Concrete Compression Research Articles

Structural Effects on Compressive Strength Enhancement of Cellular Concrete During the Split Hopkinson Pressure Bar Test

In recent years, a kind of novel cellular concrete, fabricated by spherical saturated superabsorbent polymers, was developed. Its compressive behavior under high strain rate loadings has been studied by split Hopkinson pressure bar equipment in previous research, which revealed an obvious strain rate effect. It has been found by many researchers that the dynamic increase factor (DIF) of compressive strength for concrete-like materials measured by SHPB includes considerable structural effects, which cannot be considered as a genuine strain rate effect. Based on the extended Drucker–Prager model in Abaqus, this paper uses numerical SHPB tests to investigate structural effects in dynamic compression for this novel cellular concrete. It is found that the increment in compressive strength caused by lateral inertia confinement decreases from 5.9 MPa for a specimen with a porosity of 10% to 2 MPa for a specimen with a porosity of 40% at a strain rate level of 70/s, while the same decreasing trend was found at other strain rate levels of 100/s and 140/s. The lateral inertia confinement effect inside the cellular concrete specimen can be divided into the elastic development stage and plastic development stage, bounded by the moment dynamic stress equilibrium is achieved. The results obtained in this research can help to obtain a better understanding of the enhancement mechanism of the compressive strength of cellular concrete.

Advanced Machine Learning Techniques for Predicting Concrete Compressive Strength

Advanced Machine Learning Techniques for Predicting Concrete Compressive Strength

Analysis of the Effect of Brick Waste on Concrete Compressive Strength

Analysis of the Effect of Brick Waste on Concrete Compressive Strength

Durability of high-performance concrete at high temperatures: effects of water-binder ratios and use of silica fume

ABSTRACT This work examines the impact of altering the water-binder ratios (w/b) and cement/silica fume (SF) replacements on the strength at the compression of High-Performance Concrete (HPC), both before and during prolonged contact with extreme temperature. After preparation and testing, eighteen mixtures were produced. Based on the variation in weight/bulk density, the compressive strength test results at room temperature varied from 58 to 102 MPa. In addition, a novel technique known as “heat endurance” has been implemented to compare HPC responses at high temperatures. The findings demonstrate that pozzolanic interaction with the fillers component of SF improves HPC’s residual compressive strength following exposure to high temperatures. Comparative measurements of retained strength of compression were greatest for blends containing 6%, 12%, and 15% of SF at w/b ratios of 0.30, 0.35, and 0.40. As a consequence, altering the w/b ratio had a substantial impact on the outcomes. Lastly, a variety of measuring methods were offered to assist with the study, such as CT, SEM, and thermogravimetric (TG) analysis to evaluate the microstructure modification, porosity, and mass loss of HPC.

Full Probability Conversion Model for Predicting Concrete Compressive Strength Using the Rebound Method

Full Probability Conversion Model for Predicting Concrete Compressive Strength Using the Rebound Method

Effect of Concrete Compressive Strength on the Bond Performance of Flexural Prisms Externally Strengthened with CFRP Laminates

This paper presents a study from an ongoing research project on the bond performance of flexural prisms strengthened using carbon-fiber-reinforced polymer (CFRP) laminates. The primary objective is to evaluate the effect of normal-strength concrete (NSC – 30MPa) and high-strength concrete (HSC - 50MPa) on the bond performance of plain concrete prisms notched at the mid-span and strengthened using CFRP laminates. Six of the twelve plain concrete prisms were strengthened using CFRP laminates, while the remaining prisms were unstrengthened to serve as control specimens. After achieving 28 days of curing in standard lab conditions, all prisms were tested under a four-point bending test. The ultimate mid-span deflection, maximum and ultimate strains at the mid-span, strain distribution at different positions along the length of the laminate, and bond/shear stress versus slip were analyzed to evaluate the bond performance of flexural prisms. The average ultimate load-carrying capacities and mid-span deflection of the NSC and HSC groups were 31.33 and 35.02 kN and 0.55 and 1.54 mm, respectively. The average CFRP strain values at the mid-span corresponding to the ultimate load were 5005 and 3544 με for the NSC and HSC groups, respectively. The maximum attained bond-stress values for NSC and HSC groups were 1.71 and 1.42 MPa, respectively. The corresponding values for slip at maximum bond stress are 0.27 and 0.24 mm for the two groups, respectively. It was concluded from the study that the concrete compressive strength has minimal effect on the flexural bond performance of concrete prisms externally bonded with CFRP laminates.

Sustainable Alkali-Activated Self-Compacting Concrete for Precast Textile-Reinforced Concrete: Experimental-Statistical Modeling Approach.

Industrial and construction wastes make up about half of all world wastes. In order to reduce their negative impact on the environment, it is possible to use part of them for concrete production. Using experimental-statistical modeling techniques, the combined effect of brick powder, recycling sand, and alkaline activator on fresh and hardened properties of self-compacting concrete for the production of textile-reinforced concrete was investigated. Experimental data on flowability, passing ability, spreading speed, segregation resistance, air content, and density of fresh mixtures were obtained. The standard passing ability tests were modified using a textile mesh to maximize the approximation to the real conditions of textile concrete production. To determine the dynamics of concrete strength development, compression and flexural tests at the ages of 1, 3, 7, and 28 days and splitting tensile strength tests of 28 days were conducted. The preparation technology of the investigated modified mixtures depending on the composition is presented. The resulting mathematical models allow for the optimization of concrete compositions for partial replacement of slag cement with brick powder (up to 30%), and natural sand with recycled sand (up to 100%) with the addition of an alkaline activator in the range of 0.5-1% of the cement content. This allows us to obtain sustainable, alkali-activated high-strength self-compacting recycling concrete, which significantly reduces the negative impact on the environment and promotes the development of a circular economy in the construction industry.

Advanced Analysis of Concrete Compressive Strength: Combining NDT Techniques with Digital Image Processing

Concrete is a fundamental material in civil engineering, widely used for its durability, versatility, and load-bearing capacity in infrastructure and building projects. The compressive strength of concrete is crucial as it directly impacts structural integrity, longevity, and safety. This study investigates the compressive strength of M50 grade concrete through a comprehensive approach that combines non-destructive and destructive testing techniques. Methods employed include the Rebound Hammer (RBH) test, Ultrasonic Pulse Velocity (UPV) test, Digital Image Processing (DIP), and conventional destructive testing. The integration of these techniques aims to provide accurate and reliable estimates of compressive strength, critical for evaluating concrete quality in structural applications. Specifically, this research compares the non-destructive techniques (RBH, SonReb Method, and DIP) against standard destructive testing results across different curing ages. Findings reveal a strong correlation between DIP and destructive testing, suggesting that image-based processing can serve as an effective non-destructive alternative in compressive strength assessment. The comprehensive analysis of M50 grade concrete presented in this study offers valuable insights for researchers and practitioners seeking enhanced, non-invasive methods for concrete strength evaluation.

Comparison of Flexural Performance of Reinforced Concrete Beams Reinforced with Steel Plates and Corrugated Steel Plates

To explore the mechanical properties of reinforced concrete beams strengthened by steel plates of various shapes, reinforced concrete beams strengthened with steel plates and corrugated steel plates were tested via a two-point loading test. Based on tests, further investigations investigated the deflection of the sample under different loads and the influence of corrugated steel plate properties (thickness, wave height, strength) on the flexural capacity of the reinforced beam, culminating in the development of corresponding numerical models. The findings indicate that the corrugated steel plate has the best reinforcing effect. In contrast to reinforcement utilizing steel plates containing an equivalent quantity of steel material, the corrugated steel plate augments the space within the reinforced beam and the lower shaft region, enhancing the efficiency of the upper compressive steel reinforcement and concrete in bearing loads, bolstering overall load-bearing potential, and exhibiting superior resistance to deformation. To maintain the ductility of the specimen, interface failure must be prevented. Too high wave height will affect the coordination of wave thickness and strength and inhibit the improvement of flexural performance. Therefore, reinforcement design should prioritize wave height determination.

Shear Behaviour of the Post-tensioned Segmental Precast Concrete Pontoon Deck with the GFRP Rods

The present experimental and numerical study evaluated the structural performance of segmental concrete pontoon decks reinforced and post-tensioned with GFRP rods. Four large-scale decks were tested and the load-displacement response, strain behaviour of rods, concrete, and failure mechanism in four different prestressing levels were assessed. It was found that a small post-tensioning of 7.4% of the rod's ultimate tensile strength reduced the self-weight deflection by 92% and increased initial stiffness by 8.7 times compared to segmental decks without prestressing. Failure in prestressing decks typically began with concrete crushing at the joint with an increased compression depth due to increased initial post-tension; however, the ultimate failure mechanism of the hand-tight deck was governed by the interlaminar shear of the rod. A finite element model was developed and verified against test results A parametric study evaluating the influence of the post-tensioning at higher load, rod depth, concrete properties, rod number, and deck geometry was implemented. It was shown that increasing the post-tension load and depth of the rod improved the stiffness and reducing the spacing can result in a more uniform compression stress in the joint. This study provides design recommendations for ACI 440.4 R-04, by considering the concrete compression depth between joints rather than the depth of the FRP rod and contributes to a more accurate load estimation of the concrete crushing caused by joint openings. The results of this research could rectify the present problems with the construction design of maritime infrastructure and offer an innovative solution.

Numerical research on the constraint effect of double steel plate–concrete composite structures

Double steel plate–concrete composite structures comprise two outer steel plates, steel flange plates, connectors, and infill concrete. Owing to their superior mechanical properties, double steel plate–concrete composite structures have been extensively used in construction engineering. Outer steel plates and connectors create a significant constraint effect on the infill concrete. However, no confined concrete constitutive model applies to double steel plate–concrete composite structures. To address this gap, this study established approximately 2000 shell-solid finite element models and derived a confined concrete compression constitutive model suitable for double steel plate–concrete composite structures through regression analysis. The structural parameters potentially affecting the confined performance were initially identified through theoretical analysis. Subsequently, an Abaqus shell-solid finite element model was established, with its accuracy verified through experiments. Thereafter, regression analysis was conducted by varying different parameters in batch modelling. Ultimately, a uniaxial compression constitutive model for concrete suitable for double steel plate–concrete composite structures was established.

Evaluation of Concrete Compressive Strength Prediction Using the Maturity Method Incorporating Various Curing Temperatures and Binder Compositions.

This study aims to systematically analyze the effects of different curing temperatures, unit binder content, and the mixture ratios of ground granulated blast-furnace slag and fly ash based on ordinary Portland cement in binders on the development of concrete compressive strength. Particularly, the study evaluates strength characteristics by calculating the maturity equivalent to 28 days of curing at 20 °C. A model based on the relationship between maturity and strength was applied to predict the compressive strength, and the experimental data were analyzed to derive strength coefficients for each variable. The results showed that at a low temperature of 5 °C, the actual strength was lower than the predicted strength, leading to higher error rates. In contrast, at temperatures of 20 °C and 40 °C, the coefficient of determination (R2 > 0.90) for the predictive equation was high, and the error rates were reduced to within 10%. The study demonstrates that by combining the maturity method with the strength-maturity relationship, the concrete compressive strength can be effectively predicted under specific curing and binder design conditions.

Prediction of Concrete Compressive Strength Based on ISSA-BPNN-AdaBoost.

Strength testing of concrete mainly relies on physical experiments, which are not only time-consuming but also costly. To solve this problem, machine learning has proven to be a promising technological tool in concrete strength prediction. In order to improve the accuracy of the model in predicting the compressive strength of concrete, this paper chooses to optimize the base learner of the ensemble learning model. The position update formula in the search phase of the sparrow search algorithm (SSA) is improved, and piecewise chaotic mapping and adaptive t-distribution variation are added, which enhances the diversity of the population and improves the algorithm's global search and convergence abilities. Subsequently, the effectiveness of the improvement strategy was demonstrated by comparing improved sparrow search algorithm (ISSA) with some commonly used intelligent optimization algorithms on 10 test functions. A back propagation neural network (BPNN) optimized with ISSA was used as the base learner, and the adaptive boosting (AdaBoost) algorithm was used to train and integrate multiple base learners, thus establishing an adaptive boosting algorithm based on back propagation neural network improved by the improved sparrow search algorithm (ISSA-BPNN-AdaBoost) concrete compressive strength prediction model. Then comparison experiments were conducted with other ensemble models and single models on two strength prediction datasets. The experimental results show that the ISSA-BPNN-AdaBoost model exhibits excellent results on both datasets and can accurately perform the prediction of concrete compressive strength, demonstrating the superiority of ensemble learning in predicting concrete compressive strength.

Mechanical properties and constitutive model of waterborne polyurethane modified concrete in compression at different temperature

The surface cracking is one of the main causes for the deterioration of concrete structures exposed to large temperature variations in plateau, and a tough concrete is of critical importance for the service life of concrete structures. In this paper, a waterborne polyurethane modified concrete (WPMC) was prepared, and the compressive strength of WPMC at temperatures ranging from 20 °C to 80 °C was investigated. Digital image correlation (DIC) technology was employed to elucidate the evolution of compressive deformation in WPMC across various temperatures. Furthermore, Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP) were employed to reveal the mechanism behind the enhancement of WPMC's toughness. The results indicate that WPMC maintains good mechanical properties within the temperature range of 20 °C–80 °C. Compared to the controlled group of concrete, WPMC exhibits an increase in ultimate compressive strain by 16.67 %–109.09 %, an enhancement in energy absorption capacity by 30.45 %–118.61 %, and an augmentation in full-field lateral ultimate strain by 20.0 %–48.0 %. A constitutive model for WPMC that considers the influence of temperature is proposed, providing an accurate assessment method for the stress-strain relationship of WPMC under compressive loading.

Comparative Study on the Impact of Various Non-Metallic Fibres on High-Performance Concrete Properties

The performance of high-performance concrete has been enhanced in the present study by incorporating non-metallic fibres without altering the binder content. The impact of these fibres on high-performance concrete flexural and compression characteristics and the arrangement of fibres within the composite were systematically analysed. Unlike conventional practices, the authors of the research introduce various non-metallic fibres, including alkali-resistant glass fibres, carbon microfibers, three types of polypropylene microfibers, and one type of polyvinyl alcohol fibre while maintaining an equal amount of binder. The research aims to comprehensively evaluate the fibre’s influence on cement composite properties. Various types of non-metallic fibres, highlighting differences in diameters and their physical-mechanical properties with a constant amount by volume, have been considered in the research. Alkali-resistant glass and carbon fibres exhibit low values of residual post-cracking force but polyvinyl alcohol fibres demonstrate the best post-cracking behaviour, with a residual post-cracking force value. This detailed examination of fibre distribution and composition sheds light on the nuanced effects on fresh and hardened concrete properties. Notably, this work diverges from existing research by maintaining a constant binder amount and considering the quantitative distribution of fibres in a unit volume of the cement matrix, along with their aspect ratio. These findings provide valuable insights for selecting the most suitable non-metallic fibres for enhancing high-performance concrete properties.

Performance of Molasses Waste as a Cement Replacement to Study Concrete Compressive Strength

To reduce the negative environmental impact of cement production and preserve natural resources, an experimental investigation was conducted to study the performance of concrete specimens at different curing ages and to determine the compressive strength of these specimens by replacing cement with molasses. Experimentation was carried out on the concrete specimens at a temperature range of 25 °C to 30 °C; six specimens were cast for each replacement ratio, except for 0.75% wt. of cement (86.55 g) and 1% wt. of cement (113.6 g), where five samples were considered for each ratio. The average 28-day compressive strength of the conventional concrete specimens came out to be 29 MPa, but increased to 40 MPa with the addition of 0.25% wt. of cement molasses (28.85 g). It was observed that as the percentage of molasses waste in the concrete mix was further increased by replacing the cement, the compressive strength of the concrete specimens increased gradually and then significantly decreased. The findings shed light on the prospect of using molasses waste instead of cement in the concrete mix. Also, it is worth mentioning that about 30% of the cost–benefit was obtained with reference to that of conventional admixtures available in the market for the production of concrete. However, it is notable that a long-term durability study needs to be conducted before making it viable. This work not only addresses a sustainable and innovative method of waste management (SDG12), but also contributes to low carbon emissions (SDG13). The novelty of this work lies in the fact that no such kind of study has been conducted in Pakistan so far, in addition to the very limited international literature available, and, in particular, no evidence on the compressive strength results at higher molasses dosages, i.e., 1% wt. of cement (113.6 g) and 2% wt. of cement (230.8 g).

Novel Optical-Inspired Rain Forest for the Explainable Prediction of Geopolymer Concrete Compressive Strength

Novel Optical-Inspired Rain Forest for the Explainable Prediction of Geopolymer Concrete Compressive Strength

Optimized bp Neural Network Based on Improved Dung Beetle Optimization Algorithm to Predict High-Performance Concrete Compressive Strength

In modern architecture, the structural safety of buildings largely depends on the compressive strength of high-performance concrete (HPC), which is determined by the complex nonlinear relationships between its components. In order to more accurately forecast HPC’s compressive strength, this paper proposes a prediction model based on an improved dung beetle optimization algorithm (OTDBO)-optimized backpropagation neural network (BPNN). Extreme Gradient Boosting (XGBoost) is employed to determine the inputs for the BPNN, enhancing the computational efficiency under high-dimensional data feature conditions. To address the issues of local optima entrapment and slow convergence in the dung beetle optimization algorithm (DBO), four improvements were made to enhance its performance. In the initial population generation stage, the optimal Latin hypercube method was used to increase the population diversity. In the rolling stage, the osprey optimization algorithm’s global exploration strategy was introduced to improve the global search capability. The variable spiral search strategy was employed in the reproduction stage, and an adaptive t-distribution perturbation strategy was combined in the foraging stage to enhance the algorithm’s adaptability and search efficiency. The improved dung beetle optimization algorithm (OTDBO) outperformed other algorithms in performance tests on the CEC2017 benchmark functions. In terms of predicting the compressive strength of HPC, the XG-OTDBO-BP model developed in this study outperformed models optimized by other algorithms in terms of fitting outcomes and prediction accuracy. These findings support the XG-OTDBO-BP model’s superiority in the compressive strength of HPC prediction.

Ductility assessment of GFRP reinforced concrete beams with a wedge-based mechanical model accounting for discrete fibers and confinement

Glass fiber-reinforced polymer (GFRP) bars for internal reinforcement for concrete have gained attention due to their non-corrosive properties, high resistance, and electromagnetic transparency. On the other hand, the brittle behavior and low modulus of elasticity of FRP bars limit their application and diffusion in the civil construction market. From this perspective, this work investigates the influence of three components on the increase of ductility of GFRP beams: i) discrete alkali-resistant glass fibers added to the concrete; ii) confinement of the concrete with GFRP stirrups; and iii) use of longitudinal reinforcement on the compression zone. An experimental program including four over-reinforced beams with different reinforcement configurations was conducted. The beams were tested in four-point bending configuration and the use of fibers, stirrups and compression reinforcement contributed to substantially increasing the beam ductility index. Finally, a concrete wedge model was developed to obtain equivalent stress-strain relationships for the concrete in compression. The model was successfully validated against experiments and proved to be a useful tool for rationally evaluating GFRP RC beams’ ductility.

Evaluating the Impact of Marble Waste and Fly Ash as Sand Replacements on Concrete's Compressive Strength and Workability

Evaluating the Impact of Marble Waste and Fly Ash as Sand Replacements on Concrete's Compressive Strength and Workability