Mechanical Properties Of Concrete Research Articles

Investigation of foam concrete's mechanical properties and multi-scale damage evolution characteristics under uniaxial loading

The macroscopic mechanical behavior of foam concrete damages its mesoscopic pore structure. To study the macroscopic mechanical properties of foam concrete, a series of uniaxial compression tests were carried out. AE-DIC and SEM characterization were used to reveal the multi-dimensional damage evolution characteristics of foam concrete under load. Furthermore, the porosity response law of the foam concrete damage characteristics was analyzed using the finite element method. The results show a significant linear relationship between the residual and peak stress of foam concrete under uniaxial load (σr = kσp), and the coefficient k decreases with an increase in porosity. During uniaxial compression, tensile and shear damages were dominant on both sides of the yield point of foam concrete. The macroscopic load retention characteristics in the failure stage typically result from microscopic fracture structure reorganization and stress path optimization. The damage-dissipation energy during this period accounts for approximately 100% of absorbed energy. An increase in the porosity led to frequent adjustments in the stress path of the foam concrete, and the tensile damage tended to be significant and diffuse.

Effect of the Inorganic Modification Mode on the Mechanical Properties of Rubber Recycled Concrete

The reasonable and effective application of waste tires and discarded concrete in concrete is an important branch of green concrete development. This paper investigates the effects of the inorganic modification mode on the basic mechanical properties of rubber recycled concrete based on indoor tests. Inorganic modification, such as water washing, acid washing, and alkaline washing modification, was mainly used to treat and modify rubber particles. The factors affecting the compressive strength, the splitting tensile strength, the flexural strength, the axial compressive strength, and the modulus of elasticity of modified rubber recycled concrete were analyzed. The study results show that the incorporation of recycled aggregates and rubber reduced the mechanical properties of concrete, with the compressive and splitting tensile strengths showing the greatest reductions of 27.36% and 27.24%, respectively. Three modification methods significantly improved the mechanical properties of rubber recycled concrete. The alkali washing modification method was the most effective, maximally improving the mechanical properties of rubber recycled concrete by 7.53–15.51%. The effects of the three modifications on the mechanical properties of concrete were ranked as follows: alkali washing > acid washing > water washing. This study provides a data basis for the practical application of rubber recycled concrete in engineering and a test basis for the development of green concrete.

Corrosion characteristics of concrete by landfill leachates of different ages

Landfill leachate is a highly corrosive pollutant, and the composition of landfill leachate varies greatly between landfill ages. Landfill leachates of different ages pose a corrosive danger to concrete structures. In this study, four landfill leachates of different ages were selected for concrete immersion corrosion tests to elucidate the corrosion characteristics of concrete. Measurements of concrete mechanical property indices were combined with microscopic analysis methods, such as X-ray diffraction and scanning electron microscopy. The effects of the compositional differences of the landfill leachate of different ages and contact times on the concrete were analyzed and evaluated. The test results showed that the young landfill leachate slowed down the hydration process of concrete and promoted the generation of expansive corrosive crystals such as gypsum and calcium sulfate, which changed the internal microstructure of the concrete and caused irreversible damage. Exposure to leachates caused a decrease of the concrete quality, compressive strength, and dynamic elastic modulus to below their initial values. The participation of intermediate and mature landfill leachate in the hydration process of concrete promoted the hydration reaction in the short term. However, with the prolongation of the test period, this enhancement gradually weakened, and at the same time, the sulfate in the landfill leachate and the hydration products generated ettringite, which produced expansion stress on the internal structure of the concrete, destroying the structure and decreasing its strength. The experimental results of this study provide theoretical support for the treatment of different ages of landfill leachates and the design and protection of landfill concrete structures.

Ultra-stable foam enabled by nano silica engineering for foam concrete improvement

Foam concrete is increasingly applied in construction due to its lightweight, good thermal insulation and fire resistance, and environmental sustainability, while its low strength limits its further popularization and applications. To enhance the stability and performance of foam concrete, amphiphilic nano silica (ANS) was employed in this study to modify the sodium dodecyl sulphate (SDS) based foaming agent. Then, the designed foam was utilized to fabricate foam concrete, of which the micro/macro performance was analysed in detail. The results showed that ANS-modified foam exhibited superior stability with a thicker foam wall thickness, contributing to the enhancement of foam stability within the cement matrix. The foam concrete with ANS exhibited higher strength compared to the control groups. The analysis of pore structures revealed that the ANS modification led to a more rounded and homogeneous pore configuration, characterized by an increased proportion of small and medium-sized pores and a decreased average pore size. The increase in pore roundness was accompanied by a reduction in the number of sharp edges of the pores and therefore a reduction in the stress concentration factor, while the moderately sized pore also was more conducive to increasing strength due to its lower stress concentration. As a result, the strength of the concrete is significantly increased. These findings demonstrate the potential of ANS as an effective foam stabilizer for foam concrete production, leading to enhanced foam stability and improved mechanical properties of concrete.

Study on the Effect of Post-Freezing Mechanical Properties of Polypropylene Fibre Concrete Based on BAS-BPNN

An indoor accelerated freezing and thawing test of polypropylene fibre-reinforced concrete in chloride and sulphate environments was conducted using the “fast-freezing method” with the objective of investigating the damage law of the post-freezing mechanical properties of hydraulic concrete structures and studying the effects of different mixing amounts of polypropylene fibres on the mechanical properties of concrete. Furthermore, in order to reduce the cost of concrete tests and shorten the time required for conducting concrete tests, a backpropagation neural network based on a Beetle Antenna Search algorithm (BAS-BPNN) was established to simulate and predict the mechanical properties of polypropylene fibre-reinforced concrete. The accuracy of the model was verified. The results indicate that the order of improvement in the macro-physical properties of concrete due to fibre doping is as follows: PPF1.2 exhibited the greatest improvement in macro-physical properties of concrete, followed by PPF0.9, PPF1.5, PPF0.6, and PC. When the freezing and thawing medium and the number of cycles are identical, all four assessment indexes (R2, RMSE, SI, MAPE) demonstrate that the four groups of polypropylene fibre concrete exhibit superior performance to the control group of ordinary concrete. This indicates that polypropylene fibre can enhance the mechanical properties and freezing resistance of the concrete matrix, delay the process of freezing and thawing damage to the matrix, and extend the lifespan of the matrix, yet cannot prevent the ultimate failure of the matrix. The application of intelligent algorithms to optimise the parameters of an artificial neural network model can enhance its capacity to generalise and predict the mechanical properties of concrete. In terms of the coefficient of determination (R2), the Beetle Antenna Search algorithm (0.9782) outperforms the Particle Swarm Optimization (PSO; 0.9676), the Genetic Algorithm (GA; 0.9645), and the backpropagation neural network (BPNN; 0.9460). The improved backpropagation neural network based on the Beetle Antenna Search algorithm not only avoids the trap of local optimality but also improves the model accuracy while further accelerating the convergence speed. This approach can address the complexity, non-linearity, and modelling difficulties encountered during the freezing process of concrete. Moreover, it offers relatively accurate prediction outcomes at a reduced cost in comparison to traditional experimental methodologies.

Effect of Incorporation of Recycled Polypropylene Plastic on Mechanical Properties of Concrete

Effect of Incorporation of Recycled Polypropylene Plastic on Mechanical Properties of Concrete

Experimental study on Corn Straw Fiber (CSF) toughening EPS concrete

The natural Corn Straw Fiber (CSF), it has the advantages of light weight, high strength, good toughness and renewable, can delay the cracking and improve the toughness of cement-based materials. The effects of different mass fractions of CSF and Expanded-Polystyrene (EPS) particles on the compressive strength, flexural strength, splitting tensile strength and their failure modes, load-displacement curves and toughness of EPS concrete were analyzed by full factorial experimental design method. The compressive toughness index (I0, I1) and fracture energy (Gf) were defined to evaluate the effect of CSF on toughening EPS concrete. The results show that the addition of CSF can improve the compressive strength, flexural strength and cracking toughness of EPS concrete to a certain extent. The maximum compressive strength occurred in the E1F3 specimen with a CSF content of 3 % in Group I, which was 1.12 MPa, and the improvement rate was also the highest among the four groups, reaching 69.7 %. The compressive toughness index I1 also reached its maximum in the E1F3 specimen; The maximum flexural strength occurred in the E3F4 specimen with a 4 % CSF content in Group III, which was 0.885Mpa, with the highest improvement rate of 127.38 %. The maximum fracture energy Gf reached 0.827 in the E3F4 specimen. However, another additive, EPS particles, did not significantly improve the physical and mechanical properties of concrete. According to the SEM images and toughening mechanism analysis, it was discovered that tight adhesion between EPS particles and CSF with cement matrix, and the failure mode of CSF was tensile fracture, which could maximize the effect of CSF high tensile toughness. On the basis of mechanical properties and toughening effect, the relationship formulas between variable factors and strength, toughness index were fitted, and the optimal content of EPS and CSF were determined to be 1.3 % and 3 %, respectively.

A Review on Mechanical Properties of Concrete by Partial Replacement of Cement with Eggshell Powder and Fly Ash

A Review on Mechanical Properties of Concrete by Partial Replacement of Cement with Eggshell Powder and Fly Ash

Mechanical properties of silica fume based concrete: A review

The significant industrial growth accompanying rapid urbanization has spurred a heightened demand for concrete. Cement production, a primary ingredient of concrete, results in substantial carbon dioxide (CO2) emissions. To mitigate this impact, alternative pozzolanic materials like silica fume (SF) can be incorporated. SF, an industrial byproduct, serves as a supplementary cementitious material (SCM), offering benefits of waste recycling. This study aims to comprehensively review the addition of SF as an SCM replacement, with a specific focus on the mechanical properties of concrete. Numerous scientific papers were analyzed and carefully examined from the period of 1998 to 2023, which forms the bibliometric core of this study. The entire scopus database was examined for co-occurrence of keywords and actively contributing countries and results were shown through network diagrams. The effect of SF addition on fresh properties as well as mechanical properties were discussed. The inclusion of SF in range of 10–25% by quantity of cement was found to have increased split tensile strength, compressive strength and flexural strength. However, the addition of SF beyond 25% replacement level can have an adverse impact on the overall characteristics of the composite mix. The present study summarizes the major trends as reported in the available literature where SF has been used as SCM. Apart from finding the general trends, various research gaps have been identified.

Strengthening effect of monolayer graphene oxide on the impact mechanical properties of concrete and the mechanism analysis based on fractal theory

Graphene oxide (GO), a new nanomaterial with excellent properties, having the prospect of improving the performance of cementitious composites. Graphene oxide reinforced concrete (GORC) was prepared and the impact tests were performed through a φ100 mm SHPB test apparatus, to investigate the effects of impact velocity and GO content on the impact mechanical properties of concrete. The effects of GO on the pore structure and microscopic morphology of concrete were analyzed by MIP and SEM tests. Furthermore, the pore structure fractal dimension and fragment fractal dimension were calculated to quantitatively relate the microscopic pore structure to the macroscopic impact mechanical properties, and the enhancement mechanism of GO was investigated from microstructure optimization and stress dispersion mechanism. The results show that GO promotes the growth and aggregation of cement hydration products, and significantly improves the quasi-static and impact mechanical properties of concrete through filling-compacting effect and anticracking-unloading effect. When the GO content is 0.06 wt %, GO shows the best improvement effect. Compared with plain concrete (PC), the quasi-static compressive strength, dynamic compressive strength, elastic modulus, DIF, peak strain, ultimate strain and impact toughness are increased by a maximum of 29.95 %, 52.27 %, 9.79 %, 75 %, 51.54 %, 59.6 % and 86.2 % respectively. GORC has an obvious strain rate effect in the impact velocity range of 5.5 m/s-9.5 m/s, and the average particle size of specimen fragments satisfies a logarithmic relationship with the impact velocity. In addition, the pore structure fractal dimension and fragment fractal dimension satisfy a positive correlation. Larger pore structure fractal dimension indicates more defects in concrete and worse mechanical properties of it.

Uncertainty quantification and global sensitivity analysis of bearing capacity of push-out specimen considering randomness in bond-slip behaviour

As an artificial composite material, the uncertainty in mechanical property of concrete significantly impacts the bond-slip behaviour of the shaped steel concrete structure. To investigate the effect of the uncertainty of concrete mechanical properties on the bearing capacity of push-out specimens, based on the data of a small number of push-out test with identical design parameters, the improved Bootstrap method is utilized to execute sample augmentation for the bond stress-slip curves, and the stochastic bond slip constitutive model is established after considering five parameters (K1, …, K5) in the deterministic bond-slip model as random variables. Simultaneously, considering the randomness in elastic modulus of concrete (Ec), uncertainty quantification (UQ) of the bearing capacities of the push-out specimens is conducted using the arbitrary polynomial chaos (aPC) method. Subsequently, the global sensitivity analysis of the ultimate and residual bearing capacities is accomplished through the aPC surrogate model. The results indicate that the probability distribution types of the parameters in the stochastic bond-slip constitutive model can be arbitrary when considering the randomness of concrete material, and the aPC method with at least a third-order expansion is recommended to execute UQ for the push-out test due to the strong nonlinearty between the bearing capacities and the random parameters. The ultimate bearing capacity is primarily affected by the parameter K2, followed by K4, K3, and K5. Whereas the residual bearing capacity is predominantly influenced by the parameter K4, followed by K5, the remaining parameters exhibit negligible influence. In contrast, K1 and Ec have the greatest influence on equivalent plastic strain of the concrete near the loading end of the push-out specimen.

Mechanical Properties of Concrete with Recycled Bottle Glass Powder Substitute

Concrete is a material that is widely used in the construction of structural buildings. One of the influential factors for obtaining high quality concrete is the aggregate gradation. If the aggregate gradation has a small size and varies, it can reduce the porosity of the concrete so that the concrete becomes denser which makes the quality of the concrete high. In order to use aggregates with fine gradations, this study proposes glass powder derived from glass bottle waste as a partial replacement for fine aggregates. The glass powder used is in the sizes about 0.150 mm - 0.075 mm. Then, the maximum size of 15 mm for the coarse aggregate and the fine aggregate with the gradation of zone 4 (fine sand) were used for the concrete mix. The purpose of this study is to investigate the mechanical properties of concrete i.e. the compressive and split tensile strength of concrete with glass powder as a partial substitution of fine aggregates with a percentage of 10%, 15%, and 20% at a concrete age of 28 days. This study uses the testing method that refers to ASTM standard. From the test results, it was found that the compressive strength of concrete with 20% glass powder variation (GPC 20%) increased by 11.32% with a value of 38.97MPa compared to the compressive strength of normal concrete (NC) with a value of 35.01 MPa. For the split tensile strength, the concrete with a 20% glass powder variation increased by 15% with a value of 2.71 MPa compared to the split tensile strength of normal concrete with a value of 2.36 MPa. The results showed that the use of glass powder as a partial replacement for fine aggregate in this study was reasonably good to improve its mechanical properties.

Nanomaterials in concrete: Enhancing strength and durability

Carbon nanotubes (CNTs) have received great attention for their applications in concrete due to their unique properties such as high strength, flexibility, and electrical conductivity. This study aims to investigate the effect of adding carbon nanotubes on the energy combination of the material. Concrete samples were prepared with different concentrations of carbon nanotubes and their mechanical properties were measured and compared with control samples without carbon nanotubes. The results show that the addition of carbon nanotubes increases the compressive and flexural strength of concrete. The findings suggest that incorporating carbon nanotubes into concrete could be a good way to improve concrete's mechanical properties and improve its performance in construction. Compared with white cement M20 samples aged 7, 14 and 28 days. The 28day maximum strength is stated below for 0.0045 wt.% SWCNT and MWCNT and 0.0030 wt.% SWCNT and MWCNT. It was determined that nanocomposites containing a lower proportion of long MWCNTs had properties comparable to nanocomposites containing a higher proportion of short MWCNTs. Many of the walls of the carbon nanotubes reach microcracks, indicating that the carbon nanotubes are cracked and pulled out. Besides the compression test, we also calculated the slit tensile strength by adding different percentages of carbon nanotubes. The usage percentage increased for 0.0015% MWCNTs and 0.0030% and 0.0045% SWNTs.

Performance of Steel Fiber Reinforced Concrete under Different Cooling Methods at High Temperature

Performance of Steel Fiber Reinforced Concrete under Different Cooling Methods at High Temperature

Studi Komparatif Pengaruh Bahan Tambah Aditif Terhadap Sifat Fisik dan Mekanik Beton

This research aims to conduct a comparative study analyzing the influence of additives on the physical and mechanical properties of concrete based on the results of previous research.  Three relevant previous studies were used as a reference in analyzing the effect of additives on compressive strength, split tensile strength, modulus of elasticity and compressive strength of concrete.  In Agus Setya Budi’s research, the use of fly ash with a content of 15% resulted in an increase in the compressive strength of concrete, while the use of fly ash levels of 30% and 40% resulted in a decrease in the compressive strength of the concrete.  Samun Haris’ research shows that using silica fume powder at a level of 5% produces higher compressive strength results compared to a level of 15%.  Meanwhile, Muhhamad Sadat’s research indicates that the use of slag as a substitute for fine aggregate increases the compressive strength of concrete along with increasing levels of slag substitution. Based on the analysis of the research results, it can be concluded that the use of additives in concrete has a significant influence on the physical and mechanical properties of concrete.  However, the effect of added additives depends on the type and level of additives used.  Therefore, it is necessary to pay attention to the selection of the right additives to achieve the desired concrete characteristics.

Experimental Investigation of Sustainable Concrete Production using Blast Furnace as A Cement Substitute- A art of Review

The pursuit of sustainable construction practices has led to a growing interest in alternative materials that can reduce the environmental impact of traditional concrete production. This experimental study focuses on the utilization of blast furnace slag as a substitute for cement in concrete, aiming to assess its mechanical properties, environmental impact, and overall sustainability. The primary objectives of this research are threefold. Firstly, the study seeks to evaluate the mechanical properties of concrete by varying the content of blast furnace slag in the mix, with a specific emphasis on strength, durability, and structural performance. This involves conducting a comprehensive analysis of the concrete's compressive strength, flexural strength, and other relevant mechanical characteristics. Secondly, a life cycle assessment (LCA) will be employed to analyze the environmental impact of the concrete mixtures. This assessment will compare carbon dioxide (CO2) emissions, energy consumption, and overall sustainability of the concrete produced with varying percentages of blast furnace slag. The LCA will provide valuable insights into the environmental implications of using slag as a cement substitute, aiding in the identification of eco-friendlier concrete production practices. Lastly, the research aims to assess the environmental impact of blast furnace slag itself when employed as a cement substitute. This involves examining the production, transportation, and incorporation of blast furnace slag into the concrete mix, providing a holistic view of its sustainability across the entire life cycle. The experimental approach involves the meticulous design of concrete mixes with different percentages of cement replaced by blast furnace slag. The varying mix designs will be tested for mechanical properties, and the data obtained will be used to draw correlations between slag content and concrete performance. In summary, this research endeavors to contribute to the body of knowledge surrounding sustainable concrete production by exploring the mechanical, environmental, and sustainability aspects of utilizing blast furnace slag as a cement substitute. The findings of this study are anticipated to provide valuable insights for the construction industry to adopt more environmentally friendly practices while maintaining or enhancing concrete performance.

Utilizing ensemble machine learning and gray wolf optimization to predict the compressive strength of silica fume mixtures

AbstractThe concrete compressive strength is essential for the design and durability of concrete infrastructure. Silica fume (SF), as a cementitious material, has been shown to improve the durability and mechanical properties of concrete. This study aims to predict the compressive strength of concrete containing SF by dual‐objective optimization to determine the best balance between accurate prediction and model simplicity. A comprehensive dataset of 2995 concrete samples containing SF was collected from 36 peer‐reviewed studies ranging from 5% to 30% by cement weight. Input variables included curing time, SF content, water‐to‐cement ratio, aggregates, superplasticizer levels, and slump characteristics in the modeling process. The gray wolf optimization (GWO) algorithm was applied to create a model that balances parsimony with an acceptable error threshold. A determination coefficient (R2) of 0.973 demonstrated that the CatBoost algorithm emerged as a superior predictive tool within the boosting ensemble context. A sensitivity analysis confirmed the robustness of the model, identifying curing time as the predominant influence on the compressive strength of SF‐containing concrete. To further enhance the applicability of this research, the authors proposed a web application that facilitates users to estimate the compressive strength using the optimized CatBoost algorithm by following the link: https://sf-concrete-cs-prediction-by-javid-toufigh.streamlit.app/.

Assessing the risk of ASR in LC3 binders based on low-grade calcined clay

The research investigates the impact of limestone calcined clay cement (LC3) on the mechanical properties and durability of cement-based materials in the context of alkali-silica reactions (ASR) for sustainable construction. Comparative experiments were conducted on binary and ternary blends of low-grade kaolinitic calcined clays and conventional supplementary cementitious materials (SCMs). Two distinct low-grade kaolinitic clays were calcined, and blends with Portland cement, ground-granulated blast-furnace slag (GGBFS), and silica fume (SF) were prepared for comparative analysis. Results reveal that replacing 30 wt% of Portland cement with these calcined clay blends substantially reduces expansion in mortar and concrete during accelerated and long-term tests, altering micropore structure. These blends demonstrate superior performance compared to other studied SCMs. Despite a slight decrease in compressive strength compared to the control mixture, there is a noteworthy improvement in permeability and resistance against expansion. Also, in the early stages of ASR, an improvement in concrete's mechanical properties and durability is observed, attributed to the ASR gel filling the pores.

Effect of Graphene Oxide Surface Deposition Process on Synthetic Macrofibers and Its Results on the Microstructure of Fiber-Reinforced Concrete.

The improvement of the mechanical properties of concrete can be achieved with the use of synthetic macrofibers. However, this fiber-matrix interaction will be sufficiently efficient for tensile efforts only when there is a binding agent that associates the characteristics of the paste with the characteristics of the surface of the reinforcing material. As already identified, in a first phase of this research using synthetic microfibers, a better fiber-matrix interaction can be achieved with the surface treatment of synthetic fibers with graphene oxide. In this way, we sought to evaluate the surface treatment with graphene oxide on two synthetic polypropylene macrofibers (macrofiber "A" and macrofiber "B") and its contribution to the concrete transition zone. The surface deposition on the macrofiber was carried out using the ultrasonication method; then, the macrofiber with the best deposition for creating reinforced concrete mixtures was identified. To evaluate the quality of GO deposition, scanning electron microscopy (SEM-FEG) and energy-dispersive spectroscopy (EDS) tests were carried out; the same technique was used to evaluate the macrofiber-matrix transition zone. The SEM-FEG images indicated that macrofiber "B" obtained greater homogeneity in surface deposition and it presented a 13% greater deposition of C in the EDS spectra. The SEM-FEG micrographs for reinforced concrete indicated a reduction in voids in the macrofiber-matrix transition zone for concretes that used macrofibers treated with GO.

Research on the Mechanical Properties of Concrete under Low Temperatures.

As construction projects in cold regions continue to increase, it has become necessary to understand the performance of concrete at low temperatures. Conducting uniaxial compressive tests on non-standard prismatic concrete specimens under low-temperature conditions and analyzing the test results allows for a comprehensive understanding of the strength variations of concrete with different strength grades at temperatures of 20 °C, 0 °C, -20 °C, -30 °C, and -40 °C. When the temperature decreases from 20 °C to 0 °C, the compressive strength of the specimens decreases, while the elastic modulus and peak strain increase. As the temperature continues to decrease, the compressive strength of the specimens increases, the elastic modulus continues to grow, and the peak strain decreases. The rising segments of the curves can be fitted using a cubic polynomial, and as the temperature decreases further, the parameters of the fitting curve gradually decrease. For concrete, being the most widely used material in the construction field, understanding its performance in low-temperature environments has become a significant research topic in the field of materials engineering and construction.