Resistance Of Concrete Research Articles

Computational approach to the current and chloride ions distribution of reinforced concrete cathodic protection system

A numerical method considering both corrosion kinetics and ion transport is proposed to investigate the distribution of current and chloride ions in a cathodic protection system. The impact of impressed current density, concrete resistivity, chloride ion concentration, rebar arrangement, anode arrangement and thickness of protective layer on the current and ion distribution is discussed. Results show that the rebars located closest to anode exhibit the largest current and lowest chloride ion concentration. The utilization of multiple external anodes proves to be an effective means to enhance the cathodic protection’s effect, but it impairs the ability of removing chloride ions.

A prediction method for salt frost resistance of carbon-glass mixed fiber concrete based on improved BP neural network

Abstract Low temperature and freeze-thaw can greatly reduce the service life of concrete, leading to serious safety hazards. Salt frost resistance is one of the important characteristics of concrete. Therefore, in order to more accurately evaluate the salt frost resistance of carbon glass hybrid fiber reinforced concrete. This article proposes a prediction method using measured data based on an improved BP neural network. Firstly, conduct freeze-thaw cycle tests on fiber reinforced concrete with different proportions. Studied the variation law of concrete quality loss rate and dynamic elastic modulus. Then, based on BP neural network and particle swarm optimization algorithm, a salt frost damage prediction model for carbon glass hybrid fiber reinforced concrete was established. Finally, conduct optimization based on the learning samples and compare and analyze the prediction errors of the model. The simulation results demonstrate that the proposed method has good accuracy and stability.

Mechanical Damage and Freeze–Thaw Damage of Concrete with Recycled Brick Coarse Aggregate

The influence of different recycled brick coarse aggregate (RBA) substitution rates on the mechanical performance and frost resistance of concrete was observed. The test findings revealed that RBA deteriorated the compressive and flexural properties in concrete and improved the tensile properties and plasticity in concrete to some extent. The frost resistance of concrete can be effectively improved by adding RBA. The influence degree of the RBA concrete frost resistance factor was quantified by gray entropy correlation theory, and the gray entropy correlations between freezing and thawing cycles, natural coarse aggregate substitution rate, recycled brick aggregate substitution rate, and freezing and thawing damage value (DN) were 0.9979, 0.9914, and 0.9876, respectively. Moreover, the freezing and thawing damage model about GM(1, 1) theory was developed (R2 > 0.87), which can better predict the freezing and thawing damage of RBA concrete. The damage mechanism of RBA concrete during freezing and thawing was revealed.

QUALITY IMPROVEMENT EFFECTIVENESS OF ROAD SLABS PRODUCED USING MICROSILICA AND FIBER

Here we present the results of testing the concrete physical and mechanical properties for road slabs reinforced with bulk fiber, including polypropylene macro- and microfibers. We have analyzed the effect of the use of macrofibers and microfibers in the concrete composition. There was established the impact of low-modulus synthetic fibers on the characteristics of strength, density, water resistance and frost resistance of concrete for road pavement. It was established that polypropylene macrofibers impact on the physical and technical characteristics of concrete, increase compressive and bending strength, and polypropylene microfibers improve the structure of the cement component of concrete, optimize the pore space, increase the frost resistance and water resistance of concrete. It has been experimentally proved that owing to the combined use of various sized fiber fibers, it is possible to produce concrete that has good characteristics in strength, density and frost resistance. It was established that with the combined concrete fiber reinforcement with microsilica addition, we get the possibility of increasing bending strength up to 35%, frost resistance up to F375 and water resistance up to W14. The research results make it possible to recommend multi-dimensional polypropylene fibers for volumetric reinforcement and microsilica to create additional crystallization centers and reduce the pore space in the concrete body at road slabs manufacture.

STUDY OF THE PROPERTIES OF MODIFIED BINDER OBTAINED ON THE BASIS OF BENEFICIATION WASTE OF THE MINING AND PROCESSING PLANT

The introduction of active mineral additives into cement makes it possible to obtain concrete with high physical, mechanical and operational characteristics, namely, they increase the density, water resistance, frost, sulfate, alkali resistance and salt resistance of concretes and mortars, while reducing the consumption of clinker cement. The scale of construction of facilities using cement concrete is growing every year, which raises the question of reducing the consumption of clinker cement, due to the high energy intensity of production using active mineral additives. The use of active mineral additives in the form of waste from enrichment has high economic and environmental significance. The article examines the ways of using waste tailings of polymetallic ore enrichment in cement as a complex modified binder with an active mineral additive. To select the optimal ratio of silica and Balkhash GOK enrichment waste, their pozzolan activity was determined, which is 3.8-4 times higher for silica than for BGOK waste. The pozzolan activity of Balkhash GOK enrichment waste 16 hours after mixing with lime solution is 24 mg/g, and microsilicon is 114 mg/g. The pozzolan activity of a complex mineral additive for cements consisting of 60% of Balkhash GOK enrichment waste and 40% of microsilicon is 48 mg/g. The introduction of 40% silica into the Balkhash GOK enrichment waste increases the pozzolan activity of the complex additive by 2 times. This made it possible to obtain a modified binder using a complex mineral additive of up to 20%.

Optimizing Retrofit Strategies for RC Frames through Combined Techniques

Over the past twenty years, researchers have directed their efforts towards enhancing the earthquake resistance ofconcrete frames through repair and retrofitting. Two main approaches have emerged for bolstering the seismicresilience of previously intact structures prior to earthquake exposure. The first involves augmenting the existingstructure with additional components like steel bracing, while the second entails reinforcing specific structuralelements, such as employing steel cages. Seismic response analyses have been conducted on multi-story reinforcedconcrete (RC) frames originally designed without seismic considerations. This study aims to assess the effectiveness ofretrofitting techniques by comparing the outcomes of employing steel braces, steel cages, and their combinations. Theseismic performance is evaluated according to the RPA 2003 seismic code for Algeria, following the latest guidelines.Static nonlinear analysis was utilized to compare the seismic responses of existing non-ductile RC frames under variousretrofitting schemes.

Coupled effects of UV radiation and freeze–thaw cycles on the fracture behavior of asphalt concrete

The Qinghai-Tibet Plateau in China is characterized by extreme climate conditions, including intense ultraviolet (UV) radiation, frequent freeze–thaw cycles (FTCs), and significant temperature fluctuations. These conditions contribute to severe cracking in asphalt pavements. This study aims to investigate the impact of coupled damage from UV radiation and FTCs on the fracture behavior of asphalt concrete. To simulate the coupled environmental damage (CED) experienced by asphalt pavement in the field, an alternating two-factor laboratory procedure was developed. This procedure reflects the climatic conditions of the Qinghai-Tibet Plateau. The semi-circular bending test, combined with digital image correlation technology, was employed to evaluate the effects of temperature and CED cycles on fracture-related parameters of asphalt concrete. These parameters include the load–displacement curve, fracture toughness, and fracture energy. Fracture behavioral characteristics such as horizontal strain, crack length, crack propagation path, and crack mouth opening displacement were also analyzed. The results indicate that coupled damage from UV radiation and FTCs significantly weakened the fracture resistance of asphalt concrete. Compared with other fracture-related indicators, the most significant reduction observed was the fracture energy of 68.1%. The two environmental factors exhibited a mutually reinforcing effect on the fracture properties of asphalt concrete, with low temperatures further intensifying their influence. CED cycles delayed the initiation of cracks in asphalt concrete but accelerated crack propagation. This led to a reduction in time to failure by up to 57.6% and a maximum reduction in horizontal strain of 24%. Additionally, the cracking propagation path of asphalt concrete became more linear with increased crack mouth opening displacement. Future research should focus on the evolution of damage accumulation in asphalt concrete under CED cycles, with the goal of establishing predictive models for long-term service life.

Influence of Corrosion on Lifespan of Reinforced Concrete Structures: A Comprehensive Review

Carbonation-induced corrosion is a major concern for reinforced cement concrete (RCC) structures, impacting their long-term durability and structural integrity. This review synthesizes the findings on the deterioration mechanisms in concrete structures, focusing on carbonation, chloride-induced corrosion, and time-dependent deterioration. The analysis includes discussions on predictive likelihood methods for estimating bridge reliability, the impact of environmental factors on carbonation, and standardized testing methods for assessing concrete durability. The review highlights the importance of understanding material characteristics and environmental conditions in designing durable concrete structures, emphasizing the processes of carbonation, its impact on rebar corrosion, and strategies for mitigation. Sheltered concrete carbonation resistance in metropolitan tropical climates is 10-20% lower than open exposure. SCM concretes exhibit equivalent or greater long-term carbonation resistance to OPC concretes, as evidenced by the increase in carbonation depth ( Δ xd) at ages greater than 5 years. The paper concludes with recommendations for integrating advanced modeling techniques and empirical studies to develop robust maintenance strategies and improve concrete mix designs for enhanced durability.

Utilizing Electrochemical Techniques for Assessing the Probability of Concrete Resistivity and Corrosion Potential in Reinforced Concrete Structures

Corrosion of reinforcing steel is a major durability issue for reinforced concrete structures exposed to aggressive environments. Early assessment of corrosion probability is important for effective maintenance planning. This study investigates the application of non-destructive electrochemical methods like concrete resistivity and half-cell potential measurement, along with integrated assessment and advanced techniques, for evaluating corrosion risk in reinforced concrete. Concrete specimens with and without Albizia amara resin coating were subjected to accelerated corrosion testing. Concrete resistivity and half-cell potential values showed an inverse correlation, with lower resistivity indicating higher corrosion risk. Resistivity and potential results for the coated samples exhibited intermediate values compared to the control and corroded samples, demonstrating the resin's partial passivating effects. Rebar diameter measurements before and after exposure confirmed corrosion led to reductions in diameter and cross-sectional area, which coating mitigated. Statistical analysis validated the significant impacts of original bar diameter and corrosion level on subsequent geometry changes. Mechanical testing of reinforcing steel bars found the control samples had the highest strength and ductility, while the coated bars exhibited properties closer to the controls than the corroded bars. The protective capabilities of the bio-based Albizia amara resin coating were validated through multipoint monitoring of material durability parameters. Overall, results demonstrated the effectiveness of integrated electrochemical testing with non-destructive techniques for comprehensive condition assessment and corrosion risk evaluation in reinforced concrete structures

Abrasion resistance of glass fiber silica fume concrete

Abrasion resistance of glass fiber silica fume concrete

Effect of different fiber reinforcements on the strength and acid attack resistance of alkali-activated concrete

The study analyzes the effect of steel, polyvinyl alcohol (PVA), polypropylene (PP), and glass fiber reinforcements in alkali-activated concrete (AAC) by conducting various mechanical strength tests. The fiber dosages are maintained at 0.1-0.3% by volume of AAC. Furthermore, the study evaluates the effect of acidic exposures on the strength of fiber-reinforced alkali-activated concrete (FRAAC) by immersing the samples in 10% v/v solutions of HCl. H2SO4 and HNO3 for 28 days. The findings revealed that fiber additions improved the compressive and flexural strength properties by up to 13% and 27%, respectively, while the modulus of elasticity improved significantly by up to 52%. Acid attack tests on AAC specimens demonstrated H2SO4 to be highly detrimental to the mechanical and chemical properties of AACs. The strength loss in FRAAC after acidic exposures was up to 50% lesser as compared to the plain mix. Glass-FRAACs were found to be highly resistant to acid attack, whereas steel-FRAACs had a relatively lesser resistance. These findings were further validated by the SEM micrographs, XRD, and FTIR analyses, which depicted the changes in the microstructure of the specimens subjected to acidic environments. Overall, fiber reinforcements improve the mechanical and durability properties of AACs.

Enhancing the chloride ion penetration resistance of concrete using metal-organic frameworks

This study focuses on a novel technique to improve the resistance of cement-based concrete to chloride ion penetration by incorporating NH2-MIL-125(Ti) metal-organic frameworks (MOF) into the mix. The MOF was produced and assessed against its chloride adsorption capacity. Subsequently, it was added to cement-based concrete in proportions of 1 %, 3 %, and 5 %, by cement mass. The effect of incorporating MOF on the concrete resistance to chloride penetration, reaction kinetics, and compressive strength was investigated. The experimental results revealed that the NH2-MIL-125 (Ti) MOF effectively removed/adsorbed the chloride ions from sodium chloride solutions, with a maximum removal capacity of 31.5 % after 7 days of exposure. Furthermore, the depth and rate of chloride ion penetration into the concrete were reduced as the mass of MOF incorporated into the concrete mix increased. Yet, the efficiency of the MOF to reduce chloride penetration decreased over time, owing to its saturation by continuous exposure to chloride ions. Furthermore, the addition of up to 5 % MOF, by cement mass, had a limited impact (<10 %) on the concrete compressive strength but did not affect the hydration reaction. Owing to its small particle size, MOF strengthened the cement paste by reducing the volume of permeable voids. Such research findings highlight that MOF could be added to cement-based concrete to enhance its resistance to chloride ingress without significantly impacting its compressive strength. This novel approach can effectively impede chloride penetration, thereby delaying corrosion and extending the service life of concrete structures.

Experimental Research on Crack Resistance of Steel-Polyvinyl Alcohol Hybrid Fiber-Reinforced Concrete.

This paper investigates the effects of steel fiber and PVA fiber hybrid blending on the compressive strength (fcc), splitting tensile strength (fts), compression energy (W1.0), and shrinkage properties of concrete. It also establishes a multi-factor crack resistance index evaluation model based on the Analytic Hierarchy Process (AHP) to comprehensively evaluate the crack resistance of concrete. The results show that the steel-PVA hybrid fiber (S-PVA HF) further enhances fcc, fts, the compression energy, and the shrinkage suppression properties of the concrete. The crack resistance of the steel-PVA hybrid fiber concrete (S-PVA HFRC) is the best when the proportion of steel fiber is 1.0% and that of the PVA fiber is 0.2%, and it increases up to 143% compared to the baseline concrete. The established concrete crack resistance evaluation model has a certain reliability.

CEMENTITIOUS SYSTEMS FOR HIGH-PERFORMANCE CONCRETES WITH IMPROVED CORROSION RESISTANCE

The article presents the results of research on cementitious systems "Portland cement CEM I 42,5 R - active mineral additives - microfillers - superplasticizer - hardening accelerators" for high-performance concrete with improved corrosion resistance. The resistance of concrete to corrosion caused by the influence of chemical substances was investigated - sulfate corrosion (class XA), which combines the processes of formation and accumulation of sparingly soluble salts in concrete, which are accompanied by internal stresses and destructive phenomena in concrete. The increase in corrosion resistance of high-performance concretes based on modified cementitious systems is explained mainly by the creation of a fine-crystalline microstructure with the formation of C-S-H phases, which contribute to the pores colmatation with age of hardening.

Utilization Potential of Aerated Concrete Block Powder and Coffee Grounds Ash in Green-Growing Concrete.

The purpose of this research is to investigate the utilization potential of recycled powder made from spent coffee grounds (SCGs) and aerated concrete blocks (ACBs) in green-growing concrete. The green-growing concrete is prepared using ACB powder and SCG ash as raw materials instead of 5%, 15%, and 25% and 5%, 10%, and 15% cement, respectively. Then, the two raw materials are compounded with the optimal content. The compressive strength and alkalinity of green-growing concrete at 7d and 28d and the frost resistance after 25 freeze-thaw cycles at 28d are studied. The results showed that the optimum content of ACB powder and SCG ash was 5%. Replacing 5% cement with recycled powder could improve the strength of concrete. The alkalinity of concrete containing ACB powder gradually increased, while the alkalinity of concrete containing SCG ash gradually decreased. The alkalinity of ACB-SCG powder was lower than that of ACB powder but slightly higher than that of SCG ash. The frost resistance of concrete containing ACB powder decreased gradually, and the frost resistance of concrete containing SCG ash increased first and then decreased greatly. The frost resistance of ACB-SCG powder could neutralize that of ACB powder and SCG ash.

Test Method of Segregation Resistance of High Fluidity Concrete Based on Numerical Simulation of Dynamic Segregation of Coarse Aggregate

Test Method of Segregation Resistance of High Fluidity Concrete Based on Numerical Simulation of Dynamic Segregation of Coarse Aggregate

Prediction of frost resistance and multiobjective optimisation of low-carbon concrete on the basis of machine learning

The use of Portland cement is a major source of carbon dioxide emissions, causing considerable environmental pollution worldwide. Therefore, reducing carbon emissions in concrete is of paramount importance. This study presents a multiobjective optimisation method for low-carbon concrete mix design, combining the use of optimal machine learning models for prediction, with the aim of minimising the cost and carbon emissions of concrete. Several optimisation models, including SVR, CatBoost, RF, XGBoost, DBO-RF and VMD-DBO-RF, were employed to predict the frost resistance of low-carbon concrete. The research findings demonstrate that the VMD-DBO-RF optimisation algorithm achieves high prediction accuracy in terms of RDEM and MLR. For RDEM prediction, R2 = 0.9346, MSE = 0.0508, MAE = 0.1686, and RMSE = 0.2253. For MLR prediction, R2 = 0.9557, MSE = 0.0245, MAE = 0.1042, and RMSE = 0.1565. Furthermore, the model’s interpretability was improved by combining SHAP and PDP analyses.

Hybrid Steel-Polyethylene Fiber-Reinforced Iron Ore Tailing Concrete: Mechanical, Sulfate Freeze–Thaw Resistance, and Microscopic Characteristics

This study examines the effects of iron ore tailing (IOT) replacement ratios and the hybridization of steel fiber (SF) and polyethylene (PE) fiber (PF) on the mechanical, sulfate freeze–thaw (F–T) resistance, and microscopic characteristics of IOT concrete. The mechanical properties of specimens including compressive strength (fcu) and splitting tensile strength (fsts) were evaluated. Sulfate F–T cycle indices of specimens including surface damage, fcu loss, relative dynamic elastic modulus (RDEM), and mass loss are examined. Meanwhile, microscopic characteristics are analyzed using industrial computer technology (CT) and scanning electron microscopy (SEM). Results indicated that IOT replacement ratios below 40% positively influenced mechanical properties and sulfate F–T resistance, whereas ratios exceeding 40% exhibited adverse effects. Incorporating hybrid SF and PF further enhanced the mechanical properties and sulfate F–T resistance of IOT concrete. The IOT concrete containing 1.5% SF and 0.6% PF (designated T40S1.5P0.6) demonstrates significantly improved mechanical properties and sulfate F–T resistance. A set of parameters was proposed to predict the fsts. The Weibull damage model, capable of quantitatively reflecting the F–T damage of IOT concrete, was established. The pore structure of IOT concrete gradually deteriorates with increasing sulfate F–T cycles. The pore characteristics of T40S1.5P0.6 were superior. This was further validated through SEM observations.

Research on the Application of New Polylactic Acid (PLA) Fiber Concrete Materials in Urban and Rural Flood Resistance

This paper aims to study and apply new polylactic acid (PLA) fiber concrete materials to improve urban and rural flood resistance, enhance flood control and drainage capabilities, and promote sponge city construction. Through the analysis of the characteristics, proportion optimization and performance of PLA fiber concrete in actual projects, it is found that the material has good mechanical properties, environmental adaptability, economy and environmental protection, and has important application prospects in urban and rural flood control and drainage. By adjusting the proportion, selecting the appropriate fiber type and addition amount, the flood resistance and drainage capacity of concrete can be improved. Combined with 3D printing technology and modern scientific and technological means, the application and development of PLA fiber concrete will be further promoted to achieve a win-win situation of continuous improvement of urban and rural flood resistance and environmental protection. With the support of relevant technologies and policies, PLA fiber concrete has broad application prospects in sponge city construction and urban and rural flood control and drainage, and will make important contributions to improving the level of urban and rural disaster prevention and mitigation.

Research on improving the frost resistance and self-repair performance of limestone calcined clay cement concrete by microcapsules

Limestone calcined clay cement (LC3) concrete has emerged as a pivotal construction material aimed at mitigating carbon emissions and bolstering sustainability. However, LC3 concrete confronts durability challenges in frigid regions attributable to freeze-thaw cycles. Microcapsule self-repair technology, as an innovative paradigm, presents a promising avenue to augment the freeze-thaw resistance and self-repair attributes of LC3 concrete. Within this inquiry, microcapsules containing isophorone diisocyanate (IPDI) and encapsulated with microcrystalline wax, ceresine wax, and CaCO3 were synthesized and effectively integrated into LC3 concrete matrices. Freeze-thaw cycle investigations were conducted to juxtapose LC3 concrete specimens with and without microcapsules. The findings evinced that LC3 concrete augmented with microcapsules demonstrated enhanced resistance to freeze-thaw cycles, thereby mitigating mass loss and compressive strength degradation. Microscopic structural analyses, pore size distribution assessments, mechanical property evaluations, impermeability, and ultrasonic waveform analyses of LC3 concrete samples featuring microcapsules corroborated the heightened freeze-thaw resistance, thus fortifying its applicability in rigorous environments. Moreover, deliberate pre-cracking of the concrete surface unveiled the self-repair efficacy of microcapsules, with empirical observations underscoring the prompt crack remediation capabilities of the implemented technology.