Concrete Technology Research Articles

Analytical evaluation of stress–strain behavior of rubberized concrete incorporating waste tire crumb rubber

The advancement of rubberized concrete technology and its application in engineering can significantly promote the complete recycling and safe disposal of waste tire rubber. Integrating crumb rubber into concrete alters its compressive stress–strain behavior. This study investigated the stress–strain characteristics of rubberized concrete containing waste tire crumb rubber, addressing the absence of standard guidelines for the design of rubberized concrete. By examining the complete stress–strain curves of rubberized concrete, key parameters such as peak stress, initial elastic modulus, peak strain and secant modulus were meticulously evaluated. The study delved into the mechanisms through which crumb rubber influences the stress–strain behavior of concrete, considering factors including variations in rubber content and pretreatment methods. The experimental data were analyzed using conventional concrete constitutive theories to quantify the impact of crumb rubber on rubberized concrete's stress–strain relationship. Significant variations were observed, including a notable decline in strength with increasing rubber content. For instance, increasing the rubber content from 0.0% to 5.0% led to reductions of 44.2% in peak stress and 47.0% in secant modulus compared to the reference concrete. In addition, pretreating the crumb rubber markedly improved rubberized concrete strength, and the peak stress of concrete with 1.0%–5.0% pretreated crumb rubber increased by an average of 7.0% compared to that with untreated crumb rubber. The study identified that crumb rubber's inclusion significantly altered the coordination of stress and strain in concrete, thereby affecting its stress–strain behavior. A set of evaluation equations for the stress–strain relationship of rubberized concrete was developed, offering a reliable method for predicting its behavior. This research fills a critical gap in the analytical assessment of rubberized concrete and marks a significant stride towards its broader use in sustainable construction practices.

The main trends of 2023 in concrete construction

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

Features of Processes for Preparation and Performance of Foamed Lightweight Soil with Steel Slag Micronized Powder and Granulated Blast Furnace Slag

Steel slag micronized powder, granulated blast furnace slag, and cement were used as cementitious materials to prepare a foamed lightweight soil for roadbed filling to reduce the settlement and additional stress of the foundation and to solve the environmental problems caused by the storage of large amounts of steel slag. However, the instability of steel slag and the multi-angular nature of its surface limit the resource utilization of steel slag. Currently, concrete technology is unable to achieve a large amount of steel slag. Therefore, it is necessary to deeply explore the influence of steel slag content and the specific surface area of steel slag on the working performance, compressive strength, durability, and micro-mechanism of foam light soil. Through the modification of steel slag and the improvement of the production process, the preparation of foam light soil with a large amount of steel slag can be realized. In this study, the foamed lightweight soil with 1.0 Mpa was prepared by cementitious materials composed of 40% cement and 60% multi-mixture of steel slag micronized powder and granulated blast furnace slag. The study of SEM images and BET demonstrated that the larger specific surface area of steel slag powder was more conducive to improving the durability of the foamed lightweight soil. Meanwhile, XRD analyses confirmed that the reactions of f-CaO and f-MgO in steel slag were slowly released in the porous foamed lightweight soil system, which compensated for the shrinkage properties of porous materials. When the SSMP content was 0%, the shrinkage rate was 2.34 × 10−3, while when the SSMP content was 60%, the shrinkage rate was only 0.54 × 10−3. Furthermore, our study of the hydration process of samples indicated that the strong alkalinity of steel slag micronized powder hydration was helpful to stimulate the potential activity of the slag powder, which was beneficial to the improvement of the compressive strength of foamed lightweight soil. Thus, this study provides a valuable idea for reducing the settlement and additional stress of the original foundation and for solving the environmental problems caused by a large amount of steel slag storage.

New insights into early-stage time-dependent dielectric characteristics coupled with frequency dependency and hydration-driven reaction of hydraulic cement pastes: Experiments and statistical modelling

In the field of cement and concrete materials engineering, a comprehensive understanding of dielectric properties is crucial for optimising hydraulic cement paste mix designs. This study examines the relationships among the dielectric constant (ε’), loss tangent (tan δ), frequency, hydration time, water content and admixture dosage in different compositions of hydraulic cement paste. A consistent pattern can be observed across the frequency spectrum, where dielectric constants decrease as frequency increases. This aligns with the expected behaviour of cementitious materials. The most notable finding is the inversely proportional relationship between the loss tangent and frequency. As the frequency increases, the loss tangent consistently decreases, indicating improved energy retention and reduced dissipation. This characteristic is of significant value for various applications, including sustainable infrastructure and smart materials. Furthermore, the interactions among hydration time, water content and admixture dosage present an opportunity for dynamic optimisation within the cement paste matrix. These factors collectively impact dielectric properties, providing insights into the potential for tailored material performance and durability, especially in applications where dielectric properties are critical, such as sensing applications and structural health monitoring of concrete structures. This study emphasises the importance of customising cementitious compositions for specific applications in cement and concrete materials engineering. It achieves this through a detailed comparative analysis of different compositions, each representing varying water content and admixture dosage levels. This approach has the potential to significantly transform the field by enabling engineers to create hydraulic cement pastes with customised dielectric properties that meet the specific requirements of construction, infrastructure and other related applications.

Modified concrete: reality and prospects

Aim. To review the history of concrete technology over the past 30 years and to analyze current trends in the field.Reality. New concepts and terms that manifest the level of modern science in the field of concrete technology are given. It is shown that the use of complex organomineral modifiers produced on an industrial scale, which are characterized by unique compositions, forms, and processability, allowed Russia to organize promptly mass production of concrete with high performance properties in the amount of about 5 million m3. Examples of construction of unique structures from new modified concretes are presented. The list of such structures includes high-rise buildings, sports facilities, bridges, overpasses, tunnels, etc.Prospects. Priority tasks for further development of concrete technology in Russia have been formulated. Among them are the development and improvement of physical and technical characteristics of concretes; extended use of large-tonnage technogenic wastes in production of concrete mixtures; updating and development of new normative documents for calculation, design, and erection of modern structures with high operational reliability, durability, and aesthetic properties.

Investigation of stress-wave-induced crack penetration behavior at the rock-Ultra-High-Performance Concrete (UHPC) interface

The propagation behaviour of initial cracks in concrete penetrating the rock-concrete interface is still unclear. This study investigated the behaviour of stress wave-induced crack penetration through the Ultra-High-Performance Concrete (UHPC)-granite interface and crack propagation speed (CPS) using a combination of the crack propagation gauge (CPG) system and a split Hopkinson pressure bar. The influence of loading rate and UHPC strength grade on the dynamic fracture toughness of the penetration crack entire process was analyzed by experimental–numerical method. The results indicate that the Rock-UHPC interface can suppress the crack opening displacement in UHPC, thereby limiting the CPS. The loading rate significantly enhances the dynamic fracture toughness of the penetration crack's entire process. The interface is the boundary point, and the dynamic fracture toughness at the crack tip shows a trend of first increasing and then decreasing. The increase in concrete strength grade can improve the interface dynamic fracture toughness. Compared to the interface roughness, the enhancement effect of concrete grade on the interface dynamic fracture toughness is one order of magnitude higher. For concrete engineering on rock foundations, increasing the concrete strength grade can effectively prevent the inherent crack defects inside the concrete from expanding into the interior of the rock foundation.

Fibre reinforced concrete under in-plane shear stresses

Steel fibres have a positive influence on the shear behaviour of concrete elements, such as beams and walls, the more so as the developments in fibre reinforced concrete (FRC) technology allow reaching increasingly higher residual post-cracking strengths. The partial, or total, replacement of shear reinforcement by steel fibres allows increasing the construction speed and reducing labour costs, potentially offering economic benefits in the context of industrialized fabrication. However, the combined behaviour of steel fibres with reinforcement in shear critical elements is still not fully understood hindering the development of consistent design procedures.In this study, a detailed mechanical model based on the Cracked Membrane Model using fixed and interlocked cracks (F-CMM) is presented, which is capable of describing the behaviour up to failure of concrete panels reinforced with both steel fibres and rebars (R-FRC) subjected to in-plane shear and axial forces. The model explicitly considers all the individual mechanical phenomena governing shear behaviour of R-FRC and can serve as the basis for the development of methodologies for shear safety verifications.The model is validated against the existing experimental results from R-FRC panels subjected to in-plane shear loading. A calculation example is used to discuss in detail the model outcomes and the impact of the spatial variability in the fibre distribution. A parametric study is developed to understand the effects of fibres on the shear strength and failure modes, and its interactions with both the reinforcements and crack shear stress transfer mechanics.

An Experimental Investigation on Partial Replacement of Cement with Powdered Glass Wastes in Paver Block

There is now a significant world-wide interest to solve the environmental problems caused by industrial waste and other materials by including such materials in the manufacture of concrete. This technology has been introduced in India in construction, a decade ago, for specific requirement namely footpaths, parking areas etc. but now being adopted extensively in different uses where the conventional construction of pavement using bituminous mix or cement concrete technology is not feasible or desirable. The characteristics of concrete containing fine crushed glass during its process, the best ratio of fine crushed glass which leads to higher strength of concrete in order to produce concrete blocks, and the effect of waste glass replacement on the expansion caused by Alkali-silica reaction (ASR). This study looked at the feasibility of waste glass inclusion as partial Cement replacement systems. Properties of concrete incorporating waste glass as partial substitution for Cement amounts of 50% and 60% were investigated. The waste glass material used was obtained waste collectors. The results obtained show clearly that glass enhances the compressive strength properties of the final concrete product. The study indicated that waste glass can effectively be used as Cement replacement with little substantial change in strength.

Temperature Measurement in Massive Concrete Structures

Massive concrete structures are exposed to the risk of high temperatures due to cement hydration. In accordance with requirements for sustainable development, the clinker content in commonly produced cements is reduced and mixed cements are developed and gradually introduced into production. The development of temperatures in massive foundation structures made of concrete containing modern mixed cements is the subject of an experimental program. Its results are evaluated from the point of view of the final properties of the concrete, but also from the point of view of the possibilities of concrete production and implementation technologies. In conclusions, general recommendations are formulated for the design of concrete mixtures for application in massive structures.

Modern theory and practice of concrete technology for 3D printing in construction

Modern theory and practice of concrete technology for 3D printing in construction

Recent Progress in Geopolymer Concrete Technology: A Review

Recent Progress in Geopolymer Concrete Technology: A Review

Evaluation of combined addition of nitrite and chloride on the corrosion behavior of steel bars in modified magnesium oxysulfate cement paste

Magnesium oxysulfate (MOS) cement, a new breed of eco-friendly and carbon-efficient material, boasts exceptional corrosion resistance, especially in harsh environments such as high salt and high humidity. Understanding how it affects the corrosion of steel bars is crucial for its widespread application in coastal concrete engineering. Nitrite-based inhibitors are known for their rust-preventing qualities in cementitious materials. However, more research is needed to determine if nitrite remains effective in MOS cement mixed with chloride salts. This study focuses on the combined effect of chloride and nitrite salts on the corrosion of steel bars in MOS cement. Methods like corrosion area rate, weight loss rate, natural potential, and electrochemical station are employed to study the corrosion behavior of steel in MOS cement. Microscopic techniques help unravel the influence mechanism of phase composition and microstructure on these materials. Furthermore, the study examines how chloride and nitrite contents affect the concentration of free nitrite and chloride ions in MOS cement paste. The analysis model is also established to compare simple linear adsorption, Langmuir adsorption, and Freundlich adsorption. The results indicate that chloride accelerates steel corrosion, while nitrite slows it down in the environment of mixed chloride and nitrite. In low-chloride environments, nitrite content has minimal impact on steel corrosion, but its effect becomes more pronounced in high-chloride settings. The MOS cement mixed with chloride and nitrite primarily consists of Mg(OH)2, MgCl2, MgCO3, MgO, and the 5Mg(OH)2·MgSO4·7 H2O (517 phase). The phase content of passive film on the surface of steel bar is composed primarily of Fe2O3, FeO, Fe, and FeOOH in descending order. As nitrite content increases, the absorption and concentration of free nitrite ions in the MOS cement paste gradually rise, exhibiting a linear trend. Based on the fitting calculations for three distinct adsorption relationships, notably, due to the limited adsorption capacity of MOS cement for nitrite, there's a considerable difference between the simple linear adsorption relationship and the two nonlinear adsorption models in high nitrite environments. However, in low nitrite concentrations, the difference among these three fitting adsorption relationships is little. This research can provide theoretical basis for enhancing the corrosion resistance and durability of coastal concrete engineering with high chloride exposure.

Exploring IoT Integration for Innovative Advancements in Civil Engineering

Civil engineering developments have allocation with the recent trends of integration with IoT technologies and devices. This technology significantly improves automation and remote monitoring for various tasks in the construction process, building maintenance and safety, allowing operators to remain remote free ever than before. IoT is simply the connection of several devices to the internet as per the need. The real implication of IoT is beyond and complex than this. The IoT is meant to signify the establishment of entire networks of devices which are connected to the internet and with each other. Various sensors and monitors recognize the conditions, communicate them to online network or app, and transmit relevant information to your phone automatically. Internet of Things (IoT) is the technology that transforming construction industries, automate processes, and improves construction area and other relevant fields in civil like Global Positioning System (GPS), Water Resources Management and Water Supply, Smart Construction, Water & Waste Water Treatment, Traffic Management and Control, Waste Management, Concrete Technology, Environmental Impact Assessment & Monitoring and Smart Lighting System. This research paper covers implementation of IoT in all these fields of civil engineering and updating the current scenario. IoT is potentially used to increase the productivity, on-site safety, and operational efficiency. Through the placement of low-power sensors, managers can improve worksite visibility at every stage of a project in realtime, from planning to construction, and even task post-construction. The construction industry is bringing real-time information into processes that are long-standing. Internet of Things (IoT) devices and sensors are collecting job site data in a more affordable, efficient and effective way than can ever previously imagined. This latest technology represents exciting hikes forward in the civil engineering world. Foremost principles among these are integrated in this study for Internet of Things with the world of civil engineering.

Integrating continuous mineral-impregnated carbon fibers into digital fabrication with concrete

Digital concrete technologies, such as 3D concrete printing, have the potential to be game changers in the construction industry by reducing material consumption and offering a high level of automation. This not only provides a solution to the shortage of qualified workers but also makes construction sites more attractive workplaces. However, a significant challenge lies in integrating reinforcement, as traditional methods quickly reach their limits, particularly in geometrically complex, material-minimized structures. A potential solution is the use of mineral-impregnated carbon fibers (MCF) reinforcement, which offers high flexibility for 3D printing and better bonding to concrete compared to polymer coating, among other advantages. This article presents the integration of both freshly impregnated and cured MCF into two different concretes in the context of digital fabrication: 3D-printed concrete (3DPC) and self-compacting concrete (SCC). A particular focus was on the mechanical performance of MCF and MCF-reinforced concrete, as well as on the bond behavior between MCF and concrete. The second focus was on the production method. Therefore, samples were conventionally cast with SCC, while layered pouring or printing were used for producing specimens with 3DPC. It was found that the cured MCF exhibited a notably better bond, enhanced by 50%, to both 3DPC and SCC compared to freshly impregnated yarns. Subsequently, when subjected to uniaxial tensile loading, a significantly higher crack density and more uniform crack distribution could be observed in composites with cured MCF using digital image correlation (DIC). This effect was particularly pronounced in printed specimens and confirmed with computed tomography (CT) and environmental scanning electron microscope (ESEM) images.

Experimental and mesoscopic modeling numerical researches on steel fiber reinforced concrete slabs under contact explosion

This paper presents experimental research on the damage characteristics of steel fiber reinforced concrete slabs (SCS), steel fiber reinforced concrete slabs mixed with fly ash (CFS), and steel fiber reinforced concrete slabs mixed with fly ash and slag (CFSS) under contact explosion loads. The findings reveal that SCS and CFS exhibit crater damage on the top surface, spalling failure on the bottom surface, and certain damage cracks under the same contact explosion load. Additionally, the CFSS displays crater and spalling damage along with a through-hole at the center. Comparative analysis demonstrates that CFS offers the best explosion resistance properties. A reliable three-dimensional mesoscopic modeling using PYTHON and ABAQUS is established to analyze the dynamic response of the CFS, emphasizing its dependence on fiber volume. Furthermore, the study evaluates energy changes in the matrix and steel fiber to understand their impact on the slab's damage dimensions under contact explosion. Results indicate that the mesoscopic modeling effectively reflects structure damage and failure behavior under explosive super dynamic loads. Specifically, for CFS, with a steel fiber volume of 1.3%, the internal energy and stress generated by steel fiber are maximized, resulting in the smallest damage dimension under contact explosion and the best explosion-resistant effect. This research provides valuable insights for guiding the design of explosion-resistant structures and their deployment in concrete engineering applications.

The development of a prototype footbridge composed of biological self-healing and ultra-high-performance concretes

Developments in concrete technologies have allowed engineers to design lightweight, slender, and aesthetically attractive structures. The application of new concrete types in real projects, however, is uncommon. The lack of regulation, uncertainty in material performance, and the absence of successfully implemented projects hinders the use of modern concretes in everyday design projects. The present paper examines the application of two specific concrete types in a prototype footbridge: ultra-high-performance concrete (UHPC), and biological self-healing concrete (BSHC). The material properties of UHPC were selected and tailored specifically for the prototype structure, applying the principles of performance-based design. To evaluate the efficiency of self-healing under real environmental conditions, BSHC beams were designed as a structural part of the bridge. The step-by step presentation of the bridge development demonstrates the specifics in material design and a structural analysis of the prototype structure. The prototype structure serves as demonstrative example of the use of BSH and UHP concretes, encouraging engineers towards the wider application of advanced materials in construction projects.

Precast concrete project image dataset for deep learning object detection

Computer vision technology in precast concrete (PC) projects has the potential to enhance site management but faces challenges due to the lack of specialized datasets for this field. This study developed a PC components dataset for object detection (PCCODA) in four steps: component range selection, image collection, image preprocessing, and labeling. The performance of PCCODA was assessed using multiple algorithms, including You Only Look Once (YOLO), YOLO X, faster region-based convolutional neural networks (Faster R-CNN), and Double Head R-CNN. The dataset resulted in average accuracies of 0.88–0.97, average robustness of 0.84–0.96, and average detection speed of 3.64–23.3 frames per second. This performance fulfills the level required by most studies on construction automation. The applicability of the dataset was tested at a real site. This study contributes to the off-site construction project management theory and enhances productivity in PC projects by automating object detection-related tasks.

REVIEW OF THE EFFECT OF INDUSTRIAL WASTE ON SELF COMPACTING CONCRETE

Self-Compacting Concrete (SCC) is an innovation in concrete technology used in building elements with dense and complex reinforcement frameworks. SCC is characterized by its high fluidity and the ability to self-compact without the use of vibrators. Superplasticizer is one of the components applied in the production of SCC. The use of superplasticizer aims to reduce water consumption, accelerate the setting time, improve concrete workability, and also make the concrete impermeable.
 As time progresses, industrial waste continues to increase, highlighting the importance of recycling industrial waste. The purpose of this research is to investigate the influence of industrial waste as a substitute material for fine aggregates on the workability and compressive strength of SCC. This study is the result of a literature review obtained by examining various sources including books, proceedings, as well as international and national journals.
 The results of this literature study involve the use of industrial waste materials such as recycled glass, granite waste, nickel slag, and copper slag as substitutes for fine aggregates. The results of the workability and compressive strength of SCC are influenced by the characteristics of each industrial waste used. This indicates an improvement in the flowability (slump flow) with an increasing percentage of industrial waste, ranging from 0% to 60%, in the concrete composition.
 Compressive strength test results indicate that the optimal percentage of industrial waste addition in the concrete composition lies between 20% and 40%."

Experimental Research on the Impact Resistance Mechanical Properties and Damage Mechanism of Rubberized Concrete under Freeze–Thaw Cycling

To improve the long-term performance of concrete engineering in high-altitude areas, waste tire rubber was added to a concrete mix, and freeze–thaw and impact tests were conducted. The effects of waste tire rubber with different particle sizes (10, 20, 30 mesh) and freeze–thaw cycles (0, 25, 50, 75, 100, 125) on the dynamic mechanical properties of concrete materials were studied. The stress–strain curves, peak stress, and fracture morphology of the specimens were analyzed. The microstructure changes of the specimens were also analyzed using scanning electron microscopy (SEM). The results showed the following: (1) Both macroscopic and microscopic analysis results showed that the internal damage of rubber concrete specimens was smaller after freeze–thawing, and the integrity was better after impact, maintaining a loose but not scattered state. The addition of waste tire rubber significantly improved the material’s impact resistance to a certain extent. (2) As the impact pressure increased, the strain rate of the specimens increased linearly, and the dynamic peak stress was linearly positively correlated with the strain rate. (3) After 125 freeze–thaw cycles, the peak stress of the specimens with 30-mesh added rubber decreased significantly less than that of ordinary concrete under 0.3, 0.45, and 0.6 MPa impact pressure. The dynamic peak stress was higher than that of specimens with 10-mesh and 20-mesh added rubber, and the addition of 30-mesh rubber significantly improved the frost resistance and impact resistance of concrete materials. This study can provide new ideas for the engineering application of rubber concrete.

3D printed concrete with sewage sludge ash: Fresh and hardened properties

In this study, the possibility of application of sewage sludge ash (SSA) in 3D printed concrete (3DCP) technology was explored. The replacement of partial cement with SSA in the concrete mix design was investigated, followed by a comprehensive analysis of its impact on the workability, printability, and mechanical properties of the 3DCP. The findings indicated that the incorporation of SSA accelerated the loss of workability of 3DCP, such as fluidity and consistency. However, it significantly improved the green strength and buildability. Further investigation revealed that the addition of SSA hampered the hydration process of cement, resulting in a reduction in the mechanical properties of the hardened material. CT scanning indicated that the addition of SSA increased the interlayer porosity, leading to further degradation of the mechanical properties. The toxicity characteristic leaching procedure demonstrated that the maximum leaching concentration of 3DCP incorporating SSA was 0.14 mg/L. This result confirmed the effective immobilization of heavy metals, fulfilling the prerequisites for the application of 3DCP incorporating SSA.