Mineral Additives Research Articles

The effect of carbonate mineral additions on biogeochemical conditions in surface sediments and benthic–pelagic exchange fluxes

Abstract. Coastal sediments are hotspots of biogeochemical processes that are impacting subsurface and overlying water conditions. Fluid composition in sediments is altered through the mineralization of organic matter which, under oxic conditions, further lowers both pH and the carbonate saturation state. As a potential mitigation strategy for this sediment acidification, we explored the effects of mineral additions to coastal sediments. We experimentally quantified carbonate mineral dissolution kinetics of carbonate shells suitable for field application and then integrated these data into a reactive transport model that represents early diagenetic cycling of C, O, N, S, and Fe and traces total alkalinity, pH, and saturation state of CaCO3. Model simulations were carried out to delineate the impact of mineral type and amount added, porewater mixing, and organic matter mineralization rates on sediment alkalinity and its flux to the overlying water. Model results showed that the added minerals undergo initial rapid dissolution and generate saturated conditions demonstrating the potential of alkalinity enhancement in mitigating surface sediment acidification. Aragonite dissolution led to higher total alkalinity concentrations than calcite. Simulations of carbonate mineral additions to sediment environments with low rates of organic matter mineralization exhibited a substantial increase in mineral saturation state compared to sediments with high CO2 production rates, highlighting the environment-specific extent of the effect of mineral addition. Our work indicates that carbonate additions have the potential to effectively buffer surficial sediments over multiple years, yielding biogeochemical conditions that counteract the detrimental effect of low-pH sediment conditions on larval recruitment and potentially increase benthic alkalinity fluxes to support marine carbon dioxide removal (mCDR) in the overlying water.

Developing an activated biochar-mineral supplement for reducing methane formation in anaerobic fermentation

Abstract The effects of biochar on methane emissions from soils are well understood. However, biochar effects on methane production from livestock have received less attention. In this study, a biochar-mineral supplement for livestock was developed by pyrolyzing a mixture of wheat straw, aluminosilicates, iron sulfate, and zinc oxide at 600 ℃. The supplement was then activated using peracetic and propionic acids, and potassium nitrate. The activated biochar-mineral supplement was characterized using analytical techniques. A high surface area, a high concentration of oxygen-containing functional groups, and a high concentration of free radicals, associated with O and Fe unpaired electrons, assisted the supplement with catalysing the oxidation of methane. Microstructural analysis of the supplement suggested the formation of organo-mineral phases, rich in C, O, Fe, Si, Al, K and Ca, indicating that the biochar reacted with mineral additives to preserve them. To assess the potential of the supplement to reduce methane produced form livestock, an in vitro batch culture incubation was conducted (n = 3) with rumen fluid sourced from Holstein–Friesian steers. The supplement was incubated at inclusion rates of 0% (control), 1.5%, 4.0% and 6.0% of dry matter (DM), with a Rhodes grass hay substrate. Compared to the control, the supplement reduced cumulative gas production by 10.1% and 12.7% and methane production by 19.03% and 29.32% after 48 h when included at 4.0% and 6.0% DM (P < 0.05), respectively, without causing any detrimental impacts on fermentation parameters. The supplement assisted with reducing the concentration of dissolved mineral nutrients, such as P and Mg, when included at 4.0% and 6.0% DM (P < 0.05). Graphical abstract

Improving the Carbonation Resistance of Alkali-Activated Slag Containing Mineral Additions: Investigation under Natural and Accelerated Conditions

Improving the Carbonation Resistance of Alkali-Activated Slag Containing Mineral Additions: Investigation under Natural and Accelerated Conditions

Rheology of reactive powder concrete mix - a rewiev

The paper presents issues on the rheology of RPC mixtures based on data from the literature. First, the properties of pastes as multiphase systems are described, taking into account their structures and the interacting forces in these systems. The influence of small particles introduced to cement with mineral additives on the rheological properties of cement pastes has been discussed. Particular attention has been paid to their role in increasing cement packing density and their effect on increased fluidity in the presence of superplasticizer in cement pastes and RPC mixes. The effect of mixing the RPC ingredients on its rheology has been discussed, taking into account a sequence for the addition of ingredients, the speed, and the time of mixing.

The Effects of the Addition of Secondary Phyllosilicate Minerals on the Decomposition Process and Products of Maize Straw in Black Soil

The interaction between secondary phyllosilicate minerals and straw is crucial for preserving soil organic carbon (SOC) and fertility. However, the specific mechanism through which these minerals affect straw decomposition and its products in northeast China’s black soil remains unclear. In this study, montmorillonite, illite, and vermiculite were mixed with quartz sand and maize straw, inoculated with microbes, and incubated to analyze the effects of different secondary phyllosilicate minerals on the degradation of organic components in maize straw and the formation of soil humus. The results showed that montmorillonite significantly facilitated the decomposition of maize straw hemicellulose and lignin, which decreased by 95.85% and 76.38%, respectively. Conversely, vermiculite decelerated hemicellulose and lignin degradation. Regarding soil organic acids, lactic acid and malic acid were predominant, with the highest content being found after the montmorillonite treatment. Montmorillonite was the most effective in enhancing extractable humic-like substances, which increased by 71.68%. Montmorillonite increased the content of G0 (water dispersion group), G1 (sodium ion dispersion group), and G2 (sodium grinding dispersion group) complexes. The addition of secondary phyllosilicate minerals increased the organic carbon (OC) content in the G0, G1, and G2 samples, with montmorillonite demonstrating the most pronounced effect. Secondary phyllosilicate minerals increased the abundance of fungi, particularly Ascomycota, with the highest abundance being found after the montmorillonite treatment. In conclusion, our results indicated that montmorillonite facilitated the decomposition of lignocellulose in maize straw, enhanced the accumulation of humus, and promoted the formation of organic–mineral complexes. These findings provide valuable insights into the interaction between secondary phyllosilicate minerals and maize straw and have important implications for improving the quality of black soil in northeast China.

Effect of redispersible polymer powders on some properties of mortars with complex mineral additives

Effect of redispersible polymer powders on some properties of mortars with complex mineral additives

Experimental Study of Carbonation and Chloride Resistance of Self-Compacting Concretes with a High Content of Fly Ash and Metakaolin, with and Without Hydrated Lime.

The durability of reinforced concrete is associated with several factors that can trigger the corrosion of reinforcement bars. Among these factors, the most significant are chloride-ion attack and carbonation. This study evaluated, through accelerated testing, self-compacting concretes (SCCs) with reduced cement content in binary, ternary, and quaternary mixtures using high-early-strength Portland cement, fly ash (FA), metakaolin (MK), and hydrated lime (HL). These systems are proposed to address the slow compressive strength gains at 28 days in concretes with high fly ash content and to minimise the effects of carbonation in concretes with high levels of mineral additives. Laboratory tests were conducted to measure chloride-ion migration in a non-steady-state system, accelerated carbonation in a controlled chamber, electrical resistivity, void indices, and compressive strength. Based on the results obtained, it was found that the combined use of MK, FA, and HL was effective in reducing cement consumption to extreme levels, such as 120 and 150 kg/m3, while still achieving durability indices superior to those of SCCs with cement consumption of 500 kg/m3.

The Influence of Mineral Additives on Aggregate Reactivity.

In this article, the authors present the results of their research on assessing the effect of selected mineral additives on the alkaline reactivity of aggregates. The main objective of this research was to check whether the reactivity of aggregates that do not meet the standard requirements can be reduced. Due to the decreasing availability of crushed aggregates and the decreasing resources of sand used for cement concrete road surfaces, solutions should be sought that allow the use of lower-grade aggregates. Among the available mineral additives, dense microsilica, white microsilica, limestone flour, glass flour, basalt flour, and glass granulate were selected. Laboratory tests were carried out in accordance with the requirements for testing the alkaline reactivity of road aggregates in NaOH solution applicable in Poland. The tests included the use of mineral additives in the amounts of 10% and 20%. Based on the research conducted, it was observed that the most beneficial effect was obtained with the addition of white microsilica, for which a decrease in aggregate reactivity was observed by 76.7% for 10% of the additive and 95.8% for 20% of the content. The least beneficial effect, on the other hand, was the use of compacted microsilica, for which an increase in alkaline reactivity was observed by 9.3% for 10% of the additive and 20.9% for 20% of the additive. The research conducted shows that the alkaline reactivity of the aggregate can be reduced, due to which it is possible to use reactive aggregates for the construction of road surfaces made of cement concrete.

Design of Self-Compacting Concrete with Reduced Cement Content by Aggregate Packing Method.

This article presents the procedure for designing self-compacting cement concrete characterized by minimal free space and a maximally compacted mineral skeleton. Such a designed mix allows for lower cement consumption and an increased amount of mineral additives. The paper presents a broad analysis of the influence of different aggregate proportions (36 recipes) and verification of the properties of the concrete mix using CEM I 42.5 R cements and fly ash. As a result of the appropriately compacted mineral skeleton, only 17% free space was obtained, which will allow the amount of cement to be reduced from 500 kg/m3 to 350 kg/m3 while fully maintaining the properties of the mix and hardened concrete. After 90 days of curing, SCC concrete was characterized by a compressive strength above 68 MPa and a small 2.1% decrease in compressive strength after 100 freeze-thaw cycles.

Characterization of genetic diversity and identification of genetic loci associated with carbon allocation in N2 fixing soybean

BackgroundEfficient capture and use of resources is critical for optimal plant growth and productivity. Both shoot and root growth are essential for resource acquisition, namely light and CO2 by the shoot and water and mineral nutrients by roots. Soybean [Glycine max (L.) Merr.], one of the most valuable crops world-wide, uses an additional strategy, symbiotic N fixation (SNF), for N acquisition. SNF relies on development of specialized root organs known as nodules, which represent a distinct C sink. The genetic diversity of C partitioning in N fixing soybean to shoots, roots, and nodules has not been previously investigated but is valuable to better understand consequences of differential C allocation and to develop genetic resources, including identification of quantitative trait loci (QTLs).ResultsA diversity panel of 402 soybean genotypes was phenotyped outdoors in a deep-tube system without addition of mineral N to measure allocation of biomass to the shoot, root, and nodules, as well as to determine nodule number, mean nodule biomass, and total shoot N accumulation. Wide ranges in phenotypes were observed for each of these traits, demonstrating extensive natural diversity in C partitioning and SNF in soybean. Using a set of 35,647 single nucleotide polymorphism (SNP) markers, we identified 121 SNPs tagging 103 QTLs that include both 84 novel and 19 previously identified QTLs for the eight examined traits. A candidate gene search identified 79 promising gene models in the vicinity of these QTLs. Favorable alleles of QTLs identified here may be used in breeding programs to develop elite cultivars with altered C partitioning.ConclusionsThis study provides novel insights into the diversity of biomass allocation in soybean and illustrates that the traits measured here are heritable and quantitative. QTLs identified in this study can be used in genomic prediction models as well as for further investigation of candidate genes and their roles in determining partitioning of fixed C. Enhancing our understanding of C partitioning in plants may lead to elite cultivars with optimized resource use efficiencies.

Assessment of the durability of hardening products of modified fly ash cement compositions

This work is devoted to the study of the durability of hardening products of modified gold-cement compositions. The influence of sulfate and carbonate additives of various origins on the kinetics of increasing the strength of artificialstone was studied.To reveal the mechanism of the processes of strength synthesis of the developed binder systems, their hydration products and the composition of new formations were studied using X-ray diffraction (XRD), differential thermal analysis(DTA) and electron microscopy.It was established that with simultaneous modification of the plasticized fly ash cement composition with sulfate and carbonate additives, the synthesis of strength is ensured due to the formation of hydration products in the composition atthe early stages of hardening of ettringite and its analogues containing carbonate and ferric components. It has been determined that the presence of hydrosulfoaluminate-type new formations in the hydration products and the presence of active mineral additives in its composition on the one hand, and on the other hand, the contact of cement stonewith the environment can cause the appearance of dangerous compounds (such as thaumasite) in hardening systems, the synthesis of which leads to the emergence of stresses in the structure of the material and its destruction. It has been established that as a result of the processes of isomorphic substitution, compounds of variable composition are formed, similar to solid solutions, due to which the strength of artificial stone is ensured in the later stages of hardening. On the other hand, the released sulfate ions can replace silicon groups in the tobermorite gel and form compounds similar to epistilbite (Ca6(Si(OH)6)3·(SO4)3·24H2O) (d=0.584; 0.399; 0.369; 0.354 nm). The strength indicators of artificial stone basedon modified fly ash cement binder compositions were investigated. It is associated with the directed formation of crystallochemically similar phases that can grow together, and the formation of artificial stone capable of structural and functional adaptation in various operating conditions will likely be due to the formation of solid solutions of hydrosulfoaluminocarbosilicate composition, hydrogarnet phases of the composition 3СаО·Al2O3·1,6SiO2·2,8H2O and modified calcium hydrosilicates of the epistilbite type Ca6(Si(OH)6)3·(SO4)3·24H2O) and scoutite (Са6Si6O18·2H2O·CaCO3). in the composition of new formations.

Investigation of ASR-induced crack development on mortars with mineral additives using image processing

Investigation of ASR-induced crack development on mortars with mineral additives using image processing

Selection of Components and Methods of Modification of Soil Cement to Improve the Performance Properties of Subgrade

Purpose. The main objective of the scientific article is a reasonable selection of soil-cement reinforcing structural elements and methods of modifying the soil-cement structure to strengthen the subgrade for railroad tracks. Methodology. For the construction of soil-cement reinforcing elements for a combined railway track using drilling and mixing technology, a number of tasks were solved, including: a reasonable selection of the components and modifiers of the soil-cement element; determination of the properties of the components; establishment of operational requirements for soil-cement and its composition; design of optimal compositions with specified performance characteristics, taking into account the properties of soils and operating modes. Findings. The influence of soil-cement components on the rheological properties of soil-cement mixtures and the physical and mechanical properties of soil-cement was studied. Based on the data processing by statistical analysis, the optimal content of the constituent components of soil-cement mixtures was selected to ensure the technological and operational performance of soil-cement for different types of soils and to strengthen the soil base during track construction. The influence of mineral granular, fibrous and chemical modifiers on the properties of soil cement was investigated. Originality. The possibility of using vertical reinforcing elements made of soil cement with the necessary technological and operational parameters obtained by drilling and mixing technology to strengthen the subgrade, taking into account the stress-strain state and morphology of the soil bases, has been determined. Based on the study, the author made an attempt to select the components and develop optimal soil cement compositions for strengthening the subgrade of a railroad for a combined track. The directions of modification of soil cement with mineral, fiber and chemical additives are also considered. Practical value. The study makes it possible to obtain soil-cement elements of optimal composition and properties for different types of soils and stress-strain states in order to vertically strengthen the soil bases for the railway track. To modify the structure of soil cement and minimize cement consumption, it is proposed to use fiber fibers as modifying reinforcement components. To increase the density, crack resistance, strength, and modulus of deformability and improve the plasticity of the mixture, it is recommended to use chemical modifiers up to 0.3 % and to save cement – particles of fine industrial waste in the form of ground slag or stone grinding screenings in the amount of 20...30 %.

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

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

Technology of manufacturing copper and bronze tools of the Petrovka Culture of the Southern Trans-Urals and Middle Tobol region

The article presents the results of metallographic analysis of the Petrovka Culture tools from the southern Trans-Urals and Middle Tobol River region of the 19th–18th centuries BC (47 items). A certain correlation has been determined between the functional purpose of an item, the type of raw material, and the tool manufacturing scheme. The tools were mainly made of copper contaminated with impurities, obtained from oxide-carbonate ores with the addition of chalcocite-covellite minerals. A butted axe, sickles, knives with handles, tanged chisels, hooks, and some awls were made of copper, both by casting in a mold with subsequent finishing and by forming forging. Copper tools obtained by casting often had casting defects — shrinkage cracks and warping of the metal. In most cases, the tools were finished either in the regime of incomplete hot forging at 300–500°C, or hot forging at 600–800°C and pre-melting temperatures of 900–1000°C. During the Petrovka period, tin and tin-arsenic bronze started being used for manufacturing adzes, chisels, handled knives, the majority of awls, needles, spear-heads, and arrows. More progressive types of alloys in terms of fluidity, filling mold without defects in the form of low-alloy tin and tin-arsenic bronzes (Sn up to 7%, As up to 4%) came from related tribes of the Petrovka Culture of Saryarka, possibly from the Petropavlovsk Ishim region. The resulting castings were of high quality with smooth surface without metal warping defects. Subsequent finishing was carried out by selecting optimal heat treatment regimes mainly at 600–800°C or 900–1000°C, as well as using incomplete hot forging at 300–500°C. The hardness of the tools finished by forging with heating significantly exceeded the microhardness of the processed copper by 1.5–2 times.

Determining datum temperature and apparent activation energy: an approach for mineral admixtures incorporated cementitious systems

The maturity method is used to predict the strength of concrete by monitoring its temperature history. Accuracy of maturity method relies on the dependable determination of the datum temperature and the apparent activation energy. The current study introduces a new approach, complementing those in ASTM C1074-11, for determining the datum temperature and apparent activation energy. The experimental study involved using two different mineral additives to portland cement at 6%, 20%, and 35% replacement amounts. The mortars were then cured at temperatures of 5, 20, and 40 °C, and their strengths were determined. Subsequently, the datum temperatures and apparent activation energies for these mixtures were calculated using both the proposed approach and the alternatives from ASTM C1074-11. Strength estimations were conducted in conjunction with commonly used maturity functions. The results indicate that the proposed approach determines the datum temperature and apparent activation energy reliably for mineral admixture-incorporated mortars. Furthermore, the predicted strengths, derived from the datum temperature and apparent activation energy calculated through the proposed approach, show a closer alignment with the experimental results when applying the Nurse-Saul and Hansen-Pedersen equations, as opposed to the Rastrup and Weaver-Sadgrove models.

Study of shrinkage and durability of mortars based on slag mineral addition and prepared sand

The present investigation aims to study principally the durability of mortars based on a local prepared sand from the region of Oued Souf (southeeast, Algeria), in accordance with standard sand classification.. The main objective of the research is to replace the fine part between (0.08 and 0.16 mm) which is of the order of 15% and to substitute it with active mineral addition; slag (S)]. Dosages of 5, 10 and 15% for the addition were varied as replacement of the finer sand fraction (0.08 – 0.16 mm) for these tested specimens in the experimental program. However, the rest of the coarser granular fractions of the prepared sand were kept at fixed standard proportioning. Thus, the influence of this additive [S] as replacement of finer part fraction of activated sand on physical properties, density and shrinkage is considered in this investigation. Furthermore, the durability performances in an aggressive chemical environment (HCl, H2SO4) of the prepared sand mortars were evaluated. The results obtained showed the advantageous effect of replacing prepared sand with (slag) addition on the physical characteristics of studied mortar mainly, density, shrinkage and durability. Furthermore, this replacement by slag addition proved to be improving mechanical performances as gain in strength loss or even mass losses with regard to the durability property in aggressive medium of such cementitious product based on activated sand. Finally, it can be concluded that the optimum percentage of 10% has been shown to deliver the best results for a much more performant sustainable mortars based on slag in aggressive environment (HCl, H2SO4) for the present study.

Research Possibilities for Efficient Capitalization in Construction Eco-Products, of Mineral Additions Generated by the Local Romanian Industries as Wastes or By-Products

The current paper intends to present the directory lines and paths for the development and implementing construction eco-products, with advanced functionality (materials, elements and structures, models and technologies), considering the efficient and customized valorization of by-products and generated waste of local industries, in the context of National Strategy for Research, Innovation and Smart Specialization 2022-2027 regarding the transition to Circular Economy (EC). This represents one of the two main axes of the research project Nucleu Programme of the National Research Development and Innovation Plan 2022-2027, supported by MCID, "ECODIGICONS" project no. PN 23 35 04 01: “Fundamental-applied research into the sustainable development of construction products (materials, elements, and structures, as well as methods and technologies) that utilizes current national resources to enhance the eco-innovative and durable aspects of Romania's civil and transport infrastructure”, financed by the Romanian Government starting with the beginning of 2023. One of the novelties of the proposed approach of the project is considering the entrepreneurial environment of construction industry or complementary branches as essential stakeholders for the future results of the current scientific research. This dramatically changes the dynamic of the project, in terms of specific objectives, namely their focus on solving the current wastes’ problem by innovatively integrating them into competitive construction products with fast applicability and in accordance with support market requests. By the use of strategic management specific methods (e.g., External Environment (EE) and Internal Environment (IE) evaluation, SWOT analysis and derived specific strategies, etc.), four research directions have been identified for the valorization, at regional or even national level, of mineral additions (inert/hydraulically latent/pozzolanic, etc., derived from waste and industrial by-products (metallurgy, processing industry, construction/demolition, etc.)) by development of eco-smart materials and products for construction. The three directions are related to the considered mineral additions: Power plant ashes (fly ash and/or bottom ash), Steel slag and Garnet type residue Hence, the paper is willing to present the identification and the preliminary analyses of the specified research axes, plotted as necessary steps for achieving an intelligent and sustainable transition of the Romanian construction infrastructure. This approach implicitly ensures in the short and medium term, the increase of the degree of implementation of the principles of the Circular Economy (EC) in Romania, in the existing context which includes relevant factors like: geo-political, industrial and economic, urban and demographic, scientific, socio-cultural and environmental, in accordance with the imperatives of National, European and World Sustainable Development strategies.

Evaluation of Sargassum spp. Oil as a Potential Additive for Biolubricant Formulations

Macroalgae-derived oils offer a sustainable and environmentally friendly alternative to conventional mineral oils and additives in lubricant formulation. Their favorable fatty acid profiles can contribute to mitigating the environmental impacts caused by using fossil-based products. This study evaluates the potential of Sargassum spp. oil, collected from the Mexican Caribbean, as a lubricity-enhancing additive in synthetic base oils. The impact of Sargassum spp. oil on viscosity and tribological performance was analyzed. The results indicated that Sargassum spp. oil has potential as an anti-wear additive since a formulation using 10% v/v Sargassum spp. oil in a synthetic lubricant (PAO6) resulted in a wear scar diameter value of 703.03 ± 15.56 µm, which is about 10% lower than PAO6 used as commercial synthetic control. Additionally, the formulation significantly enhanced the viscosity index, with a value of 169, which was notably higher than the control (137). The parameter of the coefficient of friction was significantly reduced from 0.1 to 0.08 (about 27%) when using the formulation with 10% v/v Sargassum spp. oil. These findings underline the potential of algae oils as additives in synthetic lubricants, promoting a transition towards greener products and reducing the environmental impact derived from conventional formulations of polyalphaolefins and esters.

Critical review of standardized test methods for determining the carbonation resistance of concrete

Principal part. The article considers the recommendations on preliminary preparation and curing of specimens given in the existing domestic and foreign standards of concrete carbonization tests. The conditions of exposure to accelerated carbonization affect the mechanism of processes and the degree of changes that the material will experience. The concept of “maturity index” should be prioritized in future iterations of standards. There is a need to provide direct comparison of the results of different studies and to improve the understanding of how the internal properties of individual concrete types relate to their resistance to carbonation, to define principles for accurately translating carbonation rates in accelerated tests into natural carbonation rates for different types of concrete. Prescriptive and performance-based approaches to durability design of reinforced concrete structures are reviewed in this article. Often a direct correlation between carbonization ratio and compressive strength in concretes with mineral additives is not revealed, especially when the performance characteristics are determined by accelerated tests. Therefore, models of degradation of such concretes under the influence of carbon dioxide in semi-probabilistic, probabilistic calculations, and service life assessment need some refinement. Conclusions. The existing standards for carbonation depth determination have significant differences from each other, in particular in the variants of specimen preparation, curing conditions, conditions during testing in the carbonation chamber. This leads to different results when tested to different standards. The performance-based approach to assessing the durability and service life of reinforced concrete structures can be considered an important advancement in structural concrete design. At present, the limitations in this approach are due to the fact that the various failure processes affecting the behavior of reinforced concrete structures are not fully studied and described in all necessary details, laboratory test methods do not always reflect the actual operating conditions, and the variation of concrete quality within a structure are determined by the heterogeneity and anisotropy of properties, the presence of defects, time-dependent parameters (shrinkage, creep), and other probabilistic factors.