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Price changes in construction materials have a significant impact on building construction projects. Such price variations occur at random and at varying rates over time. A system that can estimate the magnitude and quantity of the change in material prices with reasonable accuracy is required. The primary goal is to create a machine-learning model that can predict the type of building material chosen based on environmental factors. The compressive strength of concrete is critical in defining its mechanical qualities. Long laboratory testing is needed to determine the compressive strength of concrete. The capacity of powerful machine learning algorithms to forecast concrete compressive strength speeds up these lengthy experimental methods while also lowering expenses. This study provides abilities to precisely anticipate and categorize numerous qualities and traits of distinct materials. The framework includes a broad dataset that details materials, composition, and performance characteristics. Machine learning algorithms such as logistic regression (LR), decision trees (DT), and random forests (RF) train models on the training data. The models are hyper-parameter tweaked and feature developed to achieve the most outstanding performance. The k-fold method is used throughout the training and assessment phase to guarantee robustness and reduce bias. The F1 score and Receiver Operating Characteristic-Area Under Curve (ROC-AUC) curve are two performance measures used to measure how accurate and predictive the trained models are. The study findings provide insights into the qualities of the materials, facilitating improved material selection, quality assurance, and decision-making in the building sector. In the analyses, the best accuracy value was 99.92%, and the precision value was 88.83% using the LR algorithm. As a result, it was determined that the LR algorithm had the least execution 57.826 ms, and is thus the most suitable for use in concrete compressive strength estimation. [ABSTRACT FROM AUTHOR]

The accelerated calcium dissolution tests of concrete with different replacement rates of manufactured sand (ρms) and different contents of stone powder (ρsp) were carried out using the ammonium chloride solution. The results show that the dissolution resistance of manufactured sand concrete (MSC) is higher than that of ordinary concrete, although the ρms and ρsp influence its physical and mechanical properties. When the ρms is low, the mass loss ratio and dissolution depth of MSC after dissolution both increase with the increasing ρsp. They also increase with the increasing of ρms, but the ρsp no longer influences them when the ρms is high. The ρsp corresponding to the maximum ultrasonic velocity of MSC is different for the various ρms. The addition of manufactured sand inhibits the reduction of the compressive strength after dissolution, while stone powder has no significant impact on this. Finally, the fitting model of dissolution depth and prediction model of compressive strength of MSC after dissolution are established. [ABSTRACT FROM AUTHOR]

Many critical concreting activities require the determination of the in-place concrete strength. It can be costly to wait too long to execute these activities, but acting too early can have a negative impact on structural performance. Conventional moulded concrete cylinders and alternative strength assessment methods such as the maturity method are commonly used to assess concrete's in-place strength. This study is focused on a special case when the maturity method is applied for evaluating concrete strength in cold weather at an early age. Specifically, the study proposes an alternative method for calibrating the activation energy, an input for the maturity method. Concretes cured at two different temperatures are used to calibrate the activation energy. The maturity method based on this activation energy predicted the cold weather concrete's compressive strength satisfactorily. It was also found that for a successful application of the proposed activation energy calibration, the two temperatures should represent the expected minimum and maximum temperature at the site. Furthermore, the results showed that the maturity method based on the proposed activation energy calibration method performed better than the conventional cylinder method. [ABSTRACT FROM AUTHOR]

Conduct alkali silica reaction (ASR) tests on concrete by using cement with different alkali contents and according to different test standards. The influence of cement alkali content on the alkali-silica reaction of concrete was explored, and the effects of different test methods on the results of alkali-silica reaction tests were compared. The results indicate that: the type of cement and the testing method used have no significant impact on the experimental results of the alkali silica reaction. The rate of alkali silica reaction accelerates with the increase of cement alkali content. When the alkali content of cement is greater than 2.0 %, there is no potential harm of alkali silica reaction in the aggregate, which will cause harm of alkali silica reaction. The research conclusion can provide reference for the control value of alkali content in engineering cement. [ABSTRACT FROM AUTHOR]

Suitcase bricks are widely used in the construction sector, due to their resistance, thermal and acoustic capacity; Furthermore, the subsistence of many families dedicated to this activity is involved in its manufacture. However, the potential for contamination in the manufacture of brick due to the burning that they are exposed to brings with it multiple effects that considerably deteriorate the environment every day. Given this problem, this research has been developed those deals with the manufacture of suitcase brick. artisanal by applying various concentrations of cement, for which 8 treatments were carried out with the following percentages of cement (0.10%, 0.25%, 0.5%, 1%, 2%, 4%, 6%, 8% and a control), in which each treatment consisted of 4% bricks and then two of each treatment were exposed to the burning process, to finally compare their resistance between the bricks that were not subjected to this process compared to the brick of Traditional manufacturing, using a four-column compression machine to break concrete specimens, each of the artisanal bricks under study was broken. According to the results obtained, the bricks from the treatment with 4% cement from the burning process showed the result of greater resistance of 121.01 Kgf/cm2, it can also be noted that the treatment with 1% cement without burning processes presented a value of 28.43 Kgf/cm2, which represents more than half the compressive strength of traditional brick with a burning process of 46.51 Kgf/cm2 (Control). [ABSTRACT FROM AUTHOR]

Additive manufacturing with concrete – guidance for planning and implementation of projects This guideline, created by the DAfStb Working Group "Digital Concrete Construction through Additive Manufacturing," serves as a comprehensive resource to support the planning and implementation of additive manufacturing projects in concrete construction. It is intended for architects, planners, applicants, material manufacturers, construction companies, and other parties involved in construction. After a brief introduction to the classification, terminology, and methods of additive manufacturing, legal aspects and approval procedures are highlighted to ensure seamless integration of this technology into construction practice. The guide addresses the integration of additive manufacturing methods with concrete into construction law, explains the approval process, and offers assistance for coordinating responsibilities in projects. It addresses technical rules for the design and construction of structures, particularly for walls produced by additive manufacturing, and covers constructive aspects of reinforcement. An important component is concrete and component testing, including methods for sample preparation and testing procedures for fresh and hardened concrete, making the guide a useful tool for professionals in the field of digital concrete construction. [ABSTRACT FROM AUTHOR]

The 7-d compressive strength, 28-d compressive strength, 28-d uniaxial compressive strength, 28-d splitting tensile strength, 28-d flexural strength and stress–strain test of steel-polyvinyl alcohol fiber recycled coarse aggregate self-compacting concrete (SF–PVA–RCASCC) were carried out by orthogonal test method. It was shown that the incorporation of SF and PVA enhances the bearing capacity of the concrete. Six mechanical properties of SF–PVA–RCASCC, such as the 7-d compressive strength, were higher than those of the reference group, with the largest increases of 19.2%, 12.21%, 22.02%, 12.2%, 21.73% and 93.53%, respectively. The six mechanical properties of the SF–PVA–RCASCC were analyzed using a range analysis of variance, a factor-level analysis, and a correlation analysis of gray entropy. The optimal mixing ratio of SF–PVA–RCASCC is obtained, and the effect of the VS, VP and RR variation rules on the mechanical properties of SF–PVA–RCASCC is obtained. The established constitutive model of axial compression is highly accurate. The best mixture ratios for SF–PVA–RCASCC are 0.75vol% VS, 0.05vol% VP and 75 wt% RR. We performed nonlinear regression analysis on the six mechanical properties of SF–PVA–RCASC, and obtained regression equations with high accuracy. The results can provide a theoretical basis and technical support for the engineering application of SF–PVA–RCACSCC. [ABSTRACT FROM AUTHOR]

One of the most significant damages of reinforced concrete is caused by chloride attacks. Solutions including the use of coatings or special concrete with low permeability have been proposed to promote concrete durability in previous research. Geopolymer mixes is a viable alternative in this context. Notwithstanding the advantages of geopolymer, problems with quick setting, shrinkage, increased cost, etc., may make its use problematic. Using permanent formworks (PFs) will therefore be a solution in this respect. PFs can be used both during the construction and during the repair of the structures. In this study, the considerations of fabricating PFs as well as their on-site implementation are examined. Compressive strength, impact resistance during transportation and installation, chloride ions penetration depth, and capillary absorption (from the seams and bulk) are among the experiments which are carried out to assess the performance of PFs. The significant increase in the service life of structures under chloride attack, the elimination of a part of the molding process in the construction of new structures, and the minimization of the low quality of execution are among the advantages of using PFs. The results reveal that the performance of PFs under harsh environmental conditions is appropriate. Although the use of polyurethane mastic in the seams has favorable results, reducing the number of seams decreases the probability of PFs damage. Although the implementing cost of PFs is slightly higher than conventional concrete (~ 37%), the life cycle cost assessment of the structure shows economic savings if PFs are applied. [ABSTRACT FROM AUTHOR]

The ultimate load is known as the ultimate strength of a structure. It is the maximum load a structure can withstand before collapsing. Structural reinforcement is needed for structures experiencing low strength due to dead load, live load, fatigue load, and earthquakes. In this research, Glass Fiber Reinforced Polymer (GFRP) shows a highly viable solution because of its benefits, encompassing exceptional corrosion resistance, lightweight properties, high strength, ease of installation, and commendable durability. This research aimed to compare the three sample groups to evaluate the effect of GFRP on reinforced concrete beams. The collected data included assessments of maximum load and deflection. Test specimens were constructed in three sets of distinct variations. The first set comprised concrete beams reinforced without GFRP, designated as control beams (BN), totaling three pieces. The second set entailed concrete beams reinforced with GFRP, labeled as BG. The third variation consisted of reinforced concrete beams subjected to collapse or post-ultimate load conditions and subsequently strengthened with GFRP, labeled as BGPU. The purpose is to observe the influence of GFRP-S reinforcement on reinforcing three beams. The analysis showed that direct GFRP-reinforced beams exhibited load increases ranging from 13.59% to 29.76% compared to control beams. In the case of post-ultimate load GFRP reinforcement, load enhancements of 6.80% to 16.78% were observed. These results showed the potential of GFRP reinforcement in repairing damaged beams, providing a viable solution for structural enhancement. [ABSTRACT FROM AUTHOR]

Aggregates recycled from construction sites may exhibit slightly inferior characteristics compared to natural aggregates in terms of porosity, friability, and variability. However, it must be acknowledged that although recycled aggregates are currently used only in small proportions for manufacturing concrete, their usage is steadily increasing. It is now widely recognised that the reuse of recycled aggregates in mortar and concrete significantly contributes to the preservation of alluvial aggregates. The valorisation of recycled aggregates in concrete and mortar offers a clear economic advantage in the construction sector. Indeed, the reuse of materials from demolition could be envisaged directly on site or at construction waste recycling and treatment platforms. Additionally, it should be noted that to date, there is no specific standard for measuring the water absorption of recycled aggregates. Regarding the physical properties, the estimation of the absorption kinetics of the recycled aggregates has proved necessary. Moreover, other equally important measurements must be undertaken to determine all the other properties. The results obtained demonstrated that a good correlation exists between the substitution rate and the physical and mechanical properties of the prepared concrete. Furthermore, it was decided to vary the substitution rate of natural sand with recycled sand during the manufacture of concrete according to the following percentages: 25% recycled sand with 75% natural sand, and 50% recycled sand with 50% natural sand. [ABSTRACT FROM AUTHOR]

Herein, we conducted a comprehensive statistical assessment of the ultrasonic pulse velocity (UPV) method's effectiveness in predicting concrete strength under diverse conditions, specifically early age, middle age, and high-temperature exposure. The concrete mixtures, with water-to-cement (W/C) ratios of 0.33 and 0.28, were classified as granite aggregate or coal-ash aggregate mixes. Compressive strength and UPV measurements were performed under these conditions, and subsequent statistical analyses treated the identified factors as distinct groups. The results revealed a substantial difference in compressive strength between specimens at early age (average of 13.01) and those at middle age (average of 41.96) and after high-temperature exposure (average of 48.08). Conversely, UPV analysis showed an insignificant difference between the early-age specimens and those after high-temperature exposure. The analysis of the W/C ratio and coarse aggregate demonstrated significant differences (p-value < 0.05) in compressive strength between specimens in middle age and those exposed to high temperatures, excluding the early-age specimens. However, UPV analysis revealed insignificant differences, with p-values of 0.67 and 0.38 between specimens at an early age and post-high-temperature exposure, respectively. Regression analysis identified suitable functions for each scenario, emphasizing the importance of a strength prediction model for concrete after high-temperature exposure, particularly considering the W/C ratio. Since concrete showed statistically different compressive strength, UPV, and strength prediction models in three conditions (early age, middle age, and high temperature), different strength prediction models must be used for the purpose of accurately predicting the strength of concrete. [ABSTRACT FROM AUTHOR]

This paper introduces a three-dimensional (3D) semi-explicit probabilistic numerical model for simulating crack propagation within the framework of the finite element method. The model specifically addresses macrocrack propagation using linear volume elements. The criteria governing the macrocrack propagation is based on the softening behavior observed in concrete under uniaxial tension. This softening behavior corresponds to a dissipated cracking energy that is equal to the mode I critical fracture energy (G I C) used in the Linear Elastic Fracture Mechanics theory (LEFM). The probabilistic nature of this model revolves around the random distribution of two mechanical properties: tensile strength (f t) and fracture energy, which varies based on the volume of finite elements. The scattering of the fracture energy increases as the volume of finite elements decreases in order to consider the strong heterogeneity of the material. This work primarily aims to estimate the relationship between the standard deviation of G I C and the volume of finite elements through the development of the numerical model. For this purpose, an inverse analysis is conducted based on a fracture mechanical test simulation. This test involves macrocrack propagation in a large Double Cantilever Beam (DCB) specimen with a crack length exceeding two meters. The proposed inverse analysis procedure yields highly significant results, indicating that the numerical model effectively evaluates both crack length and crack opening during propagation. [ABSTRACT FROM AUTHOR]

In this paper we address the question of whether high-temperature superconductors have anything in common with BCS-BEC crossover theory. Towards this goal, we present a proposal and related predictions which provide a concrete test for the applicability of this theoretical framework. These predictions characterize the behavior of the Ginzburg-Landau coherence length, ξ 0 coh , near the transition temperature Tc, and across the entire superconducting Tc dome in the phase diagram. That we are lacking a systematic characterization of ξ 0 coh in the entire class of cuprate superconductors is perhaps surprising, as it is one of the most fundamental properties of any superconductor. This paper is written to motivate further experiments and, thus, address this shortcoming. Here we show how measurements of ξ 0 coh contain direct indications for whether or not the cuprates are associated with BCS-BEC crossover and, if so, where within the crossover spectrum a particular superconductor lies. [ABSTRACT FROM AUTHOR]

Compressive strength (CS) is concrete's most important mechanical property, as it plays an important role in setting design criteria. Thus, an accurate and early assessment of the CS of concrete can minimize time, labor, and cost. This paper investigated the ability of the Radial Basis Function (RBF) to handle the prediction of CS. The nonlinearities raised from the novel utilized admixtures between the input variables and output CS is tried to be conducted with the RBF model. In order to make a flexible framework combination of the RBF model with the African Vulture Optimization (AVOA) and Salp Swarm Algorithm (SSA) techniques are considered. The results achieved from the RBF-AVOA model indicated good agreement between the actual and predicted values. The proposed model provides a very accurate HPC compressive strength prediction. In addition, the correlation coefficient R2 is equal to (0.997), and the values of mean absolute error (MAE) (0.1917 MPa), root mean square error (RMSE) (0.937 MPa), and variance account coefficient (VAF) (99.73%) are low. The performance of the RBF-AVOA model, compared to other models, provided the desired advantage and more stable predictions. AVOA plays a key role in modeling results, improving generalization capabilities, avoiding redundant data, and decreasing uncertainty. [ABSTRACT FROM AUTHOR]

Achieving the real mechanical performance of construction materials is significantly important for the design and engineering of structures. However, previous researchers have shown that contact friction performs an important role in the results of uniaxial compression tests. Strong discreteness generally appears in concrete-like construction materials due to the random distribution of the components. A numerical meso-scale finite-element (FE) method provides the possibility of generating an ideal material with the same component percentages and distribution. Thus, a well-designed meso-FE model was employed to investigate the effect of friction on the mechanical behavior and failure characteristics of concrete under uniaxial compression loading. The results showed that the mechanical behavior and failure profiles of the simulation matched well with the experimental results. Based on this model, the effect of friction was determined by changing the contact friction coefficient from 0.0 to 0.7. It was found that frictional contact had a slight influence on the elastic compressive mechanical behavior of concrete. However, the nonlinear hardening behavior of the stress–strain curves showed a fairly strong relationship with the frictional contact. The final failure profiles of the experiments showed a "sand-glass" shape that might be expected to result from the contact friction. Thus, the numerical meso-scale FE model showed that contact friction had a significant influence on both the mechanical performance and the failure profiles of concrete. [ABSTRACT FROM AUTHOR]

Understanding and predicting process–structure–property–performance relationships for concrete materials is key to designing resilient and sustainable infrastructure. While machine learning has emerged as a powerful tool to supplement empirical analysis and physical modeling, its capabilities are yet to be fully realized due to the massive data requirements and generalizability challenges. To address these limitations, we propose a knowledge‐informed machine learning framework for concrete property prediction that aggregates the wealth of domain knowledge condensed in empirical formulas and physics‐based models. By integrating the knowledge through data augmentation, feature enhancement, and model pre‐training, we demonstrate that this framework has the potential to (i) accelerate model convergence, (ii) improve model performance with limited training data, and (iii) increase generalizability to real‐world scenarios (including extrapolation capability to other datasets and robustness against data outliers). The overall improvement of machine learning models by knowledge integration is particularly critical when these models are scaled up to tackle the increasing complexity of modern concrete and deployed in practical applications. While demonstrated for predicting concrete strength, this versatile framework is applicable to a wide range of properties of concrete and other composite materials, paving the way for accelerated materials design and discovery. [ABSTRACT FROM AUTHOR]

The durability of bridges plays a vital role in their regular operation and transportation, particularly as service life increases. The ability of a bridge to reach its expected service life is closely linked to its durability. In cold regions, the deterioration of bridge concrete durability due to freeze-thaw damage is a common cause of failure, posing a threat to structural safety. In this study, a highway bridge over a sluice that was built 63 years ago was selected for coring and freeze-thaw testing. Two nondestructive testing methods were employed: three-dimensional optical scanning and X-ray computed tomography (X-CT). The former was used to observe and analyze the external surface of the concrete, while the latter was used to analyze its internal structure. The surface morphology was characterized using height, spatial, hybrid parameters, and fractal dimension, and the Abbott–Firestone curve reflected the profile characteristics of the material surface. Moreover, the internal components of concrete were identified and reconstructed in three dimensions based on threshold segmentation, and the changes in internal porosity, pore fractal dimension, and pore size distribution were calculated. Finally, the evolution of bandwidth in the color heat map was analyzed, combining the gray level cooccurrence matrix (GLCM) to reflect the growth of cracks and defects with freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

The Influence of the Physical and Chemical Properties of Hardened Cement Paste on the Fire‐induced Spalling of Concrete A number of major fire incidents in recent decades, particularly in tunnels and indoor car parks, have increased the awareness among construction designers towards the potential susceptibility of concrete to fire‐induced explosive spalling. In some fields of application, this violent breaking‐off of concrete layers may reduce the fire resistance time of fire‐exposed construction elements. The mechanisms causing explosive spalling are not yet fully understood and discussed controversially among scientists.Fire tests of concrete specimens have shown that the type of cement may have a marked influence on the susceptibility of concrete to explosive spalling. Three common characteristics of those concretes that were found to have an increasedsusceptibility of spalling were identified. For each of the three common characteristics, acorresponding hypothesis describing its possible contribution to the fire‐induced concretespalling was proposed. This second part of the article describes the experiments to verify the hypotheses using a dedicated test programme. The evaluation of the tests identified the main mechanisms by which spalling is caused. [ABSTRACT FROM AUTHOR]

Determination and validation of material parameters for the non‐linear modelling of concrete This article shows that the load‐bearing behavior of concrete and reinforced concrete beams can be successfully simulated using the material models included by default in the widely used ANSYS Mechanical software. The necessary material parameters are determined using laboratory tests. These are tests on concrete cylinders to determine the compressive and tensile strength as well as the modulus of elasticity. The fracture energy is determined on notched beams. This test is then simulated using the Drucker‐Prager model in combination with Rankine yield surfaces and exponential softening. The calculated load‐deformation behavior matches the test curves well when using the experimentally determined material parameters. A comparative calculation with normatively proposed parameters overestimates the fracture energy and thus the load‐bearing capacity of the test specimens. The numerical model is then validated using reinforced concrete beam tests. The model with the experimentally determined material parameters can reproduce the load‐bearing behavior of the test specimens well, but it also becomes clear that appropriate modeling of the bond behavior is important. In this case, the load‐bearing behavior of the beams with spring elements between concrete and reinforcement nodes is best described. Furthermore, it is shown that the use of reduced or fully integrated elements can have a major influence on the simulated softening behavior of concrete. [ABSTRACT FROM AUTHOR]

This experimental study evaluated the correlation between measured concrete expansion from a modified version of the miniature concrete prism test (MCPT) with the concentration of chemical markers leached from the prisms into an alkaline soak solution. Fifteen concrete mixture designs were tested for expansion and soak solution concentrations over time. The changes in expansion and soak solution concentrations were found to correlate well even with variations in alkali loading and substitution of cement with Class F fly ash. A model was developed to estimate the expansion potential of concrete based on an expansion reactivity index (ERI) that incorporated the concentrations of silicon, sulfate, calcium, and aluminum. The relationship between ERI and expansion was then used to identify potentially expansive concrete mixtures using the ERI of cores taken from a structure exhibiting potential alkalisilica reaction (ASR) expansion and concrete cylinders matching the mixture designs of the MCPT specimens. [ABSTRACT FROM AUTHOR]

Composite concrete structures, commonly found in urban infrastructures, such as highways and runways, are pivotal research object in the protection field. To study the dynamic response of composite concrete structures subjected to reactive jet penetration coupled with an explosive effect, a full-scale damage experiment of composite structures under the action of 150 mm caliber shaped charges was performed, to derive the dynamic damage modes of different concrete thicknesses under the combined kinetic and chemical energy damage effects. The results indicated that under aluminum jet penetration, concrete layers exhibited minor funnel craters and penetration holes. However, concrete layers displayed a variety of damage modes, including central penetration holes, funnel craters, bulges, and radial/circumferential cracks when subjected to the PTFE/Al jet. The area of the funnel crater expanded as the thickness of the concrete increased, while the height of the bulge and the number of radial cracks decreased. The diameter of penetration holes increased by 76.9% and the area of funnel crater increased by 578% in comparison to Al jet penetration damage. A modified-RHT concrete model that reflected concrete tensile failure was established, utilizing AUTODYN. Segmented numerical simulations of damage behavior were performed using the FEM-SPH algorithm and a restart approach combined with reactive jet characteristics. The spatial distribution characteristic of the reactive jet and the relationship between kinetic penetration and explosion-enhanced damage were obtained by the simulation, which showed good concordance with the experimental results. This study provides important reference data and a theoretical basis for the design of composite concrete structures to resist penetration and explosion. [ABSTRACT FROM AUTHOR]

The design of geopolymer concrete must meet more stringent requirements for the landscape, so understanding and designing geopolymer concrete with a higher compressive strength challenging. In the performance prediction of geopolymer concrete compressive strength, machine learning models have the advantage of being more accurate and faster. However, only a single machine learning model is usually used at present, there are few applications of ensemble learning models, and model optimization processes is lacking. Therefore, this paper proposes to use the Firefly Algorithm (AF) as an optimization tool to perform hyperparameter tuning on Logistic Regression (LR), Multiple Logistic Regression (MLR), decision tree (DT), and Random Forest (RF) models. At the same time, the reliability and efficiency of four integrated learning models were analyzed. The model was used to analyze the influencing factors of geopolymer concrete and determine the strength of their influencing ability. According to the experimental data, the RF-AF model had the lowest RMSE value. The RMSE value of the training set and test set were 4.0364 and 8.7202, respectively. The R value of the training set and test set were 0.9774 and 0.8915, respectively. Therefore, compared with the other three models, RF-AF has a stronger generalization ability and higher prediction accuracy. In addition, the molar concentration of NaOH was the most important influencing factors, and its influence was far greater than the other possible factors including NaOH content. Therefore, it is necessary to pay more attention to NaOH molarity when designing geopolymer concrete. [ABSTRACT FROM AUTHOR]

This study further explores the problems in the concrete material studied in terms of variations in the structure of the constituent materials and the grain size of red sand on the compressive strength test of quality concrete material with code K-350. The primary raw material uses red sand with compositions ranging from 0%, 2%, 4%, and 6% with sizes ranging from 120, 100, and 80 mesh. After all the ingredients are mixed, printing is carried out according to the predetermined sample size; after the sample is deposited for one day and one night, the sample is opened from the mold mall. To see the quality of the sample, testing was carried out by testing the concrete structure through the SEM test, and the sample elements were looked at by testing XRD, compressive strength, and water absorption. The results obtained were a successive decrease in water absorption in red sand samples with a composition of 4%. In addition, the maximum compressive strength value was obtained at the proportion of 120 mesh material, and 6 percent of the material composition obtained a compressive strength value of 35.27 MPa. When viewed from the size of the concrete structure using the scanning Electron Microscope test, it was found that the size of the red sand mixture concrete structure has a much smaller pore structure when compared to other mixtures. and in the X-Ray Diffraction test, it was found to contain elements in the form of SiO2, CaO3, Ca (OH)2 with the highest intensity of silicon. [ABSTRACT FROM AUTHOR]

The mitigation of sewage sludge is quite challenging, as the general method of disposal of sludge after being treated at the waste water treatment plant is landfilling, which makes land unfit for either agricultural or commercial growth. The disposal of sewage sludge in India presents significant environmental challenges due to increasing urbanization and limited land availability. Understanding the potential use of sewage sludge as a construction material has been verified to be the best method of recycling and environmental protection. The possible use of sewage sludge in civil engineering firms is discussed in this paper, along with the various testing methods. Carefully treated sewage sludge is proven to be an effective material, either as a replacement for cement or aggregates in construction. This paper indicates that sewage sludge can be effectively utilized as a raw material in concrete, contributing to resource conservation and environmental sustainability. It supports the feasibility of using sewage sludge in various construction applications, such as eco-cement, bricks, and lightweight aggregates, offering an eco-friendly solution to sewage sludge disposal. [ABSTRACT FROM AUTHOR]

The main Aim is that finding a strength of repaired bonded structure by Epoxy performing Slant Shear Test. Our structure is damaged due to some natural and manmade events after all we need to rehabilited and repaired the old structure or a damaged structure. There are many Research and study that focuses on repairing concrete structure by using epoxy based resin as a binding material. Our Focus is make use of concrete is very less and instead of these we use a binding material that is Epoxy resin to make a construction faster and easier and having a strength as like as concrete mix. The slant shear test strength is conducted for block of repaired concrete are based on concrete grade of substrate and thickness of epoxy. Casting of different grades of cylindrical slants and cured up to 28 days. After that taking these cylindrical slants and bonded them with epoxy using different thickness and test using specification of ASTM C882. It is observed that increase in thickness the strength of concrete is also increase and also observed that failure of bonding is occur when two substrate of different material is bonded and fails the substrate whichever is low grade. [ABSTRACT FROM AUTHOR]

The paper concerns destructive and non-destructive (NDT) evaluation of the effect of the addition of superabsorbent polymer (SAP) used as a carrier of mixing water and a means of internal curing on the durability of concrete. The research concerns testing of five concretes—an ordinary reference concrete and four concretes differing in the content of mixing water introduced into the concrete mix in the form of pre-saturated SAP particles (25%, two variants of 50% and 75% of the total mixing water in the form of SAP hydrogel). The research consisted of 4 stages of tests. The subsequent stages involved the analysis of the effect of using SAP as a carrier of mixing water on the particular characteristics of concrete mix and hardened concrete, i.e., consistency and density of concrete mix (1st stage), carbonation tested using two indicators—phenolphthalein and thymol phenolphthalein (2nd stage), and finally: the homogeneity of the concretes' structure by means of ultrasonic method (determination of ultrasonic pulse velocity) 28 days after production (3rd stage) and 3 years after production (4th stage). The ultrasonic pulse (or wave) velocity was then correlated with the content of water applied in the form of SAP hydrogel. The statistical analysis of results showed that the method of introducing the mixing water into the concrete mix in the form of pre-absorbed superabsorbent polymer, although it changed the concrete mix consistency, did not significantly affect the concrete ability to resist carbonation. Meanwhile, after 3 years, the densification of the microstructure of concrete with SAP has been observed. [ABSTRACT FROM AUTHOR]

The design process for pile foundations necessitates meticulous deliberation of the calculation pertaining to the bearing capacity of the piles. The primary objective of this work was to investigate the potential use of Coot bird optimization (CBO ) techniques in predicting the load-bearing capacity of concrete-driven piles. Despite the availability of several suggested models, the investigation of Coot bird optimization (CBO ) for estimating the pile-carrying capacity has been somewhat neglected in this research. This work presents and validates a unique approach that combines the Coot bird optimization (CBO ) model with the Multi-layered perceptron (MLP ) neural network and adaptive neuro-fuzzy inference system (ANFIS ). The findings of 472 different driven pile static load tests were put in a database. The proposed framework's building, validation, and testing stages were each accomplished utilizing the training set (70%), validation set (15%), and testing set (15%) of the dataset, respectively. According to the findings, MLP CBO and ANFIS CBO both offer remarkable possibilities for accurately predicting the pile-bearing capacity of a given structure. The R 2 values for ANFIS CBO during the training stage were 0.9874, while during the validating stage, they were 0.9785, and during the testing stage they were 0.987. After considering various kinds of performance studies and contrasting them with existing literature, it has been concluded that the ANFIS CBO model provides a more appropriate calculation of the bearing capacity of concrete-driven piles. [ABSTRACT FROM AUTHOR]

This paper presents a fiber element analysis model that simulates the structural responses of square steel‐reinforced concrete‐filled steel tubular (SRCFST) short columns under concentric compression including local buckling effects. The method of effective widths is utilized to model the gradual postlocal buckling of the steel tube walls of a SRCFST column loaded axially to failure. A new confinement model is developed for the concrete based on test results, considering the confinement induced by the embedded steel section. This confinement model is incorporated into the fiber model, and its accuracy is verified by experimental results. The accuracy of various confinement models proposed for concrete‐filled steel tubular (CFST) square columns in predicting the performance of SRCFST columns is evaluated. A parametric study is performed to investigate the performance of SRCFST columns with various parameters. The applicability of the design formulas specified in current standards for CFST columns to the design of SRCFST columns is examined. A formula is proposed to predict the strength of SRCFST short columns. The developed inelastic simulation model, confinement model, and design formula are found to yield performance predictions of SRCFST columns with good accuracy. [ABSTRACT FROM AUTHOR]

The potential reactivity of a coarse recycled concrete aggregate (CRCA) obtained from concrete damaged by alkali–silica reaction (ASR) was evaluated by the concrete prism test method. Different recycled aggregate replacement percentages and exposure conditions were considered. Moreover, the use of Portland-limestone cement (PLC) as a preventive measure to mitigate the deleterious effect of ASR according to the Argentinian regulation was considered to evaluate the residual expansion of the CRCA. Expansions were recorded up to the age of 156 weeks, and different mechanical properties were also determined. The use of ordinary Portland cement (OPC) leads to an increase in ASR expansions for recycled concretes as CRCA content increases, whereas when PLC is used, expansions remain lower than the limits fixed in the standard test method, even at older ages. [ABSTRACT FROM AUTHOR]

This study connects and compares the results from two different rheological measurement techniques, namely, the slump test and rotational rheometry, on UHPC (Ultra-High-Performance Concrete) through the use of commercially available numerical simulation software ANSYS Fluent 2022 R2. The workability and resulting mechanical properties of the UHPC (a material used in construction) are highly dependent on its rheology and, hence, also on the composition and level of homogeneity of the assessed mixture. It is generally understood that the most suitable rheological model for concrete mixtures is the Hershel–Bulkley model. However, obtaining reliable rheological data is complicated as the wide-gap rotational rheometers developed for concrete show bias in their measurements even on precise laboratory equipment, while common industrial tests, such as the slump test, do not produce the usual shear rate–shear stress relation and, hence, do not allow for more complex analysis. Recently, a new methodology for the rheological measurement of non-Newtonian fluids that utilises a simple power input–rotation speed measurement was published. However, in this study, only model liquids were evaluated, and the method was not validated for more complex fluids such as pastes. Therefore, it was the goal of this study to show this method's suitability for fine pastes through a comparison with the slump test, using numerical simulation. [ABSTRACT FROM AUTHOR]

Due to the growing need for sustainable and ultra-high-strength construction materials, scientists have created an innovative ultra-high-performance concrete called Geopolymer based ultra-highperformance concrete (GUHPC). Besides, in the last few decades, there have been a lot of explosions and ballistic attacks around the world, which have killed many civilians and fighters in border areas. In this context, this article reviews the fresh state and mechanical properties of GUHPC. Firstly, the ingredients of GUHPC and fresh properties such as setting time and flowability are briefly covered. Secondly, the review of compressive strength, flexure strength, tensile strength and modulus of elasticity of fibrous GUHPC. Thirdly, the blast and projectile impact resistance performance was reviewed. Finally, the microstructural characteristics were reviewed using the scanning electron microscope and X-ray Powder Diffraction. The review outcome reveals that the mechanical properties were increased when 30% silica fume was added to a higher dose of steel fibre to improve the microstructure of GUHPC. It is hypothesized that the brittleness of GUHPC was mitigated by adding 1.5% steel fibre reinforcement, which played a role in the decrease of contact explosion cratering and spalling. Removing the need for cement in GUHPC was a key factor in the review, indicating a promising potential for lowering carbon emissions. However, GUHPC research is still in its early stages, so more study is required before its full potential can be utilized. [ABSTRACT FROM AUTHOR]

An auditorium offers immense potential to increase connections with community to a large extent. From the literature, it is observed that most of the auditoriums were designed for only two-way slab and by considering different types of footing. Analysis and designs were not available for auditoriums with different types of slabs. Comparative studies are also not available for the same and that necessitated this project. The main objective is to plan, analyse and design an auditorium with one-way, two-way and grid slab. The project involves the planning, analysis, and design of an auditorium with a seating capacity of 500 people as per the of (IS 2526-1963 [5]). The plans of an auditorium were developed using AutoCAD software. Analysis and design of an auditorium were carried out using STAAD Pro software. An auditorium with two-way slab is found to be economical compared to an auditorium with one way slab and grid slab based on the volume of concrete required. The critical elements of auditorium such as slabs, beams, columns and footings were manually designed for the forces and moments obtained from the analysis. From this project, it is concluded that the grid slab offers lesser thickness. However, by considering design an auditorium with two way slab was found to be more economical. [ABSTRACT FROM AUTHOR]

The construction industry grapples with significant challenges posed by climate change and urbanization, driving the imperative for innovative materials to elevate the performance and durability of civil infrastructure in the pursuit of sustainability. In this research, the application of crystalline waterproofing admixtures (CWA) to improve concrete durability is investigated. The study aims to analyze the effect of CWA on concrete performance by conducting a series of tests on different concrete mixtures. These tests include slump tests, compressive strength tests, water penetration tests, and chemical resistance tests using sulfuric acid (H2SO4) and hydrochloric acid (HCl) solutions. The results indicate that incorporating CWA into concrete leads to notable improvements. Specifically, the addition of 1% CWA enhances compressive strength from 41 MPa to 43.2 MPa, a 5.4% improvement. Similarly, 2% CWA results in a 6.1% increase, reaching 43.5 MPa. Water penetration tests indicate substantial benefits, with 1% CWA reducing penetration from 43 mm to 20 mm (53% improvement), and 2% CWA further reducing it to 15 mm (65% improvement). Additionally, CWAtreated concrete exhibits improved chemical resistance, resulting in higher compressive strength values and lower mass loss percentages after chemical exposure. The combination of CWA with cement type I demonstrates comparable performance to cement type V in terms of compressive strength and chemical resistance. The research contributes to the understanding of concrete technology, guiding engineers in selecting suitable materials to enhance the longevity and serviceability of concrete structures in various environmental conditions. [ABSTRACT FROM AUTHOR]

Engineered cementitious composite (ECC) functional gradient concrete has a promising application future, and its mechanical features are piquing the interest of researchers. The impacts of this strength class of concrete, interface reinforcement technique, ECC thickness (i.e., fiber dosage), and other factors on the splitting tensile strength qualities are explored using an experimental investigation of functional gradient concrete. The splitting tensile tests of 150 mm × 150 mm × 150 mm functional gradient concrete specimens were used to explore the link between concrete strength grade, interface reinforcing technique, and ECC thickness with polyvinyl alcohol (PVA) fiber additive and functional gradient concrete. The test results show that the splitting tensile strength of functional gradient concrete increases as the concrete strength grade increases; different interfacial treatments have a significant effect on the splitting tensile strength of functional gradient concrete; and the effect of ECC thickness change on the splitting tensile strength of functional gradient concrete shows different trends, which research can be used as an experimental reference for functional gradient concrete engineering applications. [ABSTRACT FROM AUTHOR]

This study conducts an extensive comparative analysis of computational intelligence approaches aimed at predicting the compressive strength (CS) of concrete, utilizing two non-destructive testing (NDT) methods: the rebound hammer (RH) and the ultrasonic pulse velocity (UPV) test. In the ensemble learning approach, the six most popular algorithms (Adaboost, CatBoost, gradient boosting tree (GBT), random forest (RF), stacking, and extreme gradient boosting (XGB)) have been used to develop the prediction models of CS of concrete based on NDT. The ML models have been developed using a total of 721 samples, of which 111 were cast in the laboratory, 134 were obtained from in-situ testing, and the other samples were gathered from the literature. Among the three categories of analytical models—RH models, UPV models, and combined RH and UPV models; seven, ten, and thirteen models have been used respectively. AdaBoost, CatBoost, GBT, RF, Stacking, and XGB models have been used to improve the accuracy and dependability of the analytical models. The RH-M5, UPV-M6, and C-M6 (combined UPV and RH model) models were found with highest performance level amongst all the analytical models. The MAPE value of XGB was observed to be 84.37%, 83.24%, 77.33%, 59.46%, and 81.08% lower than AdaBoost, CatBoost, GBT, RF, and stacking, respectively. The performance of XGB model has been found best than other soft computing techniques and existing traditional predictive models. [ABSTRACT FROM AUTHOR]

This paper presents a groundbreaking method for predicting the compressive strength (Fc) of recycled aggregate concrete (RAC) through the application of K-nearest neighbors (KNN) analysis. The task of designing mixture proportions to achieve the desired Fc can be remarkably intricate, owing to the intricate interplay among the components involved. Machine learning (ML) algorithms have exhibited considerable promise in tackling this complexity effectively. In pursuit of enhanced prediction accuracy, this research introduces a semi-empirical approach that seamlessly integrates strategies, including optimization techniques. This study incorporates two meta-heuristic methods, the Fire Hawk optimizer (FHO) and Runge–Kutta optimization (RUK) to enhance model accuracy. The research results reveal three separate models: KNFH, KNRK, and a single KNN model, each providing valuable insights for precise Fc prediction. Remarkably, the KNFH model stands out as a top performer, boasting an impressive R2 value of 0.994 and a meager RMSE value of 1.122. These findings not only validate the accuracy and reliability of the KNFH model but also highlight its effectiveness in predicting Fc outcomes. This approach holds great promise for precise Fc forecasting in the construction industry. Integrating meta-heuristic algorithms significantly improves model accuracy, leading to more reliable forecasts with profound implications for construction projects and their outcomes. This research marks a significant advancement in predicting Fc using ML, offering valuable tools for engineers and builders. [ABSTRACT FROM AUTHOR]

Non-destructive testing is becoming a major tool for estimating the adequacy of concrete for existing structures. However, there is a need to establish reliability of the non-destructive testing equipment as compared to the conventional destructive test methods. The study focuses on comparisons conducted on a sample size of 24 concrete cubes prepared by two different batches of concrete ratios. i.e (1:2:4) and (1:1.5:3). This research study was designed to compare strengths and behavior of concrete using the two batches of concrete. Cubes that were tested at 03, 07, 14, and 28 days by using Rebound Hammer, Compression Testing Machine (CTM), Cut and Pull out (CAPO) test, Air permeability Coefficient and Ultra Sonic Pulse Velocity Tester available with the Council for Works and housing Research (CWHR). The results of all tests indicate that nondestructive test methods are by and large reliable and comparable to the destructive testing methods at CWHR. [ABSTRACT FROM AUTHOR]

As one of the concrete admixtures, water reducing admixtures and superplasticizers are usually used to reduce the mixing water volume and improve the performance of the harden concrete while maintaining better workability of the fresh concrete. However, the concrete strength and durability properties are affected differently by different types and dosages of the water reducing admixtures and superplasticizers. Based on the published literatures, this paper comprehensively reviews and analyzes this problem. Different types of the concretes, including ordinary Portland cement concrete, ordinary Portland cement concrete containing pozzolan, fly ash and ground granulated blast furnace slag, calcium sulfoaluminate cement concrete, ferrite aluminate cement concrete, recycled aggregates concrete, lightweight aggregate concrete, self-compacting concrete and ultra-high performance concrete, are considered to discuss the influence of types and dosages of the water reducing admixtures and superplasticizers on their strengths. Water absorption, frost resistance and permeability resistance of the concrete are mainly reviewed to discuss this influence on the durability properties of the concrete. Then, some suggestions on the application of the water reducing admixtures and superplasticizers in reinforced concrete structures and projects are proposed. [ABSTRACT FROM AUTHOR]

A novel chlorine- and fluorine-free liquid accelerator was developed in this study. The proportion of each component of the accelerator was determined using an orthogonal test method. Various additives' impact on the cement setting time and concrete compressive strength was analyzed. The mechanism of the accelerator on cement hydration was examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) experiments. The results showed that the optimal ratios for the raw materials were 45% aluminum sulfate, 15% sodium metaaluminate, 5% magnesium sulfate, 3% citric acid, 7% triethanolamine (TEA), and 1% polyacrylamide to make the liquid accelerator. At a concentration of 5% accelerator, the initial setting time of cement was 210 s and the final setting time was 380 s. The compressive strength of the concrete test block was 11.4 MPa after 1 day and it increased to 28.32 MPa after 28 days. This represents a 141.6% increase in compressive strength after 28 days. The addition of the accelerator consumes Ca2+ and promotes the formation of ettringite (AFt) and gypsum (Gyp), thus promoting cement hydration, reducing initial setting time, and densifying cement's internal structure. The accelerator not only has low production cost and excellent quick-setting effect, but also can improve the strength of concrete, making it suitable for a wide range of applications. [ABSTRACT FROM AUTHOR]

The Influence of the Physical and Chemical Properties of Hardened Cement Paste on the Fire‐Induced Spalling of Concrete A number of major fire incidents in recent decades, particularly in tunnels and indoor car parks, have increased the awareness among construction designers towards the potential susceptibility of concrete to fire‐induced explosive spalling. In some fields of application, this violent breaking‐off of concrete layers may reduce the fire resistance time of fire‐exposed construction elements. The mechanisms causing explosive spalling are not yet fully understood and discussed controversially among scientists. Fire tests of concrete specimens have shown that the type of cement may have a marked influence on the susceptibility of concrete to explosive spalling. The main objectives of the experimental programme described in this article were therefore to – determine the way in which the physical and chemical properties of the hardened cement paste influence the spalling propensity of heated concrete; and in this manner – contribute to a better understanding of the mechanisms causing explosive spalling. Three common characteristics of those concretes that were found to have an increased susceptibility of spalling were identified. For each of the three common characteristics, a corresponding hypothesis describing its possible contribution to the fire‐induced concrete spalling was proposed. The first part of this article describes the tests in which the influence of the type of cement on the susceptibility of concrete to explosive spalling was investigated, as well as thethree hypotheses. Each of the three hypotheses in turn was verified through a dedicated experimental programme. The experiments to verify the hypotheses are described in the second part of this article. The evaluation of the experiments identified the main mechanisms by which spalling is caused. [ABSTRACT FROM AUTHOR]

The focus of this study is on the shrinkage differences between new and old concrete, which can cause cracks at the bonding surface of the interface. The effects of various factors on shrinkage, such as the content of shrinkage reducing admixtures (SRA) the content of basalt fibers (BF) and the roughness at the new-to-old concrete interface (RI) are also examined. In this research, nine groups old-new concrete composite specimens were tested for shrinkage to gather experimental data. The restrained shrinkage mechanical model (RSMM) was deduced, and the restrained shrinkage model based on grey correlation analysis (RMGC) was proposed. The effectiveness and convenience of both prediction methods were evaluated by comparing their results to the experimental data. It was determined that the RMGC was more effective and convenient. Additionally, the research found that as the content of SRA and BF increases, shrinkage decreases. The effect of SRA was found to be more significant. As RI increases, shrinkage undergoes an initial increase and then decreases. The study can be used to inform the design and construction of structures that use both new and old concrete. [ABSTRACT FROM AUTHOR]

Large concrete structures such as buildings, bridges, and tunnels are aging. In Japan and many other countries, those built during economic reconstruction after World War II are about 60 to 70 years old, and flacking and other problems are becoming more noticeable. Periodic inspections were made mandatory by government and ministerial ordinance during the 2013-2014 fiscal year, and inspections based on the new standards have just begun. There are various methods to check the soundness of concrete, but the hammering test is widely used because it does not require special equipment. However, long experience is required to master the hammering test. Therefore, mechanization is desired. Although the difference between the sound of a defective part and a normal part is very small, we have shown that neural network is useful in our research. To use this technology in the actual field, it is necessary to meet the forms of concrete structures in various conditions. For example, flacking in concrete exists at various depths, and it is impossible to learn about flacking in all cases. This paper presents the results of a study of the possibility of finding flacking at different depths with a single inspection learning model and an idea to increase the accuracy of a learning model when we use a rolling hammer. [ABSTRACT FROM AUTHOR]

The standard approach for testing ordinary concrete compressive strength (CS) is to cast samples and test them after different curing times. However, testing adds cost and time to projects, and, therefore, construction sites experience delays. Because carbon nanotubes (CNTs) vary in length, composition, diameter, and dispersion, experiment and formula fitting alone cannot reliably predict the strength of CNTs-based composites. For empirical equations or traditional statistical approaches to properly forecast complex materials' mechanical characteristics, various significant parameters, databases, and nonlinear relationships between variables must be considered. Machine learning (ML) tools are the most advanced for accurate predictions of material behaviour. This study employed gradient boosting, light gradient boosting machine, and extreme gradient boosting techniques to forecast the CS of CNTs-modified concrete. Also, in order to explore the influence and interaction of various features, an interaction analysis was conducted. In terms of R2, gradient boosting, light gradient boosting machine, and extreme gradient boosting models proved their accuracy. Extreme gradient boosting had the highest R2 of 0.97, followed by light gradient boosting machine and gradient boosting with scores of 0.94 and 0.93, respectively. This type of research may help both academics and industry forecast material properties and influential elements, thereby reducing lab test requirements. [ABSTRACT FROM AUTHOR]

This study examines the properties of ordinary and high-strength fiber-reinforced pervious concrete, aiming for a 28-day compressive strength exceeding 40 MPa with a target porosity close to 15%. Utilizing glass fiber (at 0.25% and 0.5% volume ratios) and steel fiber (at 1% and 2%), the study conducts mechanical and abrasion resistance testing on pervious concrete specimens. Sand dust clogging experimental simulations assess permeability coefficients for both application and maintenance purposes, revealing optimized maintenance, including vacuum cleaning and high-pressure washing, can restore water permeability to over 60%. The specific mix designs demonstrate high-strength pervious concrete achieves a 28-day compressive strength ranging from 40 to 52 MPa, with corresponding porosities ranging from 7% to 16%. Results highlight the significant impact of the ASTM C1747 impact abrasion test, where ordinary pervious concrete exhibits a cumulative impact abrasion rate reaching 60%, contrasting with approximately 20% for other high-strength specimens. [ABSTRACT FROM AUTHOR]

Early freezing of concrete is common in the construction of water conservancy projects in northern China. Early freezing damage induces the deterioration of the mechanical properties of concrete structures, which seriously affects the safety, stability, and service life of engineering structures. Through a laboratory uniaxial compression test and a computed tomography (CT) test, the influence law of freezing time and freezing temperature on the mechanical properties of concrete is analyzed herein. The three-dimensional pore structure of concrete at different freezing times is reconstructed. The pore distribution and pore structure characteristic parameters of concrete at different freezing times are studied. The correlation between mechanical properties and the pore structure of early frozen concrete is determined. The results show that with the delay of freezing time, the porosity of concrete test blocks increases first and then decreases. The average pore surface area primarily decreases and then increases. The average pore diameter increases with the trend of a quadratic parabola. The average pore form factor primarily decreases, then increases, and then decreases. The average pore surface area has the best correlation with the compressive strength and elastic modulus of early frozen concrete. The outcomes suggest that the average pore surface area should be preferred when constructing the mesoscopic damage index of early frozen concrete. Relevant results provide support for revealing the macro and micro damage mechanisms of early frozen concrete. [ABSTRACT FROM AUTHOR]

To ensure the safe operation of concrete structures of deep-burial storages, it is necessary to research the degradation mechanisms of such structures. Concrete carbonation is one of the key factors determining the service life of concrete structures. Existing methods for the concrete carbonation process research at various stages of the building structure life cycle make it possible to conduct model tests in the shortest possible time by simulating the operational factors influencing the corrosion process development. The authors carried out model tests of concrete of deep-burial storages using the method of accelerated concrete carbonation and by taking into account the effects of elevated temperatures. When exposed to elevated temperatures during carbonation, concrete samples exhibit a decrease in compressive strength in the first 56 days of testing by an average of 1.6 MPa. However, by the end of the tests (168 days), the strength of concrete samples at elevated temperatures is on average 4 MPa higher. The microstructure and carbonation dynamics were studied by XRD, TGA and SEM. The data obtained in the research can be used to develop models for predicting the service life of concrete structures of deep-burial storages. [ABSTRACT FROM AUTHOR]

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