Properties Of Concrete Research Articles

Study on Mechanical Behavior of Concrete by Temperature and Steel Fiber Content

Temperature and steel fiber content have a great influence on the mechanical behavior of concrete, so it is urgent to study the mechanical properties of concrete at different temperatures and steel fiber content. The effects of temperature and steel fiber content on the mechanical properties of concrete are studied in this paper. Based on the uniaxial compression testing machine, the uniaxial compression tests of concrete under different temperatures (150°C, 300°C, 450°C) and different steel fiber content (0%, 1%, 2%, 3%) are carried out. With the increase of temperature, the compressive strength of concrete first increases and then decreases, which indicates that there is a critical temperature for the influence of temperature on the compressive strength of concrete. In addition, the addition of steel fiber content significantly improves the compressive strength of concrete. In addition, temperature and steel fiber content significantly affect the peak strain of concrete. Based on the SEM test results, the temperature effect of concrete was investigated from the microscopic perspective.

Synergistic effects of combined multi-walled carbon nanotubes and glass fibers on concrete: experimental and economic analysis

This article deals with the combined application of MWCNTs and GFs to improve mechanical property and durability of concrete. MWCNTs were dispersed by sonication and added in dosages of 0.05, 0.10, and 0.15% of cement weight, while GFs were added at 0.5, 1.0, and 1.5% of mixture weight. Compressive, flexural, and tensile strengths, as well as modulus of elasticity, rebound number, and ultrasonic pulse velocity, were tested at various curing ages. Accordingly, the addition of 0.10% MWCNTs and 1.0% GFs resulted in the enhancement of compressive strength while improving modulus of elasticity by up to 14%. In addition, durability improved owing to reduced sorptivity with the aid of pore refinement by MWCNTs and crack-bridging by the GFs. Scanning electron microscopy showed that the optimum mix developed a denser microstructure; however, mixtures with higher dosages of MWCNTs exhibited agglomeration, influencing their performance adversely. In addition, economic assessment pointed out that the best property improvement-cost ratio corresponded to a benefit-cost ratio equal to 0.104. The present research provides an insight into the development of high-performance concrete materials and delivers practical recommendations on how MWCNTs could be combined with GF in order to create durable yet economically viable concretes.

Preparation and Performance Study of Novel Foam Vegetation Concrete.

Vegetation concrete is one of the most widely used substrates in ecological slope protection, but its practical application often limits the growth and nutrient uptake of plant roots due to consolidation problems, which affects the effectiveness of slope protection. This paper proposed the use of a plant protein foaming agent as a porous modifier to create a porous, lightweight treatment for vegetation concrete. Physical performance tests, direct shear tests, plant growth tests, and scanning electron microscopy experiments were conducted to compare and analyze the physical, mechanical, microscopic characteristics, and phyto-capabilities of differently treated vegetation concrete. The results showed that the higher the foam content, the more significant the porous and lightweight properties of the vegetation concrete. When the foam volume was 50%, the porosity increased by 106.05% compared to the untreated sample, while the volume weight decreased by 20.53%. The shear strength, cohesion, and internal friction angle of vegetation concrete all showed a decreasing trend with increasing foaming agent content. Festuca arundinacea grew best under the 30% foaming agent treatment, with germinative energy, germinative percentage, plant height, root length, and underground biomass increasing by 6.31%, 13.22%, 8.57%, 18.71%, and 34.62%, respectively, compared to the untreated sample. The scanning electron microscope observation showed that the pore structure of vegetation concrete was optimized after foam incorporation. Adding plant protein foaming agents to modify the pore structure of vegetation concrete is appropriate, with an optimal foam volume ratio of 20-30%. This study provides new insights and references for slope ecological restoration engineering.

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.

Influence of Engineering Properties of Machine-Made Sand on Concrete Performance: A Review

As the demand for high-quality concrete in the construction industry increases, mechanically produced sand, which is a substitute for natural sand, has received widespread attention due to its abundant resources and environmental friendliness. This review aims to explore the engineering properties (such as particle shape, gradation, and fines content) of manufactured sand and their impact on concrete performance, emphasizing its important role in promoting green construction and sustainable development. By systematically reviewing recent relevant studies, this paper determines the optimal range of fines content and discusses the impact of different particle shapes on workability and strength, highlighting the critical role of reasonable gradation and parent rock properties. The study shows that the application of manufactured sand can significantly improve the mechanical and durability properties of concrete, reduce dependence on natural resources, and reduce carbon emissions. To further promote research and technological progress in this field, it is suggested that future studies should explore the long-term durability of manufactured sand, develop more efficient sand production technologies, and optimize the mix design to achieve more environmentally friendly and economical construction solutions.

The Effect of Plant-Based Polysaccharide (Gum Arabic) as a Super-Plasticizer on the Mechanical Properties of Concrete

The Effect of Plant-Based Polysaccharide (Gum Arabic) as a Super-Plasticizer on the Mechanical Properties of Concrete

Study on Mechanical Properties and Carbon Emission Analysis of Polypropylene Fiber-Reinforced Brick Aggregate Concrete.

Given the current construction waste accumulation problem, to utilize the resource of red brick solid waste, construction waste red brick was used as a concrete coarse aggregate combined with polypropylene fiber to prepare PPF (polypropylene fiber)-reinforced recycled brick aggregate concrete. Through a cube compression test, axial compression test, and four-point bending test of 15 groups of specimens, the influences of the aggregate replacement rate of recycled brick and the PPF volume on the mechanical properties of recycled brick aggregate concrete reinforced by PPF were studied, and a strength parameter calculation formula was constructed and modified based on the above. Finally, combined with a life cycle assessment (LCA), the carbon emissions of raw materials were analyzed and evaluated. It was found that the mechanical properties of recycled concrete enhanced by PPF are critical at an addition rate of 50% and then decrease slowly with an increase in the aggregate content. PPF effectively alleviates the problem of strength reductions caused by regenerated aggregate substitution through the fiber-bridging effect. Based on the experimental data, a mechanical transformation model considering fiber reinforcement and BA weakening was constructed, and the regression accuracy R2 was around 0.90. The environmental benefit obtained when only replacing the natural aggregate is low. Although the incorporation of fiber improves the carbon emissions of the material to a certain extent, the benefits are more noticeable compared with the increase in strength. The results show that garbage recovery and strength demand benefits are achieved when the amount of recycled brick aggregate is 50% of the total. The strength conversion model established in this paper has of high accuracy and was created with careful consideration of fiber reinforcement and the regenerated aggregate weakening correction, providing it with more robust adaptability and extensibility. The mechanical properties of the recycled brick aggregate concrete enhanced by PPF are excellent and sustainable when the replacement rate of BA is 50% and the PPF volume is 0.1%.

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

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

Properties of alkali activated cellular lightweight binder blocks with industrial and agro waste

The construction industry is continuously seeking sustainable alternatives to conventional building materials. Alkali-Activated Cellular Lightweight Binder Blocks (AACLBs) present a promising solution by utilizing alkali activation technology to augment the properties of lightweight concrete. This research focuses on optimizing the composition of AACLBs by replacing conventional binders with alkali-activated materials derived from industrial by-products and agro waste with the help of a protein based foaming agent (FA). The industrial waste materials investigated include Fly Ash (F) and Blast Furnace Slag (BFS) while agro waste such as Rice Husk Ash (RHA) are considered as sustainable alternatives. With Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3) as activators, 8 different combinations are adopted in this study. Properties such as density and compressive strength (CS) are analyzed to assess the structural capabilities of the AACLBs and are compared with that of cement-based blends. The alkaline solution to binder ratio is kept constant as 2.5 for two dilution ratios (1:30 & 1:60) and ambient curing is adopted. The target densities for conventional cement-based mixes are set as 1200–1600 kg/m3 and 1500–1800 kg/m3 for alkali-based mixes. The findings show that, the highest CS of 42.76 MPa and a density of 1870 kg/m3 is observed for FB1 combination at a dilution ratio of 1:30. Conversely, the FBR2 combination at a dilution ratio of 1:60 yielded a CS of 21.23 MPa, accompanied by a minimum density of 988 kg/m3.

Advanced machine learning techniques for predicting concrete mechanical properties: a comprehensive review of models and methodologies

Advanced machine learning techniques for predicting concrete mechanical properties: a comprehensive review of models and methodologies

Impact of waste Brick and Limestone Fillers on Self-Compacting Concrete Properties

The present paper discuss the results of an experimental study about self-compacting concretes (SCC) prepared with different mineral admixture (cal,Pz and Br). It was evaluated the effects of the use of the mineral additives on the properties of SCC. Four types of SCC mixes were produced. The amount of cement, fine and coarse aggregate of water and superplasticizer was kept constant for all mixtures. The blended cement (Portland cement + admixture) remained constant at 490 kg/m3 and included 20% by weight of recycled mineral additives. The different between the mixtures done in the 20% of fillers . TheThe rheology of fresh SCC was determined according to the requirements of the 206-9 standard, using the spread (sprawl), L-box, and stability (sieve) tests. The properties of the hardened SCC were evaluated through compression strength tests at 3, 7, 28, and 90 days, physico-thermal properties (λ, Cp, α) at 90 days, and absorption by total immersion at 90 days. The results showed that among the mineral additives used, the incorporation of waste bricks significantly reduced the rheology of SCC. However, ternary mixtures of limestone and waste bricks improved the rheological properties of SCC. Mechanical properties, such as compressive strength and physico-thermal properties, were also influenced by the addition of fillers, although the effects varied depending on the type of additive used. Nevertheless, the ternary mixtures of limestone and waste bricks yielded the best results in terms of strength, porosity, and durability.

Effect of multi-scale hybrid fiber reinforcement on mechanical properties of ultra-high performance concrete

An experimental investigation was conducted on the effect of multi-scale hybrid fiber reinforcement incorporating steel fiber and wollastonite fiber on mechanical properties (i.e. compressive strength, splitting tensile strength, flexural toughness and direct tensile properties) of ultra-high performance concrete (UHPC). The results indicate that, compared with macro-fiber, hybrid steel fiber composed of macro-fiber and meso-fiber improves the strength and toughness of UHPC significantly. The higher the dosage of meso-fiber, the better the effect of hybrid steel fiber. Meanwhile, longer meso-fiber provides a better performance in terms of interfacial bonding strength between the fiber and the matrix of UHPC, leading to an increase in the anti-cracking effect of hybrid steel fiber, and hence the improvement in the splitting tensile strength and flexural toughness of UHPC. Moreover, adding wollastonite fiber as micro-fiber is efficient to enhance the mechanical properties of UHPC incorporating with hybrid steel fiber. It may be related to the respective anti-cracking effect of three types of fiber and their synergistic snubbing effect, as well as the filling effect of wollastonite fiber and the chemical bonding effect caused by the reaction between wollastonite fiber and Ca(OH)2 in the paste.

Probabilistic modeling of ballistic penetration in reinforced concrete panels

AbstractStudying ballistic impact on reinforced concrete (RC) structures is essential for enhancing the safety and cost‐effectiveness of these structures. The depth of penetration (DOP) and residual velocity (RV) of projectiles are critical design parameters requiring precise quantification to improve the ballistic‐resistant design. Traditional empirical models are available for quantifying these parameters but are deterministic and often yield inaccurate results due to the inherent uncertainties in ballistic impacts. This paper introduces a probabilistic approach to quantify DOP and RV accurately. Bayesian inference models are developed using dimensionless explanatory functions to estimate these parameters in RC panels under hard projectile impacts, accounting for associated uncertainties. Numerical modeling is performed using LS‐Dyna, and the model is validated against experimental data from past studies. Data from refined numerical simulations, along with available experiments from the literature, are utilized to develop the probabilistic models. The findings reveal the significant influence of projectile and concrete properties, as well as the projectile's incidence angle, on DOP and RV. The probabilistic models developed are validated with previous experimental results, demonstrating their reliability and accuracy. Consequently, robust design formulae are proposed for estimating DOP and RV for RC panels under hard projectile impacts, providing a valuable tool for precise impact assessments in engineering applications.

The corrosion resistance of white ultra-high performance concrete under the coupling environment of acid rain and carbonization.

Acid rain and carbonization are two primary types of environmental corrosion that threaten the health of urban concrete structures over time. However, the coupling effects of acid rain and carbonization on concrete deterioration have been rarely reported. In this paper, four coupling regimes were designed using accelerated simulation experiments to investigate the deterioration properties of white ultra-high performance concrete (WUHPC). The results showed that under acid rain corrosion, the WUHPC surface was covered with white crystals before peeling off after 7 days, resulting first in an increase, followed by a rapid decrease in weight and strength, and the erosion depth linearly increased at a rate of 33.0 μm per day. Meanwhile, negligible changes occurred with only carbonization. However, under coupling corrosion, the deterioration worsened after environmental alternation. The strength of WUHPC with acid rain after carbonization decreased by 27.7%, reaching a minimum of 72.0 MPa. The erosion depth growth under acid rain followed by carbonization was 20.0 μm per day, which was much faster than that (3.9 μm per day) of single carbonization. The major corrosion products under acid rain were gypsum crystal, and the crystal shrank with time, leaving more voids and a weakened bonding strength. The calcium carbonate sediment generated during carbonization blocked the pores on the surface, hindered the diffusion of acid solution, and partly consumed acid ions via dissolution, resulting in facilitated acid rain corrosion. Once carbonate was consumed in a short time, more capillary pores were unblocked to promote further acid rain corrosion.

The Influence of the Solid Phase on the Properties of Foam Concrete

An overview of literary sources related to the formation and development of the technology of aerated concrete is given. It is shown and systematized in which directions scientific research aimed at improving their functional properties was conducted. It is noted that almost all researchers associate the dependence of the properties of porous concrete with the character of their porosity. The conducted analysis allowed the authors to hypothesize that the properties of aerated concrete are exclusively determined by the nature of the distribution of the solid phase, that is, by the nature of its structure. Determination of the influence of the solid phase and its nature on the properties of aerated concrete is devoted to experimental studies. They were conducted in two stages. At the first, when applying physical modeling, the effect of the total porosity and water consumption of the dry mixture on the change in the nature of the solid phase of the model was studied. Internal interfaces between structural elements are taken as characteristics of the solid phase - their total length and width. It is shown that the water consumption of the mixture has different effects on materials with a dense and porous structure. At the next stage of experimental research, the influence of the water consumption of the mortar mixture on its strength (strength of the matrix material) and the strength of foam concrete was studied. The initial rheological conditions of the formation of the structure were changed by changing the size and amount of filler, changing the amount of liquid and plasticizing additives. The results of the experiments confirmed that the initial rheological conditions have different effects on the materials of dense and porous structure. Under certain conditions, in materials with a porous structure (in foam concrete), an increase in the water-solid ratio leads to an increase in the strength of concrete. Which indicates that with such water consumption, more favorable conditions are created for the formation of a porous structure, which is reproduced on the character of the solid phase. The given results confirm the given hypothesis and can be used in the synthesis of new building materials, including with the use of artificial intelligence.

The Impact of Fly Ash and Sea Sand on Strength and Durability of Concrete

Fly ash is a solid waste produced by power plants. To overcome the bad effects on the environment, fly ash is used as a substitute for cement in making concrete. Apart from that, the innovation of aggregate replacement materials in mixing concrete also has several alternatives, one of which is the use of sea sand as a substitute for fine aggregate. This research was conducted to determine the best proportion of sea sand use 10–40% with two treatments (washed and unwashed) and the use of fly ash of 20-30% on the corrosion resistance of reinforcing steel and the mechanical properties of concrete. The research results show that using up to 30% washed sea sand and 10% unwashed sea sand can increase compressive strength when compared to normal concrete. The use of up to 30% fly ash together with 20% sea sand has the same compressive strength as normal concrete. Apart from that, the use of sea sand and fly ash together has a low-risk category for reinforcing steel corrosion (10% risk of corrosion).

A Review on the Effect of Synthetic Fibres, Including Macro Fibres, on the Thermal Behaviour of Fibre-Reinforced Concrete

The mechanical properties of concrete degrade rapidly when exposed to elevated temperatures. Adding fibres to concrete can enhance its thermal stability and residual mechanical characteristics under high-temperature conditions. Various types of fibres, including steel, synthetic and natural fibres, are available for this purpose. This paper provides a comprehensive review of the impact of synthetic fibres on the performance of fibre-reinforced concrete at high temperatures. It evaluates conventional synthetic fibres, including polypropylene (PP), polyethylene (PE), and polyvinyl alcohol (PVA) fibres, as well as newly emerging macro fibres that improve concrete’s fire resistance properties. The novelty of this review lies in its focus on macro fibres as a promising alternative to conventional synthetic fibres. The findings reveal that PE fibres significantly influence the residual mechanical properties of fibre-reinforced concrete at high temperatures. Although PVA fibres may reduce compressive strength at elevated temperatures, they help reduce micro-cracking and increase flexibility and flexural strength. Finally, this review demonstrates that while conventional synthetic fibres are effective in limiting fire-induced damage, macro fibres offer enhanced benefits, including improved toughness, energy absorption, durability, corrosion resistance, and post-cracking capacity. This study provides valuable insights for developing fibre-reinforced concrete with superior high-temperature performance. Steel fibres offer superior strength but are prone to corrosion and spalling, while PP fibres effectively reduce explosive spalling but provide limited strength improvement. PE fibres enhance flexural performance, and PVA fibres improve tensile strength and shrinkage control, although their performance decreases at high temperatures. Macro fibres stand out for their post-cracking capacity and toughness, offering a lightweight alternative with better overall durability.

The Influence of Resin Volume Fraction on Selected Properties of Polymer Concrete.

Polymer concrete is a promising material with applications in construction and architecture; however, guidelines for its design and optimization are not well-established in the literature. This study aimed to evaluate how resin volume fraction and aggregate size distribution affect key properties of polyester polymer concrete, including flexural strength, compressive strength, water absorption, and material cost. Three types of quartz aggregates with different particle size distributions were used, as follows: small (below 0.5 mm, quartz dust), medium (0.2-2.0 mm, quartz sand), and large (2.0-10.0 mm, quartz gravel). The resin volume content varied from 5% to 30%. Differences in apparent density, open porosity, water absorption, flexural strength, compressive strength, and material cost were analyzed as functions of resin volume content and aggregate size. The results showed that apparent density and mechanical properties are positively correlated with resin content for small and medium aggregates; however, in the case of large aggregates, flexural strength decreased when the resin volume content exceeded 20%. A significant reduction in material porosity and water absorption (to ~0.4% and ~0.2%, respectively) was observed at high resin volume fractions.

Impact of Surface Treatment and Curing Conditions on the Mechanical Properties of OPS Lightweight Concrete

This study investigated the use of Styrene Acrylic Emulsion (SAE) as a surface treatment for Oil Palm Shell (OPS) aggregates to enhance the mechanical properties of lightweight concrete. SAE, known for its superior adhesion, was applied to OPS to create a protective layer, addressing a gap in current research on OPS concrete. The research examined the impact of SAE-treated OPS under various curing conditions, assessing the compressive, flexural, and splitting tensile strengths. Results demonstrated that continuous water curing (NW) was the most effective for improving the compressive strength of treated specimens, particularly those with moderate SAE treatment (5%, 10%, and 15%). Specimens with 25% SAE treatment (ST25) exhibited reduced strength due to clumping and increased porosity. Flexural and splitting tensile strengths also improved with SAE treatment, with ST5 showing the highest flexural strength and ST10 performing best in splitting tensile strength tests. Alternating curing (AC) conditions showed moderate success, while external curing (EC) conditions negatively impacted strength due to rapid thermal cycling. Overall, the SAE treatment significantly enhanced the bond between the OPS particles and cement matrix, improving the mechanical performance of OPS lightweight concrete. These findings suggest that SAE-treated OPS could provide a sustainable and effective solution for concrete production.

The Effect of Nanosilica on the Fresh Properties of Sustainable Self-Compacting Concrete

The purpose of the current investigation was to lower the CO2 footprint of an industrial self-compacting concrete mix, which currently consists of CEMI 42.5R solely, without any natural pozzolanas or supplementary cementitious materials. The target compressive strength of the industrial mix needed to exceed 55 MPa at 28 days of curing. In the present study we attempted a 20% reduction of CEMI 42.5R (by total mass of solids) by adding 20% of limestone filler and subsequently added 1% of colloidal nanosilica, aiming (i) at leveraging strength loss due to the reduction of Portland cement, (ii) at providing early strength and (iii) at enhancing the microstructure. A water to binder ratio of 0.42 was selected and superplasticizers were added. Fresh properties were studied in terms of slump-flow test, density and 1-day strength. In addition, the 28 day compressive strength was also tested, meeting the mix design strength requirement. Interestingly, the slump flow was improved, indicating better packing effect, however the compressive strength of the control formulations was higher than that of the nanoenhanced formulation. Further insights are also provided.