Durability Of Concrete Structures Research Articles

Development of Environmental Monitoring Sensor for Steel Corrosion in Concrete based on Micro-Electro-Mechanical Systems (MEMS)

Many bridges located near marine environments usually have high risk to lose their structural performance due to corrosion of reinforcing bars with chloride attack. While a huge amount of budget to maintain may be consumed for the structural maintenance methodologies, an efficient monitoring system for Reinforced Concrete (RC) structures in the corrosive environment is strongly demanded. Thus, structural health monitoring in real situations is significant for bridge asset management. The alternative way for preventing severe damage propagation is proactively monitoring the environmental condition containing chloride ion and its effect on the durability of concrete structures, for which numerous methods have been conventionally suggested such as dry gauze method to capture chlorides in air. In this study, Micro Energy Harvester (MEH) based on Micro-Electro-Mechanical Systems (MEMS) is technically applied to develop a sensor to identify the corrosion environment with chlorides in the exposure condition. MEMS is a rapidly evolving device, which enables to monitor the changes in natural frequency and amplitude at nodal locations of the targeting structure due to vibration-based electrostatic power generation induced by the corrosive environment. The purpose of this research is to develop a system for detecting the high corrosion-prone areas and finding the suitable metal sheet material for various chloride ion conditions, using the metal sheet as a cantilever structure for the MEMS device. 4 types of metal, aluminium, copper, iron and zinc are considered for the parametric experiments. Several scenarios are considered including chloride ion concentration, temperatures, and wet and dry conditions to compare the dominant frequency changes of each metal sheet and determine their sensitivity to corrosion environment. From the preliminary results, iron and zinc have a significant drop in frequency with the elapsed exposure period, which indicates that they are highly sensitive to the external chloride ion environment. These results offer an innovative and proactive approach to structural health monitoring for further developed applications. It enables prompt maintenance and early detection of potential issues for corrosion of steel bars in concrete, ensuring the longevity and safety of RC bridge structures.

Durability of alkali-activated fly ash-slag concrete- state of art

India ranks among the foremost global producers and consumers of cement, and the cement industry contributes significantly to carbon emissions. Alkali-activated materials have gained significant attention as a sustainable alternative to Portland cement, offering the potential to mitigate carbon dioxide emissions and promote effective recycling of waste materials. Fly ash (FA) and Ground granulated blast furnace slag (GGBS) are preferred raw materials for Alkali-activated concrete (AAC) owing to their effective repurposing of waste, widespread accessibility, advantageous chemical composition, and performance attributes. This review provides a comprehensive analysis of the current state-of-the-art on the durability aspects of fly ash/slag-based AAC. The paper explores the unique characteristics of FA/GGBS-based AAC, emphasizing their potential to enhance the durability of concrete structures. Insights into the material behaviour under various environmental exposures, including aggressive chemical environments and freeze–thaw cycles, are presented. Furthermore, the article addresses both the obstacles and prospects associated with implementing fly ash/slag-based AAC as a potential construction material suitable for large-scale infrastructure projects. This overview is designed to direct future research efforts and provide practitioners with insights into the potential of FA/GGBS-based AAC for ensuring the prolonged durability of concrete structures.

Updating Durability Models for Concrete Structures in Chlorine Environment Based on Detection Information

The assessment of concrete structure durability in chlorine environments is significantly impacted by the uncertainty inherent in existing durability models. It introduces an integrated approach for updating these models based on the detection information of existing structures. This approach narrows the gap between theoretical predictions and observed structural durability. Specifically, we refined the probability model of critical chloride content by analyzing steel bar corrosion sample proportions using Bayesian theory for greater accuracy. The enhanced model enables more reliable life expectancy prediction, forming a solid foundation for maintaining and strengthening existing structures. This method was demonstrated through a case study of a reinforced concrete industrial building with a service life of 12 years.

Comprehensive assessment and monitoring of bond deterioration in GFRP-reinforced concrete beams using guided wave and acoustic emission techniques

The debonding between glass fiber-reinforced polymer (GFRP) rebars and concrete significantly reduces the bond strength and jeopardizes the safety and durability of GFRP-reinforced concrete (GFRP-RC) structures. As a result, it is imperative to monitor the structural integrity of infrastructures being built using these composite materials in structural elements during their service lives. Previous studies have primarily focused on artificially induced debonding scenarios for guided wave (GW)-based monitoring, which has resulted in an inability to capture debonding events that arise naturally due to external loads. Furthermore, flexural bond test investigations simulating real loading scenarios in GFRP-RC structures have not been linked with acoustic emission (AE) and GW monitoring. The present study addresses these research gaps by comprehensively examining the flexural bond integrity in GFRP-RC structural elements subjected to realistic loading conditions using a hybrid approach combining GW and AE as active and passive structural health monitoring techniques, respectively. A series of bond tests, conforming to RILEM specifications, have been performed to investigate various parameters (including rebar surface characteristics, embedment length, and confinement conditions) that affect the flexural bond degradation response of GFRP-RC members. Damage indices based on GW and AE signal parameters have been developed to evaluate the characteristics of confined and unconfined specimens distinctly. It has been observed from the test results that the L (0,3) GW mode is more sensitive to debonding than other modes and that a threshold of 25% has been established for the GW damage index to denote significant bond damage. Furthermore, AE damage indices have provided valuable insights into concrete damage, including splitting and damage at the rebar-concrete interface. Thus, a thorough understanding of bond deterioration in GFRP-RC structures has been developed by combining GW and AE health monitoring techniques, with implications for enhancing structural safety and durability.

Early-Age Cracking of Fly Ash and GGBFS Concrete Due to Shrinkage, Creep, and Thermal Effects: A Review.

Supplementary cementitious materials (SCMs) are eco-friendly cementitious materials that can partially replace ordinary Portland cement (OPC). The occurrence of early-age cracking in OPC-SCM blended cement is a significant factor impacting the mechanical properties and durability of the concrete. This article presents a comprehensive review of the existing research on cracking in OPC-SCM concrete mix at early ages. To assess the effects of SCMs on the early-age cracking of concrete, the properties of blended cement-based concrete, in terms of its viscoelastic behavior, evolution of mechanical performance, and factors that affect the risk of cracking in concrete at early ages, are reviewed. The use of SCMs in OPC-SCM concrete mix can be an effective method for mitigating early-age cracking while improving the properties and durability of concrete structures. Previous research showed that the shrinkage and creep of OPC-SCM concrete mix are lower than those of conventional concrete. Moreover, the lower cement content of OPC-SCM concrete mix resulted in a better resistance to thermal cracking. Proper selection, proportioning, and implementation of SCMs in concrete can help to optimize the performance and reduce the environmental impact of OPC-SCM concrete mix.

Influence of inorganic compounds on self-repairing capability and frost resistance of concrete incorporating ion chelating agent

Cracks can decrease the durability of concrete structures. The ion chelating agent (ICA) can repair concrete cracks through precipitates formed by chelation crystallization reactions. However, its capacity to repair internal damage in concrete is limited, and the chelation crystallization reaction slows down in cold environments. Some inorganic compounds (magnesium fluosilicate and sodium silicate) can promote precipitation formation within concrete, potentially enhancing its self-repairing capability. This study explores the synergistic effects of ICA and these inorganic compounds on the self-repairing capability and frost resistance of concrete. To achieve this research objective, parameters such as visual crack closure, compressive strength reserved ratio, pore structure change, chloride diffusion coefficient, and the microstructure and composition of the repair products were investigated. Sodium silicate and ICA demonstrated significant improvements in the self-repairing capability and frost resistance of concrete. Concrete containing 0.5wt% sodium silicate and 0.5wt% ICA, after 28 d of standard curing, fully repaired surface cracks with a width of 0.49 mm. After 300 freeze-thaw cycles, the chloride diffusion coefficient increase rate and harmful pores proportion in the concrete containing 0.5wt% sodium silicate and 0.5wt% ICA were reduced by 51.7% and 76.6%, respectively, compared to the control concrete. Following 28 d of curing after freeze-thaw damage, the compressive strength reserved ratio of concrete with 0.5wt% sodium silicate and 0.5wt% ICA increased by 38.5%, while the chloride diffusion coefficient increase rate and the harmful pores proportion decreased by 68.5% and 84.9%, respectively, compared to the control concrete. Furthermore, SEM-EDS analyses revealed significant amounts of calcium carbonate and some calcium silicate within the cracks of the concrete containing ICA and sodium silicate, and that the internal damage was primarily repaired by a combination of calcium carbonate and calcium silicate.

Experimental Study of Partial Replacement of Cement with GGBS and Silico Manganese with M30 Grade Concrete

Abstract: Cement in concrete is a several disadvantages when used without any replacement to it in concrete such as high carbon footprint high cost of construction, and low tensile strength. To address these materials such as GGBS, and silico manganese can be used, designing concrete mixtures with lower cement content can reduce the carbon print, cost, and potential cracking, resulting in more sustainable, cost effective and durable concrete structures. In our project we are going to use GGBS (Ground granulated blast furnace slag) and silico manganese as a replacement of materials to cement in varying percentage. GGBS and silico manganese cementitious properties and can particularly replace cement in concrete mixtures. It improves the durability, workability, and strength of concrete. GGBS has a lower carbon footprint than traditional cement, making it an environmentally friendly alternative. Silico manganese is the process involves high temperature to melt the raw materials and reduce them to their metallic forms. This project represents the results of an experimental investigations accomplish to understand the suitability of GGBS and Silico manganese on strength of referral concrete M30 Grade concrete was prepared by replacing PART OF 0%, 30%, 40%, 50% (by weight of cement) for GGBS and Silico manganese. Fresh concrete was properties viz. slump cone was carried out. Strength of concrete were determined by performing compressive strength test on (150mm×150mm×150mm) size cubes.

Enhancing concrete durability in chloride-rich environments through manual application of healing agents

Concrete structures in chloride-rich environments are prone to deterioration, especially when ions can intrude via cracks towards the steel reinforcement. Self-healing concrete could significantly extend the service life of reinforced concrete. Hence, selecting appropriate healing agents to improve the durability is a critical challenge for the construction industry. This study investigates the use of three potential healing agents: water-repellent agent (WRA), sodium silicate (SS), and polyurethane (PU). The agents are tested separately under two conditions: exposure to a 3.3 % NaCl concentration at 20 °C and exposure to cyclic freeze-thaw conditions. The agents are manually injected into the cracks and evaluated for their healing efficiency using the capillary absorption test and microscopy analysis. Additionally, their resistance to freeze-thaw cycles by monitoring mass loss and chloride bulk diffusion is measured using sprayed silver nitrate, titration, and EDX mapping. The results demonstrate the effectiveness of PU in completely preventing chloride ingress and withstanding the freeze-thaw cycles. On the other hand, WRA showed a significant reduction in scaling, being the only healing agent to keep scaling below the appropriate scaling level of 1 kg/m2. Although WRA had the best performance in the scaling test and prevented chloride ingress, some influence was observed from the freeze-thaw cycles with regard to chloride ingress. Samples treated with SS performed better than the reference samples but did not show the same effectiveness as samples treated with PU or WRA in preventing chloride ingress. Overall, the study highlights the potential of healing agents in improving the durability of concrete structures in chloride-rich environments, with PU and WRA being the most promising for further development and optimization.

Study on time range of definite integral in derivation process of chloride ion diffusion theoretical model of concrete

In the study of the durability of concrete structures, the chloride ion diffusion coefficient (Dt) is a key parameter that directly affects the prediction of concrete's service life. This study aims to explore the relationship between the chloride ion diffusion coefficient in concrete and the "curing age (tref)" and "exposure time (t)." By conducting long-term curing and seawater exposure experiments on three different mixes of high-performance concrete samples, we collected experimental data with a curing age of 3 years and a seawater exposure time of 4.5 years. Through in-depth analysis of these data, we found that there is a significant power function relationship between the chloride ion diffusion coefficient and exposure time, while the relationship with curing age is not significant. This finding suggests that in the derivation of the concrete chloride ion diffusion theory model, the time range of the definite integral of Dt should be from 0 to t, rather than from tref to tref+t. Furthermore, we have validated the concrete life prediction model using actual data from the Swedish Marine Exposure Station, further confirming the accuracy and reliability of our research results. This study provides a more scientific and accurate theoretical basis for the durability assessment and service life prediction of concrete structures.

Calculation of the mechanical properties of high‐performance concrete employing hybrid and ensemble‐hybrid techniques

AbstractThis study aims to execute machine learning methods to predict the mechanical properties containing TS and CS of HPC. They are essential parameters for the durability, workability, and efficiency of concrete structures in civil engineering. In this regard, obtaining the estimation of the mechanical properties of HPC is complex energy and time‐consuming. Due to this, an observed database was compiled, including 168 datasets for CS and 120 for TS. This database trained and validated two machine learning models: SVR and RT. The models combine the prediction outputs from the meta‐heuristic algorithms to build hybrid and ensemble‐hybrid models, which include dwarf mongoose optimization, PPSO, and moth flame optimization. According to the observed outputs, the ensemble models have great potential to be a recourse to deal with the overfitting problem of civil engineering, thus leading to the development of more supportable and less polluting concrete structures. This research significantly improves the efficiency and accuracy of predicting vital mechanical properties in high‐performance concrete by integrating machine learning and metaheuristic algorithms, offering promising avenues for enhanced concrete structure design and development.

Identification of the Surface Cracks of Concrete Based on ResNet-18 Depth Residual Network

To ensure the safety and durability of concrete structures, timely detection and classification of concrete cracks using a low-cost and high-efficiency method is necessary. In this study, a concrete surface crack damage detection method based on the ResNet-18 residual network was developed. This method was implemented by training a model with images to extract the cracks, where the image processing algorithms and deep learning were combined. The results show that the computational accuracy can meet the requirements by utilizing the established image dataset and appropriate model hyperparameters. The trained model had high recognition accuracy when the 256 × 256 resolution images were adopted, and the worst accuracy of crack recognition in the test set was over 90%. The average accuracy in the test set was 91.3% when considering environmental interference generated by processing the images with a brightness adjustment, salt-and-pepper noise, and localized interference. Then, it was demonstrated that the present model possesses good robustness for crack identification in different environments. The average recognition accuracy when dealing with images of a real bridge, which are outside the training dataset, was 99.7%. The residual network model developed in this study has the advantages of low cost, high efficiency, and practicality compared to traditional detection methods. Compared to the existing deep learning methods, the model created in this study requires less computational resources and storage space, and shows a faster training speed and higher accuracy.

Experimental Study on the Effect of Steel Reinforcement Ration on the Cracking Behaviour of FRP-Strengthened RC Elements

This paper examines the cracking behaviour of reinforced concrete beams strengthened by externally bonded fiber-reinforced polymer. The crack opening of RC structures is a key parameter for the durability of concrete structures. It is of vital importance for designers to be able to make correct estimations of the crack opening values of strengthened structures. FRP strengthening affects the cracking behaviour of RC beams with different steel percentages. Beams have been tested under four-point bending mechanical tests until failure with three steel ratios and two layers of externally bonded wet carbon fibers (CFRP). In order to measure the crack opening during loading, Digital Image Correlation is used to obtain the crack opening along the beam during load functioning. The results allow for a comparison of the RC beams with and without FRP and enhance the effect of FRP on crack opening. The crack width was compared with the theoretical values obtained based on the relation proposed by Eurocode 2 (EC2). The comparison enhanced the need to propose a modified relation. Subsequently, an empirical model was established as a modification of EC2, considering the presence of a CFRP system. The corresponding results were compared and discussed to validate the model. For the same level of loads, the crack opening can be reduced by 20 to 50% depending on the level of steel ratio.

Novel multi-scale experimental approach and deep learning model to optimize capillary pressure evolution in early age concrete

Early-age shrinkage of concrete can initiate pre-mature cracking, which can compromise the durability of concrete structures. Monitoring capillary pressure, the leading cause of concrete shrinkage, and understanding its evolution is crucial for the performance-based design of concrete, particularly at early-stages when it is more prone to cracking. This study deploys an innovative multi-scale experimental program using high-capacity tensiometers to monitor the capillary pressure up to 2000 kPa. This allowed investigating the effects of key design parameters, including the water-to-cement ratio, GGBS, SRA, and measurement depth, on the capillary pressure evolution in concrete. A new robust deep neural network model was developed to conduct extensive numerical experiments to predict the capillary pressure evolution of diverse mixtures. The net effect of multi-parameters on the capillary pressure can be investigated with this model, providing insights into the optimum design of more durable concrete mixtures with the lowest capillary pressure evolution, and guiding the implementation of appropriate cost-effective shrinkage-mitigating strategies.

Enhancing concrete durability with polymer impregnation: A comparative study of corrosion and freeze-thaw resistance

This study explores the efficacy of Polymer Concrete (PC) in bolstering the durability and performance of concrete structures under diverse environmental conditions. Three variants of PC were examined: Polymer Impregnated Concrete (PIC), Polymer Portland Cement Concrete (PPCC), and Polymer Concrete (PC). The study focused on their resistance to corrosion and freeze-thaw cycles. The research also delved into the protective influence of various polymers, including silicone and epoxy, on both concrete and steel. The findings revealed that PIC surpassed other PC types in terms of corrosion and freeze-thaw resistance, while PC and PPCC necessitate further improvements. Silicone emerged as the most potent polymer for enhancing the durability of concrete and steel. PIC, exhibiting superior compressive strength and durability compared to control samples, was proposed as an apt material for construction projects in cold and corrosive environments. The PIC samples, composed of polymer, silicone, and polyvinyl acetate, displayed a significant improvement in their corrosion potential. Over a 90-day period, these samples showed a reduction of approximately 70 units, resulting in a value of 560 mV. When juxtaposed with other PC variants tested in the study, the PIC samples demonstrated superior corrosion resistance. The PIC samples also exhibited a higher average compressive strength and improved frost resistance compared to the PPCC and PC samples. The strength of PIC samples was 16.7% and 14.3% higher than control before and after cycles, respectively. Conversely, PPCC and PC samples displayed lower strengths than control, with PC samples recording the lowest. The strength reduction due to freeze-thaw cycles was least in PIC samples. In conclusion, PIC holds promise as a material for enhancing the durability and performance of concrete structures. Further research is recommended to assess its cost-effectiveness and environmental impact.

WATER PERMEABILITY OF CONCRETE TESTING INSTRUMENT

Instrument we mentioned for checking water permeability in concrete sounds super cool! It's designed with advanced technology and non-destructive testing methods to accurately evaluate how resistant concrete is to water. The instrument has End Cap Set , Booster Pump , Pressure Guage , Pressure Cutoff Switch. Making it comprehensive and efficient for testing. And the best part? It provides real-time measurements and immediate results, saving time and improving accuracy. Plus, it's non-destructive, so it's safe for evaluating concrete structures already in use. This instrument has the potential to revolutionize the construction industry and help engineers, researchers, and construction professionals make informed decisions for more durable concrete structures. Key Words: (Water permeability , Concrete , Durability ,testing methods , booster pump, pressure cut of switch , end cap set , pressure Guage)

Evaluation of Cherts in Gumushane Province in Terms of Alkali Silica Reaction

Alkali–silica reaction (ASR) occurs when alkali oxides coming from the cement composition in concrete come together with reactive silica and moisture coming from the aggregate. Additional maintenance and repair costs caused by the development of ASR in concrete cause the cost to increase. However, thanks to the measures taken against ASR in the early period, it contributes to the creation of sustainable and durable concrete structures. The article investigated the usability of cherts with eight different chemical compositions as aggregates in ready-mixed concrete plants in Gümüşhane. Cherts have been investigated for alkaline reactivity and are intended to be used largely as a source for concrete plants. ASR length changes of the samples prepared according to ASTM C1260 standard were determined after 3, 7, 14, and 28 days of the curing period. Microstructural examination, ultrasonic P-wave velocity, and bending and compressive strength experiments supporting ASR were carried out. The obtained test results were compared between the reference (limestone) sample and each other, as well as with the values specified in the standards. The compressive and bending strength values of the samples increase depending on their ASR. It was observed that the crack structures and types increased depending on the increase in the crack values.

A novel LDHs-VB3- inhibitor for rebar corrosion in simulated concrete pore solution: Synthesis, performance and mechanism

Developing novel chloride-trapping inhibitors is of great significance for enhancing the durability of marine concrete structures. In this study, a novel LDHs-VB3- inhibitor was synthesized through the ion exchange method. Then, the corrosion inhibition mechanism of LDHs-VB3- inhibitor for rebar in the whole process of release - capture - adsorption - retardation was studied using experiments and density functional theory (DFT) simulations. The chloride ion exchange test demonstrates that the LDHs-VB3- inhibitor has a chloride trapping capacity of 35.5 mg/g in the saturated Ca(OH)2 solution containing 0.14 M NaCl, implying that it could capture Cl- in concrete pore solution. According to the electrochemical tests, the critical chloride concentration of rebar in the simulated concrete solution containing LDHs-VB3- falls within a range of 0.22 M–0.28 M, which is much higher than that in the solution without LDHs-VB3- (0.10 M–0.14 M). DFT simulations indicate that LDHs-VB3- exhibits more positive binding energy and uneven binding forces in contrast to LDHs-Cl-. Consequently, VB3- could be easily replaced by Cl- and then released into the pore solution of concrete. Moreover, the released VB3- could adsorb on the α-Fe2O3 surface in a concrete environment via the interaction of surface Fe atoms with N and O atoms of VB3-. The preadsorbed VB3- could diminish the interaction of Cl- with the α-Fe2O3 surface by reducing electron transfer, thereby mitigating the risk of passive film breakdown and retarding the chloride-induced corrosion of rebars.

Unraveling the Effects of Compound Additives on the Strength of Cast Concrete

Purpose: The aim of this study is to examine the influence of a complex additive on the fundamental physico-mechanical properties of cast concrete. Methods: The research involves the introduction of a complex additive, comprised of plasti-cizers such as "ACF," "SAFA," and "SOAPSTONE," into the concrete mixture. This leads to structural changes in the cast concrete, impacting its physico-mechanical properties, including strength, uniformity, deformability, durability, and cement utilization coefficient. The significance of each component of the additive is thoroughly examined to identify optimal dosages and meth-ods of introduction for achieving desired results. Results and Conclusion: The conducted analysis reveals insights into the impact of the complex additive on the final characteristics of the concrete. Optimal dosages and incorporation methods are identified, contributing to enhanced performance and durability of cast concrete structures. Research Implications: The practical aspects of utilizing the complex additive in real con-struction conditions are elucidated, with examples provided to optimize construction processes, increase efficiency, and reduce environmental burden. Furthermore, the study underscores the im-portance of further research in developing more effective and sustainable construction materials and technologies. Originality/Value: The research contributes to the advancement of knowledge in the field of construction materials by highlighting the influence of complex additives on the physico-mechanical properties of cast concrete. The obtained results have implications for improving the quality and durability of concrete structures across various construction sectors.

Cementitious composites modified by nanocarbon fillers with cooperation effect possessing excellent self-sensing properties

Abstract The safety and durability of concrete structures are prone to damage and result in significant harm to human society. Hence, monitoring and estimating the states of concrete structures is of great significance to protecting human safety. Graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) are promising candidates to endow cementitious composites with piezoresistivity for the health monitoring of concrete structures. Therefore, the aim of this article is to explore the effect of the hybrid GNPs and CNTs on behavior of cementitious composites with cooperation effects. The cementitious composites containing the hybrid GNPs and CNTs with simplified manufacturing methods are developed first. And then, the mechanical behaviors, electrical conductivities, and piezoresistive performances of the composites are investigated systematically. Finally, the modification mechanisms are also discussed. The results proved that the electrical resistivity of the composites with the hybrid GNPs and CNT concentration of 5.0 wt% is reduced by three orders of magnitudes, and the FCR and sensitivities are reached at 36.0% and 1.1% MPa−1/177.9, respectively. Its compressive strength/elastic modulus is achieved at 73.3 MPa/16.9 GPa. Therefore, the hybrid GNPs and CNTs modified cementitious composite present great potential application in monitoring and evaluating service states of civil infrastructures.

The synergistic effect of microorganisms and multiple admixtures on improving the self-healing of cracks in biogenic mortar exposed to different marine environments

Existing research has inadequately addressed the synergistic effects of microorganisms and admixtures in promoting self-healing behavior and mechanisms of cracks in marine environments, including the atmospheric zone, tidal-splash zone, and submerged zone. This study primarily involved the incorporation of multiple admixtures and microorganisms into cement to prepare two types of biogenic mortars: Bacillus pasteurii-based mortar (BPM) and Bacillus subtilis-based mortar (BSM), with ordinary mortar (OM) serving as the control group. The mechanical properties, electrical flux, and pore structure of the mortars were investigated. Additionally, the self-healing behavior and mechanisms of cracks were studied under atmospheric, tidal-splash, and submerged conditions. The results indicate that with increasing curing age, the synergistic effect of admixtures and microorganisms continuously refined the pore structure of the specimens and enhanced their flexural strength, compressive strength, and resistance to chloride ion penetration. The atmospheric environment was found to be unfavorable for the self-healing of cracks in the specimens. However, in the submerged and tidal-splash zones, the combined action of microorganisms and admixtures led to more pronounced self-healing phenomena in the biogenic mortars compared to OM. Particularly, the self-healing effect of BSM cracks was more pronounced in the tidal-splash zone, with a 100% self-healing efficiency observed after 53 days. This was attributed to the ability of microorganisms in the tidal-splash zone to induce calcium carbonate precipitation on the surface of cracks in admixture-modified cementitious materials, thereby reducing the penetration of seawater, CO2, and O2 into the cracks, lowering the carbonation reaction of Ca(OH)2 crystals, and reducing the formation of brucite crystals inside the cracks, consequently enhancing the water permeability resistance of the specimens. These research findings hold significant engineering implications for improving the durability and service life of coastal self-healing concrete structures.