Hasil untuk "Cement industries"

M. Juenger, F. Winnefeld, J. Provis et al.

C. Meyer

Rishabh Bajpai, K. Choudhary, Anshuman Srivastava et al.

Abstract Alkali activated geopolymer is an attractive solution to limit the adverse consequences of cement manufacturing. In this paper, an evaluation of environmental impacts of geopolymer containing fly ash and silica fume is conducted. Life cycle assessment is performed by benchmarking the environmental impacts of three geopolymer concrete mixes against the conventional cement concrete, namely: fly ash geopolymer (with hydroxide and silicate of sodium); fly ash–silica fume blend geopolymer (with hydroxide and silicate of sodium); and fly ash–silica fume blend geopolymer (with sodium hydroxide). Impact analysis is performed by using ReCiPe midpoint and endpoint methods in life cycle assessment software UMBERTO NXT using database of Ecoinvent 3.0. Sensitivity analysis is performed to determine the effect of transportation. One mix design for each concrete of equal water to binder ratio and 28-days compressive strength of more than 35 MPa is analysed. Results of life cycle assessment indicate that alkaline activators and cement are the major sources of negative environmental impacts for geopolymer and cement concrete, respectively. Global warming potential of geopolymer concretes is lower than conventional cement concrete. Fly ash–silica fume geopolymer concrete activated without sodium silicate has lowest environmental impacts. Transportation of raw materials is found to increase the overall negative of all four concrete mixes. Cost reduction of 10.87%–17.77% per unit volume is achieved with the use of fly ash – silica fume based geopolymer concrete. Sustainability in terms of cost and environmental benefits of geopolymer concrete can be further increased by using silica fume. It can be concluded that the use of fly ash – silica fume blended geopolymer in the construction industry has huge possibility to improve its sustainability. Furthermore, waste management can be effectively done by utilization of industrial by-products in concrete.

Furqan Farooq, Xin Jin, M. Javed et al.

Abstract The rise in population and improvement in the lifestyle of human beings has caused a rapid increase in energy demands for buildings in the present day. An upsurge in energy demand, lack of fossil fuels, and environmental issues provide a crucial motive to the development of sustainable and viable infrastructure. Geopolymer (GP) composite free from cement, made from various waste materials with a high amount of Al2SiO3 and Na2SiO3/NaOH (alkali-activated silica) is evolving as an eminent material for sustainability purposes. They are also preferred due to the lesser emission of greenhouse gases as compared to ordinary Portland cement (OPC). This paper aims at presenting a sustainable domain and state of the art review of GP composite. The properties of composites made from various geopolymeric waste binders are presented. Besides, the microstructure and chemical characterization of GP composites are also discussed. The durability of GP composite is also highlighted considering its deterioration in various aggressive environments. In the end, a global warming potential (GWP) assessment was conducted and the practical applications of GP composites in the building industry are also provided.

S. Alterary, N. Marei

Abstract Fly ash (FA) is the principal industrial waste byproduct from the burning of solid fuels. FA is a powdery solid that is constituted mostly of unburned carbon (UC), metal oxides (Si, Fe, Ca, and Al), and other inorganic substances. UC is an inexpensive source of activated carbon that plays an important role in FA adsorption capacity. Due to the broad variability in its composition, FA characterization is challenging. Accordingly, FA is categorized into class F, and class C according to the maximum and minimum % of SiO2, Al2O3, Fe2O3, and SO3. X-ray diffraction, and fluorescence, and scanning microscopy with an energy dispersive spectroscopy are the common techniques employed to characterize FA. FA was used to remove hazardous contaminants, organic and inorganic chemicals, and dyes from wastewater. Furthermore, investigations revealed that FA has promising potential beneficial usage in the construction industry, particularly in cement and concrete production. FA has been added to cement in a reduced nanosize form giving good durability and minimizing concrete pores size to resist adverse environment. In this article, significant properties, characterization methods and, applications of FA were summarized.

Uddav Ghimire, Tejo V. Bheemasetti, Hee-Jeong Kim

Approximately 3.44 billion tons of copper mine tailings (MT) were produced globally in 2018 with an increase of 45% from 2010. Significant efforts are being made to manage these tailings through storage facilities, recycling, and reuse in different industries. Currently, a large portion of tailings are managed through the tailing storage facilities (TSF) where these tailings undergo hydro-thermal-mechanical stresses with seasonal cycles which are not comprehensively understood. This study presents an investigative study to evaluate the performance of control and cement-stabilized copper MT under the influence of seasonal cycles, freeze-thaw (F-T) and wet-dry (W-D) conditions, representing the seasonal variability in the cold and arid regions. The control and cement-stabilized MT samples were subjected to a maximum of 12 F-T and 12 W-D cycles and corresponding micro-and-macro behavior was investigated through scanning electron microscope (SEM), volumetric strain (εv), wet density (ρ), moisture content loss, and unconfined compressive strength (UCS) tests. The results indicated the vulnerability of Copper MT to 67% and 75% strength loss reaching residual states with 12 F-T and 8 W-D cycles, respectively. Whereas the stabilized MT retained 39%–55% and 16%–34% strength with F-T and W-D cycles, demonstrating increased durability. This research highlights the impact of seasonal cycles and corresponding strength-deformation characteristics of control and stabilized Copper MT in cold and arid regions.

Elijah D. Adesanya, Alastair T.M. Marsh, Sreejith Krishnan et al.

This study investigated the effect of the co-calcination temperature (600, 700, and 800 °C) and the blending ratio of green liquor dreg (GLD) and kaolinitic clay (2:1, 1:1, 1:2) to produce a limestone calcined clay (LC2)-type supplementary cementitious material (SCM). The phase assemblage and hydration process of composite cements comprising CEM I and varying replacement ratios (15 and 30 wt%) of the produced SCM were evaluated. An effective co-calcination temperature of 700 °C was identified considering the chemical reactivity of the LC2-type SCM determined by the rapid, relevant, and reliable (R3) testing. X-ray diffraction and scanning electron microscopy showed variations in the phase assemblage of the composite cements and the reference CEM I. Calcium carbonate from GLD and metakaolinite from the calcined clay contributed to the formation of carboaluminate in the composite cements, lowering its porosity. The 7- and 28-day compressive strengths of the mortars produced by replacing 15–30 wt% of the cement with this SCM, were comparable to those of the CEM I reference mortar. These findings demonstrate the industrial symbiosis potential between the paper and cement industries via applying co-calcination for resolving challenges for utilization of GLD, while producing a suitable kaolinitic clay based SCM.

Tejas Joshi, Urmil Dave, Sonal Thakkar et al.

In industries where thermal endurance is critical, such as metallurgy, power generation, and construction, heat-resistant concrete (HRC) represents a specialised form of concrete engineered for high-temperature applications and thermal cycling. Traditional concrete, when exposed to elevated temperatures, undergoes significant morphological and chemical transformations that lead to disintegration and a reduction in mechanical strength, as the thermal, mechanical, and deformation properties of concrete govern the response of structural elements to fire exposure. In this investigation, three distinct concrete mix designs were prepared and subjected to controlled heating, and their compressive strengths were evaluated against those of the control concrete to assess performance under thermal stress. The study also examined the composition, characteristics, and potential applications of HRC by exploring the use of various binders, additives, and aggregates aimed at enhancing thermal stability. Basalt aggregates, combined with high-temperature-resistant binders such as Portland slag cement, were employed as primary constituents. The results demonstrated that concrete containing basalt aggregates exhibited superior thermal performance compared with natural aggregates, with a binder content of 420 kg/m³ showing optimal strength retention across all curing and heating conditions. Consequently, the investigation confirmed the applicability of HRC for industrial construction environments exposed to high temperatures of 105, 350, and 700 °C.

E. Bernard, Hoang Nguyen, S. Kawashima et al.

The cement industry is a major contributor to the anthropogenic CO2 emissions, with about 8% of all emissions coming from this sector. The global cement and concrete association has set a goal to achieve net-zero CO2 concrete by 2050, with 45% of the reduction coming from alternatives to Portland cement, substitution, and carbon capture and utilization/storage (CCU/S) approaches. Magnesia-based cements offer a conceivable solution to this problem due to their potential for low-to-negative CO2 emissions (CCU/S) but also being alternatives to Portland cement. The sources of magnesia can come from magnesium silicates or desalination brines which are carbon free for raw-material-related emissions (cf. carbonated rocks). This opens up possibilities for low or even net-negative carbon emissions. However, research on magnesia-based cements is still in its early stages. In this paper, we summarize the current understanding of different MgO-based cements and their chemistries: magnesia oxysulfate cement, magnesia oxychloride cement, magnesia carbonate cement, and magnesia silicate cement. We also discuss relevant research needed for MgO-based cements and concretes including the issues relating to the low pH of these cements and suitability of steel reinforcement. Alternatives reinforcements, suitable admixtures, and durability studies are the most needed for the further development of MgO-based concretes to achieve a radical CO2 reduction in this industry. Additionally, techno-economic and life cycle assessments are also needed to assess the competition of raw materials and the produced binder or concrete with other solutions. Overall, magnesia-based cements are a promising emerging technology that requires further research and development to realize their potential in reducing CO2 emissions in the construction industry.

Robert J. Flatt

Ziyad Tariq Abdullah

Solid recovered fuel (SRF) is an alternative to fossil fuels that is produced from recovered municipal solid waste. SRF is often used to provide heat for energy-intensive industries, such as cement production. Here, the alternative use of SRF for industrial bread production is proposed for the first time. Five industrial bread-making portfolios based on SRF gasification were developed based on commercially available industrial machinery and technology. The developed industrial-scale alternatives were subjected to the cost and profit feasibility analyses to quantify their economic sustainability. The technical feasibility of SRF-fueled bread making was mathematically modelled considering the maturity of the industrial machinery. Regression plots were used to analyze the effects of the productivity (manufacturing scale) on the cost, power, syngas consumption, number of workers, and delivery cost of these relationships. Good consistency between the data in these plots, i.e., the machinery specifications, indicates a high level of technical maturity. Furthermore, the social sustainability was calculated based on the technical, employment, and human development potentials, where automated bread-making lines increase productivity, but reduce the required number of workers. Finally, a comprehensive sustainability performance index was evaluated by combining the technical, economic, environmental, and social indexes. The final sustainability index of 0.65 is very close to the threshold for a sustainable profitable business. The economic analysis showed that a maximum profit of 36,718 USD/day can be achieved based on the production of 1.5 t/h of bread, where cost can be lowered to 1630 USD/t by using SRF. Replacing traditional fossil-based gas fuels (liquid petroleum gas and liquid natural gas) by SRF-derived gas has both economic and environmental advantages, resulting in high economic and environmental sustainability indexes.

Maher Al-Jabari, Radi Al-Rashed, Michael E. Ayers

Concrete deterioration by Alkali Silica Reactions (ASR) is a severe issue of concrete durability associated with porosity and permeability. Most of the industrial solutions for mitigating ASR rely on controlling the mix design by mineral admixtures or lithium compounds. An innovative approach for mitigating ASR through a secondary role of crystalline waterproofing materials is presented. An aqueous solution of Multi-Crystallization Enhancer (MCE) is intermixed with water or added to the concrete mixture, at a dosage of 2% by weight of cement, then upon curing reduces the permeability under pressure by more than 99%. This study shows that ASR mitigation can be accomplished by incorporating the MCE in the fresh concrete mixture or by prewetting the aggregates. The experiments were made according to the methods of ASTM C1260. The investigated independent experimental variables included water to cement ratio, types of aggregates, method of the MCE addition, and time. The MCE can change the performance of aggregates from reactive to be equivalent to non-reactive. The findings demonstrate that the length expansion from ASR increases with increasing the w/c ratio for all types of aggregates attributed to the increase in the permeability. The MCE addition to mixtures with reactive aggregates enhances the resistivity against ASR by a percentage in the range of 45%-77%. The functionality of the MCE in mitigating the ASR is also confirmed using concrete specimens with long term ASR testing (ASTM C1293).

Sourav Ray, Md Masnun Rahman, Mohaiminul Haque et al.

Waste management has become a new challenge for the construction industries since rapid urbanization is taking place worldwide. Ceramic waste is one such material which is being originated from construction sites and industries, imposing a significant risk to the environment due to its non-biodegradable nature. With the goal of waste utilization, this study aims to predict the compressive and splitting tensile strength of concrete made with waste Coarse Ceramic aggregate (CCA) and Nylon Fiber (NF) by using two distinct machine learning algorithms, namely, Support Vector Machine (SVM) and Gradient Boosting Machine (GBM). A comprehensive data set for testing and training the models containing 162 records of compressive and splitting tensile strength test results were considered from nine mix proportions. For training the dataset, parameters like cement content, sand content, stone content, ceramic content, nylon fiber content, curing duration, and concrete strength were taken as input variables. The predicted strengths obtained from the SVM and GBM based models are found to be in close agreement with the experimental results. In terms of coefficient of determination (R2), GBM showed significantly better result for both compressive strength (e.g., SVM Overall R2 = 0.879 & GBM Overall R2 = 0.981) and tensile strength (e.g., SVM Overall R2 = 0.706 & GBM Overall R2 = 0.923) prediction. Furthermore, based on the statistical accuracy measures like the mean absolute error (MAE), mean square error (MSE), root mean square error (RMSE), it has been observed that GBM has yielded much better performance compared to SVM in predicting the mechanical strength of concrete.

Muhammad Shoaib Hassan

Employee motivation in banking has become one of the most considerable issues as every firm wants to make optimistic usage of their available human resources motivating them to achieve boosted performance. The study aimed to investigate the employee motivation dynamics in Pakistan conventional banking sector for employee performance circulating an adopted questionnaire online, considering 180 respondents as the sample size using a convenience probability sampling technique with a valid response rate of 78.89analysis using Smart PLS3 revealed a positive impact of employee motivation = 0.359, training = 0.0.354 and intrinsic rewards = 0.050 on the performance of bank employees. Furthermore, the significant effect of employee training as a mediator P=0.032, while the insignificant impact of intrinsic rewards moderation P=0.744 has been found. The study outcomes validate employee training and intrinsic rewards as the most influential factors of employee performance, followed by motivation. The study is equally valuable for all stakeholders concerned with the conventional banking sector, including employees, employers, bank officials and especially for potential researchers by offering significant directions to further research on the concerned topic of interest.

R. Trauchessec, J.-M. Mechling, A. Lecomte et al.

Priyanka Jajal, Trupti Mishra

Cement is one of the highest energy-consuming and emission generating industries around the world. To reduce greenhouse emissions, several mitigation measures have been proposed, and their effectiveness is estimated. However, estimates of the global temperature change potential of the cement industry have seldom been performed. Hence, in this study, we propose a new framework that estimates CO2 emissions and other seven pollutants to estimate temperature change potential from the cement industry. The underlying framework uses system dynamics, where the effectiveness of four mitigation measures, i.e., a shift in demand, newer methodologies to produce clinker, use of energy efficiency improvements, and implementation of renewable energy, are explored. The results indicate that renewable sources of energy show highest mitigation potential. The cement industry has contributed to an increase in 2 mK temperature since 1990, which is likely to grow up to 14.8 mK by 2050 if no mitigation measures are applied. Energy efficiency improvements by extensions of perform achieve and trade scheme can reduce 0.33 mK from the Indian cement industry. This paper provides a unique opportunity for estimating temperature influence of the cement industry, which can be further implemented for other countries.

Ali Poormohammadi, Erfan Ayubi, Nastaran Barati et al.

Introduction: Due to the obvious adverse effects of exposure to free crystalline silica and the high exposure level in silica-related occupations, the present study aimed at the investigation of renal symptoms in cement factory workers. Materials and methods: For this reason, 128 workers who were working cement factory with a determined occupational exposure to crystalline-free silica were selected as the case group, and 143 workers who were working in the Hamedan Province Rural Water and Wastewater company without being exposed to crystalline free silica were selected as controls. Various kidney-related parameters were evaluated and compared between the selected case and control groups. Results: The results of urine analysis between cases and control showed that there was a statistical difference between the cases and controls regarding Red Blood Cell (RBC), epithelial count, and bacteria (p<0.05). Moreover, the percentage of amorphous urate crystals of the exposed workers (cases) and control were 80.7% and 38.3%, respectively (p<0.001). The results of adjusted results showed that the odd presence of amorphous urate crystals among cases was 7.65 times of the control group (p<0.001). Conclusion: Our findings clearly showed that the level of urinary levels of amorphous urate crystals in silica-exposed individuals is higher than that of non-exposed individuals. Therefore, the presence of urinary amorphous urate crystals in exposed workers may be used as a cheap, non-invasive, and efficient method and urine biological maker for detecting silica exposure in silica-related industries.

Bahadar Zeb, Khan Alam, Allah Ditta et al.

Introduction: The elemental composition and morphological study of particulate matter are very important to understand the nature of particles influencing the environment, climate, soil, and health.Methods: The PM10 samples were collected during the winter season (2018) in Nowshera city, KPK, Pakistan, in three locations, namely, urban, industrial, and suburban. Scanning electron microscopy (SEM) and electron-dispersive X-ray (EDX) spectroscopy were used to examine the PM samples for morphological examination and elemental composition.Results: The average mass concentrations of particulate matter (PM10) at the urban, industrial, and suburban locations were 238.5, 505.1, and 255.0 μg m−3, respectively. The average PM10 mass concentration was higher than the WHO and National Ambient Air Quality Standards (NAAQS). The results of EDX showed that samples contained variable amounts of thirteen elements, such as oxygen, carbon, silicon, magnesium, sodium, calcium, iron, aluminum, potassium, sulfur, titanium, gold, and chlorine. The probable sources of PM were biogenic like plant debris, pollen, and diatoms; geogenic like road dust and resuspended soil dust; and anthropogenic like carbonaceous particles and fly ash, as confirmed by SEM–EDX. The carbonaceous species, that is, OC and EC, had average values of 55.8 ± 13.1 and 4.6 ± 0.6, 5.2 ± 3.2, and 36.4 ± 10.4, 40.0 ± 2.6 and, 6.3 ± 0.2 in industrial, urban, and suburban locations, respectively. Similarly, OC/EC had average values of 12.0 ± 1.2, 8.0 ± 3.0, and 6.3 ± 0.2 in industrial, urban, and suburban locations, respectively. Highly significant correlations among water-soluble ions (K+), OC, and EC were found in each location.Conclusions: The examined PM10 mass concentration in Nowshera city was above the thresholds of National Ambient Air Quality Standards (NAAQS) set by the U.S. Environmental Protection Agency (EPA). In addition, the concentration of pollutants was the highest at the industrial site compared to the other sites. The HYSPLIT model showed that the air mass originated from local sources like cement industries, brick kiln industries, and others.

Mohammed Fadhil Qasim, ZENA K. ABBAS , SOHAIR Kadhem Abed

Industrial development has recently increased, including that of plastic industries. Since plastic has a very long analytical life, it will cause environmental pollution, so studies have resorted to reusing recycled waste plastic (sustainable plastic) to produce environmentally friendly concrete (green concrete). In this research, producing environmentally friendly load-bearing concrete masonry units (blocks) was considered where five concrete mixtures were compressed at the blocks producing machine. The cement content reduced from 400 kg/m3 (B-400) to 300 kg/m3 (B-300) then to 200 kg/m3 (B-200). While (B-380) was produced using 380 kg/m3 cement and 20 kg/m3 nano-silica sand powder, and 10% plastic waste instead of coarse aggregate. Finally (B-285) included 285  kg/m3 cement and  15 kg/m3 nano silica sand powder and 10% plastic waste replacement for coarse aggregate. All production of concrete masonry unit types. According to IQS 1077 /1987, except (B-200) and (B-285) type B. When increasing the curing age from 14 to 28 days, blocks (B-285and B-380) change from type B to A. The compressive strength of the types (B-400, B-300, B-200, B-380, and B-285) was (9.65, 7.11, 5.35, 6.57, and 5.86) MPa, respectively, at 14 days and (11.98, 9.33, 6.84, 8.62 and 7.64) MPa respectively at 28 days.

V. Athiyamaan, PhD

The article is completely focused on the upto date development on composite materials with different optimization and curing techniques of Self Compacting Concrete (SCC); inorder to make the SCC highly durable, economical, with good rheological properties and feasible for current construction application. The key developments of concrete was attaining a proper mix proportions for the prescribed target mean strength but unlike normally vibrated concrete (NVC) SCC does not have the mix design code for obtaining the mix proportions for the required target strength. The pozzolanic materials that are generated from various types of industries were considered as a hazardous waste dumping material, which makes the huge negative impact on environment. Utilizing these pozzolans and converting them into productive material can save the environment and also be helpful in developing the high performance concrete. Hence a detailed literature survey has been carried out on unary, binary and ternary pozzolans that were used as a replacement for conventional materials (cement and fine aggregate) of concrete. The study was also made on self-curing technique imparted with SCC, which can further enhance the performance of concrete. Since Consumption of water in construction field is enormous especially for curing and developing flowable concrete; so to develop a sustainable concrete it is important to bend the different optimization techniques. Hence the study was done on several proposed methods of mix design procedures, material used, curing techniques and statistical modelling in developing optimized mix proportions. The detailed literature study serves as a flat forum for attaining a complete knowledge on updated trending in SCC, curing techniques and to suggest the area that can be improvised and for identifying the research gap for developing the innovative product in fields of SCC.