Performance Concrete Research Articles

Investigation of Axial Tensile Fracture Performance of Recycled Brick Coarse Aggregate Concrete Using a Cohesion Model.

Currently, microscopic research on the tensile fracture properties of recycled brick coarse aggregate concrete has mainly adopted microscopy techniques, which can clearly observe the actual damage situations of each phase material but are unable to individually analyze the effect of a specific material factor on the tensile properties of recycled concrete. This brings much uncertainty to the practical application of recycled concrete. Therefore, this study proposes a cohesive zone model (CZM) for simulating the tensile fracture of recycled brick coarse aggregate (RBCA) concrete. To this end, the study explores the effects of various critical factors on the fracture mode and bearing capacity of recycled brick aggregate concrete, including the replacement rate of recycled brick coarse aggregate, pore structure, interfacial transition zone (ITZ) strength, mortar strength, and volume fraction of brick aggregate. The results indicate that, when the minor to major axis ratio of elliptical pores is 0.5 ≤ K < 1, the following order of influence can be observed: random convex polygonal pores, circular pores, and elliptical pores. Moreover, excessively strengthening the ITZ and mortar does not significantly enhance the tensile performance of RBCA concrete. The distribution location of aggregate has a significant impact on the crack shape of recycled concrete, as does the pore structure, due to their randomness. Therefore, this article also discusses these. These findings contribute to a comprehensive understanding of the tensile properties of recycled brick coarse aggregate and provide insights into optimizing its behavior.

Experimental study on seismic performance of steel artificial controllable plastic hinge (ACPH) with energy-absorption box (EAB)

In order to ensure reliable seismic performance, controllable plasticity and recoverable post-earthquake function of precast concrete (PC) frame beam-column joints, this study introduces an innovative artificial controllable plastic hinge (ACPH) incorporating friction side plates (FSPs) and energy-absorption boxes (EABs) for connection and energy dissipation. Five specimens were fabricated to evaluate the performance of the ACPH. Initially, design criteria were established, and the sliding bending moment (Mslide) of the FSPs was assessed under various surface treatments and bolt preloads. The proposed theoretical formula was validated through two low cycle reciprocating tests. Subsequently, quasi-static experiments were conducted on three specimens with different forms of EABs, examining hysteresis performance, strength, and stiffness degradation. The research findings reveal a clear two-stage yield mechanism in the specimens. The first stage involves rotational friction of the FSPs, while the second stage is characterized by the failure of the EABs. Plastic damage is predominantly localized in the EABs, and the incorporation of stiffeners between the dog bone-energy absorption plates (DB-EAPs) can improve their load-bearing capacity and stiffness.

Optimisation of pervious concrete performance by varying aggregate shape, size, aggregate-to-cement ratio, and compaction effort by using the Taguchi method

ABSTRACT The porosity and compressive strength of pervious concrete are critical determinants of its suitability for various applications. Therefore, it is necessary to recognise the factors influencing the performance and its ranks to balance porosity and compressive strength ideally. This study evaluates the impact of aggregate shape, size, aggregate-to-cement ratio and compaction effort on previous concrete performance. The research involved varying aggregate sizes (5–12 mm, 12–18 mm and 18–25 mm), aggregate-to-cement ratios (3.0, 4.0 and 5.0), compaction efforts (0, 30 and 60 blows) and aggregates underwent revolutions in a ball mill (0, 200 and 1000) to change their morphological characteristics. A total of 81 mix designs were tested, resulting in 486 cubes for compressive strength and porosity testing. The acquired data underwent analysis using the statistical analysis and Taguchi method to discern the most influential factors and establish their ranking. The results indicate that revolutions, compaction, aggregate-to-cement ratio and aggregate size contribute 29.42%, 26.19%, 29.13% and 0.96%, respectively, to the compressive strength performance. Regarding porosity performance, revolutions and compaction emerge as significant factors, accounting for 39.95% and 26.91%, respectively. The influence of the aggregate-to-cement ratio and aggregate size on porosity performance appears less pronounced.

Innovative Implications of Paddy Straw in Concrete: A Review

Rice is a crop that is grown worldwide and is mostly produced in Asian countries such as China, India, Indonesia, Vietnam, and others. For every ton of harvested rice, around 1.5 tons of paddy straw is produced. Paddy straw is available in substantial amounts during the rice harvesting seasons, depending on the region. In place of burning, governments and communities can promote composting, use paddy straw as animal feed, or invest in technology that turn waste straw into goods that are valuable. Buildings with improved energy efficiency, reduced agricultural waste, and alternative building materials can all benefit from the use of paddy straw in construction. However, proper processing and treatment are required to assure structural integrity, fire resistance, and longevity in construction applications. A thorough analysis was carried out to see how paddy straw might be used to address different environmental issues. It addresses a number of issues, including market potential, sustainability, cost-effectiveness, and technological viability. In this type of research, the durability, workability, and compressive strength of the concrete mix are typically evaluated by replacing a portion of the cement with ash derived from paddy straws. Research topics often include the optimal ash concentration, effects on hydration kinetics, and long-term performance of concrete.

Investigation of the freeze-thaw deterioration behavior of hydraulic concrete under various curing temperatures

To address the issue of damage and deterioration of hydraulic concrete materials in cold regions, experiments were conducted to investigate the microstructural and mechanical properties of concrete under the combined effects of various curing temperatures and freeze-thaw (F‒T) cycles. The results indicate that as the curing temperature decreases, the peak compressive strength of concrete decreases, while the peak strain increases and the elastic modulus decreases. These trends become more pronounced with the progression of F‒T cycles. Additionally, during the compression failure process of concrete, the amplitude of the acoustic emission exhibits a more significant and rapid increase as it approaches the critical state, indicating a stronger brittle characteristic of concrete after F‒T damage. Microscopic test results demonstrate that the influence of curing temperature on the pore structure of concrete after F‒T primarily manifests in the mesopores and large pores. Moreover, the reduction in curing temperature increases internal defects in concrete, deteriorates the crystallinity of hydration products, and leads to the aggregation of unhydrated cement particles. Insufficient curing temperatures slow the hydration rate of cementitious materials, affecting the density and overall performance of concrete. Finally, damage prediction models based on the Weibull distribution were established, using the relative dynamic modulus of elasticity, compressive strength loss rate, and mass loss rate as damage factors. The model based on the relative dynamic modulus of elasticity was more sensitive to the number of F‒T cycles. All models exhibited a goodness of fit exceeding 0.89, indicating that they accurately reflect variations in the observed data and can be used to predict the service life of concrete under F‒T cycles. This provides theoretical references for the degradation and damage of hydraulic concrete in cold regions.

Study on the Effect of Fly Ash on Mechanical Properties and Seawater Freeze–Thaw Resistance of Seawater Sea Sand Concrete

When using seawater and sea sand as mixes, the mechanical properties and durability of concrete are adversely affected because the raw materials themselves contain harmful ions. Fly ash is the tailings formed in the process of industrial production, the use of which does not require the burning of clinker, reducing CO2 emissions. Moreover, it belongs to a new type of cementitious materials with low emissions and high environmental protection. Fly ash enhances the properties of concrete and reduces the effect of harmful ions on concrete. Based on the above considerations, the corresponding specimens were prepared and subjected to cubic compressive strength, flexural strength, and seawater freezing and thawing resistance tests by using fly ash admixture as the main variable. A combination of macro-analysis and micro-analysis was used to investigate the effect of fly ash on the performance of seawater sea sand concrete. The results showed that fly ash significantly enhanced the mechanical properties and resistance to seawater freezing and thawing of seawater sea sand concrete. The best improvement in compressive strength and resistance to seawater freezing and thawing was achieved at a substitution rate of 20%. The maximum increase in compressive strength was 13.22%. The maximum reduction in mass loss rate was 57.26% and the strength loss rate was 43.14% after the specimens were subjected to seawater freezing and thawing 75 times. The maximum enhancement in flexural strength was 17.06% for a substitution rate of 10%. Through microanalysis, it can be seen that the incorporation of coal ash can enhance the compactness of concrete through the microaggregate effect as well as the volcanic ash reaction to promote the secondary hydration reaction, so as to strengthen the seawater freeze–thaw resistance of seawater sea sand concrete. Finally, the damage prediction model established using the mean GM (1, 1) model of gray system theory meets the requirements of the first level of prediction accuracy and can accurately predict the damage of seawater sea sand concrete under seawater freezing and thawing.

Improving Self-Compacting Concrete Performance with Manufactured Sand: An Experimental Investigation of Workability and Mechanical Properties

Improving Self-Compacting Concrete Performance with Manufactured Sand: An Experimental Investigation of Workability and Mechanical Properties

The impact of utilizing waste tires and plastic on concrete pavement performance and environmental benefits

ABSTRACT This study focuses on the integration of sustainable practices in construction projects by utilizing waste materials like waste plastic and rubber tires, specifically in Portland Cement Concrete (PCC) mixes. While adding plastic waste fibers (PF) has shown to enhance the performance of rigid pavements, the environmental and cost benefits are limited. On the other hand, using tire-derived aggregates (TDA) compromises the mechanical properties of PCC but offers significant environmental advantages and cost reductions. This study explores the outcomes of combining PF and TDA in PCC mixtures, assessing their impact on pavement performance through KENPAVE software, which evaluates deflections and cracking indices. Additionally, the environmental and cost effects of this combination are analyzed using the PaLATE 2.0 software, aiming to develop sustainable and economically viable rigid pavements.

Hydromechanical modelling of the influence of water saturation on the penetration performance of concrete target

The objective of the present paper is to study numerically the hydro-mechanical behaviour of concrete targets subjected to a rigid projectile, with special attention to the influence of water saturation. An elastoplastic model, encompassing two primary plastic mechanisms (shear and pore collapse), is improved to capture the influence of water saturation. The adopted model is implemented in the finite element code Abaqus/Explicit and validated by simulating two dynamic compression tests at the material point level and two penetration tests at the structure level. Not only a strong influence of water saturation on both volumetric and deviatoric behaviours of concrete is observed at material point level, but also the time-evolutions of projectile velocity, projectile deceleration and penetration depth in concrete targets are also satisfactorily reproduced by the numerical simulations. After that, a series of parametric studies are performed to understand the influence of water saturation on the penetration performance of concrete. It is found that with the presence of pore water, penetration resistance of concrete increases with decreasing water saturation, indicating a higher projectile deceleration and lower penetration depth obtained in saturated targets. Numerical modelling and analysis will enhance our understanding of the vulnerability of concrete infrastructures subjected to near-field detonations or impacts.

Mechanical performance of eco-friendly self-compacting concrete (SCC) mixtures and two-way slabs partially containing cement kiln dust as cement replacement and internally reinforced with waste plastic mesh

A large quantity of cement kiln dust (CKD) is produced annually during the production of Portland cement. The majority of the produced CKD remains unused except in specific cases related to soil stabilization projects. The current research investigates the production of self-compacting concrete (SCC) mixtures, in which CKD is used as a substitute for cement in different weight proportions, 3 %, 6 %, 9 %, 12 %, and 15 %. The hardened mechanical properties of SCC, such as compressive strength, splitting tensile strength, and flexural strength, as well as the fresh state characteristics (i.e., slump flow diameter, T500, V-funnel, and L-box tests), were recorded and compared with the control mixture which was entirely cast using cement. Results revealed that with an increase in the CKD content beyond 6 %, the slump flow diameter of SCC mixtures significantly decreased. Also, the increase ratios in the V-Funnel flow time for self-compacting concrete mixtures, when replacing cement with CKD ratios of 3 %, 6 %, 9 %, 12 %, and 15 %, were 13.3 %, 30 %, 46 %, 58 %, and 66.7 % respectively, compared with the reference mixture. Additionally, the impact behavior of two-way SCC slabs cast using CKD ratios ranging from 3 to 15 % and internally strengthened using various patterns of recycled plastic mesh was investigated. Strengthening the SCC slabs using two layers of recycled plastic grids proved to be effective in preventing the projectile from penetrating the whole thickness of the SCC slabs, regardless of the CKD content.

Salt freezing-thawing damage evolution model based on the time-dependent hydration reaction incorporating rice husk ash and recycled coarse aggregate

Rice husk ash (RHA), an abundant agricultural by-product, has led to significant environmental pollution due to current treatment methods. To achieve resource utilization, the feasibility of RHA recycled concrete subjected to the salt freezing-thawing resistance was assessed, including the macroscopic properties, microstructure and sustainability, and an evolutionary model of salt freeze-thaw damage was established based on the time-dependent hydration reaction of the cement paste. The results indicate that RHA particles effectively retard damage by limiting chloride ion diffusion and preventing salt crystallization, while deteriorating the concrete performance due to reduced hydration products at high RHA replacement ratios. The established salt freeze-thaw damage evolution model has an R2 as high as 0.9817, which indicates that the model fits with high accuracy and can capture the performance variations of different types of RHA recycled concrete under extreme environmental conditions. Additionally, the synergistic preparation of concrete using RHA with a 20 % replacement ratio and recycled coarse aggregate (RCA) with a 50 % replacement ratio reduces the total global warming potential (GWP) by 16.65 %, which means that it has the potential to advance low-carbon sustainable development in the construction industry while meeting the engineering requirements. This research is expected to provide a theoretical reference for applying and promoting biobased low-carbon concrete with RHA in saline-alkali cold areas.

The Effect of RHA as a Supplementary Cementitious Material on the Performance of PCM Aggregate Concrete

The Effect of RHA as a Supplementary Cementitious Material on the Performance of PCM Aggregate Concrete

Preparation of p-isopropylphenol polyoxyethylene ether and evaluation of its performance in concrete

P-isopropenylphenol polyoxylates (IPP-PE) were obtained by alkoxylation reaction using p-isopropylphenol phenol (IPP) and ethylene oxide (EO) as raw materials, and P-PCE polycarboxylic acid superplasticizer was obtained by free radical polymerization of ipp-PE and acrylic acid (AA) under the action of initiator and chain transfer agent. The effects of reaction temperature, acid-ether ratio, amount of chain transfer agent and initiator, and reaction time on the dispersion properties of superplasticizer were studied, and the molecular structure and microscopic morphology of the superplasticizer were characterized by FTIR,1HNMR, and SEM, and the influence of superplasticizer on concrete properties was evaluated by concrete performance tests. The test results determined that the optimal synthesis process of polycarboxylic acid superplasticizer was as follows: reaction temperature 40 °C, n(AA):n(IPP-PE)=6:1, chain transfer agent and initiator were 0.4% and 0.6% of the mass of large monomer, respectively, and the reaction time was 4.5h. The experimental results of the concrete performance test showed that the workability of concrete mixed with the self-made superplasticizer was excellent, and the initial and 1h longitudinal flowability of the superplasticizer reached 228 mm and 215 mm, respectively. The water reduction rate reached 36%, the 28d compressive strength reached 56.8 MPa, the initial slump reached 226 mm, and it had a certain retarding and air entrainment effect.

Impacts of advanced metals recovery on municipal solid waste incineration bottom ash: aggregate characteristics and performance in portland limestone cement concrete

The optimization of alternative materials in concrete production continues to garner considerable attention in order to meet sustainability goals and supplement natural materials. Portland limestone cement (PLC) and municipal solid waste incineration (MSWI) bottom ash (BA) have been proposed separately as green cement and coarse aggregate supplement in low-strength concrete production, creating sustainable products and alternative disposal scenario for a waste material. This study discusses the impact of advanced ash processing techniques on aggregates and presents the performance of concrete incorporating both of these products with PLC for the first time. Two sources of MSWI BA were investigated, one as-produced (TMR) and one processed with novel advanced metals recovery (AMR). The AMR process reduced total Al content in ash compared to TMR (20,500 vs 17,000 mg/kg), though not aluminum oxide content, as the AMR process targets metallic aluminum. A composition study on both aggregates supports a reduction in ferrous and non-ferrous metals following the AMR process. All control and test mixes met 28-day compressive strength requirements (17 Mpa). Both AMR and TMR MSWI BA-amended concretes yielded compressive strengths below control specimens (no ash) ranging from 17 to 23 MPa, with little to no difference observed dependent on MSWI BA processing. The life-cycle discussion supports benefits deriving from supplementing naturally mined materials and recovering ferrous and nonferrous metals with the AMR process.

Synergistic effect of CO2-mixing and steel slag addition on performance and microstructure of concrete

This study systematically investigated the influence of varying carbon dioxide (CO2) dosages and steel slag (SS) replacement rates on the fresh and hardened properties of concrete through the injection of CO2 gas during the mixing process. The composition of hydration products, degree of hydration, and the evolution of microstructural characteristics within the CO2-SS-cement system were analyzed. The results showed that CO2 addition during the mixing process enhanced early strength in SS concrete. For concrete with a 10 wt% SS replacement rate, the incorporation of CO2 ranging from 0.4 wt% to 1.2 wt% of the total mass of cementitious materials resulted in notable compressive strength increases of 1.26%–12.47%, 0.64%–6.14%, and 11.79%–18.24% at ages of 1 d, 3 d, and 7 d, respectively. CO2 rapidly reacted with SS to form calcite-type CaCO3 and promoted the generation of C-S-H through synergistic hydration with cement. However, a high CO2 dosage (1.2 wt%) led to issues such as microcrack propagation and interface loosening due to CaCO3 deposition, which could be mitigated to some extent by appropriately increasing the SS content.

Efficient machine learning for strength prediction of ready-mix concrete production (prolonged mixing)

Purpose This paper aims to clarify the efficient process of the machine learning algorithms implemented in the ready-mix concrete (RMC) onsite. It proposes innovative machine learning algorithms in terms of preciseness and computation time for the RMC strength prediction. Design/methodology/approach This paper presents an investigation of five different machine learning algorithms, namely, multilinear regression, support vector regression, k-nearest neighbors, extreme gradient boosting (XGBOOST) and deep neural network (DNN), that can be used to predict the 28- and 56-day compressive strengths of nine mix designs and four mixing conditions. Two algorithms were designated for fitting the actual and predicted 28- and 56-day compressive strength data. Moreover, the 28-day compressive strength data were implemented to predict 56-day compressive strength. Findings The efficacy of the compressive strength data was predicted by DNN and XGBOOST algorithms. The computation time of the XGBOOST algorithm was apparently faster than the DNN, offering it to be the most suitable strength prediction tool for RMC. Research limitations/implications Since none has been practically adopted the machine learning for strength prediction for RMC, the scope of this work focuses on the commercially available algorithms. The adoption of the modified methods to fit with the RMC data should be determined thereafter. Practical implications The selected algorithms offer efficient prediction for promoting sustainability to the RMC industries. The standard adopting such algorithms can be established, excluding the traditional labor testing. The manufacturers can implement research to introduce machine learning in the quality controcl process of their plants. Originality/value Regarding literature review, machine learning has been assessed regarding the laboratory concrete mix design and concrete performance. A study conducted based on the on-site production and prolonged mixing parameters is lacking.

REVIEW: AN EXPERIMENTAL STUDY ON EFFECT OF NANO MATERIALS ON STRENGTH OF CONCRETE AND PLANE STRESS ANALYSIS USING ANSYS SOFTWARE

These days, making efficient and cost-effective use of resources has taken precedence. The main ingredient in concrete, cement has been under criticism in recent years for the quantity of CO2 released during production. Although cement has better mechanical properties, it hasn't been able to live up to the expectations in terms of durability. Owing to cement's shortcomings, scientists started looking into additives that would enhance concrete's qualities while also making it stronger and lighter. Fly ash, silica fume, and other micro particles were added to cementitious materials to improve their compactness, strength, and durability. These additives were also selected because they are eco-friendly by products of industrial waste that may be handled ethically. Fly ash has significant disadvantages because it is not good for initial strength increase and setting time. Because silica fume affects cementitious material performance, researchers have recently become interested in combining it with ceramic waste and rice husk ash. A more effective way to utilize rice husk ash, a by-product of rice cultivation, would be to replace 10% to 15% of cement. Studies have shown improvements in the durability performance of recycled ceramic waste concrete and rice husk ash concrete. There are issues since the RHA production process is quite time-consuming. With the discovery of nano-particles (NP) smaller than 100 nm, researchers have advanced the field of nanotechnology to new levels. The mechanical properties of many materials, including polymers and cementitious materials, can be enhanced by NP. NP is also helpful in the fields of food, engineering, and medicine. This led researchers to investigate the effects of nano-silica (NS) on concrete in further detail. Nano materials can improve the compressive strength and ductility of concrete. In this project an effort will be made to increase the compressive strength of concrete using Nano materials and waste product like GGBS. Also plane stress analysis of concrete cubes and cylinders is to be done using Ansys Software to find deformation, principal stresses and shear stresses. Keywords: Nano –Silica, Nano Titanium dioxide, Ansys, GGBS, Compressive strength

A Voronoi-based gaussian smoothing algorithm for efficiently generating RVEs of multi-phase composites with graded aggregates and random pores

This paper presents an innovative numerical modeling framework capable of generating highly realistic 3D mesoscale multi-phase concrete models with unprecedented efficiency and accuracy. Addressing a significant wide range in aggregate volume fraction (0 to 80%) and featuring rapid model generation capabilities, our framework marks a breakthrough in reducing computational time—achieving simulations of 1 million elements within mere 30 s on readily available hardware. By analyzing randomly generated concrete samples across varying compositions, our algorithm can provide deep mesoscopic insights into their compressive properties, validated against a wide array of experimental results. Additionally, our comprehensive analytical model sheds light on the intricate roles of aggregate volume fraction and porosity, enhancing understanding of the meso-scale compressive behavior. We also make the source code available on GitHub, offering a valuable tool for the engineering and research community to optimize concrete material design and performance.

Synergistic effects of interfacial friction on shear performance of stud-NSC composite connection

Synergistic effects of friction force on static and fatigue performance of stud-normal strength concrete (NSC) composite connection are clarified in the present study. Push-out specimens with greased interface are used to degrade the interfacial friction force. The static testing and the fatigue testing are carried out to reveal the synergistic effects of friction force on shear performance of stud-NSC connection. The frictional mechanism between stud connected steel-NSC interface is discussed and illustrated. Results show that interfacial friction synergizes with the stud to bear the shearing force and improves the shear performance of stud-NSC connection. In present test, the greased interface-induced friction degradation decreases the shear strength about 8.7 %, the shear stiffness about 13.2 % and the fatigue life about 3.9 % as compared to the case without friction degradation. Friction force between steel-NSC interface is a secondary force and influenced by shearing force from stud, which is easily to be weakened as the repeated wearing between steel plate and concrete during the fatigue loading cycles. The synergistic effects of friction force on shear performance of stud-NSC connection is much slighter than that of stud-UHPC connection, especially its influences on fatigue performance of stud-NSC connection are almost negligible.

Study on the Resistance of Concrete to High-Concentration Sulfate Attack: A Case Study in Jinyan Bridge.

Concrete structures face significant challenges in sulfate-rich environments, where sulfate attack can affect their durability and structural integrity. This study explores innovative approaches to enhancing concrete performance by integrating hydrophobic and densification technologies. It emphasizes the critical role of anti-sulfate erosion inhibitors in mitigating sulfate-induced damage, reducing water absorption, and inhibiting corrosive reactions. This research addresses prevalent issues in Chinese engineering projects where high sulfate concentrations are common, necessitating robust solutions for sulfate resistance. Through rigorous testing, including wet-dry cycling tests with 5% and 10% Na2SO4 solutions following the GB/T 50082-2009 standard, concrete formulations achieved exceptional long-term sulfate resistance, meeting or exceeding KS200-grade requirements. These findings provide valuable insights into optimizing concrete durability in sulfate-rich environments, offering practical strategies to enhance infrastructure resilience and reduce maintenance costs.