Cement Research Articles

Thermogravimetric analysis and compressive strength of cement mixes using Thai Lopburi calcined clay as supplementary cementitious material

Thermogravimetric analysis and compressive strength of cement mixes using Thai Lopburi calcined clay as supplementary cementitious material

Characterization of the inhalable fraction (< 10 μm) of soil from highly urbanized and industrial environments: magnetic measurements, bioaccessibility, Pb isotopes and health risk assessment

Soil in urban and industrial areas is one of the main sinks of pollutants. It is well known that there is a strong link between metal(loid)s bioaccessibility by inhalation pathway and human health. The critical size fraction is < 10 μm (inhalable fraction) since these particles can approach to the tracheobronchial region. Here, soil samples (< 10 μm) from a highly urbanized area and an industrialized city were characterized by combining magnetic measurements, bioaccessibility of metal(loids) and Pb isotope analyses. Thermomagnetic analysis indicated that the main magnetic mineral is impure magnetite. In vitro inhalation analysis showed that Cd, Mn, Pb and Zn were the elements with the highest bioaccessibility rates (%) for both settings. Anthropogenic sources that are responsible for Pb accumulation in < 10 μm fraction are traffic emissions for the highly urbanized environment, and Pb related to steel emissions and coal combustion in cement plant for the industrial setting. We did not establish differences in the Pb isotope composition between pseudo-total and bioaccessible Pb. The health risk assessment via the inhalation pathway showed limited non-carcinogenic risks for adults and children. The calculated risks based on pseudo-total and lung bioaccessible concentrations were identical for the two areas of contrasting anthropogenic pressures. Carcinogenic risks were under the threshold levels (CR < 10–4), with Ni being the dominant contributor to risk. This research contributes valuable insights into the lung bioaccessibility of metal(loids) in urban and industrial soils, incorporating advanced analytical techniques and health risk assessments for a comprehensive understanding.

Cost and environmentally efficient design of an absorption-based post-combustion carbon capture unit for industry applications

Carbon capture and storage technologies are currently considered promising solutions to mitigate CO2 emissions of hard-to-abate industries. Among those, the cement industry accounts alone for around 6–7 % of the global anthropogenic CO2 emissions and necessitates the integration of carbon capture and storage to substantially reduce its CO2 emissions. This work focused on the design and analysis of a cost-efficient and low-emitting cement plant integrated with an absorption-based Post-Combustion Carbon Capture (PCCC) system using an aqueous water-amine solution. An innovative system layout is presented to minimize CO2 emissions and energy consumption. Furthermore, the sizing of the absorber and stripper of the PCCC unit was performed to minimize the cost of the avoided CO2. The environmental and economic performances of the overall process are evaluated under different boundary conditions, encompassing both gate-to-gate and cradle-to-gate perspectives. A reduction of the CO2 emissions of around 66–87 % was obtained, depending on the fuel used to produce the steam needed in the PCCC unit and the analysis boundary considered. The primary energy consumption per avoided CO2 was estimated at 5.5–7.3 MJ/kgCO2. The specific cost per avoided CO2 also varies with the fuel choice and the analysis boundary. Through the optimal sizing of the PCCC unit, costs of 56–57 €/tCO2 were obtained for the integration of carbon capture in the plant. When a cradle-to-gate boundary is considered, costs for CO2 transportation and storage need to be accounted for, and costs of equivalent avoided CO2 ranging from 74.5 €/tCO2 to 124 €/tCO2 are estimated, depending on the transportation and storage scenario considered.

Dirty Tracks Across the Border: Global Operations of Extraction, Labour and Migration at a Railway Station on the Bihar–Nepal Border

This article is based on an ethnography of the railway siding at Raxaul Junction railway station, a town on the Bihar–Nepal border, which finds itself at the intersection of a massive logistical exercise by China in the form of the Belt Road Initiative, counter-logistical apparatus building by India and incremental hardening of an otherwise ‘open’ border by Nepal. The article will analyse in detail the intricate network of the labour market that operates at and through the railway siding. It will also trace the origins of commodities used in the cement factories in the industrial corridor of Nepal that are extracted from some of the most deprived regions of India at great human and social costs. Finally, I will describe some of the latest exercises in logistical operations such as containerisation, opening of a new land port, the Integrated Check Post in Raxaul and operationalisation of a new dedicated freight corridor from Vishakhapatnam port to Raxaul, which is reconfiguring the logistical arrangements away from Kolkata and Haldia port and their implications on labour and labour practices. The Raxaul railway siding will be, hence, studied on multiple scales: global, national and local. The article will also try to understand the transformation of this very peculiar border town located on a unique border. This transformation is creating new labour processes, migratory processes and networks, and new modes of production of workers’ subjectivities and resistance along the global logistical apparatus and supply chains. It will also open up the possibilities of thinking conceptually about ‘South Asian Border Systems’.

Coupled thermo-hydro-chemical modeling of accelerated carbonation of cement-based materials: Application to CO2 uptake

The use of CO2-rich hot gases from cement plants or combustion processes is considered as an attractive method to accelerate the carbonation of recycled concrete aggregates (RCA). However, there is limited knowledge regarding the kinetics and mechanisms of accelerated carbonation induced by wet gas with a temperature of approximately 80 °C. Water transport and temperature influence several parameters of the carbonation of cement-based materials, thus understanding and predicting their overall effect remains complex. The present study combines experimental and numerical investigations into the effects of temperature on carbonation processes. The experimental study focuses on understanding the effects of temperature on the evolution of the carbonation front, changes in chemical composition, and moisture transport within a cement-based material during carbonation in controlled conditions. The experimental data obtained serve as calibration parameters for a thermo-hydro-chemical coupled model of carbonation. The carbonation model incorporates heat transfer between the cement-based material and the external environment, considering the influence of temperature on water transfer, as well as the dissolution and carbonation of hydration products.

Predictive Pattern of Undrained Shear Strength in Stabilized Sulfur Rich Silty Soil Based on Binder and Initial Mixing Water Content

A laboratory investigation was conducted to identify principal variables-initial mixing water content, porosity, and binder content- impacting undrained shear strength (qu) of stabilized sulfur-rich silty soil. An equation for predicting qu of stabilized soil was established based on the experimental data. Initially, samples were prepared with soils sample with different initial water and binder contents. Multicem, a binder consisting of a mix of cement and cement kiln dust, was added to the samples. Three different percentages of Multicem were mixed at five different soil water contents to measure qu of stabilized mixtures to understand how water content and porosity levels in the samples affect the performance of the binder and their combined impact on the strength of the samples. The soil-binder mixtures were compacted and subsequently cured in laboratory-controlled environment. The prepared samples were tested in uniaxial compression test apparatus. The results evidenced that binder content and corresponding porosity affect the strength of specimens at an equal water content. The results showed that at equal initial mixing water content, the qu of a sample increased by increasing binder content. Furthermore, it was observed that increase of binder content has a reverse effect on porosity. It was appeared lowering the soil water content, initially increased the strength until an optimum water content. Further lowering water content increased the porosity and consequently decreased qu of samples. Moreover, a ratio of porosity/volumetric binder content was chosen to evaluate the impact of these two variables on strength of samples. This study showed that qu is an exponential function of porosity/binder volumetric content ratio which depends on initial mixing water content of mixtures. It was shown at water content lower than the optimum, results of stabilization are more effective than in soil at higher water contents. Therefore, reducing the water content and thereby porosity has more significant effect on improving qu than increasing the binder content.

Performance optimization of cement calciner based on CFD simulation and machine learning algorithm

In order to improve the combustion efficiency and decomposition rate of the cement calciner and reduce pollutant emission, a performance optimization method based on Computational Fluid Dynamics (CFD) numerical simulation integrated with machine learning is proposed. The Multiphase Particle-in-cell (MP-PIC) method and the chemical reaction models are employed to simulate the coal combustion and CaCO3 decomposition process, whose calculation results are combined with the industrial practical data of the cement plant, so as to establish a more comprehensive training database. On this basis, a novel Topology Particle Swarm Optimization algorithm integrating with Convolutional Neural Network and Long Short-Term Memory (RITPSO–CNN–LSTM) algorithm model is established to predict combustion efficiency, decomposition rate, and NOx emission, respectively. Results show that compared with two other relative basic algorithm models, the prediction error of the proposed algorithm model for the three targets is minimal with the average relative error of 0.045 %, 0.038 %, and 0.021 %, respectively. The addition of CFD simulation data makes the prediction model more applicable with higher stability and accuracy. Based on the prediction results, Grey Wolf Optimizer (GWO) algorithm is employed to optimize operating parameters, and finally the average optimization amount of combustion efficiency, decomposition rate, and NOx emission are 2.17 %, 2.24 %, and 6.15 ppm, respectively, which meet the optimization requirements.

Long-Term Prevention of Arthroplasty Infections via Incorporation of Activated AgNbO3 Nanoparticles in PMMA Bone Cement.

We investigated the possibility of loading PMMA bone cement with antimicrobial nanostructured AgNbO3 particles to counter biofilm formation at the cement-tissue interface. We found that a formulation containing (1-4)% AgNbO3 showed high antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa while not showing any toxicity against THP1 human cell lines. In addition, loading the particles did not impact the mechanical properties of the cement. The results thus obtained illustrate the potential of the approach to replace the current technique of mixing cement with conventional antibiotics, which is associated with shortcomings such as efficacy loss from antibiotic depletion.

The Impact of Company Characteristics on Budget Implementation: An Investigative Study Applied to a Sample of Employees at Kufa Cement Plant

The research aimed to uncover the impact of company characteristics, represented by the dimensions of size, age, type, and structure, on budget implementation, represented by its three dimensions, namely, operational budget, cash budget, and capital budget, in Kufa Cement Plant. The current research highlights the research vocabulary philosophically by collecting concepts and literary contributions of researchers in this framework in order to achieve the research objective. Methodologically, a questionnaire was used as the primary tool to collect data from the sample individuals, including managers, employees, technicians, and administrators. A total of 262 questionnaires were distributed, and 250 were retrieved. A variety of statistical methods and techniques were employed in data processing and hypothesis testing, including arithmetic mean, Spearman correlation, and regression analysis. The research adopted a descriptive-analytical methodology in dealing with theoretical and field data on its variables, which relies on describing the case and then analyzing it to reach conclusions. Several results were obtained, where the most important one was that there is a significant effect of company characteristics (age, size, type, and ownership structure) on budget implementation (operational, cash, and capital) in Kufa Cement Plant. The key recommendations emphasized focusing more on addressing the substantial deviations between actual cash and previously planned budgets in the studied plant.

Feasibility Study of Cement Plant Production Facility Upgrade Project to Support Export Business

Feasibility Study of Cement Plant Production Facility Upgrade Project to Support Export Business

Annual variation of source contributions to PM10 and oxidative potential in a mountainous area with traffic, biomass burning, cement-plant and biogenic influences

Toxicity of particulate matter (PM) depends on its sources, size and composition. We identified PM10 sources and determined their contribution to oxidative potential (OP) as a health proxy for PM exposure in an Alpine valley influenced by cement industry. PM10 filter sample chemical analysis and equivalent black carbon (eBC) were measured at an urban background site from November 2020 to November 2021. Using an optimized Positive Matrix Factorization (PMF) model, the source chemical fingerprints and contributions to PM10 were determined. The OP assessed through two assays, ascorbic acid (AA) and dithiothreitol (DTT), was attributed to the PM sources from the PMF model with a multiple linear regression (MLR) model. Ten factors were found at the site, including biomass burning (34, 40 and 38% contribution to annual PM10, OPAA and OPDDT, respectively), traffic (14, 19 and 7%), nitrate- and sulphate-rich (together: 16, 5 and 8%), aged sea salt (2, 2 and 0%) and mineral dust (10, 12 and 17%). The introduction of innovative organic tracers allowed the quantification of the PM primary and secondary biogenic fractions (together: 13, 8 and 21%). In addition, two unusual factors due to local features, a chloride-rich factor and a second mineral dust-rich factor (named the cement dust factor) were found, contributing together 10, 14 and 8%. We associate these two factors to different processes in the cement plant. Despite their rather low contribution to PM10 mass, these sources have one of the highest OPs per µg of source. The results of the study provide vital information about the influence of particular sources on PM10 and OP in complex environments and are thus useful for PM control strategies and actions.

Estimation of Some Major and Trace Elements in Human Hair in the Vicinity of Ashaka Cement Factory, Gombe State, Nigeria

This study aimed to estimate some major and trace elements in human hair samples obtained from humans living in the vicinity of Ashaka Cement Factory, Gombe State to identify the proportion of some major and trace elements in human hair samples. The samples collected from humans were kept in air-tight polyethene bags immediately. Then, they were washed with detergent to remove external dust and socked in distilled water for 10 minutes and transferred it into Acetone to remove stubborn dirt. The samples were analyzed using atomic absorption spectrometry (AAS) after several processes of determination and the graphical solution was plotted using MATLAB software package 2018a. The result of the analysis shows that 0.0091 ± 0.184, 0.169 ± 0.15, 0.16 ± 0.0102, 0.0014 ± 0.0025 mg/kg for Ca, Fe, Mg, Na and 0.085 ± 0.38, 0.0049 ± 0.0046, 0.0091 ± 0.0029, 0.099 ± 0.0069 mg/kg for Pb, Cu, Zn, Cd in human hair samples obtained in the vicinity of Ashaka cement factory. The findings of the study is greatly importance to the entire society, especially those in the area of Ashaka cement factory and it also informs people about the positive and negative effects of trace elements on human life. Based on this result, it is recommended amongst other things that, there should be a need for a study on the assessment of the elements content of cement dust using a variety of analytical approaches since; some of the elements such as Al, Si, Ni, and Hg were not detected in the sample obtained in the study using atomic absorption spectrometry.

Prevalence and Pattern of Ocular Trauma in a Secondary Eye Care Center in Nepal: A Descriptive Cross-sectional Study.

Ocular trauma stands as the leading preventable cause of monocular blindness worldwide. The aim of the study was to calculate the prevalence of ocular trauma and the circumstances, causes, and types of ocular injuries at emergency department of Community Eye Hospital. This was a descriptive cross-sectional study conducted retrospectively on patientsvpresenting to the Emergency Department in the year 2020. Ethical clearance was received from the Institutional Review Board with reference number 12/2021. Data collection commenced in April 2021, following the approval in March 2021. Descriptive statistics with mean and frequency were used for analysis. Among the 6526 emergency cases visiting the emergency department of Hetauda community eye hospital the prevalence of ocular trauma was 2143 (32.83%; 95% CI: 31.69%-33.97%). The mean age among the 2143 trauma cases was 33.55±15.63 years. Among them, 1851 (86.40%) fell in the working age group. The male-to-female ratio was 3:1. Occupational injuries due to welding, agriculture and industries were in 604 (28.19%) of all ocular injuries. The prevalence of ocular trauma in our study was higher than other studies. Occupational ocular trauma mainly welding injury, cement factory injury and agricultural injury are common cause of ocular trauma.

Effects of Mixing Techniques and Material Compositions on the Compressive Strength and Thermal Conductivity of Ultra-Lightweight Foam Concrete.

The research focuses on ultra-lightweight foam concrete with a dry density below 200 kg/m3, primarily used as insulation material. Factors that may affect material properties are categorized into mixing techniques and material composition, and experimental investigations were conducted on the impact of these factors on the rheological properties of cement slurry, density at different time intervals, compressive strength, and thermal conductivity of foam concrete samples. The experimental results indicate the influence of mixing speed and mixing duration on the instrument during the cement slurry production and mixing process with foam. Additionally, variations in foam concrete sample properties are observed due to the water-to-cement ratio, foam content, and foam density in the selected material compositions. By analyzing the material density at different time intervals, the relationship between the ambient air trapped during the mixing process and the viscosity of the material can be indirectly observed. This analysis can also reveal the correlation between the unplanned air content and the properties of the material.

Chitosan-Cement Composite Mortars: Exploring Interactions, Structural Evolution, Environmental Footprint and Mechanical Performance.

The increasing environmental concerns about synthetic polymers as reinforcement in the construction industry have highlighted the need for eco-friendly, biodegradable fibers as potential alternative materials for cementitious composites. This study examines the influence of chitosan particle concentrations on the midterm compressive strength of mortars. Chitosan particles, derived from shrimp shells, were mixed with high early strength hydraulic cement at various percentages (0, 0.05, 0.25, 0.5, 1, and 2 wt %) and silica sand to prepare the mortar samples. The findings indicate that chitosan affects the hydration process through the distribution of chitosan particles within the mortar matrix and slightly improved midterm mechanical properties. A life cycle assessment (LCA) revealed a slight increase in greenhouse gas emissions and embodied energy for chitosan-modified mortars, likely due to the use of chemicals in the chitosan synthesis and purification process. In fact, the addition of 0.25 wt % of chitosan into the mortar only added 1.3% of the global warming potential of the sample when compared to the control sample. Incorporating chitosan into a mortar matrix does not significantly affect the resistance-mechanical properties of the composite. The hydration of the cement mortar appears to be slowed by the inclusion of chitosan particles in the cementitious matrix. This research lays the groundwork as one of the first studies for the development of high-performance, early strength cement using chitosan, contributing to a more sustainable construction industry.

The Role of Green Human Capital in Promoting Environmental Sustainability an Exploratory Study in the Kufa Cement Factor

The research aims to determine the impact of green human capital on environmental sustainability, as the problem included the main question (Does green human capital affect environmental sustainability in the Kufa Cement Factory?). The questionnaire was used as a tool for collecting data, and it included two axes. The first axis dealt with the data. The personality of the workers, while the second axis dealt with the paragraphs of the research variables (human capital and environmental sustainability), The size of the community was (1789) individuals, and (308) individuals participated in the questionnaire, and the descriptive analytical approach was used, and many statistical methods were used, including (arithmetic mean, standard deviation, Cronbach’s reliability coefficient). Alpha, confirmatory factor analysis, Pearson correlation coefficient, simple linear regression), and the research reached a set of results, the most prominent of which is the existence of a correlation as well as the impact of green human capital on environmental sustainability and its dimensions. Among the most prominent recommendations is the need for the Kufa Cement Factory to adopt awareness programs for working leaders. They explain the importance of the human resource in preserving the environment, and indicate the extent of its impact on improving the environment.

Nano-fly ash and clay for 3D-Printing concrete buildings: A fundamental study of rheological, mechanical and microstructural properties

Three-dimensional printing concrete (3DPC) represents a recent innovation in the construction and building research sector and novel approach to building techniques. The focus of this study is to develop an environmentally sustainable cementitious composite optimized for 3D printing applications. The research involved preparing 3D printing mixtures that comprised of 50 % Portland Cement (PC), 50 % Colorobia Clay (CC), and varying contents (0 % 5 %, 10 %, and 15 % by weight of cement) of Nano-Fly Ash (N-FA) under standardized printing parameters. The fresh mixture's properties have been evaluated and the mechanical and microstructural properties of the printed samples were assessed, subsequently. The findings demonstrated that incorporating N-FA into the cementitious mixes enhanced their flowability and workability. Specifically, the mix containing a low N-FA concentration of 5 wt% exhibited superior compressive strength relative to the other formulations. Additionally, flexural strength assessments indicated a minimum increase of 39.4 % across all mixes compared to the control 3D-printed mixture. Microstructural investigations by SEM imaging validated the anticipated formation of hydration products, namely calcium-silicate-hydrate (CSH) and ettringite, facilitated by the synergy between clay and fly ash. The t-statistical analysis further corroborated that the inclusion of N-FA significantly bolstered the strength attributes of the mixes designated for 3D printing. In conclusion, this study underscored the efficacy of integrating clay as a sustainable construction material within 3D printing applications. The utilization of clay-cement mixes, augmented with N-FA, emerged as a viable strategy to enhance the sustainability and reduce the carbon footprint of construction practices.

Mosaic Materials in an Art Deco Steel-framed Building

ABSTRACT The mosaic coving at the Grade II* listed Freemasons’ Hall in London is an example of a mosaic on an Art Deco steel-framed building. Microstructural and chemical characterisation of loose mortars and tesserae were undertaken to inform conservation efforts and advise whether a protective coating was needed to prevent further fading of gold gilding. Rigorous testing used optical imaging, scanning electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis, Raman spectroscopy, X-ray diffraction, and thermogravimetric analysis with differential scanning calorimetry. Laboratory evidence demonstrated the glass tesserae were created using traditional techniques. The glass tesserae were soda-lime-silica glass with lead. The gold glass tessera was produced in the ancient Roman style which included a glass cartellina layer, so further protective coating was not needed. Historical records confirmed sheets of mosaic tesserae were prefabricated in Italy. The grout and thin-set mortar were the same low hydraulicity mortar mix, which enabled mosaic tesserae positions to be adjusted as required. The bedding coat mortar was a hydraulic cement mortar that was applied on top of an early example of foamed mortar from 1932. This unique study analyses a traditional style mosaic that was installed during a pivotal point in construction history where foamed mortars and steel framed buildings were introduced. It demonstrates how archival research and laboratory testing of small-sized samples enhance the building’s significance and architectural interest by improving the knowledge of its history.

Machine-Learning-Based Predictive Models for Compressive Strength, Flexural Strength, and Slump of Concrete

The process of concrete production involves mixing cement, water, and other materials. The quantity of each of these materials results in a performance that is particularly estimated in terms of compressive or flexural strength. It has been observed that the final performance of concrete has a high variance and that traditional formulation methods do not guarantee consistent results. Consequently, designs tend to be over-designed, generating higher costs than required, to ensure the performance committed to the client. This study proposes the construction of predictive machine learning models to estimate compressive or flexural strength and concrete slump. The study was carried out following the Team Data Science Process (TDSP) methodology, using a dataset generated by the Colombian Ready Mix (RMX) company Cementos Argos S.A. over five years, containing the quantity of materials used for different concrete mixes, as well as performance metrics measured in the laboratory. Predictive models such as XGBoost and neural networks were trained, and hyperparameter tuning was performed using advanced techniques such as genetic algorithms to obtain three models with high performance for estimating compressive strength, flexural strength, and slump. This study concludes that it is possible to use machine learning techniques to design reliable concrete mixes that, when combined with traditional analytical methods, could reduce costs and minimize over-designed concrete mixes.

Impact of Superplasticizers on the Performance of Low-Grade Limestone-Based Cement Mixes.

Low-grade limestone (LGL) is not used to produce cement clinker, but this leftover material in cement quarries increases the water demand when used as a filler in concrete production. In this study, the effect of six commercial superplasticizers on the performance of cement mixes containing 35% LGL and 2% gypsum was investigated. The optimal doses of these superplasticizers were found in a range of different water/binder (w/b) ratios by conducting several Marsh cone and mini-slump tests. The addition of a superplasticizer with a higher active solid content produced a maximum cement flow, regardless of the w/b ratios. The LGL-based mortar samples admixed with this superplasticizer obtained a maximum compressive strength of about 36 MPa at the end of 28 days. SEM and XRD results showed the formation of a new calcium-rich mineral in their microstructure. These findings highlight the impact of the type and properties of superplasticizers on the performance of concrete mixes containing LGL as a supplementary cementitious material.