain methodologies, scientific approaches and results. The present state of knowledge as well as main remaining uncertainties affecting the retention processes of radionuclides in cementitious environments under different conditions will be critically discussed, also in view of current international research activities and repository projects.

Properties of Magnesium Oxychloride and Magnesium Oxysulphate Cement Composites

Increasing energy consumption is forcing the building sector to seek and use building materials and products that would be environmentally friendly. As one such material should be noted magnesium based cements, which production requires much lower calcination temperature than the traditional Portland cement. During the experimental research part of this work, two types of magnesia cement were produced (using magnesium chloride and magnesium sulphate brine solutions) and physical, mechanical properties of obtained cement composites were determined.

Performance Parameter Analysis of Magnesia Based Cement Products – A Review

Magnesium oxide (MgO) based cements finds its way active in current researches where diverse range of applications and characteristics such as production process, reactivity and physical properties are essentially focus with the perception of individual expansion objectives. In general, relativity between distinctive MgO characteristics is examined in conjunction with the impact of MgO embodiment on the resources of cementitious materials is further considered. MgO is a key to develop the construction industry thereby mechanical strength and durability performance of cement paste, adhesive and concrete composites impose of MgO needs to be explored. Subsequently, this research paper explicitly defines the investigation of MgO cement composites in terms of compressive and flexural behavior, toughness, tensile and durability performances, flexibility, water susceptibility, porosity, carbonation, chloride ion diffusion, shrinkage and degree of hydration. In this regard, to application of magnesia-based cement products is influenced by various factors such as raw material, composition, performance. The review provides a detailed information of current research available related to magnesia-based cement products based on its properties.

Thermal properties and stability of reactive magnesia cement

The unique ability of reactive magnesium oxide cement (RMC) to permanently sequester environmental carbon dioxide (CO2), followed by sufficient strength gain, makes it an attractive material for greener construction. The potential of RMC and its combination with various supplementary materials have been demonstrated for construction by several researchers. In this study, the thermal properties of the RMC-based paste, along with its thermal stability after prolonged and cyclic high-temperature exposure, are reported. The results reveal that, in general, the RMC-based paste samples cured under an ambient environment as well as the ones cured under accelerated carbonation undergo strength gain after cyclic exposure to temperature as high as 300 °C. In terms of thermal properties, the general trend was found to be an increase in the specific heat and a decrease in the thermal conductivity and the thermal diffusivity with increasing temperature for both types of RMC-based paste samples. These results reveal a remarkable ability of the RMC to sustain high temperatures with excellent strength retention making it suitable for high temperature and energy storage applications.

Assessment of the properties and environmental impact of carbonated reactive magnesia containing industrial waste

To achieve the goal of carbon neutrality, carbon capture and storage (CCS) is considered to be an effective approach. This study investigated the microstructural development of reactive magnesia cement-industrial waste (i.e., pulverized fly ash and ground granulated blast-furnace slag) formulations under accelerated carbonation conditions. The density and isothermal calorimetry analyses were supported with microstructural analysis performed. Results showed that pulverized fly ash and ground granulated blast-furnace slag could be activated by reactive magnesia cement, resulting in the formation of phases such as magnesia silicate hydrate, hydrotalcite and hydromagnesite, whose formation was enhanced in the presence of accelerated carbonation. Associated with a low initial pH, samples with pulverized fly ash outperformed samples with ground granulated blast-furnace slag counterparts in terms of their strength development. The study led to the determination of a formulation containing the reactive magnesia cement and pulverized fly ash with a higher mechanical performance than the control group, also highlighting the need for the revision of the adopted carbon footprint calculation to incorporate several critical factors.

Recycling carbonated reactive magnesium cement (RMC) as a building material

This study assessed the recyclability of reactive magnesium cement (RMC). To simulate the condition of construction waste recovery, a carbonated RMC-based paste was ground and used as a replacement for fresh RMC at 20 and 40 wt%. Both paste and mortar specimens were prepared and subjected to carbonation under 20% CO2, 80% RH, and 30 °C. Calorimetry data revealed that the main hydration peaks were delayed. The cumulative heat flow values were reduced, attributable to an increase in pore solution pH and physical barrier created by amorphous phases, which were confirmed by the appearance of broad peaks coinciding with those of hydromagnesite. Under carbonation, the peaks became more apparent due to the transformation of the phases into crystalline hydromagnesite. At 20 wt% replacement, the composite incorporated with the recycled RMC attained an improved strength performance due to more formation of the amorphous phases and hydrated magnesium carbonates (HMCs) from brucite.