Chloride Penetration Research Articles

Prediction and prevention of concrete chloride penetration: machine learning and MICP techniques

The chloride migration coefficient (CMC) of concrete is crucial for evaluating its durability. This study develops ensemble models to predict the CMC of concrete, addressing the limitations of traditional, labor-intensive laboratory tests. We developed three ensemble models: an inverse variance-based model, an Artificial Neural Network (ANN)-based model, and a tree-based model using the random forest regression algorithm. These models were trained on a dataset comprising 843 concrete mix proportions from existing literature. Results indicate that ensemble models outperform single models such as ANN and Support Vector Regression (SVR) in predicting CMC, with the combined random forest and ANN model showing the highest accuracy. Sensitivity analysis using Shapley Additive Explanations (SHAP) reveals that the CMC is most influenced by the water-to-cement ratio and curing age. Additionally, we designed a graphical user interface (GUI) to facilitate the practical application of our models. This research offers a robust methodology for evaluating concrete durability and potential for extending the prediction to other concrete properties.

A study on the synthesis and performance evaluation of fly ash and alccofine as sustainable cementitious materials

Construction and global infrastructure depend on cement production. It is one of the biggest carbon emitters, making it an aspect of environmental sustainability and climate change mitigation. Each stage of cement production releases CO2 and other greenhouse gasses. About 8% of worldwide CO2 emissions come from the cement sector, making it a major contributor. Different supplementary cementitious materials (SCMs) like fly ash (FA), silica fume (SF), and slag are used to partially replace traditional raw materials like limestone, reducing the environmental impact. This study investigated the use of supplementary cementitious materials, specifically FA and alccofine (AF), as partial replacements for cement in concrete to reduce environmental impact. The study first identified an optimal replacement percentage for FA (20%, 30%, and 40%) by weight of cement. Subsequently, using the optimal FA percentage, AF was added at varying percentages (5%, 10%, and 15%) by weight of cement. The study evaluated the mechanical properties of the concrete mixtures, including workability, compressive strength, split tensile strength, and flexural strength. Durability, measured by water sorptivity and rapid chloride penetrability tests, was also assessed. The microstructural properties of the concrete were analyzed to understand their influence on performance. As a result of the significant environmental implications of producing and using concrete for all activities, an in-depth life cycle assessment (LCA) was conducted. Additionally, artificial neural networks were employed to predict the compressive strength of the concrete. The study concluded that incorporating FA and AF in concrete mixtures is a promising approach to producing more environmentally friendly concrete.

The Effects of Internal Curing and Shrinkage Cracking Avoidance on the Corrosion of Reinforced Concrete Walls with Superabsorbent Polymers

The pursuit of durable and sustainable construction has driven interest in innovative materials, with superabsorbent polymers (SAPs) emerging as a promising solution, especially for the concrete industry. SAPs offer significant benefits to the durability of concrete structures, including mitigation of autogenous shrinkage, enhanced freeze–thaw resistance, crack sealing, and stimulation of autogenous healing. This study focuses on the impact of internal curing with SAPs on crack formation and corrosion initiation in large-scale reinforced concrete walls (14 m × 2.75 m × 0.8 m). Both commercial SAPs based on acrylic acid chemistry and in-house-developed SAPs based on alginates were evaluated. Key findings reveal that the reference wall exhibited visible cracking just five days after casting, while the SAP-treated wall remained crack-free throughout a 24-month monitoring period. Moreover, the reference wall showed corrosion initiation at two locations near the cracks within six months, whereas the SAP-treated wall exhibited no signs of corrosion potential. Laboratory tests further demonstrated a slight reduction in chloride penetration and carbonation in SAP-treated specimens compared to the reference. These results highlight the efficacy of SAPs in enhancing the durability and longevity of reinforced concrete structures.

Mechanical, durability and microstructural properties of waste-based concrete reinforced with sugarcane fiber

Extensive research has focused on producing sustainable concrete by exploring waste and recycled materials as alternatives to virgin substances. However, waste-based concretes often exhibit inferior durability and mechanical performance compared to traditional concrete. Incorporating reinforcement agents can enhance their performance. This study investigates the use of sugarcane fiber as a reinforcement in waste-based concretes containing fly ash (FA), ground granulated blast furnace slag (GGBS), and recycled concrete fine and coarse aggregates (RFA and RCA). Five dosages of sugarcane fibers (0 %, 1 %, 2 %, 3 %, and 4 % by fine aggregates mass) were examined. Mechanical and durability tests, including compressive strength, flexural strength, water absorption, and chloride ion penetration, were conducted. Scanning electron microscopy and micro-porosity analysis were employed for further assessment. Results show that adding sugarcane fiber enhances the waste-based concrete properties, with 3 % being the optimal dosage. This dosage improves compressive strength by 16 %, flexural strength by 35 %, flexural load bearing capacity by 34 %, energy absorption by 107 %, and toughness index by 6 %, while reducing water absorption by 4 % and chloride ion penetration by 23 %. Further increases in fiber dosage decrease concrete properties. The enhanced behavior is attributed to reduced porosity, refined pore structure, and reduced microcrack propagation. This study underscores the potential of incorporating sugarcane fiber along with waste materials to develop eco-friendly composites, aiming to mitigate carbon dioxide emissions and address environmental concerns.

Effect of Microwave Curing on the Performance of High-volume Fly Ash Concrete

Concrete curing significantly impacts mechanical properties and durability, yet traditional methods face efficiency challenges. Microwave curing (MC) offers a promising alternative, providing rapid and uniform concrete curing. However, fully understanding the impact of MC on concrete performance, particularly in high-volume fly ash concrete (HVFC), remains a research gap. This study addresses this gap by investigating the effect of MC on key properties of HVFC, including compressive strength, drying shrinkage, chloride ion penetration, and resistance to sulfate attack. Concrete specimens underwent MC at varied energies (200–1000 W) and durations (10–30 min) to evaluate their mechanical and durability characteristics. Results show that MC significantly boosts early-stage concrete strength, notably at high applied energy. The specimen cured at 1000 W for 30 min (MC1000-30) achieved the highest 1-day strength of 23.68 MPa. However, the normal curing specimen exhibited the highest strength of 32.07 MPa at 28 days while the strength value of the MC1000-30 specimen declined to 20.25 MPa, indicating a 36.85% decrease. Although declining strength was observed after 28 days, the MC1000-30 specimen demonstrated improved durability with significantly reduced drying shrinkage (by 83.12%) and chloride ion penetration (by 31.6%). The study underscores the feasibility of utilizing MC for HVFC as it demonstrated significant enhancements in both early-stage concrete strength and durability at a later stage. Careful parameter optimization can ensure sustained effectiveness over time, offering a viable alternative to traditional curing methods.

Effect of chloride ion corrosion on the microstructure of multiple interfaces of alkali-activated GGBS/FA based recycled concrete

In this paper, the resistance to chloride ion permeability of multiple interfaces in alkali-activated slag/fly ash (GGBS/FA) based full recycled concrete was investigated using the immersion method. In order to objectively and accurately reflect the microhardness and width of the interface transition zone (ITZ), box plots were used to process the measured point data. The results indicated that the microhardness of the interface was significantly lower than that of the matrix. The microhardness of the old aggregate interface (ITZOA-OM), the new aggregate interface (ITZOA-NM) and the new mortar interface (ITZOM-NM) all decreased to varying degrees with the extension of the immersion ages, but remained higher than that of the uneroded specimens. Chloride ions penetrated into ITZOA-OM and reacted with a large amount of enriched Ca (OH)2 to form an expansive composite salt (CaCl2.Ca(OH)2.H2O), which improved the microstructure of the ITZ, increased the microhardness and decreased the width of the ITZ. The dense structure of ITZOA-NM and ITZOM-NM inhibited the migration of chloride ions to a certain extent. leading to minimal changes in the width and microhardness of the ITZ. The micro mechanisms of chloride ion penetration resistance at the interfaces of alkali-activated GGBS/FA-based recycled concrete were investigated using BSE and EDS. More reaction products were generated at the interfaces after chloride ion erosion, and the newly generated substances continuously filled the microcracks, resulting in a more uniform bond at the interfaces. This contributed to the improvement of the microstructure and the resistance to chloride ion penetration of alkali-activated GGBS/FA based recycled concrete.

Assessment of Surface Treatment Systems for Protecting Concrete Structure

The BS EN 1504-2:2004 groups surface treatments into three types: impregnations, hydrophobic impregnations, and surface applied corrosion inhibitors. Impregnations reduce surface porosity by filling concrete pores, while hydrophobic impregnations create a water-repellent surface without filling pores. Surface applied corrosion inhibitors form a protective film on the rebar surface. Impregnation strengthens the surface by blocking pores with reaction products that reduce ingress of aggressive agents. Hydrophobic impregnation produces a hydrophobic and water-repellent surface that inhibits water penetration while allowing concrete to breathe. Corrosion inhibitors migrate to the steel surface and form a mono-molecular film, preventing further corrosion. In this study accelerated corrosion test was used for determination of the effectiveness of each category in offering corrosion protection by subjecting concrete specimens coated with these surface treatments to accelerated corrosion conditions that is intended to induce corrosion in the embedded rebars. This paper presents test results for the performance of these three surface treatments on grade G30 and G40 concretes. Results show that hydrophobic agents are more effective than traditional impregnates in reducing water absorption and chloride penetration.

Mechanism of healing, strength, and durability concepts of bacteria concrete - a review

Abstract Research work is going on to explore the concept of self-healing concrete. Outcome of the investigation reveals potential of bacteria concrete. Self-healing capacity imparted to the concrete by incorporating bacteria. Traditional methods reported in the literature such as epoxy injection, grouting, drilling, and plugging and gravity filling method have environmental impact, require more maintenance and are time consuming. The self-healing mechanism can be a better alternative to compensate these defects due to ecofriendly nature. Self-healing mechanism involves the production of CaCO3 precipitate deposites in crack region. Review paper focused on self-healing efficiency, water permeability, chloride penetration, compressive strength, flexural strength and recovery of water tightness, percentage weight loss of both conventional and bacterial concrete. For good environment tomorrow and better sustainability, self-healing conceptin concrete structure contributes promising technology.

Enhancing the Performance and Behaviour of M35 Alccofine 1203 Grade Concrete

Abstract: The construction industry faces pressures to reduce its environmental footprint, prompting the exploration of sustainable materials that maintain or enhance conventional concrete's performance. This study investigates Alccofine 1203, a high-performance micro-fine material, as a partial cement replacement in concrete. The objective is to determine optimal Alccofine percentages for desired mechanical properties and sustainability benefits. We conducted experimental trials with concrete mixes where cement was replaced by Alccofine at increments of 5%, 10%, and 15%. Multiple concrete cubes were prepared and tested for compressive strength, flexural strength, workability, and durability. Fresh properties were evaluated using slump and flow tests, ensuring adequate workability, while long-term performance was assessed through durability tests, including permeability and chloride ion penetration. The results indicate that a 10% replacement of cement with Alccofine 1203 enhances the compressive strength and durability of concrete without compromising workability. Higher percentages showed varied results, necessitating further investigation to optimize the mix design. This study highlights the potential of Alccofine 1203 as a sustainable alternative to traditional cement, offering significant implications for eco-friendly construction practices. This research contributes to the field by providing empirical data on Alccofine 1203's effects in concrete, supporting the development of more sustainable building materials. Future work will focus on refining mix proportions and exploring Alccofine's impact on other concrete properties such as shrinkage and creep.

Ternary Effect in Concrete: Jaggery, Alccofine, and Graphene Oxide

Abstract: This study investigates the effects of incorporating jaggery as an additive and Alccofine 1108 and graphene oxide as partial replacements for cement in concrete. Jaggery, a traditional natural sweetener, is introduced as an organic additive to enhance the workability and mechanical properties of concrete. Alccofine 1108, a high-performance micro-fine material, and graphene oxide, a carbon-based nanomaterial known for its exceptional strength and durability, are evaluated as partial cement substitutes to improve the sustainability and performance of concrete. To determine the optimal proportions of these materials. Various mixes were prepared by replacing cement with 5%, 10%, and 15% Alccofine 1108 and 0.05%, 0.10%, and 0.15% graphene oxide, 0.05%, 0.10% and 0.155% added to jaggery by weight of cement. The concrete samples were tested for compressive strength, tensile strength, and durability properties, including resistance to chloride ion penetration and sulfate attack.To determine compressive strength result, Split tensile strength result and Ultra Pulse Velocity result.

Development of Ultra-High-Performance Concrete Using GGBS and Alccofine

Abstract: Ultra-high-performance concrete, or UHPC, is a cementitious mixture that is distinguished by its exceptionally high compressive strength—more than 120 MPa as well as its remarkable toughness, tensile ductility, and longevity. Ground Granulated Blast Furnace Slag (GGBS) and Alccofine (AF) are commonly used in the matrix composition to increase the particle system's packing density and subsequently enhance the matrix's strength in order to guarantee that UHPC has the proper strength. To investigate the engineering properties of ternary blended UHPC with GGBS, AF, a comparative study was conducted. In comparison to the control UHPC mix, the ternary blended UHPC mix's mechanical and durability qualities were improved by the percentage variation of AF within specific bounds. In this study, the experimental work included mix proportioning and preparation of ternary blended UHPC specimens and various tests like Compressive Strength, Split Tensile Strength, Flexure Strength and RCPT (Rapid Chloride Penetration Test) were performed in the laboratory. The results show that under normal water curing conditions, the strength qualities of UHPC based on GGBS are considerable, up to a cement replacement level of 40%. In addition, compared to the binary counterpart, the mixture of 20 Percent AF and 40 Percent GGBS showed better mechanical and durability properties.

Simulation of concrete cracking and chloride diffusion under uniaxial compression

The dispersion and randomness of concrete cracking under compressive loads make it challenging to predict the diffusion rate of chloride ions. In this paper, the cohesive element method was employed to quantitatively calculate and determine the form and width of dispersed cracks in concrete. These results were found to be consistent with the real concrete crack forms obtained using digital image correlation (DIC) technology. The findings indicate that both the form and width of the cracks significantly impact the diffusion of chloride ions within the concrete. Chloride ion diffusion is enhanced when the cracks are closer to the penetration side or when there are more cracks present in the concrete. Additionally, an increase in axial load amplifies the randomness of chloride ion distribution at the same penetration depth. While coarse aggregates can impede chloride ion penetration, wider cracks lead to a higher concentration of chloride ions within the concrete. Our results contribute to a deeper understanding of chloride ion diffusion in cracked concrete under varying stress levels.

Mechanical Properties of Cement Concrete with Waste Rubber Powder

To investigate the mechanical properties of cement concrete incorporating waste rubber powder, the response surface methodology was employed. The Box–Behnken central composite design was applied to analyze the three primary factors influencing the road performance of cement concrete containing waste rubber powder: the water–cement ratio, sand ratio, and waste rubber powder content. The study determined the impact of these factors on the flexural strength of waste rubber powder cement concrete at both 7 and 28 days. Additionally, the effects of the water–cement ratio, sand ratio, and waste rubber powder content on the performance of cement concrete were analyzed. To investigate the impact of waste rubber powder on cement concrete, various mechanical property tests were conducted, including compressive, flexural, dynamic elastic modulus, and impact performance tests. Furthermore, the study explored the influence of waste rubber powder on the noise reduction capacity of cement concrete using both the rubber ball impact method and ultrasonic method. Lastly, the durability of cement concrete with added rubber powder was assessed through shrinkage tests, frost resistance tests, and chloride ion penetration tests.

Improving geopolymer concrete performance with hazardous solid waste phosphogypsum

Recycling the hazardous solid waste phosphogypsum (PG) in concrete is a popular trend. However, the inherent properties of PG used alone in concrete tend to limit the strength of the concrete. In this study, PG was used as a precursor for the production of phosphogypsum-based geopolymer concrete (PGC), which effectively improved the performance of geopolymer concrete by utilising the synergistic effect of different solid wastes in geopolymer concrete. The effects of PG content (0, 10, and 20 %) and alkali modulus (0.8, 0.95, 1.1, and 1.25) on the axial compressive properties and resistance to chloride penetration of PGC were investigated. The results show that 10 % PG improved the properties of geopolymer concrete the most, with a maximum increase in axial compressive strength of 17 %. Due to the addition of SO42−, the PG content also affected the optimal alkaline modulus of PGCs. Chemical composition and microstructural analyses revealed that the promotion of the geopolymer reaction by PG is crucial for PGC performance enhancement. In addition, leaching tests and carbon emission assessment, confirmed that PGCs are an environmentally friendly option. Based on the analysis of axial compression behaviour, resistance to chloride ion permeability and environmental impact, PGC with 10 % PG content and 1.1 alkali modulus is an environmentally friendly alternative to conventional concrete. This study shows that hazardous solid waste PG can improve the performance of geopolymer concrete and create a new type of solid waste concrete.

Research Progress in Corrosion Behavior and Anti-Corrosion Methods of Steel Rebar in Concrete

The corrosion of steel rebars is a prevalent factor leading to the diminished durability of reinforced concrete structures, posing a significant challenge to the safety of structural engineering. To tackle this issue, extensive research has been conducted, yielding a variety of theoretical insights and remedial measures. This review paper offers an exhaustive analysis of the passivation processes and corrosion mechanisms affecting steel rebars in reinforced concrete. It identifies key factors such as chloride ion penetration and concrete carbonization that primarily influence rebar corrosion. Furthermore, this paper discusses a suite of strategies designed to enhance the longevity of reinforced concrete structures. These include improving the concrete protective layer’s quality and bolstering the rebars’ corrosion resistance. As corrosion testing is essential for evaluating steel rebars’ resistance, this paper also details natural and accelerated corrosion testing methods applicable to rebars in concrete environments. Additionally, this paper deeply presents an exploration of the use of X-ray computed tomography (X-CT) technology for analyzing the corrosion byproducts and the interface characteristics of steel bars. Recognizing the close relationship between steel bar corrosion research and microstructural properties, this paper highlights the pivotal role of X-CT in advancing this field of study. In conclusion, this paper synthesizes the current state of knowledge and provides a prospective outlook on future research directions on the corrosion of steel rebars within reinforced concrete structures.

Development of the passive film during passivation in passivating electrolytes containing sodium molybdate

The impact of sodium molybdate on passive films formed on lean duplex stainless steel (STS 329 FLD) was investigated. Elemental depth distribution was examined using glow discharge optical emission spectroscopy, while the analysis covered passive film capacitance, molybdenum's chemical state, and corrosion resistance. The addition of sodium molybdate to the passivation electrolyte resulted in a reduction of iron content in the iron-rich layer (from 48 % to 38 %), an increase in chromium content in the enhanced chromium layer (from 33 % to 42 %), and the presence of molybdenum on the film surface. Electrical impedance spectroscopy measurements indicated a significant increase in the capacitance of the passive film. Furthermore, molybdenum was identified as molybdate. Electrochemical anodic polarization curves revealed that the corrosion potential rose with the addition of sodium molybdate to the nitric acid electrolyte. This improvement in corrosion resistance was attributed to molybdate adsorption on the outermost part of the passive film, preventing chloride adsorption or penetration. Additionally, the corrosion current density decreased due to the presence of the chromium-rich layer.

Effect of Graphene Quantum Dots (GQDs) on the mechanical, dynamic, and durability properties of concrete

Addressing ecological concerns stemming from concrete usage is paramount, prompting exploration into additives for mitigation. Graphene quantum dots (GQDs) have been recognized for their potential to improve the mechanical attributes of cement composites. Additionally, the electrochemical reduction of a saturated solution of carbon dioxide (CO2) and monoethanolamine (CO2-MEA) effectively removes CO2 from the atmosphere. This study delves into the influence of GQDs on the mechanical and durability aspects of concrete. It is noted that the control mix of concrete without GQDs was specifically designed for concrete railway sleepers. Varied proportions of GQDs, ranging from 0.3 % to 1.2 % at 0.3 % increments, were incorporated to assess their impact on fresh and hardened concrete properties. Mechanical properties such as compressive strength, splitting tensile strength, flexural strength, and dynamic properties were evaluated. Durability assessments encompassing water absorption and chloride ion penetration were conducted. Microstructural analysis via Field Emission Scanning Electron Microscopy (FESEM) imaging and Energy-dispersive X-ray spectroscopy (EDS) elucidated the concrete's internal composition. Notably, an optimal GQDs percentage of 0.3 % was observed, signifying its efficacy in enhancing the performance of concrete. When 0.3 % of GQDs was added to concrete, compressive strength, split tensile strength, and flexural strength were enhanced by 10.8 %, 23 %, and 11 % respectively. The incorporation of GQDs resulted in a notable improvement in the fundamental frequencies and dynamic modulus of elasticity. Concurrently, a decrease in the damping ratio was observed for specimens containing GQDs. Additionally, the porosity and chloride penetration depth were lower by 6 % and 30 % for specimens with 0.3 % GQDs. The improvement in workability, mechanical, and dynamic properties of concrete, along with reducing CO2 from the atmosphere, makes GQDs an ideal eco-friendly material. This study is the first to open new pathways for the development of construction materials that are not only structurally superior but also environmentally responsible, marking a significant step forward in the field of civil engineering materials, especially in railway applications.

Chloride transport in alkali-activated materials influenced by different reaction products: a review

Alkali-activated materials (AAMs) are regarded as a substitute for Portland cement. They have high chloride resistance and a low carbon dioxide footprint. The aim of this review is to provide a multi-scale perspective to understand material–product–microstructure–property relationships in terms of the chloride binding behaviour of AAMs. The physical and chemical chloride stability of different reaction products is summarised from nanostructure, to microstructure to macro properties. An analysis of studies in the literature gives an overview of recent progress in chloride transport in AAMs influenced by different reaction products. Results show that a higher calcium/silicon, aluminium/silicon molar ratios and alkali content increase the formation of amorphous phases, leading to a denser microstructure and lower chloride penetration in AAMs. Higher magnesium oxide and aluminium oxide contents result in increased formation of hydrotalcite. The enhanced physical and chemical absorption of chloride by hydrotalcite leads to higher resistance of chloride penetration in AAMs. Investigation of increasing chloride resistance could potentially focus on increasing gel and hydrotalcite formation.

Transport Properties of Internally Cured Self Compacting Concrete with Fly Ash

Proper curing of concrete has a major beneficial effect on the transport properties of concrete which in turn influences its durability. This paper attempts to study the effect of fly ash on the transport properties of internally cured Self-Compacting Concrete specimens under ambient conditions. Two internal curing materials, Lightweight Expanded Clay Aggregates [LECA] and Superabsorbent Polymer [SAP] were chosen for the study. Properties such as sorptivity, resistance to chloride ion penetration and chloride ion migration specimens with varying percentages of fly ash replacement from 30% to 50% are presented under different curing conditions namely conventional curing, sealed curing with internal curing materials and ambient curing with internal curing materials. The results showed that the impermeability of concrete improved with an increasing percentage of fly ash replacements owing to the presence of internal curing water to improve hydration along with fly ash that moderates the heat of hydration and drying. The internal curing efficiency also improved with the increase in the percentage of fly ash replacement. Under ambient conditions, the mixes with fly ash above 45% replacement have shown very good mechanical and durability properties indicating a refined pore structure leading to enhanced transport properties.

A Review of Gene-Property Mapping of Cementitious Materials from the Perspective of Material Genome Approach.

As an important gelling material, cementitious materials are widely used in civil engineering construction. Currently, research on these materials is conducted using experimental and numerical image processing methods, which enable the observation and analysis of structural changes and mechanical properties. These methods are instrumental in designing cementitious materials with specific performance criteria, despite their resource-intensive nature. The material genome approach represents a novel trend in material research and development. The establishment of a material gene database facilitates the rapid and precise determination of relationships between characteristic genes and performance, enabling the bidirectional design of cementitious materials' composition and properties. This paper reviews the characteristic genes of cementitious materials from nano-, micro-, and macro-scale perspectives. It summarizes the characteristic genes, analyzes expression parameters at various scales, and concludes regarding their relationship to mechanical properties. On the nanoscale, calcium hydrated silicate (C-S-H) is identified as the most important characteristic gene, with the calcium-silicon ratio being the key parameter describing its structure. On the microscale, the pore structure and bubble system are key characteristics, with parameters such as porosity, pore size distribution, pore shape, air content, and the bubble spacing coefficient directly affecting properties like frost resistance, permeability, and compressive strength. On the macroscale, the aggregate emerges as the most important component of cementitious materials. Its shape, angularity, surface texture (grain), crushing index, and water absorption are the main characteristics influencing properties such as chloride ion penetration resistance, viscosity, fluidity, and strength. By analyzing and mapping the relationship between these genes and properties across different scales, this paper offers new insights and establishes a reference framework for the targeted design of cementitious material properties.