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This study delves into the realm of M70, high-performance concrete (HPC) with a focus on enhancing its mechanical and sustainable properties through the incorporation of nanomaterials, specifically nanosilica, and organic composites derived from abaca fibers. HPC is pivotal in contemporary construction for its superior durability, strength, and resistance to environmental factors. The integration of nanosilica aims to refine the microstructure of the concrete at the nanoscale, enhancing its strength and durability. Simultaneously, the introduction of organic composites from abaca fibers seeks to impart eco-friendly characteristics to the concrete mix, addressing sustainability concerns. The research methodology involves systematically varying the proportions of nanosilica (0%, 0.5%, 1.0%, 1.5%) as a partial replacement for cement in the concrete and additionally, abaca fibers (0%, 0.25% and 0.5%) were used to enrich the durability. Mechanical testing will be conducted to assess the impact of these additives on the concrete's structural performance, while durability testing will focus on resistance to environmental factors such as moisture and chemical exposure. The outcomes of this study enriching the concrete performance and optimization of high-performance concrete (1% of nanosilica and 0.25% of abaca fiber) is the superior quality compared to all other mixes. [ABSTRACT FROM AUTHOR]

The prediction of the time-dependent behavior of high-performance concrete (HPC) structures is essential to evaluating their service life. This prediction relies on the shrinkage and creep properties of HPC. However, unlike conventional concrete, the binary and ternary composite system of supplementary cementitious materials (SCMs) in HPC has demonstrated different shrinkage and creep properties. This difference makes it challenging to accurately predict these properties using existing material models in code and standard practices, i.e., ACI, fib, B4, and GL. These models exhibit significant deviations in prediction under standard statistical evaluation methods due to the influence of SCMs. To overcome this challenge, intelligent artificial neural network (ANN) models have been developed using a feed-forward backpropagation training algorithm. The ANN models consider a widely compiled indigenous database of shrinkage and creep and consist of the most realistic experimental relationship with the effecting extrinsic and intrinsic key parameters. These parameters include standard concrete mix design material proportions, mechanical and physical properties, environmental conditions, and aging factors to obtain shrinkage and creep properties of HPC. All concrete material properties influencing the behavior of shrinkage and creep have been related based on experimentally measured results and incorporated as input parameters in both intelligent developed ANN models. The accuracy of prediction of both ANN models has been substantiated by the experimentally measured database and existing material models as comparative appraisals using several statistical metrics. The developed ANN models to predict such complex nonlinear properties of HPC are more practical and beneficial than existing material models, which will help to fulfill sustainable development and improve the service life of HPC structures. [ABSTRACT FROM AUTHOR]

The article discusses the test results concerning the compressive strength, water absorption, and frost resistance of concretes produced with three types of cement: CEM I, CEM II/B-M (S-V), and CEM III/A, evaluated after different curing periods (28, 56, and 90 days). Additionally, to assess the effects of the minimum 4% air entrainment recommended by the EN 206 standard, concrete mixes with the same composition but containing an air-entraining admixture used consistently at 0.15% of the cement mass, were prepared. To achieve a more detailed characterization of the concretes, tests on the concrete mixes were also performed, and the physical properties of the concretes, including water absorption, density, and total porosity, were measured. The paper also presents significant results on the pore distribution in the air-entrained concretes, confirming the achievement of very good basic airentrainment parameters in all concretes. Based on the test results, it was found that both the type of cement and the introduction of an air-entraining admixture significantly influence not only the frost resistance of the concretes but also their compressive strength depending on the curing time of the specimens. This is particularly evident in the low-clinker cements CEM II and CEM III. It was observed that in the case of concretes with these cements, it is possible to attain nearly no reduction in compressive strength after undergoing 150 cycles of freezing and thawing following a 90-day curing period. [ABSTRACT FROM AUTHOR]

The World Bank study predicts that 4 °C warming will bring high temperatures, sea-level rise, and saltwater intrusion to coastal areas, damaging coastal concrete structures. Increased CO2 from industrialization exacerbates this, necessitating durable, low-carbon concrete. Combined use of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as high-volume OPC replacements boosts performance while reducing concrete's carbon footprint. In this perspective current study examines the durability of concrete against aggressive agents (H2SO4, MgSO4, NaCl, and CO2) causing premature deterioration of concrete structures. Initially, three cost-effective sustainable concrete mix designs were developed, incorporating 50% replacement of OPC with locally available supplementary cementitious materials, specifically FA and GGBFS. These mixes were then evaluated for their mechanical and durability performances. The impact of aggressive ions (SO42−, Cl−, and CO32−) was studied by examining the changes in mechanical performance and phase assemblages. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques were used to estimate the phase compositions. Ternary blended concrete having 50% OPC+ 30% GGBFS + 20% FA exhibited optimal synergistic performance, enhancing pozzolanic and hydraulic reactions for better resistance to harmful ions. The sorptivity test confirmed that as the GGBFS content increased, the sorption rate decreased, indicating the higher reactive nature of GGBFS to that of FA. Deleterious compounds formed due to the action of SO42-, Cl-, and CO32- were identified to be ettringite (Ca6Al2(SO4)3(OH)12.32H2O, AFt) and gypsum (CaSO4.2H2O, Gy), Friedel's salt (Ca4Al2(OH)12Cl2.4H2O, Fs) and polymorphs of calcium carbonate (CaCO3), respectively through TG mass loss curve. These results were corroborated by FTIR analysis, which showed predominant characteristic bands at 662 cm−1 for SO42−, 459 cm−1 for Mg–O stretching, 790 cm−1 for Al–OH bending, and 1431-1443 cm−1 for C–O, confirming the presence of the deleterious compounds. [ABSTRACT FROM AUTHOR]

This study aims to determine the efficiency of concrete containing multiple recycled materials, recycled concrete aggregates (RCAs) and recycled steel fibers (RSFs), and compare it with conventional concrete. Natural coarse aggregate (NCA) in the concrete mix was partially replaced with 30% RCA to achieve a target compressive strength of 30 MPa after 28 days. Different types of fibers (steel fibers, RSFs, and mixed fibers) were added at varying percentages (1.0%, 1.5%, and 2.0%) to improve the mechanical properties of the concrete mixes. The shear behavior of reinforced concrete beams containing RCA and different types of fibers was investigated. Ten concrete mixtures were designed, and 10 reinforced concrete beams were tested under a two‐point load to estimate the contribution of various fiber types to the shear resistance. The results indicate that the addition of different types of fibers significantly enhances compressive, tensile, and flexural strengths of the concrete. Specifically, the improvement in compressive strength for RSFs was 38.9% at 1.5%, tensile strength improved by 21.1%, and flexural strength by 46.2% at the same fiber percentage, thereby improving the concrete's ability to resist cracks through an increase in shear resistance. [ABSTRACT FROM AUTHOR]

There has been a significant surge in the yearly use of plastics, leading to a notable rise in plastic waste generation. Consequently, the recycling of plastic garbage has emerged as a prominent concern around the world. This research explores the feasibility of using polyethylene furanoate (PEF) plastic waste as a substitute for coarse aggregate (CA) in concrete. Graphene nano-platelets (GNPs) were added to the concrete mix in different quantities to improve its structural reliability. The research study used an experimental research design in conducting its investigation. PEF waste plastic was added in concrete in varying proportions of 0%, 5%, 15%, 20%, and 25% as a supplementary material to gravel, and GNPs were added in different percentages of 0%, 0.03%, 0.05%, 0.08%, and 0.1% by weight of cement. Mechanical tests were conducted, which includes compressive strength (CS), split tensile strength (STS), flexural strength (FS), modulus of elasticity (MoE), and ultrasonic pulse velocity (UPV), and the environmental assessment of concrete was done by assessing carbon in concrete and concrete's eco efficiency (ESE). It was found that 5% addition of PEF as the substitute to CA and 0.1% of GNPs gives the optimum strength, enhancing CS, STS, and FS by 9.10%, 18.18%, and 4.45%, respectively. Response surface technique (RSM) models were created to provide mathematical equations for predicting the predicted outcomes. All models were optimized using a multi-objective optimization approach and then validated. [ABSTRACT FROM AUTHOR]

In the event of a fire, the performance of concrete becomes pivotal for structural integrity. Concrete undergoes significant changes in its mechanical properties when exposed to high temperatures. This study investigates the mechanical and micro‐characterization of concrete incorporating ground granulated blast furnace slag (GGBFS) under ambient and exposed conditions. The study examines alkali‐activated concrete (AAC) by implementing sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) as alkali activators. Three different fractions of GGBFS and alkali activators (AAs) were employed in the concrete mixes. The mechanical properties of the AAC were evaluated under ambient and elevated temperatures, and the results were compared with those of Portland slag cement (PSC). The study's findings indicate that AAC outperforms PSC, and the study recommends using 93% GGBFS with 7% AAs as a suitable replacement for PSC. The mechanical properties of AAC are enhanced by 20%–47% at ambient conditions. The strength loss for the AAC with increased temperature is also less than that of the PSC concrete. [ABSTRACT FROM AUTHOR]

Recycled concrete incorporating additional super-absorbent polymer (SAP) and machine-made stone powder (MSP) was prepared using a two-factor, four-level orthogonal test. To enhance the frost resistance of recycled concrete and improve its mechanical properties, such as compressive and flexural strength, the prepared concrete underwent 200 freeze–thaw cycles. Before freeze–thaw cycles, the amount of SAP has a predominant influence on the mechanical properties of recycled concrete in comparison with MSP. After 200 cycles of freeze–thaw, the influence of MSP became more significant than that of SAP. Typically, the compressive strength and flexural strength exhibited a trend of initially increasing and then decreasing as the contents of SAP and MSP increased. The optimized recycled concrete was identified as S16M6, containing 0.16% SAP and 6% MSP, as demonstrated by the minimal strength loss after freeze–thaw cycles. This study also proposed a linear regression model for predicting the mechanical properties which offered valuable guidance for the engineering application of recycled concrete mixed with SAP under the freeze–thaw cycle environment. [ABSTRACT FROM AUTHOR]

The non-axisymmetric problem caused by the fluid sloshing in the tank of a mining concrete mixing tank truck during driving is affected by the excitation of complex road surfaces. The fluid sloshing is coupled with the dynamics of the vehicle body due to the excitation of the complex road surface. The traditional hydraulic drive proportional integral differential (PID) control method is not effective in dealing with such problems, which can easily lead to accidents such as overturning. To improve the accuracy and stability of the hydraulic drive control system, this paper proposes an optimized particle filter PID adaptive control method based on the elastic firefly (FA) algorithm to accelerate the convergence speed of control parameter optimization, and then analyzes its hydraulic drive control characteristics and structural applications, and discusses step steering and double lane change modes are simulated under filling rates of 1.5 and 2.0, respectively. The experimental results show that compared with traditional PID control, the proposed adaptive control method can significantly reduce the average speed error of hydraulic drive control to 0.03km/h and the maximum speed error to 0.17km/h. It also improves the control tracking performance and stability. The practicality of the adaptive hydraulic drive is verified in the filling rate experiments under step steering and double-lane shifting conditions. It has important reference value for the practical application of hydraulic drive control optimization of mining concrete mixing transport tank trucks. [ABSTRACT FROM AUTHOR]

Translation abstract Load absorption of deflection forces – Investigations into the break‐out resistance of concrete reinforcing barsIn curved reinforced concrete structures, the steel tensile forces result in radially directed deflection stresses in the concrete, which can cause the concrete cover to spall and the reinforcing bars to pull out. To investigate the absorption of these deflection forces by the concrete, the influence of various parameters on the break‐out forces of reinforcing bars was determined at Münster University of Applied Sciences. The influence of different bar diameters (16, 20, 25, 28 and 32 mm) and the influence of the interaction between several reinforcing bars with different concrete mix designs were investigated. The result of these tests is that larger rebar diameters and a higher concrete quality generally generated higher breaking loads. [ABSTRACT FROM AUTHOR]

In the process of pumping, the segregation of concrete mixture will lead to the difficulty of construction, and even the possibility of pipe blocking. There is a lack of a quickly evaluation for on‐site construction. In order to solve this problem, a rapid wet‐sieved test was proposed in this study and then its feasibility was evaluated based on concrete mixes with different water–cement ratios. Subsequently, the influence of sand ratio on the segregation degree of concrete was investigated. The test results show that a combination of 2.36 mm screen size and 20 s vibrating time did the best. The wet‐sieved mortar content and stratification degree were increased by 4.6%–25.2% and 0.3%–17.9% by pumping, respectively. With the sand ratio increasing from 0.40 to 0.60, the pumping pressure decreased by 51.9%. The linear fitting correlation between pumping pressure and wet‐sieved mortar content (0.96) is better than that between pumping pressure and stratification degree (0.85), which indicates that the proposed test method can reliably characterize the degree of segregation during the pumping of ready‐mixed concrete. [ABSTRACT FROM AUTHOR]

The sustainable utility of industrial waste and by‐products is crucial to reduce environmental impact. Particularly relevant for the cement and concrete industry, where recycling and utilization of industrial waste can help to replace normal concrete and promote stable growth. One such waste material is aluminum computer numerical control waste (ALCNCW). This study investigated the performance of reinforced concrete beams incorporated with ALCNCW. It was decided to use the effects of the ALCNCW ratio and the proportion of longitudinal reinforcement as parameters. A total of 12 reinforced concrete beams were cast and tested with varying levels of lower reinforcement ratios (0.0125, 0.0074, and 0.0032) and ALCNCW ratios (1%, 2%, and 3% by weight), in addition to a control beam. The load‐carrying capacity, failure mode, crack patterns, ductility, and serviceability were analyzed. The findings of the experiments demonstrated that the cracking and bending effects of reinforced concrete beams were different depending on the quantity of tension reinforcement and ALCNCW that was used. The results indicate that adding 1% or 2% of ALCNCW to concrete beams has a negligible effect on the load capacity. However, the ductility of the beams was adversely affected. Nevertheless, adding ALCNCW to the concrete mix can still be implemented with a specific ratio. Finally, all 12 beams met the serviceability limit state requirements. [ABSTRACT FROM AUTHOR]

In the face of the huge consumption of fresh water and river sand by the concrete industry and the poor flexural performance of plain concrete, it is theoretically feasible and environmentally friendly to use bamboo fiber as a replacement to reinforce concrete mixed with seawater and sea sand. In this research, taking the volume fraction (0.6%, 1.2%, and 2.4%), aspect ratio (10, 20, and 30) and diameter (1.0, 1.5, and 2.0 mm) of bamboo fibers as parameters, 15 groups of bamboo fiber‐reinforced concrete (BFRC) prisms and one control group of plain seawater sea sand concrete prisms were subjected to four‐point bending test, followed by analyzing the crack pattern, ultimate load, mid‐span deflection and strain. Under the condition of 1.2% volume fraction, 20 aspect ratio, 1.5 mm diameter, and 30 mm length, the maximum increase rate of flexural strength in this research was obtained, and then it was compared with that of flexural strength of concrete prisms reinforced by various natural fibers. In addition, relevant fitting equations and theoretical calculation formulas were derived, laying a foundation for the subsequent research and application of BFRC. [ABSTRACT FROM AUTHOR]

The purpose of this study is to examine the influence of additives on estimating the useful service life of self-compacting concrete (SCC). For that, durability tests were performed on 43 SCC mix designs to estimating the service life of SCC based on the FIB model. The investigated supplementary materials included xanthan gum at concentrations of 0.2% and 0.25% by weight of cement, microsilica at concentrations of 5%, 7% and 10% by weight of cement, and nanosilica at concentrations of 2%, 3% and 4% by weight of cement. All 43 designs met the reliability index of the model, thereby obtaining the estimated service life for each design. The findings revealed that in chloride-rich environments, the control sample exhibited greater penetration depth compared to the concretes incorporating xanthan gum, microsilica and nanosilica additives. This observation suggests that the inclusion of xanthan gum extends the service life of SCC due to the formation of a denser and more cohesive structure in the hydration products of xanthan gum-modified concrete. Additionally, the investigations conducted indicate that the presence of nano and micro additives effectively reduces voids, while xanthan gum plays a significant role in minimising cracking and enhancing the thickening properties of the concrete. [ABSTRACT FROM AUTHOR]

Recently, sustainability has become one of the most critical goals to be accomplished in the construction industry to mitigate its environmental impacts, energy consumption, waste, and cost. Therefore, this research aims to assess the sustainability of concrete structures using the Building Information Modeling and Life Cycle Assessment (BIM–LCA) approach. It can aid to rank and select the type of concrete based on sustainability criteria including CO2 emissions, embodied energy, and cost using analytical hierarchy process (AHP) method. One-Click LCA tool has been used for the recognition of the distinctions in the LCA results by adopting different environmental product declaration databases. HBERT is used as a verification tool for One-Click LCA results. A comparative study is applied to a multi-story car park concrete structure using both traditional concrete and green concrete that includes supplementary waste materials. Three different models of concrete that have the same compressive strength are selected: traditional concrete, green concrete using 30% fly ash, and green concrete using 50% ground granulated blast-furnace slag (GGBFS). The results showed that using 50% GGBFS in the concrete mix is the most sustainable alternative in terms of CO2 emissions and embodied energy. Finally, it is concluded that using BIM–LCA–AHP integrated approach can help engineers to design computerized models that improve the sustainability of construction by evaluation based on sustainable objectives. [ABSTRACT FROM AUTHOR]

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In order to solve the problems of limited design parameters, over-reliance on manual adjustment and failure to make full use of the existing test data in the traditional proportion design, a novel intelligent optimization strategy for high performance concrete (HPC) was proposed, which integrates artificial intelligence algorithms and meta-heuristic search technology, and can realize the proportion design under the consideration of the multi-objective demand of HPC. Firstly, a database with a large amount of HPC proportion data and performance test information was constructed. Secondly, three machine learning algorithms, XGBoost, MLP and RF algorithm, were used to establish the nonlinear mapping relationship between compressive strength of concrete and the amount of material used, and the model with the best performance was selected as the strength objective function and constraints in the multi-objective optimization intelligent. Then, the Pareto optimal predicate was solved by establishing the mathematical model with the objectives of compressive strength, economy, and environmental protection, and the Pareto optimal predicate was solved by using the NSGA-II algorithm. Lastly, the unique optimal solution was obtained by combining with the ideal-point method. The proposed method was validated by practical engineering examples, and the results show that the proposed multi-objective intelligent optimization design method of high-performance concrete proportion takes into full consideration of interactions between variables, greatly reduces the number of tests, significantly improves the efficiency of the proportion design, and can provide a reference for the multi-objective intelligent proportion optimization design of HPC. [ABSTRACT FROM AUTHOR]

This study explores the influence of different concentrations of recycled concrete aggregate (RCA) on the fresh and hardened properties of self-consolidating concrete (SCC) in order to assess the structural suitability of the use of RCA in a precast concrete plant. The study particularly emphasizes the early strength of the produced concrete. The RCA was sourced from crushed concrete used in roadway applications and was sieved to replicate the characteristics of natural aggregate. Five different SCC mixes were produced, with RCA substituting 0%, 10%, 30%, 50%, and 70% of the natural coarse aggregate (NCA) by weight. For each different mix design, the hardened properties tested were the compressive strength and tensile strength. The fresh properties investigated were the passing and filling ability. Additionally, aggregate properties including grain size distribution and absorption of coarse aggregate were studied. The selected mix design follows a typical well-graded self-consolidating concrete mix with 28-day strength of 8000 psi (55.16 MPa). It was found that replacing up to 50% of the NCA with RCA improves the early strength of concrete without a significant impact on the fresh and hardened concrete properties. [ABSTRACT FROM AUTHOR]

Moisture-induced damage is a serious problem that severely impairs asphaltic pavement and affects road serviceability. This study examined numerous variables in asphalt concrete mixtures to assess their impact on moisture damage resistance. Mix design parameters such as the asphalt content (AC) and aggregate passing sieve No. 4 (PNo. 4) were considered as variables during this study. Additionally, hydrated lime (HL) was utilized as a partial substitute for limestone dust (LS) filler at 1.5% by weight of the aggregate in asphalt concrete mixtures for the surface layer. This study also investigated the potential enhancement of traditional asphalt binders and mixtures by adding nano-additives, specifically nano-silica oxide (NS) and nano-titanium dioxide (NT), at rates ranging from 0% to 6% by weight of the asphalt binder. To quantify the moisture damage resistance of the asphalt concrete mixes, two types of laboratory tests were employed: the tensile strength ratio (TSR) and the index of retained strength (IRS). The former characterizes moisture damage using tensile strength, whereas the latter uses compression strength. The physical properties of the asphalt binder, such as its penetration, softening point, and ductility, were also evaluated to identify the effects of the nanomaterials. The results indicated that variations in the mix design variables significantly affected the moisture damage resistance of the asphalt concrete mixtures. The maximum improvement values were obtained at the optimum asphalt content (OAC) and PNo. 4 (mid-range + 6%) with TSR values of 80.45 and 82.46 and IRS values of 74.39 and 77.14, respectively. Modifying asphalt concrete mixtures with 1.5% HL resulted in improved moisture resistance compared with mixtures without HL (0% HL) at each PNo. 4 level, reaching superior performance at PNo. 4 (mid-range + 6%) by 4.58% and 3.96% in the TSR and IRS tests, respectively. Additionally, both NS and NT enhanced the physical properties of the asphalt binder, leading to substantial enhancements in asphalt concrete mixture performance against moisture damage. A 6% dosage of NS and NT showed the best performance, with NS performing slightly better than NT. TSR was increased by 14.72 and 11.55 and IRS by 15.60 and 12.75, respectively, with 6% NS and NT compared with mixtures without nanomaterials (0% NM). [ABSTRACT FROM AUTHOR]

Ground Granulated Blast Furnace Slag (GGBS) is an effective supplementary cementitious material because of its pozzolanic properties and positive environmental impact. This research explores the flexural strength of concrete pavements by analyzing several high-volume formulations of GGBS concrete against conventional mixes. The study aims to assess the viability of incorporating high-volume GGBS mixes in pavement construction, with a particular emphasis on their flexural performance. The study employs various GGBS content levels (60%, 65%, 70%, and 75%) in concrete mixes, with the control mix containing ordinary Portland cement. Specimens are prepared according to standard procedures, and flexural testing is conducted to evaluate their performance. Statistical analysis is performed to compare the flexural strength and behavior of GGBS mixes with the control mix. The results obtained from the experiments revealed that the GGBS concrete mixes had better flexural performance than the control mix, with more strength and less cost. The results provide the performance of large-volume GGBS concrete mixes under flexural loading circumstances, which helps to understand whether these mixes are suitable for use in concrete pavements. Ultimately, this research sheds light on the possibilities of utilizing large- volume GGBS concrete mixes as long-term substitutes for traditional concrete pavements, which may help in the promotion of greener and more long-lasting infrastructure solutions. [ABSTRACT FROM AUTHOR]

In the traditional mass concrete temperature field calculation, the accuracy of the thermal parameters is extremely important. However, the actual thermal parameters of mass concrete may have some errors with the laboratory-measured values or specification values due to the site ambient temperature, concrete surface insulation measures, cooling water flow, etc. Therefore, it can be combined with the measured temperature of the field temperature sensors using the sparrow search algorithm (SSA) for the inverse analysis of thermal parameters. Firstly, to address the problem that SSA has low convergence accuracy and easily falls into local optimum, a mixed strategy was adopted to improve the algorithm, including Logistic Chaos mapping initialization of the population, the introduction of adaptive weighting factors, and the use of the Cauchy mutation strategy. Then, the performance test was carried out to compare the performance of the algorithm with three different intelligent algorithms and reflect the superiority of the SSA that was improved by mixed strategies (SSAIMSs). Finally, the proposed method was applied to the thermal parameter inversion of a mass concrete pile cap. The inversion results demonstrated that SSAIMSs can improve the accuracy and speed of thermal parameter inversion, and the calculated results of the thermal parameters and temperatures obtained using the SSAIMSs matched well with the measured results in the field, which can meet the accuracy requirements of the actual engineering. [ABSTRACT FROM AUTHOR]

This paper presents the fatigue properties of polypropylene fiber-reinforced concrete (PPFRC) in flexure at various stress ratios and the sustainability of PPFRC in terms of environmental impact and material cost for jointed concrete pavements. In this study, prism specimens with a size of 100 x 100 x 400 mm were cut from slabs with a size of 1000 x 1000 x 100 mm, considering the effects of fiber distribution and orientation. A polypropylene fiber with a size of 0.7 x 30 mm was mixed into concrete at 1.0 and 1.3 vol.%. Fatigue tests were conducted under four-point flexural loading to obtain the S-N curve for each mixture. In this study, plain concrete (PLC20) with a maximum aggregate size of 20 mm was also used, and its fatigue strength was compared with that of the PPFRCs. Based on the fatigue test results, the S-N curves called the Whöler curve were proposed. The fatigue life of the 1.3 vol.% PPFRC was longer than that of PLC20 at a lower stress ratio. Using the obtained S-N curves, a jointed concrete pavement was designed. The fatigue life of the thinner PPFRC with 1.3 vol.% pavement was enhanced significantly compared with a normal jointed concrete pavement. Consequently, despite the higher initial material cost, the 1.3 vol.% PPFRC can reduce pavement thickness and CO2 emissions. [ABSTRACT FROM AUTHOR]

Concrete pouring in winter is critical to both concrete manufacturers and end users owing to the possibility of concrete damage due to cold weather. In this context, various methods have been used to prevent frost damage to concrete in winter, including adjusting the concrete mix using a chemical admixture and heat-curing with tents. Of these methods, the insulated-gang-form approach does not require concrete-mix adjustment via a chemical-admixture addition. Furthermore, its positive effect on the initial quality of concrete during concrete construction in winter has previously been confirmed. In this study, the power consumption of the conventional gang form was compared with that of the insulated gang form to evaluate the efficiency of the two protection methods. A thermal vision camera was used to examine the surface heat loss of the gang forms after concrete pouring. The insulated gang form significantly outperformed the conventional one through its significantly reduced power consumption and reduced surface heat loss. These findings can contribute to the standardization of insulated gang form application to concrete protection in cold-weather conditions. [ABSTRACT FROM AUTHOR]

In this study, it is aimed to predict the performance of concretes obtained by using supplementary cementitious materials (SCM) before and after high temperature using artificial neural network. Thus, in addition to contributing to sustainable development and circular economy by using waste materials in concrete production, predicting concrete strength using artificial neural network without the need for experimental studies will provide a great advantage in practice. In addition, it will also contribute to the literature in terms of determining the optimum amount of metakaolin to be used with fly ash in concrete production. Metakaolin, silica fume and fly ash were used as SCM in different proportions in concrete mixes. Accordingly, a total of 22 concrete series were prepared, one of which was the control series. Porosity, ultrasonic pulse velocity, pressure and tensile strength tests were applied to the series at the end of 7th, 28th and 90th curing periods before high temperature. In order to determine the strength losses after elevated temperature, porosity and compressive strength tests were applied at temperatures of 400, 600 and 800 °C. Mineral additive series showed positive mechanical properties up to 20%. However, it has been observed that the use of fly ash after a certain rate causes a decrease in strength. After elevated temperature, strength loss was observed in all series due to the increase in temperature, while it was observed that the rate of being affected by elevated temperature decreased as the percentage of metakaolin increased. Optimum mineral additive usage percentages were determined as 10% fly ash and 15% metakaolin. On the other hand, the use of mineral additives above the optimum level caused the performance of the concrete to decrease. Then, the concrete compression strengths obtained at 7th, 28th, and 90th days and at 400, 600 and 800 °C temperatures are taken as the outputs of the ANN. The artificial neural network provided the closest results to experimental data. Moreover, to prove the predictive performance of ANN, a comparative analysis was made with GPR, SVM and LR and the smallest value of the RMSE value is obtained with the ANN model. Finally, a fivefold cross-validation criteria was used to objectively present the performance of the model. [ABSTRACT FROM AUTHOR]

In order to be more efficient in the optimization of concrete mixture, a new intelligent optimization model of concrete mixture was established by using particle swarm optimization on the basis of the original optimization model, and the specific performance was fitted and predicted by using the support vector machine. Using the optimization model established in this work, the test results of 1,443 groups of mixed ratios show that the prediction accuracy of the new model is better than that of the traditional model. The average relative errors of the 7‐ and 28‐day compressive strengths and initial collapse were 10.42%, 7.43%, and 17.14%, respectively. This method is used in a practical project where a set of C25, C30, C35, and C40 concrete mix ratios are designed. The prediction and actual error of 7‐day intensity and 28‐day intensity are −14.4% to −6.1% and −17.6% to 0.6%, respectively, while the predicted value and actual slump error are 15%. The results show that the error between the measured value and the design value is basically within 15%, which meets the design requirements. The method can reduce the time and cost of concrete production, with the cost per cubic meter after optimization is 3.5–8 CHY lower than the concrete mix calculated by the conventional method. The relative decrease ranges from 1.53% to 3.22%. Finally, a practical quality and cost control system (compos) is established to make the strategy easier to apply. [ABSTRACT FROM AUTHOR]

Calcined clays (CCs) as supplementary cementitious materials (SCMs) can be a promising option to reduce clinker content and CO2 emissions in eco-friendly concretes. Although CCs as components of composite cements in combination with Ordinary Portland Cement (OPC) and limestone powder (LSP) have attracted industry interest, their use as concrete additives is limited. This study investigates the effects of the addition of CCs on the fresh and hardened properties of industry-standard ready-mixed concretes. Four concrete mix designs, each with three superplasticizer dosages, were tested, resulting in 12 variations. The CCs used, which are typical of 2:1 bentonite clays with low metakaolin content, reflect the clays available in Germany. The results showed that CCs significantly influenced the workability, which could be controlled with a high superplasticizer dosage. Increased CC contents reduced bleeding tendencies, which was beneficial for certain structural applications. Early age strength decreased with CCs, but the 28-day strength exceeded that of pure OPC concretes up to 30 wt% CCs. Resistance to CO2-induced carbonation decreased with higher levels of CCs but was comparable up to 15 wt%. Freeze–thaw damage decreased, and chloride migration resistance improved due to a denser microstructure. The global warming potential (GWP) of the concretes tested is in line with that reported in the literature for concretes made from highly blended cements, suggesting that CCs can improve the sustainability of concrete production. [ABSTRACT FROM AUTHOR]

Concrete, as a cornerstone of modern construction, heavily relies on the quality of its constituent materials, particularly aggregates. Among the critical factors contributing to high-quality concrete are proper gradation, absence of clay particles, and angular shape of aggregates. Adhering to these standards typically results in concrete with superior strength. However, aggregates sourced from riverbeds often possess a natural gradation, contain clay particles, and have rounded shapes. This study delves into a comparative analysis of aggregates sourced from two widely utilized riverbed regions, namely Hari-River and Kamar-Kalaq, situated within Herat province, Afghanistan. Given that over 90% of concrete in Herat province is sourced from these two riverbeds, the findings of this study carry immense significance. The research meticulously examines key parameters, including clay content, gradation, aggregate shape, and compressive strength, to determine the optimal choice for concrete production. Methodologically, samples were acquired following ASTM standards, and rigorous testing procedures were conducted, encompassing clay particle analysis, sieve analysis, and strength testing. The results reveal significant disparities between the two regions, with Hari-River demonstrating superior characteristics across various metrics. Particularly noteworthy is Hari-River's lower clay content of 2.7% compared to Kamar-Kalaq's 3.7%. The gradation of Hari-River for both coarse and fine aggregates is superior to that of Kamar-Kalaq when compared to size 67 aggregate range. Additionally, the average 28 days concrete compressive strength of Hari-River aggregates is 27.8 MPa, while that of Kamar-Kalaq is 23.4 MPa. [ABSTRACT FROM AUTHOR]

The development of concrete with excellent water and frost resistance providing high level of sound and thermal insulation has triggered the formulation of foamed concrete. However, multiple laboratory studies are required to produce reasonable data to design the relevant codes and mathematics with which design of mixes is made easier at low cost. In this research paper, the artificial intelligence (AI)-based symbolic regression technique estimation of the compressive strength of foamed concrete has been reported. Foamed concrete has been a subject of serious research in sustainable built-environment due to its lightweight and structural functionality. In this research work, data gathering method was applied to gather a globally representative data base comprising concrete density to water density (concrete density g/cm3) (y/yw), water-cement ratio (W/C), and sand-cement ratio (S/C) as input variable and the compressive strength (Fc) as the study output. The dimensionless factors have been derived to eliminate data handling complexities and improve model performances. The 230 data entries from foamed concrete mixes were partitioned into 75% and 25% for training and validation data, respectively. At the end of the model execution, it was found that the response surface methodology (RSM) produced a symbolic closed-form equation like the genetic programming (GP), evolutionary polynomial regression (EPR), and the group method of data-handling-neural network (GMDH-NN). Even though the RSM closed with a minimum error, the GP, EPR and GMDH-NN were faster in runtime. The overall outcomes show that the GP outclassed the EPR, RSM and the GMDH-NN, though with minor margin. Meanwhile the EPR produced the highest outliers from the ±25% test of accuracy envelope. Overall, the present models outperformed those reported in the literature due the parameter reduction through dimensionless factors derivation and provided a decisive model to predict the Fc of foamed concrete. [ABSTRACT FROM AUTHOR]

The integration of green construction practices within the built environment has been significantly advanced by biotechnological innovations, among which microbially induced biomineralization (MIB), predominantly facilitated by various strains of spore-forming bacilli, emerges as a pivotal mechanism for the self-healing of concrete. However, the practical deployment of this technology faces challenges, notably the compromised viability of bacterial spores due to germination triggered by severe shear stress during concrete mixing. To address this limitation, a water-insoluble polymer (extracellular polymeric substance) produced by Cellulomonas flavigena was utilized to encapsulate and protect the spores. The encapsulation process was rigorously verified through physicochemical methodologies, including X-ray diffraction (XRD) analysis, which revealed alterations in the interlayer spacings of the extracellular polymeric substance (EPS) structure during the encapsulation process, indicating successful EPS coating of the spores. Furthermore, a proof of concept for the enhanced biomineralization capacity of EPS-coated spores was demonstrated. Standard analytical techniques confirmed the precipitation of calcite and vaterite among other minerals, underscoring the effectiveness of this novel approach. This breakthrough paves the way for the development of innovative, sustainable bioconcrete applications, aligning with broader environmental objectives and advancing the field of green construction technology. [ABSTRACT FROM AUTHOR]

Taking the bored pile mud of Shuangliu Yangtze River Bridge on Xingang Expressway as the research object,different mud of the same bored pile were selected to carry out flocculation settlement test and medium pressure filtration test,and the mud sludge specific resistance (SRF) and capillary water absorption time (CST) under different water content werecompared. Particle size analyzer, scanning electron microscope and X-ray diffraction were used to analyze the composition inthe mud, the dehydration performance and influencing factors of bored pile mud were studied to explore the factors affecting thedehydration performance. The results show that the settlement performance of bored pile mud is poor, and the addition of PAMhas no significant effect on the improvement of settlement performance. Mud water loss based on medium pressure water lossinstrument can reflect the mud settling performance. There is a certain linear correlation between SRF and CST of the test mud,and the correlation size is affected by the mud dehydration performance, the more difficult it is to dehydrate, the better thecorrelation. Among the characteristic particle size of mud, D50 particle size has the greatest influence on the mud dehydrationcharacteristics. Mixing with concrete has the effect of increasing the particle size of mud D50 and above, and increasing thecontent of Ca, Mg, Si, and Fe elements in the mud to improve its dehydration performance. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a novel approach for defect detection in hammering inspections using Unmanned Aerial Vehicles (UAVs). Despite the promising application of UAVs for inspecting hard-to-reach structures, like bridges, their efficiency is often compromised by the significant ego noise produced by their motor-propeller systems. This noise complicates the discrimination between healthy and defective hammering sounds. In previous research, methods to improve robustness through supervised learning have been proposed; however, these methods require the labeling of hammering sounds by skilled inspectors to train the discrimination model. To overcome this problem, we propose an ego-noise reduction method based on propeller vibrations. By reducing ego noise and thereby making the characteristics of hammering sound more dramatically clear, we enable unsupervised defect detection amidst ego noise. Our experiments with concrete specimens demonstrate that our technique achieves defect detection with an accuracy on par with the supervised method. The proposed method proves especially beneficial for hammering inspections, in which the domain gap–the variability in acoustic signatures of hammering sounds caused by differences in concrete mix ratios and curing conditions from one site to another–presents a significant challenge. Our approach effectively adapts to these variations, ensuring reliable defect detection across diverse construction environments. [ABSTRACT FROM AUTHOR]

The development of new building elements, such as concrete and mortar with sustainable materials, which produce a lower carbon footprint, is an achievable milestone in the short term. The need to reduce the environmental impact of the production of cement-based materials is of vital importance. This work focuses on the evaluation of the life-cycle assessment, production costs, mechanical performance, and durability of three mortars and three concrete mixtures in which mixed recycled aggregates (MRAs) and biomass bottom ash from olive waste (oBBA) were included to replace cement and aggregates. Powdered MRA and oBBA were also applied as complementary cementitious materials with a reduced environmental footprint. Chemical and physical tests were performed on the materials, and mechanical performance properties, life-cycle assessment, and life-cycle cost analysis were applied to demonstrate the technical and environmental benefits of using these materials in mortar and concrete mixtures. This research showed that the application of MRA and oBBA produced a small reduction in mechanical strength but a significant benefit in terms of life-cycle population and environmental costs. The results demonstrated that finding long-term mechanical strength decreases between 2.7% and 14% for mortar mixes and between 1.7% and 10.4% for concrete mixes. Although there were small reductions in mechanical performance, the savings in environmental and monetary terms make the feasibility of manufacturing these cement-based materials feasible and interesting for both society and the business world. CO2 emissions are reduced by 25% for mortar mixes and 12% for concrete mixes with recycled materials, and it is possible to reduce the cost per cubic meter of mortar production by 20%, and the savings in the cost of production of a cubic meter of concrete is 13.8%. [ABSTRACT FROM AUTHOR]

This study presents test results and deep discussion regarding measurements of the fracture toughness of new concrete composites based on ternary blended cements (TCs). A composition of the most commonly used mineral additive (i.e., fly ash (FA)) in combination with nano-silica (NS) has been proposed as a partial replacement of the ordinary Portland cement (OPC) binder. The novelty of this article is related to the fact that ordinary concretes with FA + NS additives are most often used in construction practice, and there is a decided lack of fracture toughness test results concerning these materials. Therefore, in order to fill this gap in the literature, an extensive evaluation of the fracture mechanic parameters of TC was carried out. Four series of concretes were created, one of which was the reference concrete (REF), and the remaining three were TCs. The effect of a constant content of 5% NS and various FA contents, such as 0, 15%, and 25% wt., as a partial replacement of cement was studied. The parameters of the linear and nonlinear fracture mechanics were analyzed in this study (i.e., the critical stress intensity factor ( K I c S ), critical crack tip opening displacement (CTODc), and critical unit work of failure (JIc)). In addition, the main mechanical parameters (i.e., the compressive strength (fcm) and splitting tensile strength (fctm)) were evaluated. Based on the studies, it was found that the addition of 5% NS without FA increased the strength and fracture parameters of the concrete by approximately 20%. On the other hand, supplementing the composition of the binder with 5% NS in combination with the 15% FA additive caused an increase in all mechanical parameters by approximately another 20%. However, an increase in the FA content in the concrete mix of another 10% caused a smaller increase in all analyzed factors (i.e., by approximately 10%) compared with a composite with the addition of the NS modifier only. In addition, from an ecological point of view, by utilizing fine waste FA particles combined with extremely fine particles of NS to produce ordinary concretes, the demand for OPC can be reduced, thereby lowering CO2 emissions. Hence, the findings of this research hold practical importance for the future application of such materials in the development of green concretes. [ABSTRACT FROM AUTHOR]

Roadways are the main transportation mode in Brazil for both cargo and people. This strong dependence on road transport makes paving highways extremely important for the country's development. A common way to recover deteriorated pavement is through a superficial reinforcement called overlay. The whitetopping overlays are made of Portland cement concrete. The technique basically consists of building a concrete pavement over the existing asphalt pavement. The existing pavement acts as a sub-base for the concrete overlay. The addition of fibers to concrete has been increasingly frequent, especially for industrial floors and pavements, bringing longer performance life for same traffic, climate and concrete strength. The fibers promote the improvement of several characteristics of the concrete paste, such as the increase in post-cracking toughness, energy absorption, and fracture energy. This work evaluates the flexural response of composite beams of concrete and asphalt layers and the influence of adding fibers to the concrete. An experimental program is set and supports the development and validation of a finite element numerical model. The numerical model is then applied to a parametric study where tendifferent concrete mixes with different types of fibers and contents are analysed. Steel and synthetic fibers are used. The composite beams are simulated indicating the concrete mixes that best supported loads in the post-cracking regime, with some mixes managing to maintain around 90% of the peak load for large crack openings. [ABSTRACT FROM AUTHOR]

This research examines the influence of high-volume fly ash (HVFA) on reinforced concrete (RC) beam deflections over 180 days of continuous loading. The study comprises eight fly ash-based concrete mixes with varying fly ash ratios (0–60%). Experimental assessments were conducted on two load levels, corresponding to 25% and 50% of the initial cracking load. Thirty-two full-scale RC beams, each measuring 100 × 150 × 1800 mm, were fabricated for both load levels. Long-term deflections were monitored for all concrete mixes through sustained four-point bending tests at ages ranging from 1 to 180 days. A comparative analysis of the overall mid-span deflection between conventional and fly ash concrete RC beams was carried out against established design codes. It was determined that high-volume fly ash RC beams exhibited less creep and shrinkage deflection compared with conventional RC beams. Moreover, artificial neural network (ANN) modelling was also carried out to propose a significant model helpful in predicting the total deflection of RC beams containing any fly ash content and at any age of concrete. The present study offers valuable insights for engineers and designers, facilitating the evaluation of age-dependent deflection patterns in RC beams constructed with reinforced high-volume fly ash concrete. [ABSTRACT FROM AUTHOR]

Purpose: Evaluate the performance of progressive collapse of full-scale three-dimensional structure (3D) beam-slab substructures with and without the presence of reinforced concrete (RC) balconies using two concrete mixes [normal concrete (NC) and rubberized concrete (RuC)]. Design/methodology/approach: This study examines two concrete mixes to evaluate the progressive collapse performance of full-scale 3D beam-slab substructures with and without the presence of RC balconies using the finite element (FE) method. Findings: The results showed that the vertical loads that affect the structures of the specimens after including the balconies in the modeling increased by an average of 29.3% compared with those of the specimens without balconies. The specimens with balconies exhibited higher resistance to progressive collapse in comparison with the specimens without balconies. Moreover, the RuC specimens performed very efficiently during the catenary stage, which significantly enhanced robustness to substantial deformation to delay or mitigate the progressive collapse risk. Originality/value: All the experimental and numerical studies of the RC beam-slab substructures under progressive collapse scenarios are limited and do not consider the balcony's presence in the building. Although balconies represent a common feature of multistory residential buildings, their presence in the building has more likely caused the failure of this building compared with a building without balconies. However, balconies are an external extension of RC slabs, which can provide extra resistance through tensile membrane action (TMA) or compressive membrane action (CMA). All those gaps have not been investigated yet. [ABSTRACT FROM AUTHOR]

In this work, a particular type of carbon nano-material, like graphene oxide (GO), is synthesized in different batches by varying oxidation times, ranging from 1 to 4 days. The synthesis process initially starts with the oxidation of commercially available graphite powder and subsequently exfoliates the obtained graphite oxide in an aqueous solution using a high-frequency ultrasonication process. The synthesized GO batches were characterized using different characterization techniques to authenticate the formation of GO. The highly oxidized GO in an aqueous solution was selected and used as a strength-enhancing additive in concrete. The concrete mixes containing highly oxidized GO at the dosage of 0.01% 0.03%, 0.05%, 0.07%, and 0.09%bwoc were prepared to assess the strength and durability parameters. The GO (4 d) with 0.09%bwoc in concrete increases compressive strength by 58%, tensile strength by 41%, and flexural strength by 43% at 56 days. The results proved that the 0.09%bwoc GO dosage in cement concrete could effectively improve mechanical and durability performances compared to other mixes. Furthermore, the results are verified with the microstructural investigation using FE-SEM in secondary electron (SE) and backscattered electron (BSE) mode to monitor the microstructural changes and thickness of the interfacial transition zone (ITZ) during cement hydration. [ABSTRACT FROM AUTHOR]

Phosphorus tailings are solid wastes generated from mineral processing. It limits the green development of phosphorus chemical industries. Phosphorus tailings mainly consist of dolomite, fluorapatite, and quartzite, so they are used as mineral admixtures to prepare concrete, which not only reduces carbon emissions but also eliminates phosphorus tailings and solves the issues caused by the large accumulation of phosphorus tailings. In this paper, C40 concrete was prepared with different content and fineness of phosphorus tailings, and the effects of phosphorus tailings on its workability, mechanical properties, and durability were investigated. The harm of heavy metals leaching of concrete mixing with phosphorus to the environment was evaluated. The mechanism of the effect of phosphorus tailings on concrete was also analyzed by using characterization methods such as heat of hydration, XRD, and SEM. The results showed that the workability of concrete increased with the phosphorus tailings amount increased, but the mechanical property of concrete decreased. The fineness of phosphorus tailings has little effect on the workability and mechanical properties of concrete. The durability properties of concrete were impaired with the increase in the admixture of phosphorus tailings, but the fineness of phosphorus tailings has no significant effect on the durability properties of concrete. With the increase of the curing time, the structure of the concrete mixed with phosphorus tailings became denser than the concrete without phosphorus tailings incorporated. The concrete mixing with phosphorus tailings had little detriment to the environment. Finally, using the particle size of 20 μm and the content of 20% of phosphorus tailing to replace the cement was suggested. [ABSTRACT FROM AUTHOR]

Digital fabrication of concrete structures has gained substantial research traction over the last decade, enabling efficient material use and adding more architectural freedom. Current research focuses on chemical and mineral admixtures, as well as manipulating the cement hydration reaction to control the yield stress evolution with time in the cement paste. Instead of providing yield stress through the concrete fluid properties, a high yield stress can be provided by interparticle friction from the use of high aggregate volumes and large nominal maximum aggregate size, with flow enhanced for material extrusion by vibration. Granular physics was applied to concrete mixture design to develop concrete mixtures with excellent edge retention abilities that flow easily under vibration. A linear regression analysis of concrete yield stress after vibration revealed that water content is most important, followed by fineness modulus of the aggregate combination and density after vibration. A decrease in water content, increase in fineness modulus and increase in density after vibration were found to increase the static yield stress after vibration. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is a potential material for application as nano-reinforcements in cementitious composites owing to its high-water dispersibility, aspect ratio and outstanding mechanical characteristics. In this study, the combined effect of GO and fly ash on strength properties, stress–strain behaviour and static modulus of elasticity of high-strength concrete was investigated. In addition, microstructure has been characterized using SEM and EDS techniques. The addition of GO at 0.15% and the replacement of cement with fly ash at 10, 20 and 30% by weight was considered. The results exhibited that the addition of GO at 0.15% improved the compressive and flexural strength of concrete by 24.3 and 25.2%, respectively, at 7 days. The combined effect of GO and fly ash on the strength properties of concrete at 7 days was greater than control concrete demonstrating that GO can offset the effect of fly ash on delaying the strength growth at an early age. From the experimental results, it can be concluded that the addition of GO and fly ash into the concrete improved both the strength and elastic modulus, consequently exhibiting positive synergy in hybridizing GO and fly ash into the concrete. Also, the microstructure properties indicated that the GO and fly ash-based concrete mixes exhibited a denser microstructure. Furthermore, a nonlinear numerical model was also created for GO and fly ash-based concrete with finite element-based software ATENA-GiD to validate the experimental findings. The nonlinear numerical model successfully predicted the behaviour under monotonic axial compression and was quite beneficial in minimizing the tedious experimental testing. Finally, it is found that the findings of both the experimental and numerical investigations are in good agreement. [ABSTRACT FROM AUTHOR]

The article discusses a research collaboration between PCI and Oak Ridge National Laboratory (ORNL) on next-generation materials for architectural precast insulated wall panels. The project aimed to develop lighter panels with higher thermal performance and a shorter production time. The research focused on developing a concrete mixture with reduced density and early tensile strength, as well as noncorroding inserts for the panels. The collaboration has led to further research opportunities in the precast concrete industry. [Extracted from the article]

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The current study examines the physical, mechanical, and durability of eco-efficient pervious concrete produced with partial and complete substitutions of natural aggregate (NA) by recycled aggregate (RA) waste from demolished concrete and porcelain. The experimental investigation assessed the workability (slump test), compressive strength, flexural strength, and tensile strength along with the concrete's water permeability, impact, and abrasion resistance. Seven mixes were examined; the first is a control mix with natural aggregate, and the other six are made with various RA ratios, including 30%, 70%, and 100%. The sand was also fully replaced by waste porcelain, even though the ratio of sand used in pervious concrete was low. The results revealed that using waste concrete and porcelain adversely affected the workability of fresh pervious concrete mixes, reducing it by approximately 14%. Furthermore, a decrease in the strength of pervious concrete was noticed, especially in the splitting tensile strength, where the reduction reached 32%. Moreover, the impact resistance of pervious concrete made with RA reduced by 29% compared to that made with NA; the same applies to durability, with an increase of 20% in weight loss. On the other hand, using both recycled concrete and recycled porcelain improved the permeability of the pervious concrete, which reached 30%. Pervious concrete made with waste concrete and porcelain can be an acceptable alternative to that made from natural aggregate due to its improved water permeability and positive environmental impact. However, further investigation is important to consider strength and durability enhancement. [ABSTRACT FROM AUTHOR]

The use of recycled fine aggregate in the production of concrete mixes is one of the elements of a circular economy. However, it is important to ensure that such a modification does not significantly affect the durability of the produced concrete elements. One possible criterion to check whether this condition is met is the practical application of the concept of equivalent concrete properties. The presented studies analyzed the properties of concrete with multi-component cement CEM V/A (S-V) and with recycled fine aggregate. The conducted analyses of the research results showed that with a 15% replacement level of natural sand with recycled sand, it is possible to maintain durability characteristics compared to concrete using only natural sand. [ABSTRACT FROM AUTHOR]

With the advances in infrastructure construction in various countries around the world, extensive requirements have been promoted for the mechanical properties and durability of concrete. In this article, the effects of single and compound additions of nano-SiO2 (NS) and nano-Fe2O3 (NF) on the mechanical properties and durability of concrete were evaluated through different experiments. Moreover, the optimal contents of these additions corresponding to their different properties were explored. The macroscopic test results indicated that the addition of nanomaterials had a perceptible effect on the mechanical properties and durability of concrete. The concrete mixed with 1.0% NS and 0.5% NF achieved optimal performance. With this composition, the compressive strength, flexural strength, water absorption rate, and chloride ion diffusion coefficient (corrosion resistance) of the 28 days concrete were 52.94 MPa, 7.27 MPa, 4.82%, and 4.52 × 10–12 m2/s, respectively, which were 21.5%, 23.0%, 29.4%, and 37.2% higher than those of ordinary concrete at the same age. Microscopic observation and elemental analysis of the ITZ (interfacial transition zone) interface in concrete revealed that NS and NF contributed to nucleation. The two components reacted chemically with Ca (OH)2 grains, resulting in the synergistic effect of the spatial morphology of the hydration products, thus increasing the density of the internal structure of the concrete. To facilitate the application of nanomaterials in engineering, functional relationships between the content of nanomaterials in concrete and the improvements in various properties of concrete were constructed with high accuracy. In addition, the time-dependent correlation coefficients of apparent chloride ion concentration and chloride ion diffusion were introduced based on Fick's second law, and this model was applied to multiple long-term monitoring experiments to verify its accuracy under various exposure conditions, such as tidal zones, splash zones, and atmospheric zones. The improved Fick model was used to predict the service life of concrete. By taking the splash zone as an example, it was reported that under the same conditions, the expected lives of S2F0, S0F2, and S2F1 increased by 31.8%, 25.7%, and 50.2%, respectively, compared to that of OPC. The research results could provide a reference for the development of high-performance concrete. [ABSTRACT FROM AUTHOR]

A straightforward mixing approach that involves incorporating glass fiber into cement-based materials is frequently carried out at construction sites. This practice can have adverse effects on both the fresh and hardened properties of cement mixtures. The lack of quality control measures often leads to the production of fiber-reinforced cement mixtures that do not perform as intended. Additionally, the inherent variations in commercially available glass fibers of the same type add complexity to mixing, making it difficult to consistently reproduce desired effects for in situ casting. Therefore, this research aims to accomplish three main objectives. Firstly, characterizing E-glass and AR-glass fibers to enable a practical replication of performance using these specific variants. Secondly, assessing the impact of five different mixing methods on water absorption, flowability, setting time, compressive, and flexural strength in cement mixtures embedded with these glass fibers. Lastly, evaluating the fiber-matrix interaction within the hardened samples for each mixing method. The results revealed that various mixing methods yielded distinct advantages in the fresh and hardened properties. This highlights the variability in mixing approaches, indicating that the choice of method should be tailored to meet the specific construction requirements of engineers. In essence, the study underscores the importance of selecting an appropriate mixing technique based on the desired outcomes for both the fresh and hardened states of cement mixtures. [ABSTRACT FROM AUTHOR]

The shear stirrups and bend-up reinforcement in ultra-high-performance concrete (UHPC) beams could potentially be excluded due to the superior mechanical properties of UHPC. This paper reports the new findings of an experimental research into the factors that influence the shear behavior of non-stirrup UHPC beams. Fourteen beams were tested in shear, comprising twelve non-stirrup UHPC beams and two normal concrete (NC) beams reinforced with stirrups. The test variables included the steel fiber volume content (2.0%, 1.5%, and 0%), the shear span-to-effective-depth ratio (1.2, 1.8, 2.0, and 3.1), beam width (150 mm and 200 mm), and beam height (300 mm, 350 mm, and 400 mm). The results demonstrated that the steel fiber volume content had a significant influence on the shear behavior of the non-stirrup UHPC beams. The failure modes of the beams without steel fibers were typically brittle, whereas those reinforced with steel fibers exhibited ductile failure. The shear resistance of the beams could be significantly enhanced by the addition of steel fibers in the concrete mix. Furthermore, the post-cracking load-bearing performance of the beams could also be markedly improved by the addition of steel fibers. In addition, the shear span-to-effective-depth ratio had a considerable impact on the failure mode and the ultimate shear strength of the tested beams. The contribution of steel fibers to the shear capacity of the UHPC beams was observed to increase as the shear span-to-effective-depth ratio increased. The French standard formulae tended to overestimate the contribution of steel fibers, and the calculation results were found to be more accurate for UHPC beams with a moderate shear span-to-effective-depth ratio (around 2.0). Moreover, the French standard formulae demonstrated greater accuracy at a larger beam height for calculating the contribution of UHPC matrix. [ABSTRACT FROM AUTHOR]

The main objective of this research is to investigate experimentally the effect of crushed and uncrushed coarse aggregate on the properties of hardened concrete (compressive strength) by adopting the American Concrete Institute (ACI) and the British Department of Environment (DoE) methods. Concrete mixes were designed, concrete cubes and cylinders were prepared and casted by using DoE and ACI respectively. DoE concrete design method considers both types of aggregates; crushed and uncrushed, while the ACI method does not take into account the effect of uncrushed coarse aggregate in design provisions. Then compressive strength tests of concrete samples were determined at ages of 7 and 28 days full curing period. The results obtained show that ACI gave higher values of compressive strength than that obtained by DoE for M30 and M40 except M25, which resulted in lower values than that obtained by DoE for crushed coarse aggregates. The 7-day compressive strength represents 75% of the 28-day compressive strength for ACI method, whereas in DoE reaching up to 73% and 77% for crushed and uncrushed coarse aggregate, respectively. [ABSTRACT FROM AUTHOR]