Cement Research Articles

Carbonized seawater cement slurries for offshore deep cement mixing: carbonation mechanism, strength enhancement and microstructure evolution

Seawater cement slurry (SCS) is a commonly used binder in offshore deep cement mixing (DCM) construction. Seawater cement slurries are usually prepared before they are grouted into the seabed and mixed with marine clay. The aim of this study is to explore the feasibility of applying carbonation technology to fabricate SCS suitable for offshore DCM while achieving carbon sequestration and obtaining better mechanical properties for stabilised marine sediments.This study demonstrated that after appropriate carbonation, carbonized SCS can be used in DCM to replace conventional SCS. Short-term carbonation promotes cement dissolution and hydration rates under seawater conditions rich in magnesium, calcium, and other inorganic ions. The carbonates include calcite, vaterite and amorphous carbonates, which provide additional nucleation sites for the hydration of SCS, resulting in an increment for amorphous CS(A)H gel with a dense pore structure and binding interaction with soil particles. After carbonation with 20% CO2 for 5 min (0.5 wt.% of cement), the UCS and secant modulus of cement-soil mixtures by 15.7% and 111% at the age of 1 day, and by 6.82% and 10% at the age of 28 days when treating marine clay with 80% moisture content at a dosage of 260 kg/m3.

Understanding the time-dependent rheological behavior of seawater mixed cement paste with fly ash

Due to the relative scarcity of freshwater resources in coastal regions, the use of seawater in concrete construction has great potential due to its benefits in cost and resource. To further advance the application of seawater concrete, a deeper understanding of its rheological properties is essential. This study investigates the effects of fly ash on the time-dependent rheological behavior of seawater cementitious paste, such as yield stress, plastic viscosity, and structural build-up rate. The underlying mechanisms are analyzed using the theories of water film thickness (WFT), ion concentration, and hydration heat. The research findings confirm that the rheological parameters of seawater paste are generally higher than those of deionized water paste, regardless of the cementitious compositions. As fly ash content increases, the plastic viscosity of seawater paste increase, while the fluidity and dynamic yield stress decreases. Further analysis reveals that the decrease in the yield stress with fly ash content is well related to the increase in the WFT, but it cannot sufficiently explain the change of yield stress over time. Instead, the amount of hydration products in seawater paste shows a linear increasing relationship with the dynamic yield stress at 65 min. By contrast, the plastic viscosity can be related to the ion concentration in the interstitial solution, wherein an increase in the concentration of Ca2+ corresponds to an increase in the plastic viscosity. Moreover, the rheological parameters increase over time, with the growth rates between 5 and 35 minutes being higher than those between 35 and 65 minutes, possibly due to the rapid early hydration of the binder materials. This study offers a fundamental theoretical support for the use of seawater in various concrete applications.

Experimental Investigation of the Axial Load Capacity of Bilateral Helix-Stiffened Cement Mixing Piles in Soft Marine Soil

Bilateral helix-stiffened cement mixing piles (BHCMPs) are a new type of robust composite pile. In this paper, the influence of design parameters, such as the diameter of inner helix plates and the number and size of outer mixing helix plates, on the vertical bearing performance of the pile foundation and the behavior of the pile diameter are investigated through laboratory model tests. The results indicate that incorporating a reverse-mixing process in the pile formation of helix-stiffened cement mixing piles can enhance the overall ultimate bearing capacity and strengthen the soil-cement of the piles. In the case of the same double-blade inner drill pipe, for every 22 mm increase in the blades, its ultimate compressive load-bearing capacity was increased by 10% to 25%, and its pullout load-bearing capacity was increased by 15% to 45%. With further increases in the blades, the percentage increase in the compressive and pullout load-bearing capacity was reduced. With an increase in the number of external mixing blades, its compressive load capacity increased in the range of 5% to 20%, and the elevation load capacity increased in the range of 10% to 25%. Increasing the number of reverse-mixing helix plates on the outer casing enhances the soil-cement strength of the pile body by approximately 15–20% for each additional plate. The average strength of the pile-body soil-cement for each additional plate is estimated to be 1 to 1.4 times that of the previous set, indicating that increased mixing iterations can enhance the perimeter soil-cement strength of the pile. The average bond diameter of soil-cement piles with double-blade internal drilling rods could be seen from the diameter of the piles formed, which was 1.02 to 1.21 times the diameter of the blades.

The Effect of Human Blood and Platelet-rich Fibrin on the Surface Microhardness of Hydraulic Calcium Silicate-based Cements

Objectives: This study aimed to compare the effect of human blood and platelet-rich fibrin (PRF) on the surface microhardness of hydraulic calcium silicate-based cements (OrthoMTA and RetroMTA). Materials and Methods: Two types of mineral trioxide aggregate, OrthoMTA and RetroMTA, were mixed and placed into cylindrical molds. The lower surfaces of all cements were exposed to saline. The upper surfaces of cements were exposed to human blood, PRF, or phosphate buffer saline (PBS). After storage for 7 days in fully saturated humidity at 37°C, the microhardness of cement surface exposed to blood, PRF, or PBS was measured using the Vickers microhardness test. The data were analyzed using two-way analysis of variance and post hoc Tamhane’s T2 test. The significance level was set at P<0.05. Results: Exposure to blood and PRF significantly decreased the surface microhardness of OrthoMTA and RetroMTA. The microhardness of PBS-contacted cements was significantly higher than that of blood or PRF groups (P<0.001). The microhardness values for OrthoMTA exposed to PRF were significantly higher than the blood group (P=0.020). There were no significant differences between RetroMTA contacted with blood or PRF groups (P=0.985). When exposed to blood or PBS, RetroMTA had a significantly higher microhardness than OrthoMTA (P<0.001 for blood, P=0.002 for PBS). Conclusion: Exposure to blood or PRF decreased the surface microhardness of both cements. Blood-contaminated RetroMTA showed significantly higher surface microhardness than OrthoMTA contacted with blood. No significant difference was found between PRF-contacted OrthoMTA and RetroMTA.

Occurrence, non-carcinogenic and carcinogenic risk assessment of trace elements in rainwater in the vicinity of a cement factory in northeastern Nigeria

Rapid industrialization and urbanization result in atmospheric pollution with trace elements precipitated and deposited by rain, affecting human health. This study determined the concentrations and non-carcinogenic and carcinogenic risks associated with trace elements in rainwater in the vicinity of the Ashaka cement factory. Samples were collected using a bulk sampler fitted with a high-density polythene funnel. A total of 140 samples were collected in 2020 and analyzed for 15 trace elements using ICP-OES. Multivariate analysis was used to identify the sources of the rainwater trace elements. The results show that the abundance of trace elements in the collected samples was in the following order: Fe > Sb > Cu > Ba > V > Sc > Sr > Mn > Zn > Ti > Hg > Al > Mo > Co. Crustal enrichment factors (EFc) indicated that the samples were extremely enriched with Hg, Sb, Cu, and Mo, moderately enriched with Zn, Ba, V, Co, Sr, Cr, and Sc, and unenriched with Fe, Mn, Ti, and Al. Chronic daily intake (CDI) for both the ingestion and dermal pathways was in the order Fe > Cu > Ba > Cr > V > Mn > Zn > Hg > Mo. The hazard index (HI) was > 1 through the ingestion pathway, indicating a likely non-carcinogenic advertising effect. Similarly, the carcinogenic risk (CR) exceeded the (1.0 × 10–4—1.0 × 10–4) acceptable limit for children and adults, indicating the likely development of cancer among consumers. This revealed that the elements present in rainwater are anthropogenic and are brought about by cement production.

A Mini-Review on Recent Developments and Improvements in CO2 Catalytic Conversion to Methanol: Prospects for the Cement Plant Industry

A Mini-Review on Recent Developments and Improvements in CO2 Catalytic Conversion to Methanol: Prospects for the Cement Plant Industry

Bearing Characteristics of Deep Cement Mixing Integrated Drilling, Mixing and Jetting Piles Based on Numerical Simulation

The Deep Cement Mixing Integrated Drilling, Mixing and Jetting (DMJ) technique has been developed through the installation of high-pressure spray holes at the mixing blades, with the objective of enhancing the bearing capacity of deep-mixed piles in the Yellow River floodplain. In order to enhance the bearing capacity of the foundation, variable-modulus piles and capped piles were incorporated within the DMJ piles. Engineering applications have demonstrated that DMJ piles can effectively address the issue of foundation reinforcement in the Yellow River floodplain region, minimize the wastage of cement, and reduce the environmental pollution associated with waste slurry. Nevertheless, a comprehensive study of the relevant factors is still lacking in the available literature. This study addresses this gap by conducting a numerical simulation of these two types of DMJ piles based on the preliminary field test data, with the objective of analyzing both the single-pile-bearing characteristics and the composite foundation-bearing characteristics. Furthermore, the study seeks to optimize the DMJ pile’s structure based on the simulation results. The findings demonstrate that the premature failure of a single pile during the bearing process can be averted if the modulus of the pile core reaches a minimum of 0.3 GPa or if the pile cap thickness exceeds 1 m. The utilization of large-diameter drilling, stirring and spraying piles can markedly enhance the bearing capacity of the composite foundation and mitigate the differential settlement of pile and soil. The spacing of the pile has been identified as a significant factor influencing the differential settlement of pile and soil. Consequently, this study also examines the impact of pile spacing on the differential settlement of piles and soil.

Impacts of PM2.5 exposure near cement facilities on human health and years of life lost: A case study in Brazil

Cement factories significantly contribute to atmospheric pollution by generating fine particulate matter (PM2.5), which can potentially increase the mortality risk. The lack of information on the health impacts of PM2.5 pollution from cement operations in Brazil prompted this investigation. We used corrected PM2.5 measurements from low-cost sensors from March 2021 to October 2022 in Rio Branco do Sul, city in the southern region of the country and home to Latin America's largest cement plant, to assess exposure data. Disability-adjusted life years (DALY) method was applied to estimate the years of life lost (YLL) and cost estimate due to deaths from non-accidental causes, cardiovascular and respiratory diseases. The total YLL attributable to PM2.5 concentration was estimated by calculating the attributable fraction (AF) through relative risk. We also collected PM2.5 using a Harvard impactor to evaluate health risks from toxic metals components. During the study period, the analysis of chemical characterization of PM2.5 showed enrichment factors for most elements and the possible influence of the calcination process facilities on the PM2.5 levels. The mean concentration of PM2.5 exceeded the annual WHO air quality guideline (AQG) level, accounted for 3.5%, 4.7%, and 4.3% of total YLL from all causes, cardiovascular, and respiratory diseases, which corresponded to 0.23 (95% CI: 0.17–0.26), 0.06 (95% CI: 0.05–0.07) and 0.03 (95% CI: 0.01–0.06) years loss in life expectancy, respectively. An indirect health cost attributable to PM2.5 resulted in US$ 1.4 million, equivalent to about 3.5% of the total local annual health costs in Rio Branco do Sul, underscoring the significant financial burden of PM2.5 exposures. The greatest economic loss was found in the male age group of 40–69 years and among those with cardiovascular disease, rather than those with respiratory disease. Despite this, the carcinogenic and non-carcinogenic risks from inhalation of hazardous elements were within safe ranges. This work demonstrated PurpleAir's potential for air quality and public health applications. Our findings indicate health and economic benefits from reducing PM2.5 levels by adopting WHO air pollution standards. The results can guide policies toward delivering more effective health care.

Effect of dusty clinker and alite crystal size on the properties of class G oil well cement slurries

AbstractHoning the quality of cement plays a pivotal role in the petroleum industry throughout drilling operations, undoubtedly. In cement plants, producing high-quality clinker is essential for improving oil well maintenance, reducing expenditures, enhancing safety, and more, demonstrating its importance in the long term. Despite tight control of clinker operational conditions, cement kiln operators can still produce dusty clinker. This work uniquely establishes the previously unexplored relationship between dusty clinker and the qualitative characteristics of class G oil well cement slurries, offering a practical solution to prevent the production of poor-quality cement in factories. All API tests were done according to API Specification 10 A. Furthermore, a thorough microscopic analysis was conducted on both standard and dusty clinkers to establish a connection between the properties of class G oil well cement slurries and the changes in crystal size observed in the minerals of dusty clinker. According to the studies conducted in this regard, changing the size of the cement particles has a considerable influence on the cement performance. Here, results revealed that increasing the alite (C3S) crystal size to 60–70 microns in dusty clinker led to a roughly 20-minute increase in the average thickening time. In addition, the compressive strength cured at 38 and 60 °C for 8 h, decreased by 1.47 and 2.89 MPa, respectively. More importantly, it was found that the average maximum consistency in dusty clinker oil well cement increased by almost 6.4 Bc over a 15 to 30-minute period.

Industrial Production Networks and Small Towns: A Case Study from Algeria

This paper investigates the conditions and consequences of integrating small towns into industrial production networks. It is based on empirical research conducted in Algeria, a hydrocarbon-dependent rentier economy characterized by significant regional inequalities and the political aims of economic diversification and spatial rebalancing. Elaborating the case study of a state-owned cement factory in the small town of Sigus, the research provides insights into the multiple roles of the state in shaping production network integration and the characteristics of small towns as economic locations. The methodology combines secondary data and information with primary research based on semi-structured interviews. It reveals the importance of a multi-scalar regional framework in production network integration, whereby national factors played a key role due to the centralized Algerian state, the state-owned character of the investing company, and the shortcomings of the small town’s local environment. It emphasizes the contradictory impacts of production network integration in economic, social, and environmental terms, primarily on a local level. These contradictions underscore the necessity for critical evaluations to maximize the benefits of production network integration while mitigating its adverse effects. They also call for the more consistent involvement of the local community in similar economic development decisions. Notably, this research contributes significantly to the existing body of literature by addressing the underexplored topic of integrating small towns into production networks within the Algerian context. Doing so offers a more nuanced understanding of the particular economic, social, and environmental dynamics at play in these locations, thereby enriching the discourse on economic development strategies for small towns in rentier economies like Algeria.

Optimized Machine Learning Model for Predicting Compressive Strength of Alkali-Activated Concrete Through Multi-Faceted Comparative Analysis

Alkali-activated concrete (AAC), produced from industrial by-products like fly ash and slag, offers a promising alternative to traditional Portland cement concrete by significantly reducing carbon emissions. Yet, the inherent variability in AAC formulations presents a challenge for accurately predicting its compressive strength using conventional approaches. To address this, we leverage machine learning (ML) techniques, which enable more precise strength predictions based on a combination of material properties and cement mix design parameters. In this study, we curated an extensive dataset comprising 1756 unique AAC mixtures to support robust ML-based modeling. Four distinct input variable schemes were devised to identify the optimal predictor set, and a comparative analysis was performed to evaluate their effectiveness. After this, we investigated the performance of several popular ML algorithms, including random forest (RF), adaptive boosting (AdaBoost), gradient boosting regression trees (GBRTs), and extreme gradient boosting (XGBoost). Among these, the XGBoost model consistently outperformed its counterparts. To further enhance the predictive accuracy of the XGBoost model, we applied four state-of-the-art optimization techniques: the Gray Wolf Optimizer (GWO), Whale Optimization Algorithm (WOA), beetle antennae search (BAS), and Bayesian optimization (BO). The optimized XGBoost model delivered superior performance, achieving a remarkable coefficient of determination (R2) of 0.99 on the training set and 0.94 across the entire dataset. Finally, we employed SHapely Additive exPlanations (SHAP) to imbue the optimized model with interpretability, enabling deeper insights into the complex relationships governing AAC formulations. Through the lens of ML, we highlight the benefits of the multi-faceted synergistic approach for AAC strength prediction, which combines careful input parameter selection, optimal hyperparameter tuning, and enhanced model interpretability. This integrated strategy improves both the robustness and scalability of the model, offering a clear and reliable prediction of AAC performance.

Evaluating human error probability in maintenance task: An integrated system dynamics and machine learning approach

AbstractHuman error is often implicated in industrial accidents and is frequently found to be a symptom of broader issues within the sociotechnical system. Therefore, research exploring human error during maintenance activities is important. This article aims to assess the probability of human error in maintenance tasks at a cement factory using the Cognitive Reliability and Error Analysis Method and System Dynamics modeling. Given that human error probability (HEP) is influenced by various common performance conditions (CPCs) and their sub‐factors, and changes dynamically in response to other variables, the SD method offers a practical approach for estimating and predicting human error behavior over time. This study identifies and quantifies the variables affecting HEP, explores their interactions and feedback in maintenance tasks, and assesses the associated costs. The machine learning technique is then used to estimate the relationship between HEP and these costs. The optimal value of the HEP function, 0.000772, is determined by identifying the minimum point of a cubic function, thereby minimizing associated costs and occupational accidents. Determining the optimal HEP is crucial for minimizing excessive costs and investing in improved ergonomics and CPCs for better performance. This addresses a significant gap in existing research where the impact of human error on maintenance tasks has not been estimated as a function. Furthermore, three scenarios are presented to help managers allocate the organization's budget more effectively.

Relevant biochar characteristics influencing compressive strength of biochar-cement mortars

To counteract the contribution of CO2 emissions by cement production and utilization, biochar is being harnessed as a carbon-negative additive in concrete. Increasing the cement replacement and biochar dosage will increase the carbon offset, but there is large variability in methods being used and many researchers report strength decreases at cement replacements beyond 5%. This work presents a reliable method to replace 10% of the cement mass with a vast selection of biochars without decreasing ultimate compressive strength, and in many cases significantly improving it. By carefully quantifying the physical and chemical properties of each biochar used, machine learning algorithms were used to elucidate the three most influential biochar characteristics that control mortar strength: initial saturation percentage, oxygen-to-carbon ratio, and soluble silicon. These results provide additional research avenues for utilizing several potential biomass waste streams to increase the biochar dosage in cement mixes without decreasing mechanical properties.Graphical

The Why, What, Who, When, and Where of Carbon Capture and Storage in Southern Ontario

This paper reviews the five Ws (Why, What, Who, When, and Where) of carbon capture and storage in southwestern Ontario. This area is home to nearly one quarter of Canada’s population and approximately three-quarters of one million people work in the manufacturing sector. Fifteen of the province’s top 20 CO2 emission point sources are in this area. The industries responsible for these emissions include steel mills, refineries and petrochemical plants, and cement plants. These industries are part of the hard-to-abate sector, in that CO2 is used or generated as an integral part of the industrial process. As such, eliminating or even reducing emissions from these industries is a difficult task. Carbon capture and storage (CCS) projects aim to sequester that gas in sedimentary basins over periods exceeding several thousand years. To this end, deeply buried (> 800 m) porous and permeable rocks (a repository) must be overlain by impermeable rocks that act as a seal, preventing the upward migration of CO2 into the atmosphere. The possibility that injection activities could trigger seismicity is but one of the additional considerations. When operational, CCS projects have a negative carbon footprint and the desirability of developing and using this technology has been established for over 20 years. True CCS projects differ from carbon capture, utilization, and storage (CCUS) projects in that the former are only designed with sequestration in mind. One type of CCUS project involves using CO2 for enhanced oil recovery (EOR) and this technology has been employed for several decades. Cambrian sandstones are the most suitable injection targets for CCS in southwestern Ontario because previous oil and gas drilling has shown the rocks to have the necessary characteristics. They are buried below 800 m, can be tens of metres thick, and have adequate porosity and permeability. However, the Cambrian section is lithologically and stratigraphically heterogeneous and oil, gas, and brine can all be present in the pore space. The extent to which this complexity will affect CO2 injection has not yet been evaluated.

Efficiency Assessment of the Production of Alternative Fuels of High Usable Quality within the Circular Economy: An Example from the Cement Sector

This article aims to present the mechanisms regulating the waste management system of one of the European countries that affect the cement industry. This publication analyses the possibility of using selected fractions of municipal and industrial waste as alternative fuels, including an analysis of ecological costs and benefits. The methodology includes the analysis of production data and the calculation of savings resulting from the use of alternative fuels. On this basis, ecological aspects were also indicated that should be taken into account when analyzing the profitability of the investment. Production data from an example Polish cement plant were used to analyze the research problem. Based on the guidelines of environmental standards and technical specifications, the parameters that PASr alternative fuels should meet were calculated in the company laboratory. This fuel type was then calculated in terms of emission intensity and production efficiency. The research results obtained in this paper study emphasize that the change in cement clinker production technology toward the use of waste raw materials and secondary fuels does not lead to an increase in heavy metal emissions to the extent that would justify qualifying cement as a material requiring systematic control of its harmful impacts on humans and the natural environment. The conclusions show that the use of alternative fuels reduces CO2 emissions and production costs, without negatively affecting the efficiency and production volume. The average energy requirement for the production of 1 ton of cement is approximately 3.3 GJ, which corresponds to 120 kg of coal with a calorific value of 27.5 MJ per kg. Energy costs account for 30–40% of the total cement production costs. Replacing alternative fuels with fossil fuels will help reduce energy costs, providing a competitive advantage for cement plants that use it as an energy source. The presented considerations can provide an answer to all interested parties, including representatives of the executive and legislative authorities, on what path the sector should follow to fit into the idea of sustainable building materials and the circular economy.

Dynamic modeling of human error in industrial maintenance through structural analysis and system dynamics.

Human error constitutes a significant cause of accidents across diverse industries, leading to adverse consequences and heightened disruptions in maintenance operations. Organizations can enhance their decision-making process by quantifying human errors and identifying the underlying influencing factors, thereby mitigating their repercussions. Consequently, it becomes crucial to examine the value of human error probability (HEP) during these activities. The objective of this paper is to determine and simulate HEP in maintenance tasks at a cement factory, utilizing performance shaping factors (PSFs). The research employs the cross-impact matrix multiplication applied to classification (MICMAC) analysis method to evaluate the dependencies, impacts, and relationships among the factors influencing human error. This approach classifies and assesses the dependencies and impacts of different factors on HEP, occupational accidents, and related costs. The study also underscores that PSFs can dynamically change under the influence of other variables, emphasizing the necessity to forecast the behavior of human error over time. Therefore, this paper utilizes the MICMAC method to analyze the interdependencies, relationships, and impact levels among different variables. These relationships are then utilized to optimize the implementation of the system dynamics (SD) method. An SD model is employed to forecast the system's behavior, and multiple scenarios are presented. By considering the HEP value, managers can adjust organizational conditions and personnel to ensure acceptability. The paper also presents various scenarios related to HEP to assist managers in making informed decisions.

Experimental investigations on strength and microstructural characteristics of air-cell impregnated light weight concrete

Concrete structures have high massive building materials than steel structures and possess very low thermal conductivity and high specific heat capacity. However, an efficient approach to reducing high production cost and structural weight of concrete elements without impacting their strength evolve as a growing necessity that leads to innovation in the Light weight concrete (LWC) fields such as aerated concrete and foamed concrete. Those large bubbles seem highly likely to get a break, move upwards through buoyancy and may get lost, while concrete has been mixed, transported, placed and vibrated. Hence to prevent increased bubble spacing, and air loss and to increase concrete durability, a sort of micron-sized air-cells could be generated in aerosol form, by passing out compressed air to dense form generating surfactants. Therefore to circumvent certain drawbacks of conventional LWC, the study delineated to bring out an innovative air-cell impregnated concrete (AIC) material, with homogenous mixing of cement, sand, water and uniformly distributed micron-sized air-cells wherein course-aggregates were replaced with air-cells. This uniform air-cell distribution creates durable concrete with unique feature characteristics since the micron-sized air-cells will be stable and does not collapse. The suitable surfactant towards contributing the strength and durability of proposed AIC structure are assessed, based on results.

Occupational exposure assessment of heavy metals among construction workers in Rawalpindi Pakistan

Construction is one of the primary drivers of development and economic activity in Pakistan. Many activities are performed at the construction site including cement mixing, carpentry, and painting. Workers working in these activities are exposed to toxic heavy metals. Due to exposure to these heavy metals, subjects are at high risk of developing diseases mainly respiratory diseases. Human hair and nail samples of construction workers in Rawalpindi, Pakistan were collected to assess the heavy metals. Heavy metals such as Al, As, Cd, Cr, Ni, K, Pb, and Zn were analyzed in the hair and fingernails of the construction workers. To determine the level of selected heavy metals, Inductively Coupled Plasma optical emission spectrometry was used. Results revealed that Al was the highest with a mean concentration of 7.54 μg/g in all three groups. Whereas Cd was below the detection limit. Heavy metal concentration was high in hair (1.77 μg/g) in two groups including cement mixing and carpentry. However, in the carpentry group heavy metal concentration was high in nails (1.19 μg/g). Additionally, the workers of the carpentry group have higher metal concentrations when compared to the other two groups and this group was at high risk of toxic metal exposure. After the correlation analysis, the results revealed that age was significantly correlated to body burden of metals (r = 0.496, p ≤ 0.05). Moreover, some of the heavy metals in hair and nails were significantly correlated with each other. Since all groups, especially carpenters, show high levels of heavy metals, there is a need for regular monitoring of heavy metals at construction sites. Most importantly, the implementation of training programs is needed to raise awareness among construction workers.

Effectiveness of pulpotomy in managing carious exposure in mature permanent teeth: A systematic review and meta-analysis

ObjectivesThis quantitative systematic review evaluated whether pulpotomy performed with hydraulic calcium silicate cements may be used as an alternative to root canal treatment (RCT) in mature permanent teeth with carious pulp exposure. Data sourcesA comprehensive search was conducted in PubMed, Web of Science, Scopus, and the Cochrane Library. No language restrictions were applied. The search included randomised controlled trials that compared pulpotomy to root canal treatment for managing carious exposure in mature permanent teeth. Study selectionStudies were selected based on predetermined inclusion criteria: randomised controlled trials involving mature permanent teeth with carious pulp exposure, using hydraulic calcium silicate cements for pulpotomy. Non-comparative studies, case reports, and trials involving primary or immature permanent teeth were excluded. DataData were extracted on success rates, clinical outcomes, follow-up periods, pain profiles, and potential complications. A meta-analysis was performed, revealing no statistically significant differences in success rates between pulpotomy and RCT. Both interventions demonstrated success rates exceeding 90 % at one-year and two-year follow-up periods. Pain profiles consistently showed lower post-operative pain intensity in the pulpotomy group compared to the RCT group during the first week. Potential complications, such as non-responsive pulp and difficulties in determining pulp vitality, were reported more frequently in the pulpotomy group. ConclusionsPulpotomy with bioactive hydraulic calcium silicate cements shows comparable success rates to RCT in managing carious pulp exposure in mature permanent teeth. The results suggest pulpotomy as a viable, less invasive alternative to RCT, particularly in cases where preservation of pulp vitality is paramount. Clinical significanceThis systematic review highlights pulpotomy as a less invasive and cost-effective alternative to root canal treatment in mature permanent teeth. With comparable success rates and lower post-operative pain, pulpotomy offers a promising approach to managing carious exposure and preserving tooth vitality.

Effects of Anisotropic Mechanical Behavior on Nominal Moment Capability of 3D Printed Concrete Beam with Reinforcement

In this study, 3D-printed reinforced concrete beams were tested for flexural performance and compared with the analytical model based on the material test results. Two cementitious mixes (PSU and GCT) were designed for concrete printing and were mechanically tested and compared. Anisotropies in the compressive strength and modulus of elasticity of printed concrete were observed, applied to the analytical prediction of flexural bending behavior, and validated by actual test results. Significant differences between analytical predictions and experimental tests of the bending behaviors of the printed concrete beams were observed. Furthermore, higher compressive strengths and moduli of elasticity were observed when the loading direction was perpendicular to the printed layers or with the PSU mix. The effect of anisotropic mechanical properties on a reinforced beam was compared to the flexural bending tests for both mixes. The analytical model based on the material test results was compared to the flexural bending test results. The significant errors in the prediction of printed concrete’s structural performance, from 10% to 50%, suggest that factors other than reduced compressive strengths may influence the structural behaviors of printed concrete beams.