Frost Resistance Of Concrete Research Articles

Research on the Resistance Performance and Damage Deterioration Model of Fiber-Reinforced Gobi Aggregate Concrete.

Concrete prepared using Gobi sand and gravel instead of ordinary sand and gravel is referred to as Gobi concrete. In order to explore the effect of fibers on the frost resistance of Gobi concrete, as well as to enhance the service life of Gobi aggregate concrete in Northwest China, experiments were conducted with fiber types (polypropylene fibers, basalt fibers, polypropylene-basalt fibers) and fiber volume fractions (0%, 0.1%, 0.2%, 0.3%) as variable parameters. This study investigated the surface morphology, mass loss rate, and relative dynamic elastic modulus of fiber-reinforced Gobi concrete after different freeze-thaw cycles (0, 25, 50, 75, 100). Corresponding frost damage deterioration models were proposed. The results indicate that fibers have a favorable effect on the anti-peeling performance, mass loss rate, and dynamic elastic modulus of Gobi aggregate concrete. The improvement levels of different fiber types are in the following order: 0.1% basalt-polypropylene fibers, 0.2% polypropylene fibers, and 0.3% basalt fibers. Compared to Gobi concrete exposed to natural environmental conditions, the freeze-thaw cycle numbers increased by 343, 79, and 69 times, respectively. A quadratic polynomial damage model for fiber-reinforced Gobi concrete, using relative dynamic elastic modulus as the damage variable, was established and demonstrated good predictive performance.

Study on the influence of fractal dimension and size effect of coarse aggregate on the frost resistance of hydraulic concrete

In cold regions, hydraulic concrete structures are exposed to harsh environmental conditions that greatly impact their durability and safety. The role of aggregates in influencing concrete performance is paramount. This study aims to investigate how the fractal distribution and size of aggregates affect the frost resistance of hydraulic concrete, with air void characteristics, mass loss rate, Elastic Modulus of dynamic, and strength serving as primary references. Two experiment series, fractal distribution influence and aggregate size influence of concrete frost resistance, were conducted to analyze the frost resistance of hydraulic concrete with different aggregates. Based on the fractal theory, four grading fractal distributions were utilized to fractalize aggregate gradation, aiming to investigate the influence of aggregate fractal dimension on the frost resistance of hydraulic concrete. Simultaneously, concrete specimens of fully graded aggregate and wet-screened aggregate were also constructed to simultaneous freeze-thaw cycle tests, the impact of aggregate size on concrete's frost resistance performance was also studied by analyzing the air void structure in the frost-resistant concrete specimens. Results indicate that the specimens exhibit varying frost resistance performance under different aggregate gradation fractals, ranking from strongest to weakest as follows: D=2.5, D=2.3, D=2.1, D=2.7, which is attributed to the differences of air void spacing factors. Increasing aggregate size leads to greater internal structural heterogeneity in concrete, resulting in an increase in defects and weak points. This causes microcracks to develop more rapidly in the transition zone of fully graded concrete during freeze-thaw cycles, leading to more severe damage. The findings of this study can serve as a fundamental scientific basis for the designing and constructing of hydraulic concrete structures in cold areas.

Frost Resistance of Silicate Bricks

The article presents the results of a research frost resistance of silicate bricks one of the Russian factories produced in different periods. The change in appearance, weight and strength of silicate bricks during alternate freezing-thawing was evaluated. It has been established that silicate bricks, can meet high frost resistance grades F150-200, in terms of appearance, while the reduction in compressive strength does not exceed 9%. Some increase in brick strength at the initial stage of testing was noted, which is probably explained by the processes of carbonization of free calcium hydroxide and high-basic calcium hydrosilicates, accompanied by their recrystallization into low-basic ones, which is confirmed by the results of differential-thermal and X-ray phase analysis. It is concluded that the frost resistance of silicate bricks is decisively influenced by the mineralogical composition of the cementitious bond. High strength and frost resistance of silicate concrete is provided by the simultaneous presence of low-basic calcium hydrosilicates and α-C2S hydrate in the composition of the new formations. The condition for the formation of such composition of neoplasms is excessive content of lime in the composition of the raw material mixture.

Effect of nanosilica and fiber on mechanical properties and microstructure of recycled coarse aggregates road concrete

Recycled coarse aggregate has its own characteristics of large porosity, high water absorption and high crushing index, which adversely affects the mechanical strength and durability of recycled aggregate concrete. In this study, the mechanical properties, durability and microstructure of recycled aggregate concrete (RAC) modified with nano-SiO2 (NS) and fibres were investigated to prepare road RAC, using NS polypropylene fibres (PPF) and basalt fibres (BF) as test variables. Compared with RAC only incorporating NS, NS and fibre synergism can significantly enhance the mechanical properties of recycled concrete, compressive strength increased by 27–51 %, flexural strength increased by 12 %, and abrasion resistance increased by 25–72 %. The synergistic effect of NS and PPF significantly improves the frost resistance of recycled concrete. NS has a volcanic ash effect which can react with calcium hydroxide to produce a large number of C-S-H in the secondary hydration reaction, making the internal structure of the cement matrix denser. Interfacial transition zone microstructure is more compact, thus interfacial transition zone porosity is effectively reduced. The hydration products are attached to the fibre surface, which enhances the bonding ability between the fibers and matrix. Therefore, the fibres effectively inhibit the generation and development of internal micro-cracks. NS optimises the internal pore structure of recycled aggregate concrete and enhances the interfacial transition zone, and NS synergistically with PPF can improve the strength and durability of various mechanical properties of recycled concrete. The research results provide the scientific basis for the application of road RAC.

Sensitivity Analysis of Influencing Factors and Two-Stage Prediction of Frost Resistance of Active-Admixture Recycled Concrete Based on Grey Theory-BPNN.

Sensitivity analysis of influencing factors on frost resistance is carried out in this paper, and a two-stage neural network model based on grey theory and Back Propagation Neural Networks (BPNNs) is established for the sake of predicting the frost resistance of active-admixture recycled concrete quickly and accurately. Firstly, the influence degree of cement, water, sand, natural aggregate, recycled aggregate, mineral powder, fly ash, fiber and air-entraining agent on the frost resistance of active-admixture recycled-aggregate concrete was analyzed based on the grey system theory, and the primary and secondary relationships of various factors were effectively distinguished. Then, the input layer of the model was determined as cement, water, sand, recycled aggregate and air-entraining agent, and the output layer was the relative dynamic elastic modulus. A total of 120 datasets were collected from the experimental data of another author, and the relative dynamic elastic modulus was predicted using the two-stage BPNN prediction model proposed in this paper and compared with the BPNN prediction results. The results show that the proposed two-stage BPNN model, after removing less-sensitive parameters from the input layer, has better prediction accuracy and shorter run time than the BPNN model.

Пошук оптимальних складів фібробетонів жорсткого дорожнього покриття з використанням експериментально-статистичних моделей

The experiment was conducted according to a 15-point plan. In the experiment, the following three factors of the composition of rigid pavement fiber-reinforced concrete varied: the amount of Portland cement from 290 to 350 kg/m3, the amount of basaltic fiber from 0.9 to 1.5 kg/m3, the amount of superplasticizer from 0.6 to 1% of the cement mass. A set of experimental statistical models was obtained. They describe the influence of factors on compressive strength, flexural strength, frost resistance, abrasion resistance and cost of fiber-reinforced concrete. The selection of optimal compositions of fiber-reinforced concrete rigid pavement for the roads of II-III and Ib categories was carried out using these models. The selection of optimal compositions of fiber-reinforced concrete was carried out graphically using square diagrams. The method of representing the factor space as 7 "square" type diagrams was used when fixing the amount of cement in the composition from 290 to 350 kg/m3 with a step of 10 kg/m3. This discretization allows for a clearer and more accurate search for optimal solutions. The levels of compressive strength, flexural strength and frost resistance were used as limitation criteria. These levels meet the requirements of DBN B.2.3-4:2015 for rigid pavement materials of the corresponding category. The concrete cost index was used as an optimization criterion. The abrasion resistance of concrete was also controlled to guarantee a correct choice. Two compositions of fiber-reinforced concrete for the roads of the II and III categories were chosen. These compositions have a compressive strength of 43 and 45 MPa, a flexural strength of 5 and 5.1 MPa, abrasion of about 0.36 g/cm2 and frost resistance of F200. Two compositions of fiber-reinforced concrete for category Ib roads were also selected. These compositions have a compressive strength of 48 and 50 MPa, a flexural strength of 5.5 MPa, abrasion of about 0.35 g/cm2 and frost resistance of F200. The compositions have chosen the lowest cost price while ensuring the strength and durability of the material. The use of this fiber-reinforced concrete makes it possible to increase the intervals between repairs during the maintenance of cement concrete roads in typical climatic conditions in Ukraine.

Machine learning prediction of concrete frost resistance and optimization design of mix proportions

This study explores nine machine learning (ML) methods, including linear, non-linear and ensemble learning models, using nine concrete parameters as characteristic variables. Including the dosage of cement (C), fly ash (FA), Ground granulated blast furnace slag (GGBS), coarse aggregate (G), fine aggregate (S), water reducing agent (WRA) and water (W), initial gas content (GC) and number of freeze-thaw cycles (NFTC), To predict relative dynamic elastic modulus (RDEM) and mass loss rate (MLR). Based on the linear correlation analysis and the evaluation of four performance indicators of R2, MSE, MAE and RMSE, it is found that the nonlinear model has better performance. In the prediction of RDEM, the integrated learning GBDT model has the best prediction ability. The evaluation indexes were R2 = 0.78, MSE = 0.0041, MAE = 0.0345, RMSE = 0.0157, SI = 0.0177, BIAS = 0.0294. In the prediction of MLR, ensemble learning Catboost algorithm model has the best prediction ability, and the evaluation indexes are R2 = 0.84, MSE = 0.0036, RMSE = 0.0597, MAE = 0.0312, SI = 5.5298, BIAS = 0.1772. Then, Monte Carlo fine-tuning method is used to optimize the concrete mix ratio, so as to obtain the best mix ratio.

Analysis on frost resistance and pore structure of phase change concrete modified by Nano-SiO2 under freeze-thaw cycles

To study the effect of nano-SiO2 on the frost resistance of phase change concrete, and to further explore the deterioration of its internal pore structure under the effect of freeze–thaw cycles, X-ray tomography was applied to the rapid freeze–thaw test for the study of frost resistance, and the pore structure of the modified concrete was reconstructed during the freeze–thaw cycles. By image processing and registration techniques, the change pattern of mesoscopic pore inside the phase change concrete modified by nano-SiO2 and the development and ductility characteristics of the pore structure in the interface transition zone were analyzed. The results showed that the admixture of nano-SiO2 and phase change materials could effectively improve the frost resistance of concrete. Frost resistance life was improved by at least 43 % and up to 71 %. Additionally, nanomaterials could constrain the change of pore structure inside the composite modified concrete and densify the interface transition zone. The ITZ porosity of ordinary concrete increased by 10.58 times after 150 freeze–thaw cycles, while the secondary modified phase change concrete with 10mPCMs/1.5NS only increased by 1.2 times.

Dispersion and Spatial Distribution of Air Voids or Microspheres in Assessing Frost Resistance of Concrete

Abstract The standard spacing factor developed by Powers is typically used to evaluate the quality of the air void system in hardened concrete, but it does not always correlate with durability of the concrete. Several air void spacing equations, which are also applicable when polymeric microspheres are used in place of air entrainment, have been proposed because of the need for a more robust and comprehensive basis to evaluate the quality of the air void system. However, the spacing parameters provided by the various proposed equations, when used as sole measures in predicting the frost resistance of concrete, do not seem to do any better than the standard spacing factor. Dispersion and spatial distribution have been shown to be effective ways of describing air void or microsphere systems in hardened concrete because they have been quantified to establish criteria to assess the frost resistance of concrete. In this paper, dispersion and distribution factors are further elaborated upon to explain how they characterize zones that are protected by air voids or microspheres in the concrete. Criteria to assess the durability of concrete under rapid cycles of freezing and thawing based on the dispersion and distribution factors are linked to the exposure classes defined in the ACI 318 Code and in the recently proposed Unified Durability Guidance in ACI Committee Documents.

A study on the effect of microspheres on the freeze–thaw resistance of EPS concrete

Abstract This study investigated the influence of microbead dosages (0, 5, 10, 15, and 20%) on the frost resistance of expanded polystyrene (EPS) concrete. Five groups of EPS concrete specimens were prepared and subjected to rapid freeze–thaw tests. The freeze–thaw deterioration of EPS concrete was assessed using macroscopic indicators, including mass loss, strength loss, and dynamic elastic modulus loss. The underlying deterioration mechanism was revealed through the analysis of the EPS particle–matrix interface. A concrete damage plasticity model of EPS concrete based on damage mechanics theory was established. The results indicate that the addition of microbeads increased the strength of EPS concrete by 38–53%, reduced the strength attenuation after freeze–thaw damage by 8.1%, and improved the frost resistance level by 10–60 grades. The optimal dosage of microbeads is 15% of the cementitious material. The interfacial transition zone gaps in EPS concrete with added microbeads after freeze–thaw cycles are smaller, contributing to a more complete hydration reaction. The freeze–thaw damage model established in this study accurately reflects the freeze–thaw damage law of EPS concrete and provides a reference for studying the mechanical properties of EPS concrete under freeze–thaw cycles. The research findings of this study can enhance the strength and service life of EPS concrete, expanding its application scope as a structural material. The study provides valuable insights for future research and engineering applications related to the frost resistance of EPS concrete.

Features of the Behavior of Highly Frost-Resistant Modified Concretes

One of the main criteria of construction is reliability and durability. Therefore, for the implementation of modern construction projects, especially in harsh operating conditions, cement composites with increased resistance to aggressive external cyclic influences are necessary. For the climatic conditions of the Russian Federation, special attention should be paid to ensuring the frost resistance of concrete. Thus, in accordance with GOST 31384–2017 “Protection of concrete and reinforced concrete structures from corrosion. General technical requirements”, for the lowest temperature and under the condition of alternating freezing and thawing of concrete in a saturated state, the frost resistance mark must be at least F2450. In addition, high mechanical characteristics of the materials used, including the modulus of elasticity, are required, for example, in the construction of infrastructure facilities in the Arctic zone of Russia. To ensure these characteristics, effective modifying additives must be introduced into the concrete mix. However, there is evidence in the literature that water-reducing additives of various genesis, with similar values of water reduction, have different effects on the structure of the formed cement stone. Therefore, in order to ensure high durability of concrete, this article will consider the relationship between the emerging structure of cement stone in concrete and its resistance parameters.

The frost resistance performance of basalt fiber-reinforced concrete (BFRC) subjected to fatigue loads coupled with hydrodynamic pressure

In this work, the effects of different stress levels, exposure conditions and freeze‒thaw (F-T) cycles on the mechanical properties of base concrete (BC) and basalt fiber-reinforced pavement concrete (BFRC) were studied. The concrete mass loss, relative dynamic elastic modulus (RDEM) and fracture energy under various loading conditions and F-T cycles were analyzed to characterize its damage evolution. Additionally, through mercury intrusion porosimetry and scanning electron microscopy (SEM), the pore structure characteristics and micromorphology were investigated to explore the mechanism controlling the increase in concrete performance with basalt fiber (BF). Finally, the relationship between the pore structure and damage variable was investigated, and the frost resistance of concrete was evaluated by using gray correlation analysis and rough set theory (RST). The concrete deterioration under coupling actions and F-T cycles could be divided into stages of (i) slow and (ii) rapid increases. The stress level played a decisive role in Stage I, while the effect of hydrodynamic pressure was more obvious in Stage II. The addition of BF significantly decreased the concrete damage degree throughout testing. After 300 F-T cycles, the RDEM and fracture energy of the BFRC under coupling actions were 1.41 and 2.20 times those of the BC, respectively. Moreover, the addition of BF notably lowered the porosity and most probable pore diameter of the concrete under coupling actions and F-T cycles and thus greatly influenced the increase in pore fractal dimension. The RST indicated that the frost resistance of concrete was closely related to the mixture and stress level.

ОЦЕНКА МОРОЗОСТОЙКОСТИ КЛАДОЧНЫХ СТЕНОВЫХ ИЗДЕЛИЙ С УЧЕТОМ МЕТОДИКИ ВЛАГОНАСЫЩЕНИЯ В РОССИЙСКИХ НОРМАХ И СТАНДАРТАХ.

In order to improve the Russian codes in the field of brick and masonry structures, a comparative analysis of frost resistance assessment of masonry wall products of wide application in construction practice was carried out. The Russian codes revealed inconsistencies in the assessment of frost resistance of masonry products. In particular, in SP 15.13330.2020 [2] and GOST 7025-91 [4] one index F for determining the frost resistance of ceramic, silicate products, as well as the frost resistance of concrete, expanded clay and cellular concrete blocks, which misleads consumers and designers. In order to eliminate the noted inaccuracies, the article gives proposals for adjustments to SP 15.13330 and GOST 7025.

Effect of polypropylene fiber and nano-silica on the compressive strength and frost resistance of recycled brick aggregate concrete

Abstracts Wasted clay bricks as coarse aggregate of recycled concrete is an effective solution to save energy and reduce CO2 emissions in the construction industry. However, the mechanical properties and frost resistance of recycled brick aggregate (RBA) concrete are inferior to those of ordinary concrete, which limits its widespread application. In this research, the effects of RBA, polypropylene fiber (PPF) and nano-silica (NS) on the mechanical properties and frost resistance of concrete were investigated. The effect of RBA, PPF, and NS on the compressive strength was quantitatively analyzed, and microstructural analysis and fractal dimension calculation of the concrete were performed. The results show that the concrete compressive strength decreased with the increase in RBA replacement rate, and it was effectively improved by adding PPF and NS (PPF-NS). The compressive strength first increased and then decreased with the increase in PPF and NS. The improvement effect of 0.12% PPF and 2% NS on the compressive strength of 50% replacement rate of RBA concrete was most effective. The gray relational degrees between the compressive strength and RBA, PPF, and NS were 0.6578, 0.8297, and 0.5941, respectively. The frost resistance of PPF-NS modified concrete was better than that of ordinary concrete, mainly manifested in its superior apparent phenomena, mass loss, and strength loss. Compared with normal concrete, the microstructure was denser and the fractal dimension of the cross-section was higher for RBA concrete modified with PPF-NS before and after freeze–thaw cycles.

Freeze-Thaw Damage Degradation Model and Life Prediction of Air-Entrained Concrete in Multi-Year Permafrost Zone.

The Qinghai-Tibet Plateau is the main permafrost area in China. Concrete structures constructed on permafrost are affected by the early negative-temperature environment. In particular, the negative-temperature environment seriously affects the strength growth process and the frost resistance of concrete (FRC). Therefore, this study considered the influence of the gas content, water-binder ratio (w/b), age, and other factors on the strength variation law and FRC under -3 °C curing conditions. Nuclear magnetic resonance (NMR) was used to analyze the pore structure of concrete before and after freeze-thaw cycles (FTCs). The results showed that the compressive strength of the concrete (CSC) under -3 °C curing was only 57.8-86.4% of that cured under standard conditions. The CSC under -3 °C curing showed an obvious age-lag phenomenon. The FRC under -3 °C curing was much lower than that under standard curing. The porosity of the concrete under -3 °C curing was greater, with a higher percentage of harmful and multi-harmful pores than that under standard curing. The concrete properties deteriorated primarily because curing at -3 °C hindered the hydration reaction compared with standard methods. This hindrance resulted in diminished hydration development, weakening the concrete's structural integrity. Under both curing conditions, when the gas content was between 3.2% and 3.8%, the frost resistance was the best. This is because a gas content within this range effectively enhances the internal pore structure, therefore relieving the swelling pressure caused by FTCs. Based on the freeze-thaw damage (FTD) model proposed by previous authors, a new model for the CSC under -3 °C curing reaching that of the concrete under standard curing for 28 d was established in this study. This advanced model was capable of accurately assessing the FTD of concrete structures in permafrost regions. Finally, the life expectancy of concrete in Northwest China was predicted. The life of the concrete reached 46.9 years under standard curing, while the longest life of the concrete under -3 °C curing was only 12.9 years. Therefore, attention should be paid to constructing and curing concrete structures in cold environments.

Frost resistance and life prediction of recycled brick aggregate concrete with waste polypropylene fiber

Abstract Due to recycled aggregate concrete technology, sustainable resource utilization can be achieved, but the weak frost resistance of this type of concrete affects its application in cold regions. Using waste polypropylene fibers as reinforcing materials can improve the mechanical properties and durability of concrete. This study explores the influence of waste polypropylene fiber on the frost resistance durability and microstructure of recycled brick aggregate (RA) concrete. The results show that with the increase in freeze–thaw cycles, the mass of the concrete first increases and then decreases, while its relative dynamic elastic modulus and compressive strength gradually decrease. After 60 freeze–thaw cycles, the maximum mass loss, maximum relative dynamic elastic modulus loss, and maximum compressive strength loss of the RA concrete are 1.73, 45.1, and 73.7%, respectively. Waste fiber (WF) can improve the frost resistance of concrete, as demonstrated by the obvious reduction in mass loss, relative dynamic elasticity modulus loss, and compressive strength loss, which are 0.11, 33.0, and 64.0%, respectively, after 60 freeze–thaw cycles. The action mechanism of WF on the frost resistance of RA concrete is revealed, and the life prediction model of RA concrete with WF under freeze–thaw conditions is established.

МІЦНІСТЬ, ЗНОСОСТІЙКІСТЬ І МОРОЗОСТІЙКІСТЬ ФІБРОБЕТОНІВ ЖОРСТКИХ ДОРОЖНІХ ПОКРИТТІВ З БАЗАЛЬТОВОЮ ФІБРОЮ ТА ПОВІТРОВТЯГУЮЧОЮ ДОБАВКОЮ

Introduction. Increasing the durability of hard pavements allows you to reduce road maintenance costs by extending the intervals between repairs. Dispersed reinforcement is a well-known method of increasing the frost resistance and abrasion resistance of concrete, which has a positive effect on the durability of pavements in typical for Ukraine climatic conditions. Basalt fiber is resistant to corrosion and relatively inexpensive, which makes it promising for use in the road industry. Also, plasticizing and air-entraining admixtures must be used for concrete of hard pavement. Problem Statement. In modern economic conditions and taking into account the technological features of the preparation of mixtures, it is relevant to compare the effectiveness of the use of known methods of improving the properties of concrete for hard pavements: dispersed reinforcement and the use of air-entraining admixtures. Studying the expediency of the simultaneous use of these two methods of modifying the concrete mixture is also an important task from a scientific and practical point of view. Purpose. Determination of the influence of basalt fiber and air-entraining admixture on the strength, frost resistance and abrasion resistance of concrete of hard pavements.

Experimental study on macro–micro-structural properties and strength prediction model of wastewater concrete

This study is intended to investigate the mechanical, durability, and drying shrinkage properties of concrete mixtures incorporating wastewater from ready-mixed concrete plants. The microstructural attributes were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) imaging, energy dispersive spectrometry (EDS), and mercury intrusion porosimetry (MIP). Meanwhile, rough set theory (RST) was used to analyze the influence of mean pore radius, porosity, fractal dimensions, and pore size distribution (PSD) on the compressive strength of wastewater concrete. The results showed that the seven-day cube compressive strengths for C20, C40, and C60 concrete specimens increased when wastewater was utilized, with the highest rise in the strength properties being observed as 16.84% for C40 mixture. Nevertheless, the 28-day cube compressive strengths of C20, C40, and C60 concretes were reduced by 4.85%, 9.33%, and 18.63%, respectively. The durability results showed that wastewater mixing reduced the frost resistance of C40 and C60 concrete, but improved for C20 concrete. The microstructural investigation revealed that mixing concrete with wastewater densifies the early-age concrete microstructure and refines the pore size. Nevertheless, the compactness of concrete microstructure at the later stage was reduced, and the pores in concrete were enlarged due to the poor cohesiveness of wastewater particles. The porosity and PSD have the greatest influence on the compressive strength of wastewater concrete. A strength and pore structure model of wastewater concrete was also developed and validated by considering PSD and porosity as bivariate parameters. Highlights The addition of wastewater can improve the early compressive strength of concrete. The addition of wastewater reduces the carbonization resistance of concrete. A high-precision model of wastewater concrete strength was established.

Research on a Multi-Objective Optimization Design for the Durability of High-Performance Fiber-Reinforced Concrete Based on a Hybrid Algorithm

To achieve durable high-performance fiber-reinforced concrete that meets economic requirements, this paper introduces a hybrid intelligent framework based on the Latin hypercube experimental design, response surface methodology (RSM), and the NSGA-III algorithm for optimizing the mix design of high-performance fiber-reinforced concrete. The developed framework allows for the prediction of concrete performance and obtains a series of Pareto optimal solutions through multi-objective optimization, ultimately identifying the best mix proportion. The decision variables in this optimization are the proportions of various materials in the concrete mix, with concrete’s frost resistance, chloride ion permeability resistance, and cost as the objectives. The feasibility of this framework was subsequently validated. The results indicate the following: (1) The RSM model exhibits a high level of predictive accuracy, with coefficient of determination (R-squared) values of 0.9657 for concrete frost resistance and 0.9803 for chloride ion permeability resistance. The RSM model can be employed to construct the fitness function for the optimization algorithm, enhancing the efficiency of multi-objective optimization. (2) The NSGA-III algorithm effectively balances durability and cost considerations to determine the optimal mix proportion for the concrete. After multi-objective optimization, the chloride ion permeability resistance and frost resistance of the high-performance fiber-reinforced concrete improved by 38.1% and 6.45%, respectively, compared to the experimental averages, while the cost decreased by 2.53%. The multi-objective optimization method proposed in this paper can be applied to mix design for practical engineering projects, improving the efficiency of concrete mix design.

Impact of de‐icing salts on freeze‐thaw resistance of low‐clinker concretes

AbstractDe‐icing salts are commonly used in moderate climate zone, where concrete is subjected to freeze‐thaw cycles during winter times. The presence of de‐icing salts requires appropriate frost‐thaw resistance of concrete, which is challengingin case of low‐clinker concretes. Proper air‐entrainment of the concrete mix, which is one of the main factors affecting the frost resistance of concrete is not a simple task. Therefore, it is necessary to constantly improve the process of air‐entrainment of the concrete mix and to constantly control the effectiveness and quality of concrete aeration especially those with low clinker cements. In the paper effect of de‐icing salts on air‐entrained by polymer microspheres and traditional air‐entraining admixtures low clinker concrete was evaluated. The conducted tests indicate that low‐clinker concretes made with the use of polymer microspheres, despite greater repeatability in shaping the correct air‐entrainment structure, are characterized by lower resistance to frost in the presence of de‐icing salts compared to traditionally air‐entrained concretes. This mechanism will be investigated in future work.