Concrete Corrosion Research Articles

Novel Reinforcing Techniques and Bearing Capacity Analysis for Tunnel Lining Structures with Extensive Corrosion

Affected by the erosive environment, tunnel lining concrete in the long-term service zprocess often exhibits engineering diseases such as concrete corrosion degradation and loss of strength, decreasing the stability of the tunnel lining structure and the traffic safety. Based on HTG tunnel project, the basic distribution rule of tunnel lining corrosion and macro mechanical properties of corroded concrete were explored in this paper through engineering disease site investigation. Then, on this basis, aiming at large-scale corrosion of tunnel lining structure, two reinforcement and repair schemes are proposed, corrugated steel plate reinforcement method and channel steel reinforcement method. Indoor component tests are carried out on the two reinforcement schemes. The failure characteristics and stress and deformation law of tunnel lining members after reinforcement and repair were verified. The analysis showed that the failure process of the reinforced specimens on the tensile side could be divided into the non-cracking stage and the working stage with cracks, and the cracking load and failure load of the specimens were significantly increased. The bearing capacity of the reinforced specimens was divided into the ultimate bearing capacity against cracking and the ultimate bearing capacity during failure. Finally, the calculation methods of the bearing capacity of the channel steel reinforcement method and the corrugated steel plate reinforcement method were derived. Comparative analysis shows that the results of numerical simulation, experimental testing and theoretical simplification methods are close to each other, and the maximum deviation is less than 8%. The established method for calculating the bearing capacity of corroded components after reinforcement is reliable and can be used for the design calculation of corroded lining reinforcement.

Influences of Cu-Ti amorphous alloy on the properties of mortar: Wastewater treatment and bacteria inactivation

Due to the superior catalytic properties, amorphous alloy (AA) can be used in concrete of sewage system to achieve wastewater treatment and bacteria inactivation, thus mitigating microbial-induced concrete corrosion and promoting the durability of concrete. In this study, three types of Cu/Ti amorphous alloys (AA) prepared by ball milling method according to different copper/titanium atomic ratios (35:65, 50:50, 65:35) were employed as anti-bacteria agent for cement mortars. Detailed investigations were conducted into the physical, mechanical, and anti-bacteria properties of amorphous alloys mortars (AAM) in the range of addition 0.3%-0.9% AA. It was demonstrated that the produced AA had a higher degree of amorphism, smaller particles size, and higher zeta potential with the increase of titanium content, leading to the reduce of total porosity of AAM up to 18.33%, and the enhancement of compressive and flexural strength at 28d up to 13.30% and 25.55%, respectively. In addition, the synthesized AA showed excellent antibacterial performances, in which the bacteriostasis rates on Escherichia coli for three types of AA all reached up to 100% after 24 h immersion. After adding in the cement mortars, the anti-bacterial activity and catalytic degradation capacity of AAM increased as the AA contents increased. AAM with 0.9 % Cu50Ti50 could achieve the best performance of bacteria inactivation and wastewater, in which 95.17% of bacteria was killed after 72 h and the degradation efficiency of Rhodamine B dyes reached up to 100% after 6 h. The findings are expected to facilitate the development of new functional applications of AAM in wastewater treatment.

Durability, mechanical properties and rebar corrosion of slag-based cement concrete modified with graphene oxide

The application of nanomaterial to concrete is an innovative approach to enhancing mechanical properties and durability. In fthis work, the combined additions of graphene oxide nano-platelets (GO) to concrete mix formulated to use ground granulated blast furnace slag (GGBFS) as a substitute for Portland cement (PC) for use in salt-rich environments is studied. The need arises in both off-shore structures and also places coming to contact with brine due to de-icing of road structures or the geological peculiarities specific to saline terrain. The physical, mechanical, chloride, and water permeability and electrical conductivity tests on the developed concrete are compared with those of ordinary concrete under conditions of varying temperature and water pressure. The addition of GGBFS is known to improve the mechanical properties of concrete specimens. Results from the present work show that the addition of no more than 0.1 wt% GO to 50 wt% GGBFS substituted concrete increases the after-curing compressive strength by 40 %, and flexural strength by 60 %. The electrical conductivity of the 90-day cured samples as a measure of chloride permeability dropped from nearly 4000 Coulombs in ordinary concrete to roughly 1100 Coulombs for the modified concrete indicating a nearly 70 % reduction. Accelerated CSH gelation, followed by Ca(OH)2 crystallization after GO addition, combined with altered pore structure from the addition of finely milled slag. The nucleation mechanism is affected such that the average pore diameter falls to 6.2 nm from 11.4 nm in the PC concrete. The low porosity thus established is reflected in the measured improvements in strength, resistance to water absorption, chloride permeability, and the overall enhanced corrosion performance. Calorimetric conductivity, thermogravimetric analysis (TGA), and differential thermogravimetric (DTG) analysis under nitrogen from 105 to 1000 ◦C, total porosity and pore size distribution using Mercury Intrusion Porosimetry (MIP) with a maximum pressure of 200 MPa, X-ray diffraction, linear polarization and electrochemical impedance spectroscopy (EIS) corrosion test results further corroborate that the addition of 0.1 % by weight of GO improved the physical, durability, and corrosion resistance properties of GGBFS concrete.

Microbiologically induced concrete corrosion in the cracked sewer pipe under sustained load

Microbiologically induced concrete corrosion (MICC) and stress crack are the most common structural defects in concrete sewer pipes. To investigate the microbial corrosion behavior of cracked concrete pipes under sustained loading, coupons with no load, 100% D-Load, and 120% D-Load were pre-adjusted to a suitable environment for acidophilic sulfur oxidizing bacteria (ASOB) colonization, and then placed together in a microbial chamber for 90-day accelerated corrosion. The corrosion variances of these coupons were compared in terms of surface morphology, crystalline violet staining, pH evolutions, crack width changes, as well as characterization results including Scanning Electron Microscope- Energy Dispersive Spectrometer (SEM-EDS) and X-ray Diffraction (XRD). It was found that the stress level slightly accelerates the pH drop on the coupon surface, positively correlates with the corrosion product content of the semi-corrosive layer, and causes stress-corrosion cracking of the semi-corrosive layer, but has little effect on corrosion loss. Stress-corrosion effects were only found in the semi-deteriorated layer of the stressed coupon, but no significant acceleration effect on corrosion rate was observed. This is explained by the fact that MICC is a non-diffusive corrosion where the semi-deteriorated layer is rather thin. Thus, cracking or not of the semi-deteriorated layer does not affect the corrosion rate. This study improves understanding of the service deterioration of sewage pipes.

The Impact Of Local Industrially Produced Metakaolin On Both Cement And Concrete Reinforcing Steel physico-mechanical and corrosion resistance Properties

The Impact Of Local Industrially Produced Metakaolin On Both Cement And Concrete Reinforcing Steel physico-mechanical and corrosion resistance Properties

Novel and unusual genes for nitrogen and metal cycling in Planctomycetota- and KSB1-affiliated metagenome-assembled genomes reconstructed from a marine subsea tunnel.

The Oslofjord subsea road tunnel is a unique environment in which the typically anoxic marine deep subsurface is exposed to oxygen. Concrete biodeterioration and steel corrosion in the tunnel have been linked to the growth of iron- and manganese-oxidizing biofilms in areas of saline water seepage. Surprisingly, previous 16S rRNA gene surveys of biofilm samples revealed microbial communities dominated by sequences affiliated with nitrogen-cycling microorganisms. This study aimed to identify microbial genomes with metabolic potential for novel nitrogen- and metal-cycling reactions, representing biofilm microorganisms that could link these cycles and play a role in concrete biodeterioration. We reconstructed 33 abundant, novel metagenome-assembled genomes (MAGs) affiliated with the phylum Planctomycetota and the candidate phylum KSB1. We identified novel and unusual genes and gene clusters in these MAGs related to anaerobic ammonium oxidation, nitrite oxidation, and other nitrogen-cycling reactions. Additionally, 26 of 33 MAGs also had the potential for iron, manganese, and arsenite cycling, suggesting that bacteria represented by these genomes might couple these reactions. Our results expand the diversity of microorganisms putatively involved in nitrogen and metal cycling, and contribute to our understanding of potential biofilm impacts on built infrastructure.

Space Averaging of Electric Field accompanying Corrosion of Reinforcement and its Verification by Pseudo-Concrete

This paper aims to verify a space-averaged electric filed simulation, where the whole surfaces of reinforcing bars are blended into the 3D finite volume for identifying the electric potential to drive the macro-cell corrosion of structural concrete. Experimental verification is conducted with transparent pseudo-concrete, which has chemical pore-solutions similar to those of concrete, and with which the location of anodic poles accompanying brownish rusts and the cathodic ones surrounded by hydrogen bubbles may be visually identified. The proposed electro-chemical analysis platform to be integrated with ion transport and equilibrium is adopted for full consistency with dispersed reinforcing bars. Global macro-cell corrosions of tunnel mockup and reinforcement layers induced by electric current leakage are verified quantitatively with dispersed multi-ion concentration as well as corrosion profile.

Mechanical properties and corrosion resistance of recycled aggregate concrete exposed to accelerated and natural marine environment

This paper presents the effect of long-term exposure (simulated and natural) on the mechanical and durability characteristics of ordinary Portland cement concrete (OPCC) with and without recycled concrete aggregate (RCA) prepared using two water-cement (w/c) ratios. Each of the four concrete mixes (i.e. 0.40-R0, 0.40-R30, 0.43-R0 and 0.43-R30) was exposed to the simulated ((i.e. Fog apparatus/chamber as per provisions of ASTM B117) and two natural marine environments (on a water jetty and submerged in the seawater) for a period of 90, 180 and 365 days. To observe the long-term effect of the simulated and natural environment exposure, the exposed specimens were tested for compressive strength, splitting tensile strength, pull-out strength, and half-cell potential test as per the standard testing provisions of ASTM C39, ASTMC496, ASTMC900, and ASTMC876, respectively. The comparison of the results showed that the concrete specimens exposed to the natural marine environment submerged in the seawater resulted in reduced compressive and pull-out strengths, high and increased split tensile strength, and poor resistivity to corrosion as compared to the one placed on a deck of water jetty and simulated marine environment. The concrete prepared by using 30% RCA was significantly affected by the exposures as compared to the natural environment and a difference of nearly 30% in results of compressive strength, split tensile strength, and pull-out strength and a difference of 40% was found in resistivity to corrosion. Similarly, the high w/c ratio also affected the compressive strength, split tensile strength, pull-out strength, and resistivity to corrosion of concrete. The results of microstructure also confirmed that the concrete exposed to a harsh environment underwent severe deterioration, which led to the lessening of the mechanical properties.

Bond-slip behavior between corroded rebar and lightweight aggregate concrete

The bond-slip property between the corroded steel bar and lightweight aggregate concrete (LWAC) was investigated. The effects of concrete cover, stirrups spacing, and steel bar corrosion level were experimentally studied using beam-type specimens. The results suggested that the bond strength of LWAC specimen was improved by the increase in concrete cover and the decrease in the spacing of stirrups, and the negative effect of the corrosion on bond strength was mitigated by the increasing thickness of cover and the spacing of the decreasing stirrups. The bond strength between LWAC and steel bar was negatively correlated to the corrosion level and the corrosion-induced cracking. The models for the bond degradation coefficient of LWAC specimens were established based on different forms of function, and the prediction of the exponential model showed better agreement with the test results. The model linking bond strength degradation in LWAC elements and corrosion-induced crack width was developed by considering factors including concrete covers and equivalent width of cracks.

Effects of dissolved oxygen (DO) in seawater on microbial corrosion of concrete: Morphology, composition, compression analysis and transportation evaluation

This paper experimentally investigates the impact of dissolved oxygen (DO) in seawater on the degree of microbiologically induced concrete corrosion (MICC). The bacterial growth, microstructure of biofilm, hydration products, mechanical and transport performance of concrete are explored in both sufficient and low DO groups. The results show that DO has a positive effect on the reproduction of sulfur oxidizing bacteria (SOB), colonization of biofilm, reaction with cementitious hydration products and enhancement in compression in the early stage. The migration of Cl− erosion is reduced in rich DO environment compared with low DO content due to the inhibition in both biofilm and interior structures.

Corrosion Assessment Methods in Reinforced Cement Concrete

Worldwide huge amount was spent on infrastructure development projects, in which a major part is spent on demolishing deteriorated structures due to their reduction in serviceability due to various external factors. This may be attained by preventing reinforced cement concrete (RC) structures from factors that affect serviceability such as corrosion. The research community is developing various techniques to predict corrosion in RC structures to prevent the structure in the initial stages by carrying out maintenance work instead of going for the reconstruction of deteriorated structures. The corrosion of RC structures was mainly caused by chloride ions penetrating the structure or by carbonation. This coefficient can be used to predict the rate of corrosion in concrete. Electrochemical measurement, Eddy current, Half-cell potential measurement, etc., are the experimental techniques to forecast the corrosion rate in concrete reviewed. Recently various software’s like Life 365, Thermos calc, Concrete Compass, etc., were developed to predict the corrosion rate in RC structures. This research paper reviews the effectiveness of the application of software to predict corrosion rate in RC structures by reviewing previous research works to identify an accurate method to be followed.

Effects of Extracts of Alchornea Cordifolia on Biocorrosion Control on Sewer Concrete

Concrete infrastructures that make up the sewer system exposed to sewer waste waters are often subjected to microbial corrosion. The biogenic sulfuric acid produced by the activity of sulfur-oxidizing bacteria A.thiooxidans attacks concrete in sewers leading to loss of concrete mass and deterioration.The aim of this study was to control concrete biodegradation using plant extracts of Alchornea Cordifolia. Concrete samples were corroded for 26 months in real sewer wastewater conditions. The influence of biogenic sulfuric acid on the biocorrosion of concrete samples was determined in terms of weight loss, pH, sulfate concentration variation, chemical composition changes, and formation of corrosion by-products. Recorded corrosion rates before coating were between 0.071996mpy –1.168546mpy. Changes in sample morphology, ettringite and gypsum formed were observed by X-ray diffraction and SEM methods with corrosion progression.Phytochemicals analysis of extracts samples confirmed the presence of tannins, saponins, flavonoids, and terpenoids produced in plant tissues. GC-MS analysis of the ethanolic extracts identified 26 compounds.The most dominant being Eugenol.Biocorrosion control determined the effects of extracts on concrete corrosion in sewer waters. A marked decline in the rates of corrosion with each extract's coating was recorded for extracts coated concretes (0.002589mpy-0.003256mpy). An increase in inhibition efficiency with an increase in extract concentration was observed and was in the range of50% A.Cordifolia extracts gave the highest inhibitor efficiency. X-ray diffractive analysis and scanning electron microscopy showed morphological variations in concrete before and after coating. Results of ANOVA showed inhibitor concentration as having the most significant effect on the extracts' corrosion inhibition

Effects of supplementary cementitious materials on concrete reinforcement corrosion in magnesium sulphate

Effects of supplementary cementitious materials on concrete reinforcement corrosion in magnesium sulphate

One-class Damage Detector Using Deeper Fully Convolutional Data Descriptions for Civil Application

Infrastructure managers must maintain high standards to ensure user satisfaction during the lifecycle of infrastructures. Surveillance cameras and visual inspections have enabled progress in automating the detection of anomalous features and assessing the occurrence of deterioration. However, collecting damage data is typically time consuming and requires repeated inspections. The one-class damage detection approach has an advantage in that normal images can be used to optimize model parameters. Additionally, visual evaluation of heatmaps enables us to understand localized anomalous features. The authors highlight damage vision applications utilized in the robust property and localized damage explainability. First, we propose a civil-purpose application for automating one-class damage detection reproducing a Fully Convolutional Data Description (FCDD) as a baseline model. We have obtained accurate and explainable results demonstrating experimental studies on concrete damage and steel corrosion in civil engineering. Additionally, to develop a more robust application, we applied our method to another outdoor domain that contains complex and noisy backgrounds using natural disaster datasets collected using various devices. Furthermore, we propose a valuable solution of deeper FCDDs focusing on other powerful backbones to improve the performance of damage detection and implement ablation studies on disaster datasets. The key results indicate that the deeper FCDDs outperformed the baseline FCDD on datasets representing natural disaster damage caused by hurricanes, typhoons, earthquakes, and fourevent disasters.

ЭКОНОМИЧЕСКОЕ ОБОСНОВАНИЕ МЕРОПРИЯТИЙ ПО ПОВЫШЕНИЮ ДОЛГОВЕЧНОСТИ БЕТОННЫХ КОНСТРУКЦИЙ В БИОЛОГИЧЕСКИ АГРЕССИВНЫХ СРЕДАХ

The article assesses the impact of concrete biodegradation on the durability of concrete and reinforced concrete bridge structures. Areas of biocorrosion and other types of concrete corrosion were identified on real bridges. Based on the developed physical and mathematical model, we calculated the service life of reinforced concrete bridge supports and proposed economically advantageous terms for removing biodeposits from concrete. We also calculated the economic efficiency of removing biofouling from concrete and determined that the annual economic effect amounted to 9 % of the cost of the estimated work. If preventative measures against biofouling are carried out at least once every five years, the period for carrying out works to eliminate defects in concrete and reinforced concrete building structures can be in-creased by 1.5x. We provide recommendations to improve the durability and effective operation of bridge structures.

Horizontally loaded piles in saline soils

The influence of the aggressiveness of the environment and the variability of the saline soil properties on the operation of horizontally loaded piles is studied. The design scheme is taken in the form of a multi-span beam with a variable cross-section formed due to concrete corrosion (Winkler model) and stiffness coefficients. The calculated value of the variable modulus of deformation and the stiffness coefficients of the pile are determined based on the conditions of the construction area and the properties of saline soils.

STUDY OF A CONCRETE COLUMN FOR STABILITY UNDER ASYMMETRIC CORROSION

Reinforced concrete became widespread due to its many positive properties: durability, fire re-sistance, resistance to corrosive effects, high resistance to static and dynamic loads, low operating costs for maintaining buildings and structures, and relative cheapness of manufacturing. The presence of widespread large and small aggregate used in the production of reinforced concrete makes it applicable in all corners of the globe and even beyond its borders.The emergence and development of building structures, including reinforced concrete, is inextricably linked to the conditions of the material life of society, the development of productive forces. The appearance of reinforced concrete coincides with the period of accelerated development of industry, transport and trade in the second half of the 19th century. The period of emergence of reinforced concrete (1850-1885) is characterized by the appearance of the first structures made of reinforced concrete in France (Lam-bo, 1850; Quanier, 1854; gardener Monier, 1867-1880), England (Wilkinson, 1854), the USA (Hiatt, 1855-1877). Buildings and structures and their structures during operation experience force and non-force effects of the environment. With a symmetrical effect of the medium, centrally compressed rods remain centrally compressed, and with an extracenteral one, extracentric eccentricity appears. First, the rod experiences off-center compression. Further deformation will lead the rod to longitudinal bending, and under the action of a transverse load to longitudinal-transverse bending. In steel structures, the environment causes corrosion, in concrete ‒ corrosion and neutralization. In a physically linear formulation, these problems are solved, but it is necessary to take into account the real diagrams of steel and concrete, and to solve problems according to an unformed deformed scheme. Given the impact of the environment, new challenges arise with constructive and induced heterogeneity. Noncentrally compressed elements are part of statically definable and indeterminate structures: these are beams, threehinge systems, frames and trusses. This is a new topic, a new formulation of the question, tasks that require the development of new methods.

Exploration of Next-Generation Reinforced Concrete Corrosion Modeling with Interdependent Initiation and Propagation Stages

Most damage prediction models for reinforcing steel in concrete treat the corrosion initiation stage as being nearly independent of the propagation stage elsewhere in the system. A next-generation chloride-induced corrosion interdependent model addresses those interactions by incorporating the corrosion prevention effect of the local potential drop caused by prior active-to-passive transitions in nearby steel portions. The effect of this potential-dependent threshold (PDT) approach was examined in a 3D realization, confirming and expanding conclusions from previous 1D and 2D models. Exploratory analysis was conducted for model result sensitivity to time step duration and activation zone size. It was found that the main outcome—a strongly lowered long-term damage projection when PDT is taken into consideration was reasonably robust to changes in those variables. The precise damage amount forecast was however sensitive to an extent that needs more detailed analysis. Sensitivity to time step choice appears to be resolvable in the limit, but the selection of appropriate activation zone size needs addressing in future work.

Two- and Four-Electrode Configurations for Contactless Reinforced Concrete Corrosion Monitoring

The paper addresses the need for a fast and reliable method for field monitoring reinforced concrete structures. A proof of concept is presented where a noncontact procedure provides quantitative information on the concrete resistivity and reinforcement corrosion rate. A Wenner-type probe is presented, where a combination of two- and four-electrode measurements in a relatively high-frequency domain allows obtaining the information of interest. The method is based on the fact, verified by numerical simulations, that the embedded rebar works as an effective floating counter electrode and, thus, for distances higher than a critical value (1 cm in the simulations done), the ratio of concrete resistivity to the measured impedance at 1 kHz is constant and only dependent on the electrode diameter. The apparent polarization resistance measured with the four-electrode arrangement and normalized to the concrete resistivity allows obtaining the actual polarization resistance without contacting the rebar whose distance to the electrodes shall be known.

Apparent wave velocity inverse analysis method and its application in dynamic pile testing

AbstractThis study proposes a new non‐destructive testing method (NDT), namely the apparent wave velocity of piles (AWVP) inverse analysis method, to solve the detection problem of the gradually varying cross‐sectional defects (cracks or necking) and the material property defects (concrete disintegration or steel corrosion) of piles. The analytical solution of the AWVP has been derived based on the additional mass model. The rationality and accuracy of the theoretical model have been validated through the comparisons with the experiment results. The variation mechanism of the AWVP due to the presence of soil has been clarified. A parametric study is conducted to investigate the major factors to determine the variation tendency of the AWVP. The optimum working conditions and parameter combinations of the AWVP based NDT method have been recommend. The main conclusions can be drawn as: (1) the variation of the AWVP with respect to frequency can be generally divided into a sensitive zone and a stable zone. (2) The AWVP initially decreases rapidly with the frequency within the sensitive zone, however when the frequency decreases to the stable zone, this decline tendency becomes much smaller. (3) Although the AWVP varies extensively within the frequency sensitive zone, this frequency range can substantially relax the requirements for the parametric accuracy of the pile–soil system.