Concrete Industry Research Articles

Analysis of waste glass as a partial substitute for coarse aggregate in self-compacting concrete: An experimental and machine learning study

With the growing environmental burden to minimize debris and recycle, the concrete industry has replaced wasted glass with concrete composition elements in multiple ways. This study provides a comprehensive analysis of integrating waste glass aggregate (WGA) at various proportions (0 %, 5 %, 10 %, 15 %, and 20 %) as substitutes for coarse aggregates along with a consistent 20 % silica fume (SF) as cement replacement in self-compacting concrete (SCC). In addition to determining the mechanical, durability and microstructural properties of SCC, this research also uses advanced machine learning (ML) techniques to predict the mechanical properties accurately. By employing slump flow, j-ring flow and v-funnel time the rheology of fresh SCC was evaluated. Mechanical properties were assessed through the evaluation of compressive, splitting tensile, and flexural strength, whereas electrical resistivity, water permeability, rapid chloride permeability (RCPT), and accelerated mortar bar test (AMBT) were employed to evaluate durability. The microstructure was further examined using scanning electron microscopic (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. The replacement of WGA with a constant SF in SCC improved flowability while lessening its passing ability. Furthermore, the study indicated that adding 5 % WGA along with 20 % SF to SCC resulted in a slight decrease of 4.53 % in compressive strength and 3.61 % in flexural strength compared to the reference mix containing 0 % WGA and 20 % SF after 28 days, which yields a favorable outcome. Findings from further assessments revealed that SCC's durability characteristics were enhanced by adding WGA and SF. Expansion of the Ca/Si ratio observed in EDS analysis significantly impacts the strength, while voids and cracks patterns detected in SEM analysis, result in an inferior microstructural performance with the incorporation of WGA. Notwithstanding both the ML models exhibiting excellent regression coefficients (R2), the random forest model showed superior accuracy and reliability in its results.

Enhancing Compressive Strength of Cement by Indigenous Individual and Co-Culture Bacillus Bacteria

Using a Taguchi experimental design, this research focuses on utilizing indigenous bacteria from the Danube River to enhance the self-healing capabilities and structural integrity of cementitious materials. Bacillus licheniformis and Bacillus muralis were used as individual bacterium or in co-culture, with a concentration of 8 logs CFU, while the humidity variation involved testing wet and wet–dry conditions. Additionally, artificial neural network (ANN) modeling of the compressive strength of cement samples results in improvements in compressive strength, particularly under wet–dry conditions. By inducing targeted bacterial activity, the formation of calcium carbonate precipitates was initiated, which effectively sealed formed cracks, thus restoring and even enhancing the material’s strength. In addition to short-term improvements, this study also evaluates long-term improvements, with compressive strength measured over periods extending to 180 days. The results demonstrate sustained self-healing capabilities and strength improvements under varied environmental conditions, emphasizing the potential for long-term application in real-world infrastructure. This study also explores the role of environmental conditions, such as wet and wet–dry cycles, in optimizing the self-healing process, revealing that cyclic exposure conditions further improve the efficiency of strength recovery. The findings suggest that autochthonous bacterial co-cultures can be a viable solution for enhancing the durability and lifespan of concrete structures. This research provides a foundation for further exploration into bio-based self-healing mechanisms and their practical applications in the concrete industry.

Developing greener concretes from spent bleaching earth and sugarcane bagasse ash

Concrete is by far the most widely utilized construction material due to its excellent mechanical and durability properties. However, the concrete industries are notorious for their anthropogenic activities that contribute to climate change. Cement production alone consumes immense amounts of energy and trails a significant CO2 footprint. One solution that researchers have deemed promising over the last couple of decades is the substitution of cement with agricultural waste products, which subsequently serves to alleviate waste disposal problems. This study investigates the suitability of spent bleaching earth (SBE) and sugarcane bagasse ash (SCBA) as partial replacement of ordinary Portland cement (OPC) in increments of 0, 5, 10 and 15% by mass. Tests were conducted in accordance to British Standards to assess the consistence, compressive strength, split tensile strength and drying shrinkage strain of SBE and SCBA based concretes. Results indicated that while these concretes displayed similar degrees of consistency, the SCBA concretes exhibited superior compressive and tensile strengths. Optimum SCBA dosages were revealed to be about 5-10%, yielding a 7-12% and 3-8% increase in compressive and tensile strengths, respectively, as compared to OPC concrete. Drying shrinkage behavior was also improved in the SCBA concretes. Further, comparisons of the mechanical and durability performances of the concretes with British and American codes suggest that up to 10% replacement of cement with SCBA may be a viable approach to developing sustainable materials for the concrete industry.

Performance of normal-weight and lightweight 3D printed cementitious composites with recycled glass: Sorption and microstructural perspective

The development of sustainable mixtures has been a widely researched topic in the last decade, as the cement and concrete industries are among the most polluting sectors. Recycled materials can eliminate the need for extraction of natural materials through re-utilization of waste, reducing the environmental impact. To date, few studies have analyzed the effects of incorporating recycled glass aggregates on the water transport properties and microstructure of 3D printable mixtures.This study assesses the feasibility of incorporating recycled glass as a replacement for natural aggregate in 3D printable mixtures. For this purpose, three normal-weight and three lightweight mixtures containing 0, 50, and 100 vol.% of recycled glass aggregate as basalt aggregate replacement were evaluated in cast and printed samples. Expanded thermoplastic microspheres (ETM) were included to create the lightweight mixture composition. This experimental work evaluated the effects of incorporating recycled glass, ETM, and the impact of the printing process on the microstructure, sorption, and capillary water porosity (CWP).The printing process has proven to be an influential factor affecting the shape, size, and quantity of porosity. In addition, the printing process was demonstrated to be more influential on porosity formation than the inclusion of recycled glass or ETM. Incorporating recycled glass results in a slight decrease in the PHg porosity, more spherical pores, and lower anisotropic tendency. Furthermore, adding ETM has a filling effect, leading to a more compact microstructure.

Experimental study on non-load bearing multi-span sandwich wall panels for blast mitigation

Sandwich wall panels are known for their ability to provide resistance over a wide deformation range, rendering them suitable for blast resistance applications. These panels consist of layers of concrete with an insulating core, offering a structural solution with enhanced performance. Quasi-static testing was conducted on multi-span sandwich wall panels with intermediate connections to evaluate their behavior under controlled loading conditions. A total of twelve two-span details were examined and selected to match the standard designs employed in the Tilt-Up Construction (TCA) and Prestressed/Precast Concrete Industry (PCI). Among these details, three belonged to the TCA type with two duplicates, while the remaining two were representative of PCI designs with three duplicates. The results obtained from the quasi-static testing indicate that insulated sandwich wall panels possess sufficient deformation capability to meet the current blast response criteria. To assess the findings of the static experiments to the prevailing response limits, the outcomes were distilled into a multi-linear static resistance analysis. The findings support the use of insulated precast concrete (PC) sandwich wall panels, highlighting their suitability for blast-resistant designs within the constraints of current blast design limitations. Specimens with Halfen connectors showed 32 % higher energy absorption and a 58 % advantage over Stud connectors, making them superior for robust blast resistance applications.

Effect of recycled aggregates with different parent strength and fly ash on flexural strength of recycled aggregate concrete prisms

Fast consumption of conventional ingredients of concrete and waste generated due to demolishing old buildings is a multi-fold problem in the concrete industry. Hence the sustainable alternative of it is the need of the day. In this research work effect of binary blending of demolished waste and fly ash on the flexural strength of plain concrete prism is presented. The properties of aggregates and cement are evaluated. The physical and chemical properties of fly ash were determined. Recycled aggregates from demolished waste with different mix ratios (1:2:4 and 1:1.5:3) were used. Optimization of recycled aggregates; by evaluating concrete cylinders in 12 batches; showed 35% as optimum. At the optimum dosage of recycled aggregates fly ash was used from 2.5% to 15% with an increment of 2.5% to optimize its dosage. Compressive strength test of the standard-size cylinders and their comparison with control concrete showed a 10% dosage of a fly as the optimum percentage to replace the cement in the concrete matrix. Using both optimized dosages of recycled aggregates and fly ash prism specimens of900mmx150mmx300mm were cast in four batches. The beam specimens were cured for 28 days followed by an evaluation of flexural strength and deflection under centric load in the universal testing machine. Test results of flexural strength (only 15% loss) showed good potential for both waste materials in the concrete matrix. Recycled aggregate with higher parent strength showed better performance than its other counterparts. With higher-strength recycled aggregates residual flexural strength was recorded as equal to 93%. For all specimens recorded deflection was within the allowable limits of ACI-318.

Application of total carbon analysis for carbon dioxide fixation in cementitious materials

This study focuses on the accurate evaluation of carbon dioxide capture in cementitious materials, a critical factor in reducing the carbon footprint of the concrete industry. Currently, there is no standardized method accurately quantifying fixed CO2 in carbonated cementitious materials. Additionally, since cementitious materials may contain organic carbon (TOC), which can lead to an overestimation of total inorganic carbon (TIC), separating and quantifying TIC and TOC is essential but remains challenging. We introduce a novel, straightforward approach for separately quantifying TIC and TOC based on total carbon measurement. Experiments were conducted using carbonated cement paste and a mixture containing polypropylene powder at various mass ratios. The optimal dissolution method for measuring TIC via acid solution and subsequent pretreatment was validated using X-ray diffraction analysis. This study proposes a subtraction method for determining TIC and TOC content in cementitious materials, providing a practical solution for environmental assessments in the concrete industry.

Impact of partial substitution of sand by compost on the mechanical and thermal parameters of concrete

The study investigates recycling organic waste in Algeria due to the rising use of natural resources and energy in concrete production and the large amount of organic waste discarded. The aim is to use compost as a partial replacement for sand, reducing the use of natural aggregates in the concrete industry while also reusing previously discarded waste as part of a circular economy. An experimental study was carried out on concrete’s thermal and mechanical properties to determine the effect of partial compost replacement on these properties. Five mixtures were created by replacing sand with compost in different proportions: 0, 5, 10, 15, and 20%. Slump and density were assessed in the formulations’ original state. Mechanical tests were performed on the hardened concrete to determine porosity, compressive strength, and flexural strength. Thermal tests were also conducted on various types of concrete to determine thermal conductivity. The findings show that the texture of the compost reduced the slump, highlighting the importance of incorporating an admixture to achieve the desired workability. While meeting normal-weight concrete standards, concrete density was reduced. The mechanical properties of concrete with small amounts of compost were similar to regular concrete; instead, waste porosity improved insulation.

Sustainable and ecological construction with autoclaved aerated concrete

The article is an introduction to the scope of legal requirements regarding CO2 emissions in the autoclaved aerated concrete industry. It addresses the issue of applicable regulations regarding ESG reporting, divided into individual scopes. The article presents the history of autoclaved aerated concrete as a universal and ecological material from the beginning of its development. It outlines the possibilities of achieving zero emission in the AAC industry, and the dependence of these goals on the country’s decarbonization plan. Additionally, it analyzes existing environmental product declarations [EPDs] of autoclaved aerated concrete and discusses possible investments that will reduce CO2 emissions throughout the product’s life cycle, including re-carbonation occurring during the use of autoclaved aerated concrete products.

Study on the Weibull distribution function-based stochastic damage evolution law for uniaxial compression in high-performance concrete with full aeolian sand

The issues of environmental degradation due to natural sand overextraction are becoming increasingly severe. In desert regions, utilizing aeolian sand as a substitute for natural sand in construction projects facilitates the resource economization and the effective management of desertification. The concrete industry is expected to significantly contribute to this objective, as high-performance concrete with full aeolian sand (FA-HPC) has demonstrated excellent mechanical properties. However, current researches have yet to establish a rational damage evolution law for uniaxial compression in FA-HPC from the perspective of damage characteristics. In this study, uniaxial compression tests were conducted on FA-HPC with different mixture proportions. Simultaneously, the stress-strain behavior was examined, and acoustic emission (AE) signals were collected and localized. Based on the Weibull distribution function-based stochastic damage evolution law for uniaxial compression, regression analyses of the stress-strain and AE cumulative ringing count for FA-HPC were performed. Damage evolution model for effective stress and damage variable were established and validated with experimental data to confirm their applicability. The scale and shape parameters of the model were predicted using the mixture proportions as independent variables. The results show that the rationality of the damage evolution law assumption was validated through AE source localization. The goodness of fit values for damage variable and effective stress equation range from 0.87 to 0.98, with the ascending segment and the vicinity of the peak point closely matching the experimental data, indicating that the Weibull distribution function-based stochastic damage model for uniaxial compression is applicable for FA-HPC. The predicted values of the damage evolution model parameters based on the mixture proportions align well with the measured values, achieving a goodness of fit of 0.99, thereby guiding the study of FA-HPC's compressive characteristics prior to the formation of primary cracks. Notably, there remains a need to propose corrective equations to enhance the correlation between regression curves and experimental data in the late failure stages of FA-HPC in future research, achieving precise predictions by considering the interactions of multiple factors.

The Utilization of Carbonated Steel Slag as a Supplementary Cementitious Material in Cement.

Carbon emission reduction and steel slag (SS) treatment are challenges in the steel industry. The accelerated carbonation of SS and carbonated steel slag (CSS) as a supplementary cementitious material (SCM) in cement can achieve both large-scale utilization of SS and CO2 emission reduction, which is conducive to low-carbon sustainable development. This paper presents the utilization status of CSS. The accelerated carbonation route and its effects on the properties of CSS are described. The carbonation reaction of SS leads to a decrease in the average density, an increase in the specific surface area, a refinement of the pore structure, and the precipitation of different forms of calcium carbonate on the CSS surface. Carbonation can increase the specific surface area of CSS by about 24-80%. The literature review revealed that the CO2 uptake of CSS is 2-27 g/100 g SS. The effects of using CSS as an SCM in cement on the mechanical properties, workability, volume stability, durability, environmental performance, hydration kinetics, and microstructure of the materials are also analyzed and evaluated. Under certain conditions, CSS has a positive effect on cement hydration, which can improve the mechanical properties, workability, bulk stability, and sulfate resistance of SS cement mortar. Meanwhile, SS carbonation inhibits the leaching of heavy metal ions from the solid matrix. The application of CSS mainly focuses on material strength, with less attention being given to durability and environmental performance. The challenges and prospects for the large-scale utilization of CSS in the cement and concrete industry are described.

The use of graphene nanoplatelets for enhancement of the compressive strength of mortar containing high-levels of natural Pozzolan

High Pozzolan concrete has an extended setting time and inhibits early-age compressive strength development, which can cause construction delays and limit its application in the concrete industry. The main aim of this study is to evaluate the effectiveness of graphene nanoplatelets (GNPs) in enhancing the mechanical properties of mortar containing high levels of natural Pozzolan. In the beginning, a relatively simple ultrasonication treatment process produced an almost uniform dispersion of GNPs in the mixing water to avoid agglomeration which limits the efficiency of GNPs. Tests on engineering properties indicated that the compressive strength of mortar containing 40 and 60 % natural Pozzolan as a partial replacement of cement was enhanced with the addition of the optimum content of graphene nanoplatelets which was found to be 0.03 % and 0.01 % by weight of binder at 40 % and 60 % cement replacement levels, respectively. The compressive strength was enhanced by 29.6 %, 27.4 %, and 27.5 % at 40 % cement replacement level, and by 86.3 %, 23.7 %, and 25.8 % at 60 % cement replacement level at 7, 28, and 56 days of curing, respectively. SEM investigations indicated that the addition of GNPs densified the structure thus enhancing the performance of mortar.

EXAMINING THE USE OF MARBLE WASTE AS A SUBSTITUTE OF CONVENTIONAL MATERIALS IN CONCRETE: A BRIEF REVIEW

For decades studies have investigated using marble waste as a partial replacement for conventional materials in concrete. This review examines the findings on substituting marble waste for coarse aggregate, fine aggregate, and cement. The studies accessed suggest that replacing up to 50% of coarse aggregate with marble waste can improve the concrete's mechanical properties and durability. Using marble waste for up to 20% of fine aggregate in concrete, mortars, and self-compacting concrete improves workability, compressive strength, and sustainability. Additionally, substituting up to 10% of cement with marble dust helps reduce cement consumption and the environmental impact of concrete production. The benefits of using marble waste include better mechanical properties, cost savings, and a smaller ecological footprint. Despite the numerous benefits, gaps in research persist, particularly in long-term performance studies, standardized testing methods, and comprehensive life cycle assessments. This review highlights the potential of marble waste as a valuable resource in the concrete industry and underscores the need for further research to optimize its use and fully realize its benefits in sustainable construction practices.

Development sustainable concrete with high-volume wastes tile ceramic: Role of silica nanoparticles amalgamation

As the global concrete industry shifts towards sustainable practices, there is an increasing focus on mitigating the environmental impacts of ordinary Portland cement (OPC)-based concrete, which is notorious for its significant greenhouse gas emissions, high energy consumption, and substantial demand for natural resources. This urgency is compounded by the growing production of waste tile ceramic materials due to rapid urban development, leading to enhanced research into their recyclability within concrete for improved durability and sustainability. This study explores the development of high-strength concrete utilizing waste tile ceramic aggregates (WTCAs) and waste tile ceramic powder (WTCP) as replacements for natural aggregate and OPC, respectively. To further enhance the concrete's mechanical properties and microstructure, silica nanoparticles derived from waste bottle glass (WBGNPs) were integrated in varying proportions ranging from 2 % to 10 % of the binder content. Optimal results were achieved with a full replacement of natural aggregate by WTCAs, 60 % substitution of OPC by WTCP, and the inclusion of 4 % WBGNPs, which collectively exhibited superior compressive, splitting tensile, and flexural strengths. Microstructural analyses revealed that the addition of WBGNPs improved the hydration process, increased gel density, and reduced porosity. From the obtained numerical results, the coefficient of determination value of 0.92 further confirms the model's predictive strength, demonstrating that the Random Forest algorithm can reliably estimate the compressive strength. The findings indicate that the concrete formulated with WTCP and WBGNPs not only meets diverse construction demands but also significantly contributes to environmental sustainability by reducing impacts on global warming and minimizing landfill usage. This study advocates for the strategic incorporation of WTCP and WBGNPs in concrete applications to promote environmentally sustainable construction practices. It is highly recommended that WTCP be utilized in sustainable binders as a replacement for OPC and natural aggregates to enhance it strength and durable properties, reduce the environmental issues, costs, and the depletion of natural resources.

Shear behavior of reinforced concrete beams comprising a combination of crumb rubber and rice husk ash

In this paper, experimental studies were conducted to examine the shear behavior of reinforced concrete beams, including a combination of crumb rubber (CR) and rice husk ash (RHA). One of the key objectives of the concrete industry is to reduce global emissions and provide environmentally friendly concrete. Twelve RC beams with four replacement levels of CR (0 %, 5 %, 10 %, and 20 %) by fine aggregate (FA) and three substitution ratios of RHA (0 %, 10 %, and 20 %) by cement (one beam from each mix) with dimensions of 120 × 250×2000 mm were cast and tested under four-point loading conditions. The experimental outcomes display that incorporating a combination of CR and RHA reduces workability. The introduction of RHA enhanced both the compressive and tensile strengths. Conversely, the inclusion of CR significantly impacted the loss in concrete strength. The shear capacity, stiffness, and toughness of the tested beams were noticeably enhanced with the addition of RHA up to 10 %, then dropped with the addition of 20 % RHA but remained higher than those of the reference beam. On the contrary, the introduction of CR had a negative effect on the shear capacity and stiffness of tested beams, and incorporating RHA up to 10 % enhanced these effects. To maintain environmental sustainability and preserve natural resources, the ideal substitution ratios for the concrete mix are 10 % CR and 10 % RHA, which produce an acceptable shear capacity with a slight drop of approximately 4.0 %. Additionally, a comparison was conducted between the predicted shear capacity of four design code equations (ACI 318–2019, ECP 203, BS8110, and Euro-2) and the experimental results obtained from all test beams.

Assessment of Properties of Green SCC with and without Novel Additive

Concrete is the most widely used construction material in civil engineering industry because of its proved structural strength and stability when made properly. The concrete industry is constantly trying to evolve to make concrete more sustainable replacing a part of full cement with additives and Supplementary Cementitious Materials (SCMs). Each tonne of cement production releases one tonne of CO2 into the atmosphere and hence to greenhouse effect and global warming. A cost effective, alternative and innovative materials called novel additive is taken up for present study to reduce the cement consumption per m3 of concrete/SCC without reduction in strength of required grade. In this project an effort is made replacing cement content of SCC partially with Fly Ash, Ground Granulated Blast Furnace Slag (GGBS) in combination of novel additive. The study focused at studying the properties of fresh SCC and hardened SCC. The design mix proportion of 1: 2.63: 1.86 with a W/B ratio of 0.36 is taken up and 4 different mixes with different combinations of varied percentage replacement materials with 2% by weight of cement of novel additive. The properties of green SCC showed that fresh properties get enhanced through usage of mineral admixtures including a novel additive and hence, the addition of mineral admixture improve the flowability or rheology of SCC mixes. The strength of SCC achieved is ranging from 32- 46 N/mm2 for a cementitious content of 400 kg/m3 , highest being with lowest cement content with novel additive. Keywords: Rheology of SCC, Mineral Admixtures, Novel Additive, Sustainability

Influence of Steel Slag as a Partial Replacement of Aggregate on Performance of Reinforced Concrete Beam

Amidst the global pursuit of sustainable alternatives in concrete production, this study explores the viability of incorporating by-products or waste materials as aggregates to support the concrete construction industry, with a specific emphasis on steel slag. The objective of this study is to evaluate the effectiveness of steel slag as a partial replacement for fine and coarse aggregates in concrete production. The experiment involved casting 30 cubes and 10 beams, replacing fine aggregate from 0 to 60%. Flexural and compressive strength tests at 7 and 28 days followed the ACI method. Results revealed that a 30% replacement of fine aggregate with steel slag led to higher compressive strength at both 7 and 28 days, while a 45% replacement showed superior flexural strength at 28 days. Further chemical analysis and optimization are recommended for deeper insights. The study concludes with marginal improvements in compressive and flexural strength with steel slag partial replacement, identifying 30% for fine aggregate and 45% for coarse aggregate as optimal replacements. In addition, the mineral composition of steel slag exhibits significant variability, with compounds, including silicon dioxide (SiO2), iron oxide (Fe2O3), manganese oxide (MnO), aluminum oxide (Al2O3), and calcium oxide (CaO). Chemical analysis indicates high silicate content and minimal alkali content, contributing to enhanced strength during concreting. Higher steel slag replacement reduces workability, confirmed by slump tests. However, all mixes maintain a true slump, and unit weight increases with steel slag aggregate replacement. Compressive strength improves incrementally with higher steel slag content, echoing prior research. In addition, flexural strength rises with steel slag replacing both coarse and fine aggregates, suggesting enhanced performance in reinforced concrete structures. These findings highlight steel slag’s potential as a sustainable alternative in concrete production, aiming to advance its application in the construction industry, promoting environmental sustainability and economic viability.

Ensemble machine learning models for predicting the CO2 footprint of GGBFS-based geopolymer concrete

While geopolymer concrete (GPC) has gained popularity for its environmentally friendly attributes compared to ordinary Portland cement, the absence of a prediction model for the carbon footprint of its constituents presents challenges for optimization within the evolving concrete industry. This study offers a thorough CO2 footprint prediction for ground granulated blast-furnace slag (GGBFS)-based GPC, utilizing advanced AI techniques, including a combination of machine learning models and stacking ensembles. This research statistically examines crucial parameters responsible for CO2 emissions in GGBFS-based GPC production, identifying factors like superplasticizer content, initial curing temperature, and NaOH (dry) content as significant contributors. Emphasizing sustainability, the study advocates optimizing concrete mixtures by considering factors like the NaOH ratio to other activator materials. After rigorously evaluating 12 machine learning models, including ensemble techniques, this study identified M4—a stacking model of Support Vector Regression (SVR) and Neural Network (NN)—as weak models, and Decision Tree (DT) as a meta-model, as the most effective ensemble model for predicting CO2 footprints. The choice of M4 is supported by various performance metrics such as the lowest Mean Squared Error of 88.8 and Root Mean Squared Error of 9.42, alongside the highest R2, Adjusted R2, and Explained Variance scores, all approximately 0.95. Additional analyses, such as Euclidean distance and Taylor diagrams, further substantiate the selection of M4. The findings have practical implications for sustainable and cleaner concrete production, enabling businesses to optimize the CO2 footprint of GGBFS-based GPC.

Influence of the Addition of Palm Kernel Shell and Ash on Concrete Performances: Study of Correlations between Intrinsic Material Properties

Sustainable development objectives in the construction sector is currently hampered by the high cost of materials (cement, aggregates) and the environmental impact of waste in some developing countries. The obtained results in this work on the influence of ash (PKSA) and palm kernel shell (PKS) used as a partial addition of cement and aggregates in concrete composition, enable their valorization as local materials to manufacturing the lightweight concrete with low-cost. This is an interesting contribution to the development of sustainable construction and environmental protection. The used palm kernel shells are produced in the palm oil industry in Republic of Congo. The highest values for density Cd(2348kg/m3), compressive strength Cs(27MPa) and splitting tensile strength Ts(2.4MPa) for concrete using PKSA were obtained at 2.5%. Those for concrete using PKS were obtained at 5 %, i.e. Cd(2165kg/m3), Cs(22MPa) and Ts(1.90MPa). the increase in concrete properties with PKSA compared to PKS is explained by the pozzolanic reaction of the palm kernel ash, which acts as a hydraulic binder. Correlations between fundamental concrete properties reliably describe the influence of PKS and PKSA, with a coefficient of determination R2 (0.9) superior at 0.5; the obtained mathematical models to prediction the concrete properties are a significant contribution for engineers. PKS is a concrete plasticizer, PKSA is a concrete setting and hardening accelerator. The production of low-carbon concrete with PKSA addition is a major step forward for the concrete industry.

Fresh Concrete Properties from Stereoscopic Image Sequences

Increasing the degree of digitization and automation in concrete production can make a decisive contribution to reducing the associated CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{CO}_{2}$$\\end{document} emissions. This paper presents a method which predicts the properties of fresh concrete during the mixing process on the basis of stereoscopic image sequences of the moving concrete and mix design information or a variation of these. A Convolutional Neural Network (CNN) is used for the prediction, which receives the images supported by information about the mix design as input. In addition, the network receives temporal information in the form of the time difference between image acquisition and the point in time for which the concrete properties are to be predicted. During training, the times at which the reference values were captured are used for the latter. With this temporal information, the network implicitly learns the time-dependent behavior of the concrete properties. The network predicts the slump flow diameter, the yield stress and the plastic viscosity. The time-dependent prediction opens up the possibility of forecasting the temporal development of the fresh concrete properties during mixing. This is a significant advantage for the concrete industry, as countermeasures can then be taken in a timely manner, if the properties deviate from the desired ones. In various experiments it is shown that both the stereoscopic observations and the mix design information contain valuable information for the time-dependent prediction of the fresh concrete properties.