Properties of Chemically Combusted Calcium Carbide Residue and Its Influence on Cement Properties

Calcium carbide residue (CCR) is a waste by-product from acetylene gas production. The main component of CCR is Ca(OH)₂, which can react with siliceous materials through pozzolanic reactions, resulting in a product similar to those obtained from the cement hydration process. Thus, it is possible to use CCR as a substitute for Portland cement in concrete. In this research, we synthesized CCR and silica fume through a chemical combustion technique to produce a new reactive cementitious powder (RCP). The properties of paste and mortar in fresh and hardened states (setting time, shrinkage, and compressive strength) with 5% cement replacement by RCP were evaluated. The hydration of RCP and OPC (Ordinary Portland Cement) pastes was also examined through SEM (scanning electron microscope). Test results showed that in comparison to control OPC mix, the hydration products for the RCP mix took longer to formulate. The initial and final setting times were prolonged, while the drying shrinkage was significantly reduced. The compressive strength at the age of 45 days for RCP mortar mix was found to be higher than that of OPC mortar and OPC mortar with silica fume mix by 10% and 8%, respectively. Therefore, the synthesized RCP was proved to be a sustainable active cementitious powder for the strength enhanced of building materials, which will result in the diversion of significant quantities of this by-product from landfills.     

Photocatalytic Performance Evaluation of Titanium Dioxide Nanotube-Reinforced Cement Paste

Considering the increase in research regarding environmental pollution reduction, the utilization of cementitious material, a commonly used construction material, in photocatalysts has become a desirable research field for the widespread application of photocatalytic degradation technology. Nano-reinforcement technology for cementitious materials has been extensively researched and developed. In this work, as a new and promising reinforcing agent for cementitious materials, the photocatalytic performance of titanium dioxide nanotube (TNT) was investigated. The degradation of methylene blue was used to evaluate the photocatalytic performance of the TNT-reinforced cement paste. In addition, cement paste containing micro-TiO₂ (m-TiO₂) and nano-TiO₂ (n-TiO₂) particles were used for comparison. Moreover, the effect of these TiO₂-based photocatalytic materials on the cement hydration products was monitored via X-ray diffraction (XRD) and thermogravimetric analysis (TG). The results indicated that all the TiO₂ based materials promoted the formation of hydration products. After 28 days of curing, the TNT-reinforced cement paste contained the maximum amount of hydration products (Ca(OH)₂). Furthermore, the cement paste containing TNT exhibited better photocatalytic effects than that containing n-TiO₂, but worse than that containing m-TiO₂.     

Hydration–Strength–Workability–Durability of Binary,Ternary, and Quaternary Composite Pastes

At present, reducing carbon emissions is an urgent problem that needs to be solved in the cement industry. This study used three mineral admixtures materials: limestone powder (0–10%), metakaolin (0–15%), and fly ash (0–30%). Binary, ternary, and quaternary pastes were prepared, and the specimens’ workability, compressive strength, ultrasonic pulse speed, surface resistivity, and the heat of hydration were studied; X-ray diffraction and attenuated total reflection Fourier transform infrared tests were conducted. In addition, the influence of supplementary cementitious materials on the compressive strength and durability of the blended paste and the sustainable development of the quaternary-blended paste was analyzed. The experimental results are summarized as follows: (1) metakaolin can reduce the workability of cement paste; (2) the addition of alternative materials can promote cement hydration and help improve long-term compressive strength; (3) surface resistivity tests show that adding alternative materials can increase the value of surface resistivity; (4) the quaternary-blended paste can greatly reduce the accumulated heat of hydration; (5) increasing the amount of supplementary cementitious materials can effectively reduce carbon emissions compared with pure cement paste. In summary, the quaternary-blended paste has great advantages in terms of durability and sustainability and has good development prospects.     

Application of Iron Tailings-Based Composite Supplementary Cementitious Materials (SCMs) in Green Concrete

How to treat the iron tailings of mining solid waste with high value is an urgent problem on a global scale. In recent years, the application of iron tailings in the building materials industry has attracted the attention of many scholars. The conversion of iron tailings into green building materials helps achieve carbon neutrality and high-value utilization of solid waste, and promotes sustainable development. Although iron tailings have been extensively studied as supplementary cementitious materials, the performance of concrete is not ideal due to its low activity. In this study, the hybrid supplementary cementitious materials system was prepared by iron tailings, phosphorus slag, and steel slag, and the effects of supplementary cementitious materials type, iron tailings content, iron tailings grinding time, and supplementary cementitious materials content on concrete performance were studied. The compressive properties, iron tailings properties, pore structure, interfacial transition zone, and element distribution of hydration products of concrete were tested by compressive strength tests, X-ray Diffractometer (XRD), X-ray Photoelectron Spectroscopy (XPS), Mercury Intrusion Porosimetry (MIP), Backscattering Electron Tests (BSE), and Energy Dispersive Spectrometer (EDS). The results show that further grinding improves the iron tailings activity. There is a synergistic mechanism between steel slag and phosphorus slag in the composite supplementary cementitious materials, which overcomes the low activity defect of iron tailings and produces concrete with a compressive strength exceeding 40 MPa. The composite supplementary cementitious materials can optimize the interfacial transition zone of the concrete interface and reduce the calcium–silicon ratio of the hydration products. However, it will deteriorate the pore structure of the concrete matrix, cause part of the concrete matrix to be damaged and lead to a loss of compressive strength, and the loss is acceptable. This work broadens the methods of comprehensive utilization of iron tailings and also provides a reference for a more detailed understanding of the properties of iron tailings-based concrete.     

Cement Paste Mixture Proportioning with Particle Packing Theory: An Ambiguous Effect of Microsilica

Recently, the research of innovative building materials is focused on applying supplementary materials in the form of micro- and nanopowders in cementitious composites due to the growing insistence on sustainable development. Considering above, in paper, a research on the effect of microsilica and SiO₂ nanoparticles addition to cement paste, designed with Andreasen and Andersen (AA) packing density model (PDM), in terms of its physical and mechanical properties was conducted. Density, porosity, compressive strength, hardness, and modulus of indentation were investigated and compared regarding different amount of additives used in cement paste mixes. Microstructure of the obtained pastes was analyzed. The possibility of negative influence of alkali-silica reaction (ASR) on the mechanical properties of the obtained composites was analyzed. The results of the conducted investigations were discussed, and conclusions, also practical, were presented. The obtained results confirmed that the applied PDM may be an effective tool in cement paste design, when low porosity of prepared composite is required. On the other hand, the application of AA model did not bring satisfactory results of mechanical performance as expected, what was related, as shown by SEM imaging, with inhomogeneous dispersion of microsilica, and creation of agglomerates acting as reactive aggregates, what as a consequence caused ASR reaction, crack occurrence and lowered mechanical properties. Finally, the study found that the use of about 7.5% wt. of microsilica is the optimum in regards to obtain low porosity, while, to achieve improved mechanical properties, the use of 4 wt. % of microsilica seems to be optimal, in the case of tested cement pastes.     

Effect of Nano-Magnesium Oxide on the Expansion Performance and Hydration Process of Cement-Based Materials

Many scholars are concerned about the effect of nano-MgO as an expansion agent on the performance of cement-based materials at an early age, but over a long period less attention is paid to expansion stability and mechanical properties. This article examines the influence of nano-MgO on the long-term consistency, fluidity, expansion stability, hydration, and mechanical properties of 30% fly ash cement-based materials and improves research into nano-MgO as an expansion agent. Expansion performance, flexural and compressive strength, and stability after boiling and autoclave treatment were tested for specimens mixed with a 2, 4, 6, 8 and 10% cementitious material mass of nano-MgO. X-ray diffraction (XRD) and scanning electronic microscopy (SEM) were employed to study their hydration process and microstructure. The results showed that nano-MgO had an obvious effect on the consistency, fluidity and expansion performance of cement paste. After curing in water for 365 days and autoclaving thereafter, the hydration of nano-MgO was relatively complete. The volumetric expansion pressure of the magnesium hydroxide (Mg(OH)₂) crystals and the crystallization pressure generated after their continuous precipitation were the main reasons for the expansion of the slurry. Nano-MgO improved the microstructure of cement paste and significantly enhanced its long-term flexural strength and compressive strength. When the content of nano-MgO was less than 10%, the cement with 30% fly ash had good long-term stability with the potential to compensate for the shrinkage of large-volume concrete.     

Effect of TiO2 Nanoparticles on the Fresh Performance of 3D-Printed Cementitious Materials

3D printing (3DP) of cementitious materials shows several advantages compared to conventional construction methods, but it requires specific fresh-state properties. Nanomaterials have been used in cement-based materials to achieve specific fresh and hardened properties, being potential candidates for 3DP applications. However, there are no reports on using TiO₂ nanoparticles (nano-TiO₂) in 3DP cementitious composites. Thus, the current work aims to assess the effect of nano-TiO₂ on the fresh performance of 3DP cementitious materials. For this purpose, nano-TiO₂ was incorporated in pastes and mortars from 0 to 1.5 wt.%. Time-resolved hydration (in situ XRD) and rheological and printing-related properties (buildability and printability) were evaluated. Results showed that nano-TiO₂ particles enhanced the cement hydration kinetics, leading to further ettringite formation up to 140 min compared to plain cement paste. Rheological measurements showed that the nano-TiO₂ incorporation progressively increased the static and dynamic stress, viscosity, and structuration rate of pastes. Furthermore, nano-TiO₂ improved the buildability of the composites, progressively increasing the maximum number of successive layers printed before failure from 11 (0 wt.% TiO₂) to 64 (1.5 wt.% TiO₂). By contrast, the nano-TiO₂ addition reduced the printability (i.e., the printable period during which the sample was able to be molded by the 3D-printing process) from 140 min (0% TiO₂) to 90 min (1.5% TiO₂). Thus, incorporating “high” nano-TiO₂ contents (e.g., >1 wt.%) was beneficial for buildability but would require a quicker 3DP process. The adoption of nano-TiO₂ contents of around 0.75–1.00% may be an interesting choice since it reduced the printability of paste by 30 min compared with the control mix but allowed for printing 24 layers (118% higher than plain mortar).     

Hydration Characteristics of Low-Heat Cement Substituted by Fly Ash and Limestone Powder

This study proposed a new binder as an alternative to conventional cement to reduce the heat of hydration in mass concrete elements. As a main cementitious material, low-heat cement (LHC) was considered, and then fly ash (FA), modified FA (MFA) by vibrator mill, and limestone powder (LP) were used as a partial replacement of LHC. The addition of FA delayed the induction period at the hydration heat curve and the maximum heat flow value (q_max) increased compared with the LHC based binder. As the proportion and fineness of the FA increased, the induction period of the hydration heat curve was extended, and the q_max increased. The hydration production of Ca(OH)₂ was independent of the addition of FA or MFA up to an age of 7 days, beyond which the amount of Ca(OH)₂ gradually decreased owing to their pozzolanic reaction. In the case of LP being used as a supplementary cementitious material, the induction period of the hydration heat curve was reduced by comparison with the case of LHC based binder, and monocarboaluminate was observed as a hydration product. The average pore size measured at an age of 28 days was smaller for LHC with FA or MFA than for 100% LHC.     

Effects of Air Entrainment on Bacterial Viability in Cement Paste

This study investigated the effect of air entrainment (AE) on bacterial viability in cementitious materials. Specimens were fabricated with Portland cement, urea, calcium lactate, and ureolytic bacteria, and with varying amounts of an AE agent. Specimens with different amounts of the AE agent were fabricated, and then a compressive strength test, quantitative polymerase chain reaction, X-ray diffraction, and thermogravimetry were used to investigate the mechanical properties, viability of bacteria, and hydrates of the specimens. The highest compressive strength was achieved by the specimen with 0.3% AE agent, while the compressive strength of the specimens decreased considerably when the incorporated AE agent was over 0.6%, due to increased porosity. The quantitative polymerase chain reaction result showed that the cell number of the viable bacteria was increased by incorporation of the AE agent, which also corresponded with an increase in CaCO₃ due to microbial mineral formation. The obtained result confirmed the positive effect of AE agent incorporation in cementitious materials containing bacterial admixtures, as the viability of bacteria, which play a vital role in self-healing efficiency of concrete, was increased by the space provided by the AE agent in the cement matrix. In addition, the quantity of CaCO₃ and the compressive strength were highest when 0.3% AE agent was incorporated.     

Influence of Ultrafine 2CaO·SiO2 Powder on Hydration Properties of Reactive Powder Concrete

In this research, we assessed the influence of an ultrafine 2CaO·SiO₂ powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO₂. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO₂ powder has the potential to improve the performance of a reactive powder cementitious system.     

Hydration Processes of Four-Component Binders Containing a Low Amount of Cement

Results of research on hydration of four-component binders containing very high amounts of supplementary cementitious materials were presented. The samples were composed of blended pozzolana (a mix of conventional fly ash and spent aluminosilicate catalyst), cement (about 20 wt.% in the binder) and Ca(OH)₂. Spent aluminosilicate catalyst was proposed as activating component which can improve properties of low-cement blends, while the role of Ca(OH)₂ was to enhance pozzolanic reaction. Early and later hydration periods of such blends were investigated by calorimetry, TG/DTG, FTIR and X-ray diffraction. Initial setting time as well as compressive strength were also determined. It was concluded that enhancement of reactivity and improvement of properties of fly ash–cement binders are possible by replacing a part of fly ash with more active fine-grained pozzolana and introducing additional amounts of Ca(OH)₂. The spent catalyst is mainly responsible for accelerating action during the first hours of hydration and for progress of early pozzolanic reaction. Fly ash develops its activity over time, thus synergic effect influences the later properties of composites. Samples containing blended pozzolana exhibit shorter initial setting times and higher compressive strength, as well as faster consumption of Ca(OH)₂ compared to the reference. Investigated mixtures seem to be promising as “green” binders, alternatives to cement, after optimizing their compositions or additional activating procedure.     

Study on Preparation and Interfacial Transition Zone Microstructure of Red Mud-Yellow Phosphorus Slag-Cement Concrete

Open stockpiling and the continual production of industrial solid wastes such as red mud (RM) and yellow phosphorus slag (YPS) have caused serious environmental pollution issues. Additionally, concrete prepared easily and with high strength is a widely applied building material. Therefore, replacing part or all of the cement for preparing concrete with RM and YPS will greatly reduce this kind of solid waste and, thus, decrease environmental pressures. This study investigated the best ratio for the replacement of concrete with RM and YPS, testing the mechanical properties as well as the morphology, material composition, and microporous structure of the interface transition zone (ITZ). The results showed for the concrete prepared with ordinary Portland cement replaced by 10.00 wt.% RM and 18 wt.% YPS, compared to ordinary Portland cement concrete, the compressive strength of concrete with basalt aggregate and dolomite aggregate increased by 25.04% and 27.27%, respectively, when the concrete was cured with steam for 28 days. Furthermore, it had a smaller average pore diameter and crystal size in the ITZ. The aggregate and matrix were more closely intertwined. This was because RM had a low cementitious activity and mainly had a filling effect when added to concrete, while the highly active silica in YPS could react with the Ca(OH)₂ crystal (CH) produced from cement hydration to form calcium silicate hydrate (CSH) gel, improving the mechanical properties and microstructure of the concrete.     

An Overview on the Rheology,Mechanical Properties,Durability, 3D Printing,and Microstructural Performance of Nanomaterials in Cementitious Composites

The most active research area is nanotechnology in cementitious composites, which has a wide range of applications and has achieved popularity over the last three decades. Nanoparticles (NPs) have emerged as possible materials to be used in the field of civil engineering. Previous research has concentrated on evaluating the effect of different NPs in cementitious materials to alter material characteristics. In order to provide a broad understanding of how nanomaterials (NMs) can be used, this paper critically evaluates previous research on the influence of rheology, mechanical properties, durability, 3D printing, and microstructural performance on cementitious materials. The flow properties of fresh cementitious composites can be measured using rheology and slump. Mechanical properties such as compressive, flexural, and split tensile strength reveal hardened properties. The necessary tests for determining a NM’s durability in concrete are shrinkage, pore structure and porosity, and permeability. The advent of modern 3D printing technologies is suitable for structural printing, such as contour crafting and binder jetting. Three-dimensional (3D) printing has opened up new avenues for the building and construction industry to become more digital. Regardless of the material science, a range of problems must be tackled, including developing smart cementitious composites suitable for 3D structural printing. According to the scanning electron microscopy results, the addition of NMs to cementitious materials results in a denser and improved microstructure with more hydration products. This paper provides valuable information and details about the rheology, mechanical properties, durability, 3D printing, and microstructural performance of cementitious materials with NMs and encourages further research.     

Properties of Blended Cement Containing Iron Tailing Powder at Different Curing Temperatures

The properties of blended cement containing 0%, 20%, and 50% iron tailing powder (ITP) at 20 °C and 60 °C were investigated by determining the hydration heat, microstructure, and compressive strength. The addition of ITP decreases the exothermic rate and cumulative hydration heat of blended cement at 20 °C. The high temperature increases the hydration rate and leads to the hydration heat of blended cement containing 20% ITP higher than that of Portland cement. Increasing the amount of ITP decreases the non-evaporable water content and Ca(OH)₂ content as well as compressive strength at both of the two studied temperatures. The addition of ITP coarsens the early-age pore structure but improves the later-age pore structure at 20 °C. The high temperature significantly improves the early-age properties of blended cement containing ITP, but it is detrimental to the later-age properties development. The reaction of ITP is limited even at high temperature. The large ITP particles bond poorly with surrounding hydration products under early high-temperature curing condition. The properties of blended cement containing a large amount of ITP are much poorer at high temperature.     

Method for Manufacturing Corn Straw Cement-Based Composite and Its Physical Properties

This paper introduces an innovative method for making cement-based composites from corn straw plants, and investigates the strength, thermal conductivity, and hydration characteristics of the composites. Corn straw is a natural, renewable, and breathable thermal insulation composite that contains cellular sealed pores. Corn straw contains a large amount of soluble cellulosic sugar, which hinders the hydration reaction of Portland cement and affects the use of corn straw as a building material. In this study, a 3 wt.% siliceous solution was used for surface treatment of corn straw particles to prevent cellulosic sugar from affecting the hydration performance of Portland cement. The composition of added cement-based composite materials with treated corn straw at the dosage of 11–20 wt.% was investigated. The test results showed that the corn straw cement-based composite (CSCC) had an optimal thermal conductivity of 0.102–0.112 (W/(m·K)) and a minimum compressive strength of above 1 MPa. The hydration performance of four typical CSCCs was examined using XRD, SEM, and EDS. The experimental results of this study may help to increase the comprehensive utilization of corn straw. The manufacturing method of the composite materials is simple, effective, and convenient for popularization and application, and it provides a new important technical measure to solve the problem of high energy consumption in rural houses.     

Influence of Cement Replacement with Sewage Sludge Ash (SSA) on the Heat of Hydration of Cement Mortar

The amount of fly ash from the incineration of sewage sludge is increasing all over the world, and its utilization is becoming a serious environmental problem. In the study, a type of sewage sludge ash (SSA) collected directly from the municipal sewage treatment plant was used. Five levels of cement replacement (2.5%, 5%, 7.5%, 10% and 20%) and unchanged water-to-binder (w/b) ratio (0.55) were used. The purpose of the study was to evaluate the effect of sewage sludge ash (SSA) on the hydration heat process of cement mortars. The heat of the hydration of cement mortars was monitored by the isothermal calorimetric method for 7 days at 23 °C. The analysis of chemical composition and particle size distribution was performed on the tested material. The tests carried out have shown that SSA particles have irregular grain morphology and, taking into account the chemical composition consists mainly of oxides such as CaO, P₂O₅, SiO₂ and Al₂O₃. The concentration of these compounds affects the hydration process of cement mortars doped with SSA. In turn, the content of selected heavy metals in the tested ash should not pose a threat to the environment. Calorimetric studies proved that the hydration process is influenced by the presence of SSA in cement mortars. The studies showed that the rate of heat generation decreased (especially in the initial setting period) with the increasing replacement of cement by SSA, which also reduced the amount of total heat compared to the control cement mortar. With increasing mass of the replacement of cement with SSA up to 20%, the 7-day compressive strength of the mortar samples decreases.     

A New Preparation Method of Cement with Photocatalytic Activity

The studies of some mechanical properties and photocatalytic activity of new cements with photocatalytic activity are presented. The new building materials were obtained by addition of semi-product from titanium white production. Semi-product was calcined at 300 and 600 °C for one, three, and five hours and then this material was added to cement matrix in an amount of 1 and 3 wt.%. New materials were characterized by measuring the flexural and compressive strength and the initial and the final setting time. The photocatalytic activity was tested during NOx photooxidation. The cement with photocatalytic activity was also characterized by sulphur content measurements. The measurement of reflectance percentage of TiO₂-loaded cements in comparison with pristine cement and TiO₂ photocatalyst calcined at 600 °C were also performed. It should be emphasized that although in some cases, the addition of photocatalyst reduced the flexural and the compressive strength of the modified cements, these values were still within the norm PN-EN 197-1:2012. It was also found that the initial and the final setting time is connected with the crystal size of anatase, and the presence of larger crystals significantly delays of the setting time. This was probably caused by a water adsorption on the surface of anatase crystals.     

Effect of High-Dispersible Graphene on the Strength and Durability of Cement Mortars

Graphene’s outstanding properties make it a potential material for reinforced cementitious composites. However, its shortcomings, such as easy agglomeration and poor dispersion, severely restrict its application in cementitious materials. In this paper, a highly dispersible graphene (TiO₂-RGO) with better dispersibility compared with graphene oxide (GO) is obtained through improvement of the graphene preparation method. In this study, both GO and TiO₂-RGO can improve the pore size distribution of cement mortars. According to the results of the mercury intrusion porosity (MIP) test, the porosity of cement mortar mixed with GO and TiO₂-RGO was reduced by 26% and 40%, respectively, relative to ordinary cement mortar specimens. However, the TiO₂-RGO cement mortars showed better pore size distribution and porosity than GO cement mortars. Comparative tests on the strength and durability of ordinary cement mortars, GO cement mortars, and TiO₂-RGO cement mortars were conducted, and it was found that with the same amount of TiO₂-RGO and GO, the TiO₂-RGO cement mortars have nearly twice the strength of GO cement mortars. In addition, it has far higher durability, such as impermeability and chloride ion penetration resistance, than GO cement mortars. These results indicate that TiO₂-RGO prepared by titanium dioxide (TiO₂) intercalation can better improve the strength and durability performance of cement mortars compared to GO.     

Effects of Elevated Temperatures on the Properties of Cement Mortars with the Iron Oxides Concentrate

Using the waste materials in the production of the building materials limits the storage of the wastes, burdensome for the environment and landscape, and makes possible to manufacture the materials and products with the use of the less volume of the raw materials. Cement concretes and mortars as the basic building materials offer the broad prospects of utilization of the recyclable or waste materials. The wastes from the iron ore processing are the solid wastes resulting from the process of enrichment of the ore concentrate. The paper presents the results of testing three mortars, in which a part of fine aggregate was replaced with the iron oxide concentrate (IOC) resulting from such a process. IOC has been used as a substitute of 10%, 20% and 30% (by mass) of the fine aggregate. The effect of the concentrate on the mechanical performance of the mortars at the high temperature (up to 600 °C) was also investigated. The IOC is a neutral material, not affecting chemically the process of cement hydration. The addition of IOC slightly improves the strength of the cement mortars (by 5% to 10%). In the case of the larger amount (20–30%) of the addition, the use of superplasticizer is necessary. The IOC significantly improves the high temperature resistance of the cement mortars (300 °C). The cement mortars containing 30% of the IOC addition keep 80% of the initial flexural and compressive strength when exposed to the temperature 450 °C.     

Effect of Electrolytic Manganese Residue in Fly Ash-Based Cementitious Material: Hydration Behavior and Microstructure

Electrolytic manganese residue (EMR) is a solid waste with a main mineralogical composition of gypsum. It is generated in the production of metal manganese by the electrolysis process. In this research, EMR, fly ash, and clinker were blended to make fly ash-based cementitious material (FAC) to investigate the effect of EMR on strength properties, hydration behavior, microstructure, and environmental performance of FAC. XRD, TG, and SEM studied the hydration behavior of FAC. The pore structure and [SiO₄] polymerization degree were characterized by MIP and ²⁹Si NMR, respectively. The experimental results indicate that FAC shows excellent mechanical properties when the EMR dosage is 10%. Moderate content of sulfate provided by EMR can promote hydration reaction of FAC, and it shows a denser pore structure and higher [SiO₄] polymerization degree in this case. Heavy metal ions derived from EMR can be adsorbed in the hydration products of FAC to obtain better environmental properties. This paper presents an AFt covering model for the case of excessive EMR in FAC, and it importantly provides theoretical support for the recycling of EMR in cementitious materials.