Performance Concrete Research Articles

Modeling and numerical analysis of concrete specimen under dynamic and thermal loading taking into account non-linearity

In this study, we propose a model describing the mechanical behavior of basalt aggregate concrete under high temperatures. Basalt aggregate concrete is formulated. The bulk density, residual mechanical (compressive strength, tensile strength and elastic modulus) and microscopic properties of basalt aggregate concrete specimens are analyzed. The damage basalt aggregate concrete, the geometry and nonlinear behavior of the material is investigated. Based on Newton’s second law, the investigation is conducted on the simultaneous effects of mechanical loading and thermal treatment. The finite difference method is used for the numerical solution of the problem to determine the peak stress and strain of normal basalt aggregate concrete as a function of temperatures and time. It follows from the results obtained that, after [3–5 min] the critical temperature at which material damage, for both stress and strain, is observed to be 350 °C at the center, corresponding to a 30% reduction in peak stress on the value initially obtained experimentally; And 300 °C at the free and fixed end of basalt aggregate concrete specimen respectively, corresponding to a 38 and 30% reduction in stress in the z-axis direction. Beyond these temperatures, it is observed that the amplitude of the deformations continues to increase whatever the position announcing an imminent collapse of the material, probably due to the loss of stiffness of the cement paste which significantly reduces the mechanical performance of the normal basalt aggregate concrete observed experimentally.

Exploring the impact of CO2 sequestration on plastic properties, mechanical performance, and microstructure of concrete

In view of global warming, carbon sequestration techniques are being employed across the globe to minimize the damaging effects of greenhouse gases on the environment. Studies have revealed that adding CO2 during the mixing or curing stage of concrete enhances its mechanical properties and long-term durability. This study aims to examine the effect of CO2 addition during the mixing stage on the plastic, mechanical and microstructural properties of concrete. Various CO2 dosages, ranging from 0.1 to 1%, were injected during mixing to analyze the plastic and hardened properties of concrete. CO2 primarily reacts with calcium hydroxide in concrete to form calcium carbonate (CaCO3), thereby densifying its microstructure and improving its compressive strength by 10–20%. An optimum strength of up to 20% was achieved with 0.75% dosage. Additionally, the results show a 5–10% improvement in flexural and split tensile strength with CO2 addition over the control mix, with 0.75% dosage yielding optimal strength. Semi-adiabatic calorimetry test on early hydrating concrete shows a 14% peak temperature rise at 0.75% CO2 dosage compared to control concrete, indicating enhanced early-age strength development. Thermal Pyrolysis tests, microscopy and infrared spectroscopy indicated the presence of CaCO3, thereby confirming the carbonation process. However, CO2 dosages above 0.5% by weight of cement resulted in a drop in the workability of concrete in the plastic stage. This research attempts to create a simplified CO2 sequestration process in concrete, develop a predictive model to estimate the compressive strength and utilize material characterization techniques to identify the mineralization process.HighlightsInjecting CO2 into fresh concrete improves its strength and lowers its environmental impact.A multiple linear regression model predicts the compressive strength of CO2-injected concrete.Semi-adiabatic calorimetry shows that CO2 injection speeds up early hydration.Thermal Pyrolysis detects mass loss stages linked to dehydration and calcite breakdown.Microscopy and spectroscopy indicate CaCO3 crystal formation in CO2-sequestered concrete.

Enhancing concrete sustainability with spent diatomaceous earth from the wine industry: Long‐term experimental and statistical analysis

AbstractSpent diatomaceous earth, a by‐product of wine filtration, holds significant promise for use in concrete mixtures due to its pozzolanic properties, which enhance concrete performance. This research explores the application of spent calcined diatomaceous earth (SCDE), heat‐treated at 700°C to remove organic content, as a partial substitute for cement or sand in concrete. The high silica content of SCDE contributes to the formation of additional calcium silicate hydrates during the hydration process, leading to improvements in mechanical strength over time. The study includes a preliminary analysis of cement replacements ranging from 5% to 10% and sand replacements from 2.5% to 15%, assessing their effects on workability, density, water absorption, and compressive strength at 7 and 28 days. The testing program focuses on three key compositions: the reference concrete and optimal mixtures with 10% cement and 5% sand replacements. Compressive strength tests are conducted at 7, 28, 90, 180, and 360 days. The results, validated through ANOVA, demonstrate the influence of SCDE on concrete strength over time, with distinctive behavior patterns identified for different mixtures. The strength of concrete with replacements correlates with the reference strength, with a multiplicative factor that varies from 7 to 90 days and then. When SCDE replaces cement, the factor is less than one before 28 days due to the slow pozzolanic reaction, whereas for sand replacement, it always exceeds one because of the initial filler effect. After 90 days, the strength multiplicative factors are 1.13 for cement replacement and 1.30 for sand replacement, demonstrating the potential of SCDE for sustainable concrete manufacturing and its positive long‐term impact on mechanical performance.

Recycled coarse aggregate concrete and its application in CFRP reinforced concrete beam

This paper deals with performance of concrete by using recycled coarse aggregate (RCA) to replace 30%, 50%, and 70% of natural coarse aggregate. Three concrete types were studied: Group A using RCA with 10% of silica fume (SF) addition by weight of cement, Group B using RCA with 30% of fly ash (FA) substitution by weight of cement, and the control concrete without RCA, SF, FA. Group A demonstrated a considerable improvement in compressive strength whereas group B exhibited a noticeable reduction, in comparison to the control concrete. Secondly, three reinforced concrete beams, representing three concrete types, strengthened with carbon fiber reinforced polymer (CFRP) sheet were tested under a three-point bending fixture. All the flexural parameters of the tested beam, including load bearing capacity, deflection capacity, stiffness, ductility, and crack patterns were evaluated and discussed. Finally, an analytical model was suggested to estimate moment and shear resistance of the beams.

Evaluating the performance and environmental impact of low calcium fly ash-based geopolymer in comparison to OPC-based concrete.

The current paper explores the performance, microstructure and environmental consequences of low-calcium fly ash-based geopolymer concrete compared to OPC-based concrete. The performance of the concrete is assessed based on strength, permeability, sulfate resistance, and acid attack. Two geopolymer mixes were designed by adjusting the binder dosage. The geopolymer concrete mixes achieved 11-16% higher strength than OPC-based concrete. However, increasing the binder dosage from 30 to 40% led to 5% reduction in strength at later ages. Geopolymer concrete demonstrated superior resistance to sulfate and acid attacks, as well as lower penetration depth and permeability coefficient compared to OPC-based concrete. Microstructural analysis was conducted using XRD and SEM techniques, identifying sodium aluminosilicate gel as the product formed during the polymerization process. The environmental impact was evaluated through a life cycle assessment using a cradle-to-gate approach. Geopolymer concrete requires 25-33% less energy and emits 14-28% less kg-CO2 eq. than OPC-based concrete. The production of OPC-based concrete had the greatest negative environmental impact, except in the categories of metal depletion (MDP) and ionizing radiation (IRP_HE). In geopolymer concrete, the use of alkaline activators accounted for higher energy consumption and accounted for 73-75% kg-CO2 eq. emissions. Overall, fly ash-based geopolymer concrete showed higher strength and excellent resistance to acid and sulfate attacks, along with a lower carbon footprint and energy consumption.

Advancing self-compacting concrete performance with the use of combined marble waste as fine and coarse aggregates

Environmental protection through waste recycling is one of the major challenges of our time. Inert waste, mainly generated by industry, makes up a significant portion that harms the environment due to its accumulation in nature.The primary objective of this study is to examine the influence of marble waste valorization as sand and gravel on the rheological and mechanical properties of self-compacting concrete (SCC). For this study, marble was used as fine aggregate sand (MAS) at rates of 10%, 20%, and 30%, and as coarse aggregate gravel (MAG) at a rate of 100%. The results of this study demonstrate that the introduction of marble waste (MW) as aggregate positively influenced the rheological characteristics, notably reducing the need for superplasticizer dosage. Additionally, in terms of mechanical outcomes, the use of MAG led to improved mechanical strengths.

High temperature performance of recycled fine concrete

The objective of this study is to explore the physical and mechanical behaviour of concretes comprising four different ratios of recycled fine (RF), namely (5%, 10%, 15% and 20%) along with that of a reference concrete (Cref-0%), under three different heating–cooling cycles (200 °C, 400 °C and 600 °C). The thermal properties of concrete during heating and cooling (20 °C – 600 °C – 20 °C) were also investigated. It was determined that the physical properties (mass loss and ethanol porosity) of recycled concrete (RC) with 5% of recycled fine (RC-5%) were similar to those of Cref-0%. At ambient temperatures, the higher the ratio of recycled fines, the lower the residual compressive strength and residual elastic modulus of the recycled concrete. After thermal loading at 600 °C, the residual mechanical properties of all types of concrete were equivalent, regardless of the content recycled fine.

Effect of a novel negative temperature early-strength agent in improving concrete performance under varying curing temperatures

This study investigates the effect of a novel negative temperature early-strength agent (NEA) in enhancing concrete performance under varying curing temperatures, with a discussion on the underlying mechanism through analysis of hydration products and microstructure.The results indicate NEA markedly accelerates early cement hydration, reduces setting time, and enhances compressive strength. Moreover, the efficacy of NEA is more pronounced at lower temperatures. With an optimal dosage of 3%, the incorporation of NEA leads to a remarkable 285.9% increase in compressive strength at 28 days under -5°C curing temperature. Despite accelerating cement hydration can induce increased chemical shrinkage, NEA effectively mitigates early freezing expansion under negative temperature and significantly diminishes chloride ion permeability. Higher temperatures facilitate early cement hydration but also compromise long-term hydration continuity. Consequently, the highest hydration degree and loweast porosity are observed at 28 days under 5°C curing temperature. NEA's air-entraining component introduces numerous superfine pores into the paste, augmenting early pore volume while optimizing pore structure. As the early-strength component fosters hydration, these pores undergo further filling and refinement, ultimately reducing the total pore volume at 28 days. This study provides insights into optimizing concrete performance in cold environments.

Sustainable Internal Curing Materials’ Effect on Concrete Performance

Sustainable Internal Curing Materials’ Effect on Concrete Performance

The Feasibility of Using Lignin as Modifier for Asphalt Cement

Modifying asphalt cement is an effective approach to enhance the performance of asphalt concrete. This study evaluates the physical properties of lignin-modified asphalt (LMA) at various lignin percentages. The initial step involved extracting lignin from the pinus wood sawdust using the soda process. Subsequently, the extracted Soda Lignin Powder (SLP) was characterized through Fourier transformation infrared spectroscopy (FTIR), and Scanning Electron Microscopy-Energy Dispersive X-ray Analysis (SEM/EDX) to examine the changes in the chemical structure of lignin after extraction by soda process. Following this, three asphalt blends containing varying amounts of SLP (2%, 4%, 6%) by weight of asphalt cement were produced to assess physical properties such as penetration, softening point, ductility, and rotational viscosity test. The findings indicate that incorporating SLP into asphalt cement increases stiffness and viscosity compared to virgin asphalt cement, with increasing SLP content. These results suggest that lignin presents significant enhancement to the performance of asphalt cement under high service temperature conditions.

Performance of low-cost Concrete using Bentonite clay as a partial replacement with Cement

Performance of low-cost Concrete using Bentonite clay as a partial replacement with Cement

Improving the performance of crumb rubber concrete using waste ultrafine glass powder

Due to its superior toughness and environmental benefits over traditional concrete, crumb rubber (CR) concrete (CRC) gained considerable attention in both research and practical engineering fields. However, the static mechanical characteristics of CRC exhibit a certain level of decline as CR demonstrates a lower elastic modulus and less effective bonding capabilities with mortar when compared to natural aggregates. Consequently, this study explores the potential of substituting cement with ultra-fine waste glass powder (WGP) to enhance the mechanical characteristics and microstructure of CRC. The impact of varying WGP substitution rates on workability, wet packing density (WPD) in the fresh phase is examined. Moreover, analyses on compressive strength, flexural-tensile strength, ductility index, dynamic elastic modulus, damping ratio, and impermeability post-hardening are presented. The use of scanning electron microscopy (SEM), X-ray diffraction (X-RD), and mercury intrusion piezometry (MIP) provided insights into the influence of WGP on the micromorphology, mineral composition, and pore structure characteristics. The results revealed that WGP introduction enhanced the fresh properties of CRC, notably in terms of workability and WPD. The slump and slump-flow increased to 270 mm and 630 mm for WGP dosing increased to 30 %. A gradual enhancement in strength, dynamic elastic modulus, and impermeability was observed with increased WGP content, alongside a significant improvement in toughness. The compressive and flexural strengths of 30 % WGP were mentioned to be about 11 % and 62 %, respectively, and the permeability coefficient was reduced to 0.78 × 10−12 m2/s. The damping ratio initially decreases, then rises to a peak of 1.6 % at a WGP content of 30 %. Integration of WGP resulted in a progressive decrease in interfacial frictional zone width, average pore diameter, and porosity, while the fraction of harmless pores increased, likely aiding the strength and dynamic elastic modulus.

Prediction model for elastic modulus of recycled concrete based on properties of recycled coarse aggregate and cementitious materials

The supplementary cementitious materials (SCMs) are commonly used in recycled coarse aggregate (RA) concrete to improve the performance of RA concrete or reduce the amount of cement used. However, the diverse sources and compositions of RA and SCMs pose a challenge for predicting the elastic modulus of concrete containing both RA and SCMs. In this study, the main influencing factors on the elastic modulus of recycled concrete were analyzed, and the statistical significance of the influencing factors on the elastic modulus was quantitatively analyzed using factor analysis techniques, either individually or in interaction. The results of the factor analysis reveled that the content of recycled coarse aggregates and the reactivity index of the cementitious materials have the most significant impact on the elastic modulus, followed by the water absorption of recycled coarse aggregates and the ratio of aggregates to cementitious materials (A/C). Furthermore, the interaction between A/C ratio and the content of recycled coarse aggregates, as well as the interaction between the water absorption and the content of recycled coarse aggregates, were also found to be significant influencing factors on the elastic modulus. A unified prediction model for elastic modulus was proposed by considering the hydraulic and pozzolanic activities of OPC and SCMs, performance and content of recycled coarse aggregate simultaneously, based on a statistical analysis of the experimental database. The statistical fitting results indicted that the elastic modulus can be accurately predicted using proposed model, thus promoting the application of recycled aggregate and green binder in structures.

Experimental investigation of the electro-chemical characteristics of SFRCs under the effect of chloride ion intrusion

Steel fiber-reinforced concrete (SFRC) has been recognized for its excellent durability in severe corrosive environments and its ability to improve the mechanical performance of concrete. However, the anti-corrosion mechanisms of steel fibers towards the embedded rebar have not been clarified, and a design that reflects the inherent electro-chemo-mechanical performance of SFRC has yet to be established. To understand the electro-chemical properties, accelerated corrosion tests induced by chloride penetration were conducted in this study using transparent porous materials with embedded steel fibers and rebars, which enabled visualization of the whole polarization areas. The experimental results indicate that steel fibers delay onset of rebar corrosion and inhibit subsequent corrosion progression. Mechanisms of anti-corrosion owing to fibers are explained as: (1) When a difference in chloride ion concentration arises between surface layers and the interior, the anodic reaction gets dominant in the surface layer, but meanwhile, the cathodic reaction dominates inside where reinforcing bars are located, and: (2) A corrosion protection system appears when dispersed steel fibers affects the rate of corrosion current around the rebars. Consequently, a rebar macro-cell circuit would be hardly formed.

Utilization of sandblasting waste as additives to enhance mechanical performance of concrete mortar

Abstract This research explains about the utilization of sandblasting waste, a byproduct of the shipping industry’s blasting process, as an additive in concrete mortar. The blasting process involves spraying silica sand to remove impurities from hull layers, resulting in waste that contains heavy metals like Fe2+, Mn4+, and Cr3+. Given its hazardous nature, alternative disposal methods are necessary to reduce landfill accumulation. By pre-treating this silica sand through cleaning and grinding, a new material, Ground Sandblasting Waste (GSW), with a particle size of approximately 390.4 nm and 94.75% SiO2 content, was produced. Concrete mortar specimens with dimensions 5 x 5 x 5 cm were prepared with GSW added in 1%-5% by weight of cement. Furthermore, this research also explores the combination of GSW with another additive named silica fume with a percentage of 6%. The compressive strength tests showed that adding 2% GSW and GSW-SF combinations, with proportions of 2% and 6% from the cement weight, greatly enhanced performance of mechanical the concrete mortar. This research highlights the potential for using pre-treated sandblasting waste to improve concrete performance and manage hazardous waste effectively in the shipping industry.

Application of porous luffa fiber as a natural internal curing material in high-strength mortar

This study explores the potential of renewable plant fibers as internal curing (IC) materials, analyzing their potential in high-strength mortar (HSM) applications. Experiments involving the incorporation of different volumetric ratios of luffa fiber into concrete assessed impacts on autogenous shrinkage (AS), mechanical properties, and microstructure. The research found that the addition of luffa fibers extended both the setting times of the mixture, and after final setting, continued the hydration reaction by releasing internally stored water. Compared to the control group, luffa fibers significantly reduced AS by up to 56.87%, primarily due to their high-water absorption capacity (211%), which mitigates the internal capillary pressures during the cement hydration process. Moreover, the inclusion of luffa fibers significantly affected the concrete's mechanical properties: a 1% luffa addition enhanced the compressive strength at 28 days by 7.6% over the control; concrete with 2% luffa fiber exhibited the highest flexural strength at 28 days, showing a 9.4% increase over the control. Microstructural analysis revealed that luffa fiber not only promoted continued hydration but also increased the content of hydration products and enhanced the compactness of the cementitious matrix. Overall, luffa fibers effectively reduce HSM’s AS and enhance its mechanical properties and microstructure, showing potential to improve concrete performance.

Seismic Response Analysis of a Vibrating Stirred Steel Fiber Concrete Frame Structure Based on Probability Density Evolution

In this paper, an experimental study of steel fiber concrete using vibration mixing technology and the probability density evolution theory is applied to establish a nonlinear stochastic seismic response model for multistory concrete frame structures considering the randomness of structural parameters. The random evolution characteristics of the structural response are studied and analyzed, and a reliability analysis method for concrete frame structures based on PDEM theory is proposed. The equations are solved by the finite difference method in the TVD format, and the probability distribution of the deformation index of the concrete frame structure is obtained by summation, where the reliability is given according to the limit value of the index. The results confirm that the PDEM theory can accurately assess the functional reliability of the structure, and it is also found that the randomness of the structural parameters has a significant effect on its nonlinear dynamic response law, and that consideration of the randomness of the structural parameters at the early stage of the design can be of great help to the seismic resistance of the structure. This study not only provides a scientific basis for the optimization of the performance of steel fiber concrete but also provides a new perspective and tool for the analysis of probability density evolution in the field of structural earthquake engineering.

Influence of Fly Ash Content on Macroscopic Properties and Microstructure of High-Performance Concrete

To investigate the influence of the fly ash (FA) content on the performance of high-performance concrete (HPC), seven groups of tests were conducted, aiming to evaluate both the macroscopic properties (workability and compressive strength) and microscopic pore structure. Low-field nuclear magnetic resonance (NMR) technology and SEM images were employed to analyze the changes in the internal pore structure of the concrete. The results showed that the workability of HPC initially increased and then decreased with the increase in the FA content. When the FA content was 15%, the slump of HPC reached a maximum of 264 mm, and the 28-day compressive strength exhibited a 23.2% increase compared to the 7-day compressive strength. The pore size distribution of the concrete varied with different fly ash content. At 15% FA content, secondary hydration of the FA was sufficient, refining the pores to between 0 and 0.1 µm. Excessive FA substitution deteriorated the internal structure of the HPC matrix and reduced the workability and mechanical properties of the HPC. When the content of FA was 35%, the slump of HPC decreased to 176 mm, while the macropores within the matrix significantly increased, resulting in porosity of 6.81%.

Mechanical performance and self-sensing capability of an amorphous fiber-reinforced concrete for radioactive waste storage facilities

This study results from a research project initiated by the French National Radioactive Waste Management Agency (Andra) as a part of the Cigéo (Industrial Center for Geological Disposal) project. This project addresses many challenges related to sustainability, and health monitoring of confinement structures planned by Andra. In order to reduce issues related to corrosion in the tunnels, fiber reinforcement can be used to reduce the amount of steel reinforcement while maintaining high mechanical performance and durability. The fibers used in this study are named Fibraflex, metallic fibers provided by Saint Gobain SEVA. Various aspect ratios (82 and 123) and volume ratios (0.27% and 0.41%) of fibers were tested. These fibers feature high specific surface area (around 70 m2/m3), corrosion resistance, and high electrical conductivity. To characterize the contribution of fibers to concrete mechanical performances, European standard EN 14651 flexural tensile tests were conducted. Results show that fibers bring better performances, especially concerning the post-peak behavior. In fact, fibers effectively transfer stresses across cracks, resulting in better residual tensile strengths. Since these fibers are electrically conductive, tests were also conducted to design self-sensing concrete based on electrical measurements. Firstly, resistivity was monitored on saturated specimens with different mix design throughout the curing time. Results show that when fibers were added, concrete resistivity was reduced due to the ability of the fibers to transmit electrons. A relationship between reinforcement index and resistivity was thus revealed. The self-sensing capacity was investigated on specimens subjected to cyclic bending loading, with electrical properties measured by using a Wheatstone bridge. Results show a good agreement between the level of cracking in concrete and its electrical response.

A review paper on performance evaluation of bacteria induced concrete for rigid pavements

Concrete is a foundational material renowned for its performance across a spectrum of applications in construction and infrastructure. it is indispensable in meeting the diverse demands of modern engineering and architecture, from towering skyscrapers to intricate bridges, from residential homes to transportation networks, concrete's performance capabilities have shaped the built environment in profound ways. But conventional concrete is susceptibility to cracking, especially under tensile stresses. This can compromise the structural integrity of concrete elements and lead to durability issues and reduced service life. Rigid pavements are vulnerable to cracking due to temperature changes, shrinkage, and severe loads. Cracks have the potential to undermine the pavement's structural integrity, hastening deterioration and raising maintenance requirements. Review paper describes the method that is used in showing the performance Evaluation of concrete Through the process of carbonate ion formation, a microorganism secretes calcium precipitate externally, forming CaCo3. This fills in the holes in the concrete texture, increasing its compactness. Conversely because of the expansion of the filler fabric inside the concrete mixer's pores, this improves the strength of the concrete. In the laboratory tests has been carried out to study the impact of introducing bacteria on concrete. here compressive strength, flexure strength, split tensile strength and durability test on Bacteria induced Concrete is studied and SEM and XRD analysis is also carried about to the study the microstructure of Bacteria induced concrete.