Cement Industry Research Articles

Valorization of Water Treatment Sludge for Applications in the Construction Industry: A Review

To address the growing global water demand, it is imperative to implement advanced treatment systems and sustainable alternatives for managing the large amount of waste generated during the water purification process, known as water treatment sludge (WTS). Worldwide, researchers and companies are exploring alternatives and methods for the valorization of WTS as a raw material in other processes. It is urgent that all productive sectors, which contribute significantly to greenhouse gas emissions, adopt this management principle to ensure more sustainable production, contributing to the global goal of climate neutrality. Notably, in civil construction, incorporating WTS as a supplementary cementitious material (SCM) shows great promise, considering that the industrial waste currently used for this purpose is increasingly restricted. The use of WTS as a raw material in the cement industry not only contributes to the reduction of the carbon footprint, but also reduces the high waste load still disposed of in landfills. The emerging applications for WTP sludge are reviewed, with emphasis on its valorization in the civil construction as an SCM. The main characteristics of this waste and their impacts on the environment are also addressed.

The Influence of Quartz Powder on the Mechanical–Thermal–Chemical–Durability Properties of Cement-Based Materials

Using industrial by-products to replace cement is an important way to reduce carbon emissions in the cement industry. The purpose of this article is to understand the effect of quartz powder on the properties of cement-based materials. Experimental studies were conducted on the macroscopic and microscopic properties of cement-based materials mixed with quartz powder to evaluate their feasibility as a replacement for cement. The substitution rates of quartz powder were 0% (Qu0), 7.5% (Qu7.5), and 15% (Qu15). The test time was from 1 day to 28 days, and the main results are as follows: In the early stage of the hydration reaction, as the amount of quartz powder substitution increases, the cumulative hydration heat increases. This is mainly because the nucleation effect of quartz powder accelerates the hydration reaction of cement. In the later stage of the hydration reaction, as the amount of quartz powder substitution increases, the cumulative heat of hydration decreases. This is mainly due to the diluting effect of quartz powder. For Qu0, Qu7.5, and Qu15, the decrease in compressive strength after 1 day is not obvious. The decrease in compressive strength at 28 days is more obvious. Overall, there are exponential relationships between the UPV measurement or surface resistivity results and the compressive strength measurement results at 1, 3, 7, and 28 days. The XRD test results show that the main products of the reaction are AFt, CH, Hc, and Mc. From Day 1 to Day 28, the content of Mc becomes evident. The test results for TG showed that, as the amount of quartz powder substitution increases, the mass loss decreases. For different specimens of Qu0, Qu7.5, and Qu15 at different test times (3 and 28 days), there is an exponential function relationship between chemically bound water and strength. A numerical hydration model is proposed for cement–quartz binary blends. The parameters of the hydration model are determined based on the hydration heat normalized by the cement mass. Moreover, the hydration heat at 28 days is calculated using the proposed model. The strength development of all specimens and all test ages can be expressed as an exponential function of hydration heat.

Zero-Emission Cement Plants with Advanced Amine-Based CO2 Capture.

Decarbonization of the cement sector is essentially required to achieve carbon neutrality to combat climate change. Amine-based CO2 capture is a leading and practical technology to deeply remove CO2 from the cement industry, owing to its high retrofittability to existing cement plants and extensive engineering experience in industrial flue gas decarbonization. While research efforts have been made to achieve low-carbon cement with 90% CO2 removal, a net-zero-emission cement plant that will be required for a carbon neutrality society has not yet been investigated. The present study proposed an advanced amine-based CO2 capture system integrated with a cement plant to achieve net-zero CO2 emission by pushing the CO2 capture efficiency to 99.7%. Monoethanomaine (MEA) and piperazine/2-amino-2-methyl-1-propanol (PZ-AMP) amine systems, which are considered to be the first- and second-generation capture agents, respectively, were detailed investigated to deeply decarbonize the cement plant. Compared to MEA, the advanced PZ-AMP system exhibited excellent energy performance with a regeneration duty of ∼2.6 GJ/tonne CO2 at 99.7% capture, 39% lower than the MEA process. This enabled a low CO2 avoided cost of $72.0/tonne CO2, which was 18% lower than that of the MEA-based zero-emission process and even 16.2% lower than the standard 90% MEA process. Sensitivity analysis revealed that the zero-emission capture cost of the PZ-AMP system would be further reduced to below $56/tonne CO2 at a $4/GJ steam production cost, indicating its economic competitiveness among various CO2 capture technologies to achieve a zero-emission cement plant.

Influence of Eggshell Powder on the Properties of Cement-Based Materials.

Replacing cement with industrial by-products is an important way to achieve carbon neutrality in the cement industry. The purpose of this study is to evaluate the effect of eggshell powder on cement hydration properties, and to evaluate its feasibility as a substitute for cement. The substitution rates of eggshell powder are 0%, 7.5%, and 15%. Studying the heat of hydration and macroscopic properties can yield the following results. First: The cumulative heat of hydration based on each gram of cementitious material falls as the eggshell powder content rises. This is a result of the eggshell powder's diluting action. However, the cumulative heat of hydration per gram of cement rises due to the nucleation effect of the eggshell powder. Second: The compressive strengths of ES0, ES7.5, and ES15 samples at 28 days of age are 54.8, 43.4, and 35.5 MPa, respectively. Eggshell powder has a greater negative impact on the compressive strength. The effect of eggshell powder on the speed and intensity of ultrasonic waves has a similar trend. Third: As the eggshell powder content increases, the resistivity gradually decreases. In addition, we also characterize the microscopic properties of the slurry with added eggshell powder. X-ray Diffraction (XRD) shows that, as the age increases from 1 day to 28 days, hemicaboaluminate transforms into monocaboaluminate. As the content of the eggshell powder increases, FTIR analysis finds a slight decrease in the content of CSH. Similarly, thermogravimetric (TG) results also show a decrease in the production of calcium hydroxide. Although the additional nucleation effect of eggshell powder promotes cement hydration and generates more portlandite, it cannot offset the loss of portlandite caused by the decrease in cement. Last: A numerical hydration model is presented for cement-eggshell powder binary blends. The parameters of the hydration model are determined based on hydration heat normalized by cement mass. Moreover, the hydration heat until 28 days is calculated using the proposed model. The strength development of all specimens and all test ages can be expressed as an exponential function of hydration heat.

Using ceramic demolition wastes for CO2-reduced cement production

This study focuses on assessing the pozzolanic potential of two types of ceramic demolition waste, namely terracotta roof tiles and sanitary porcelain, as substitutes for traditional calcined clays in blended and limestone calcined clay (LC3) cement production. Experimental methods employed include the modified Chapelle test and XRD for pozzolanic activity evaluation, flexural and compressive strength tests, capillary absorption measurements, and SEM for microstructure analysis. Mortars containing 10%, 20%, and 30% ceramic powders and 5%, 10%, or 15% limestone filler were tested. The findings showed that porcelain powders exhibited lower pozzolanic activity due to their lower surface area and higher firing temperature of the material. Up to 20% substitution of OPC with terracotta had minimal strength impact, with a 103% strength activity index (SAI) at 90 days. Ultrafine terracotta powder showed promise in LC3 production with up to 30% OPC substitution, achieving a 97% SAI after 90 days. The poor mechanical properties of porcelain-containing mortars were explained by surfactants present in sanitary porcelain. This research informs the cement and processing industries on the potential use of specific ceramic demolition waste materials in eco-cement production, offering insights into blended pozzolanic cements and LC3 formulations, with the goal of reducing the carbon footprint of cement manufacturing.

Valorisation of metallurgical residues via carbothermal reduction: A circular economy approach in the cement and iron and steel industry.

The decarbonisation of the steel and cement industry is of utmost importance in tackling climate change. Hence, steel production in modern integrated steel mills will be shifted towards electric arc furnaces in the future, in turn causing dwindling supplies of blast furnace slag, which is used as a supplementary cementitious material inter alia to reduce the CO2 emissions of cement production. Achieving a sustainable circular steel and building material economy requires the valorisation of currently landfilled steel slags and investigating utilisation options for electric arc furnace slag, which is increasingly being generated. For this purpose, different metallurgical residues and by-products were treated by carbothermal reduction in an inductively heated graphite crucible and then rapidly cooled by wet granulation, yielding a slag fraction similar to granulated blast furnace slag and a metal fraction valuable as a secondary raw material. A spreadsheet-based model was developed to calculate residue combinations to accomplish target compositions of the slag and metal fractions to fulfil previously identified requirements of the targeted cementitious and ferrous products. The results demonstrate the high accuracy of the model in predicting the properties (e.g. main oxide composition) of the generated slag and metal fraction, which fulfil the needed requirements for their use as (i) a supplementary cementitious material and (ii) a secondary raw material in steel production.

Lora Based Coal Mine Safety Monitoring and Security System Using Smart Helmet

The process of removing coal from the earth is called coal mining. Coal is used as fuel by the steel and cement industries to extract iron from iron ore and to make cement. The category that includes the underground mining business includes all factors that require routine monitoring, including methane gas, high temperatures, fire accidents, and so on. The safe production level of coal mines is still low, and frequent tragedies there result in significant losses of life and property. It is crucial to keep an eye on the working conditions in coal mines since the variety of work done there and the complexity of the mine environment are the main causes of disasters. The coal mine based on LoRa Long-Range Wide Area Network (LoRaWAN) technology is used by the Safety Monitoring and Security System to improve security and safety in coal mines. This system incorporates cutting-edge sensors to continuously monitor the surrounding environment, gas concentrations, and worker welfare. LoRa enables seamless communication and quick identification of potential risks because to its long range capabilities.

Critical Assessment of Novel Developments in HPGR Technology Using DEM.

Advances in high-pressure grinding roll (HGPR) technology since its first commercial application in the cement industry include new roll wear protection techniques and new confinement systems. The latter contribute to reductions in the edge effects in an attempt to reach a more homogenous product size along the rolls. Additional advances in this technology have been made in recent years, while modeling and simulation tools are also reaching maturity and can now be used to subject such novel developments to detailed scrutiny. This work applies a hybrid approach combining advanced simulations using the discrete element method, the particle replacement model and multibody dynamics to a phenomenological population balance model to critically assess two recent advances in HPGR technology: spring-loaded cheek plates and the offset roller press. Force and torque controllers, included in the EDEM 2022.1 software, were used to describe the responses of the geometries in contact with the granular material processed. Simulations showed that while the former successfully reduced the lateral bypass of the material by as much as 65% when cheek plates became severely worn, the latter demonstrated lower throughput and higher potential wear but an ability to generate a finer product than the traditional design.

Impact Of Corporate Governance Mechanism On Capital Structure Decision On Non-Financial Sectors Of Emerging Countries

The study aimed to evaluate the effect of  Corporate Governance Dynamic on  Leverage on non-financial sectors of emerging countries (Pakistan, India, and Bangladesh ) during the study period of 2014 to 2023. The nature of the study is quantitative and secondary therefore data has been extracted from the respective websites of the companies and stock exchange  from the pharmaceutical, cement, and food industries. Moreover, the  Random effect model was used to on the bases of diagnostic test to identify the cause and effect. The findings of the study reveal that director remuneration, and board education in Pakistan showed positive and significant effects but Board size, board experience showed significant and negative effects on the capital structure decision. While board diversity, firm size found an insignificant association with leverage in Pakistan. For firm size showed an insignificant effect but board size, direct remuneration, and board education showed a negative and significant effect on leverage while board experience, board diversity was a positive and significant effect on leverage. Moreover, in India, board experience, board diversity, and board education was a significant but negative effect on leverage but board size, direct remuneration, firm size showed a positive and significant effect on the leverage of non-financial firms.

Multi-index control strategy from cement calcination denitration system: a model predictive control method for combined control of nitrogen oxide and ammonia escape.

The cement industry is one of the main sources of NOx emissions, and automated denitration systems enable precise control of NOx emission concentration. With non-linearity, time delay and strong coupling data in cement production process, making it difficult to maintain stable control of the denitration system. However, excessive pursuit of denitration efficiency is often prone to large ammonia escape, causing environmental pollution. A multi-objective prediction model combining time series and a bi-directional long short-term memory network (MT-BiLSTM) is proposed to solve the data problem of the denitration system and achieve simultaneous prediction of NOx emission concentration and ammonia escape value. Based on this model, a model predictive control framework is proposed and a control strategy of denitration system with multi-index model predictive control (MI-MPC) is built based on neural networks. In addition, the differential evolution (DE) algorithm is used for rolling optimization to find the optimal solution and to obtain the best control variable parameters. The control method proposed has significant advantages over the traditional PID (proportional integral derivative) controller, with a 3.84% reduction in overshoot and a 3.04% reduction in regulation time. Experiments prove that the predictive control framework proposed in this paper has better stability and higher accuracy, with practical research significance.

A CO2 removal technology based on mineral carbonation and the stability of product carbon storage in a cement matrix

Toward a decarbonized society, the cement industry is continuously striving to enforce energy conservation technologies and develop low-carbon cement. The use of mineral carbonation in the cement and concrete sector and the associated value chain are central in the carbon recycling system, and the importance of CO2 removal technologies has been recognized. This paper proposes a mineral direct air carbon capture and storage in product technology newly designed by a mineral carbon capture reactor through direct feeding of atmospheric CO2. Additionally, a novel concrete mix for use as CO2-storing (CDS) concrete is proposed. This mix contains recarbonates generated using treated water with high Ca content at a ready-mixed concrete plant. The CDS concrete, with a recarbonate content in the range of 2–10% of cement, exhibited very similar initial and mechanical properties compared with ordinary concrete. The CO2 release from the recarbonate in a cement matrix under acidic corrosion and the thermal decomposition were assessed, and the findings are discussed.

Emission characteristics of condensable particulate matter during the production of solid waste-based sulfoaluminate cement: Compositions, heavy metals, and preparation impacts

Recycling solid waste for preparing sulfoaluminate cementitious materials (SACM) represents a promising approach for low-carbon development. There are drastic physical-chemical reactions during SACM calcination. However, there is a lack of research on the flue gas pollutants emissions from this process. Condensable particulate matter (CPM) has been found to constitute the majority of the primary PM emitted from various fuel combustion. In this study, the emission characteristics of CPM during the calcination of SACM were determined using tests in both a real-operated kiln and laboratory experiments. The mass concentration of CPM reached 96.6 mg/Nm3 and occupied 87% of total PM emission from the SACM kiln. Additionally, the mass proportion of SO42− in the CPM reached 93.8%, thus indicating that large quantities of sulfuric acid mist or SO3 were emitted. CaSO4 was one key component for the formation of main mineral ye'elimite (3CaO·3Al2O3·CaSO4), and its decomposition probably led to the high SO42− emission. Furthermore, the use of CaSO4 as a calcium source led to SO42− emission factor much higher than conventional calcium sources. Higher calcination temperature and more residence time also increased SO42− emission. The most abundant heavy metal in kiln flue gas and CPM was Zn. However, the total condensation ratio of heavy metals detected was only 40.5%. CPM particles with diameters below 2.5 μm and 4–20 μm were both clearly observed, and components such as Na2SO4 and NaCl were conformed. This work contributes to the understanding of CPM emissions and the establishment of pollutant reduction strategies for waste collaborative disposal in cement industry.

A comparative multidimensional evaluation of parameters and alternatives for transformation of sustainable cement production in Pakistan

The United Nations has declared its latest climate report a ‘code red,’ sounding the alarm and prompting a global call for scientists and policymakers to adopt comprehensive, systems-wide integrated strategies for promoting sustainable life on Earth. The need for collaborative and holistic approaches for the transformation of cement production into a socio-ecologically sustainable industrial segment had never been more imperative. This paper rigorously evaluates the parameters and alternatives for the sustainable transformation of Pakistan's cement industry. Economic, environmental, and social parameters are explored and screened using multiple methodologies. Real-world data collected from the operating cement plants in Pakistan are analyzed using Principal Component Analysis (PCA) and Grey Relational Analysis (GRA). The consolidated list of sustainability criteria and alternatives is evaluated using the Multi Actor Multi Criteria Analysis (MAMCA) framework, which incorporates the involvement of both local and international stakeholders for prioritization of the transformation goals. Data analytic results reveal that carbon emissions have a strong degree of statistical association with production ingredients such as SiO2, Insoluble Residue (IR), Al2O3, and Fe2O3. Although there are a few interesting variations in the priorities computed from the recorded perspectives of different stakeholders, the consensus on giving top priority to environmental parameters and the alternatives like ‘Waste-heat Recovery Plants’ and ‘Vertical Rolling Mills’ is novel and promising. By taking all the main sustainability domains into account, employing multidimensional techniques, and involving multiple stakeholder perspectives under the context of a developing country, the research outcomes of this study become highly attractive for researchers, investors, and policymakers all over the world.

Effect of carbon dots with different sizes on chloride binding of cement

Carbon dots (CDs) as a novel and green nanomaterial exhibit a promising application in enhancing the chloride binding capacity of cement to extend the service life of reinforced concrete (RC) structures. However, their size influence on the enhancement of chloride binding is still a research gap, enormously hindering the further employment of CDs toward cement system. Herein, their size-induced effect on chloride binding actions of cement is comprehensively unveiled using CDs with various sizes for the first time. Specifically, three kinds of CDs with different sizes are controllably prepared through simply altering the calcinating time of citric acid. And the relationship between sizes of CDs and chloride binding capacity of cement is confirmed through the equilibrium tests. More importantly, the mechanism for the effect of CDs sizes on chloride binding is reasonably proposed according to the alteration analyses of phase compositions. The consequences demonstrate that the chloride binding capacity in cement modified by CDs with average sizes of 1.73, 5.79, and 12.37 nm increases by 41%, 20%, and 14% respectively, compared with that of the blank group after 28-d immersion in 3 mol/L NaCl solution. This testifies that the chloride binding capacity of CDs-incorporated cement is negatively correlative with CDs sizes. The related mechanism is that CDs with smaller sizes can provide more nucleation sites to promote cement hydration, further advancing the production of C–S–H gels and monosulfate (Ms), thus more markedly enhancing the physical adsorption and chemical binding of chloride ions in cement pastes. This work would guide the preparation of CDs with more suitable sizes to improve the chloride binding ability of cement, thus anticipated to extend the service life of RC structures in coastal environment, ultimately reducing the CO2 emission from cement industry.

Exploring the potential of pulverized oyster shell as a limestone substitute in limestone calcined clay cement (LC3) and its implications for performance

With the advent of rapid climate change and global warming, the cement industry has been actively striving to minimize its carbon footprint. An effective approach for reducing carbon emissions is to utilize supplementary cementitious materials (SCMs). Limestone calcined clay cement (LC3) has garnered significant attention because of its ability to reduce clinker use by approximately 45 wt%, compared to ordinary Portland cement. However, the raw materials involved in LC3 production, which are obtained through mining and heating of raw clay, also counts toward the carbon footprint. Therefore, the present study aims to explore the feasibility of using oyster shells as a replacement for limestone in LC3 systems. Various amorphousness of calcined clay were tested to investigate the hydration reaction and strength of the oyster shell calcined clay cement (OC3). Data collected using techniques such as X-ray diffraction, thermogravimetry, scanning electron microscopy, isothermal calorimetry, compressive strength testing, and 29Si nuclear magnetic resonance spectroscopy were analyzed to elucidate the hydration reaction mechanisms of OC3, considering the type of calcite (oyster shell or limestone) and the extent of the transformation of kaolinite clay to metakaolin. The findings of this study demonstrate that oyster shells can effectively replace limestone as a raw material for LC3. Furthermore, the irregular morphology of the shell particles enhanced the hydration reaction and development of the cement’s microstructure.

The initial stages of cement hydration at the molecular level

Cement hydration is crucial for the strength development of cement-based materials; however, the mechanism that underlies this complex reaction remains poorly understood at the molecular level. An in-depth understanding of cement hydration is required for the development of environmentally friendly cement and consequently the reduction of carbon emissions in the cement industry. Here, we use molecular dynamics simulations with a reactive force field to investigate the initial hydration processes of tricalcium silicate (C3S) and dicalcium silicate (C2S) up to 40 ns. Our simulations provide theoretical support for the rapid initial hydration of C3S compared to C2S at the molecular level. The dissolution pathways of calcium ions in C3S and C2S are revealed, showing that, two dissolution processes are required for the complete dissolution of calcium ions in C3S. Our findings promote the understanding of the calcium dissolution stage and serve as a valuable reference for the investigation of the initial cement hydration.

Green Synthesis of Aluminum Silicate and Aluminum Iron Oxide Nanocomposites for Industrial Applications

Nano chemistry is revolutionizing the chemical industry. This research targets the green synthesis of Al-Si and Al-Fe nanocomposites and their application in the cement industry to produce durable cement coating. The nanocomposites were prepared by incorporating the green ingredients as reducing and stabilizing agents followed by the direct heating and calcination of the samples. The X-ray diffraction analysis and SEM were performed to confirm crystallinity and the nano-dimensional structure of the prepared nanocomposites. The SEM micrographs of Al-Si and Al-Fe nanocomposites provided the sizes as 15-37 nm and 17-61 nm, respectively. BET analysis revealed the surface area as 1.084 m2/g and 0.884 m2/g respectively, for Al-Si and Al-Fe nanocomposites. These were applied in cement mortar and stability was checked for 07 and 28 days. The samples with 07 days of stability time showed an increase while the samples with 28 days showed a decrease in compressive strength.

The main trends of 2023 in concrete construction

The analytical review of 2023 was prepared based on the analysis of materials and publications of the Beton GmbH information center (Germany).
 
 Concrete construction, concrete and reinforced concrete technologies, carbon neutrality, and resource efficiency are the central topics that the Beton GmbH (IZB) information center is working on today on behalf of German cement and concrete manufacturers. As an analytical platform for manufacturers and the driving force of the industry, the center promotes new applications of cementbonded building materials and introduces innovative products and processes. Given the critical importance of cement and concrete in construction, the industry also has a special responsibility to mitigate the effects of climate change. Therefore, the German cement industry has been actively working for many years to reduce carbon emissions and conserve natural resources. Using innovative technologies, Germany plans to produce cement and concrete with zero carbon emissions by 2045.
 
 An important element of the promotion and training of sustainable concrete construction is the provision of technical advice to builders, contractors, architects and engineers in the field of civil, road, high-rise and agricultural construction. The main focus is on concrete and processes that provide sustainable, reliable solutions, as well as contribute to the implementation of major planned ideas in accordance with the main global trends: climate efficiency, resource conservation, energy conservation.

Paving the way for sustainable decarbonization of the European cement industry

AbstractCement production is a main source of carbon emissions. Decarbonization options exist, but their climate change mitigation potential, feasibility and environmental implications are still unclear. Here we assess 15 decarbonization options for the European cement industry under current and future conditions. Climate impacts per tonne of clinker produced today in European countries vary between 832 and 1,075 kg CO2-equivalents. Decarbonization options at various maturity levels can mitigate between 7 and 135 Mt CO2-equivalents per year (4–108% of today’s annual emissions from European cement plants), with a range of synergies and trade-offs. Solutions such as alternative fuels or technological improvements reduce climate impacts up to 30%, while a mix of ambitious complementary measures achieves a mitigation of about 50% by 2050. Only rapid and large-scale implementation of carbon capture and storage can approach climate neutrality. Carbon capture for production of e-fuels presents no significant mitigation benefits while it increases other environmental impacts.

Refractory and thermoelectric properties of stabilized Tricalcium aluminate allotrope: A first-principles calculation approach

Tricalcium aluminate (Ca3Al2O6) is an indispensable component of Portland cement due to its high strength and reactivity. This study investigates the equilibrium lattice structure as well as the electronic and refractory properties of a newly discovered allotrope of Ca3Al2O6 using density functional theory and random phase approximation methods. Using density functional perturbation theory, we investigate the phonon dispersion of the refined structure’s experimental stability. In addition, the lattice thermal conductivity and thermoelectric figure of merit are computed by solving the Boltzmann Transport Equation with the modified Debye Callaway model and the Relaxation time Approximation methods. The computed Figure of merit, determined by the carrier concentration, indicates a substantial enhancement of 40 to 100-fold, leading to a superior figure of merit of 0.25 and 0.6 when appropriately doped. As a result, we anticipate that stable allotropes of Ca3Al2O6 in the Pm3̄m phase will be useful as energy-harvesting, convective cooling and infrared radiation shield-based cement materials in the cement and concrete industries.