Concrete Crack Width Research Articles

Nonlinear Finite Element analysis of concrete corbels with hybrid reinforcements

This study utilizes nonlinear finite element analysis to simulate the structural response of Reinforced Concrete (RC) corbels with hybrid reinforcements under monotonic loading. The models implemented in ABAQUS examine RC corbels with combined Carbon Fiber Reinforced Polymer (CFRP) and steel reinforcing bars to study the interaction between the concrete and hybrid reinforcement system. Specifically Ultimate load capacity, energy absorption and failure mode. Compressive strength, shear span/depth ratio, and the ratio of CFRP/steel reinforcement were the main parameters that considered in this paper. Results demonstrated a significant improvement in the ultimate load capacity of concrete corbels by up to 53% when both conventional steel and CFRP bars were integrated within the concrete corbel. The numerical test outcomes revealed that an increased hybrid reinforcement ratio effectively managed crack distribution, resulting in reduced concrete crack widths.

Non-uniform distribution model of rust layer around steel bar circumference and its effect on corrosion-induced concrete cracking

This paper presents a critical review of non-uniform distribution models of rust layer around a reinforcing bar’s circumference and a numerical investigation into the effect of non-uniform distribution of rust on (a) crack patterns and (b) development of concrete surface crack width. Different shapes of rust layer simulated by mathematical models were established based on statistical distribution functions which were compared with the transport-electrochemical model and published testing results. In addition, an advanced 2D finite element model was implemented to simulate crack propagation in concrete caused by rebar corrosion. It is found that non-uniform rust distribution shape around the rebar not only affected concrete surface crack width evolution, but also crack length and crack pattern. Transport-electrochemical model and Gaussian distribution-based model could reasonably simulate rust distribution and associated corrosion-induced cracks. In addition, the authors proposed a simplified semi-empirical model that incorporated an analytical chloride transport model and a Gaussian model to simulate time-dependent advancement of non-uniform rust layer. Furthermore, a parametric study of the effect of elastic stiffness of the rust layer on crack patterns and surface crack width development was also performed.

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.

Analytical model for concrete crack width of steel lined reinforced concrete penstock

Cracking in steel lined reinforced concrete penstock (SLRCP) poses substantial challenges to both serviceability and safety, particularly when crack width exceeds specified limits. Despite its critical implications, accurately calculating crack width remains a persistent challenge. To address this issue, a multi-layer steel-concrete ring analytical model is derived through the concept of orthotropic and thick-walled cylinder theories. In this model, the cracked concrete is assumed to be an orthotropic material incorporating both elastic modulus reduction and tensile softening behavior based on its cracking characteristic of radial penetrating cracks uniformly distributed on the circumference. The steel liner and reinforcing steel bar are modeled as continuous steel rings using equivalent stress theory, while thick-walled cylinder theory is applied due to geometric features and bearing characteristics. Crack width is determined through equilibrium of force and compatibility of deformations at steel-concrete interfaces, utilizing these assumptions and the developed calculation model. To validate the proposed model, data from prototype observations and large-scale model tests of SLRCPs were systematically collected. The crack width results obtained from the proposed model exhibit strong agreement with the collected data, confirming its accuracy and reliability. In conclusion, the proposed analytical model provides an effective solution for calculating the crack width of SLRCP and offers valuable insights for durability evaluation.

Experimental study on crack performance of steel and early-age BFRC composite beams in negative moment region

The wet joint interface concrete deck in the negative moment region of steel-concrete composite beams is susceptible to tensile cracking, which compromises the durability of the structure. Herein, a basalt fiber reinforced concrete (BFRC) is proposed to examine the wet joint cracking performance of concrete deck in the negative moment region of steel-concrete composite beams. To this end, four-point bending tests were conducted on seven steel-concrete composite beams to investigate failure modes, crack distribution patterns, load-deflection relationship, and load-crack width relationship. Experimentally, the effects of the wet joint concrete types (BFRC and normal concrete), basalt fiber volume content (0, 0.3%, and 0.6%), and concrete age (28, 14, 7, and 3 days) on their mechanical behavior were performed and discussed. The results showed that typical flexural failure commonly occurred in all specimens under the negative moment, with initial cracks appearing at the wet joint interface. The wet joint concrete with basalt fiber volume content of 0.3% exhibited the highest crack resistance, which resulted in a higher number of cracks, less crack spacing, and more uniform crack distribution in the wet joint concrete deck. The prediction methods of the average crack spacing and crack width of the wet joint concrete were proposed based on the existing theoretical models. The crack width and concrete age influence coefficients were proposed to rationally assess the effects of basalt fiber and concrete age. The modified formulas for the average crack spacing and crack width showed a reasonably good agreement with the experimental results when considering the effects of basalt fiber and concrete age. These formulas can be effectively utilized to evaluate the main crack width at the non-interface joint in the negative moment region of steel-concrete composite beam decks. The proposed approaches can provide a simple and practical method to effectively predict the crack width in the negative moment region of the steel-concrete composite beam.

Evaluation of crack width and self-healing performance of concrete based on fluid flow characteristics: Comparison between water permeability test and gas diffusion test

Water permeability tests are among the most widely used test methods to evaluate a crack width and self-healing performance of concrete. The average crack width and the overall self-healing performance of each specimen have been determined by the amount of water that penetrates through a crack. Water, which is used as a medium, tends to become viscous due to gravitational pull among its molecules. This viscosity causes the flow velocity in the cross section exhibits parabolic distribution. Also, this is the reason why it is difficult to apply the water permeability test for a specimen with a narrow crack. In an attempt to overcome the limitation caused by the viscosity of the water, a gas diffusion test have recently been proposed, wherein a gas with low viscosity is used to replace water as a medium. However, given that water and gases behave differently when passing through cracks, the two methods may have different characteristics in the estimation of crack width and healing performance. The present study analyzed trends found in the estimation of crack width by these two methods. Despite the fact that the tests were conducted on the same specimen, the results of these two experiments showed different trends. This study analyzed the causes of these differences. It was found that the differences in the characteristics of the fluids and the healing products influenced the trend of the experimental results. The gas diffusion test could be used as an effective method for evaluating the crack width and healing performance of self-healing concrete.

Flexural performance of a new type of slightly curved arc HRB400 steel bars reinforced one-way concrete slabs

Abstract In the present study, a new type of slightly curved arc HRB400 steel bars (SCAHSs) was proposed to solve the problem of temperature-induced stress loss in mass concrete structures without cutting off steel bars. The flexural performance of SCAHSs and straight HRB400 steel bars reinforced one-way concrete slabs were first experimentally investigated. Then, the effects of the shape and dimension of SCAHSs on the distribution and width of concrete cracks were analyzed and discussed. Subsequently, the synergistic tensile work characteristics between SCAHSs and concrete were presented. Finally, equations for the bearing capacity and allowable crack widths for SCAHSs in hydraulic massive structures were proposed. The test results indicated that after replacing the straight steel bars in the concrete slab with SCAHSs, the crack width of the concrete slabs increased, with the maximum crack width at the bottom of the concrete slabs increasing by a factor of 1.2–1.4. As the rise-span ratio of SCAHSs increased, the flexural stiffness of SCAHSs reinforced concrete slab decreased slightly, but the deflection increased. The allowable crack widths of SCAHSs reinforced concrete slabs under environment categories I, II, and III were 0.20, 0.17, and 0.12 mm, respectively.

Experimental study on crushing of concrete slabs by high-voltage pulse discharge

To investigate the effectiveness of high voltage pulse discharge (HVPD) in crushing concrete slabs, HVPD in-liquid tests were conducted in pre-drilled holes in three double-layer bi-directionally reinforced and twelve single-layer bi-directionally reinforced concrete slabs. The parameters that were varied in the tests included the concrete strength, discharge hole diameter and spacing, discharge voltage and number of copper wires discharged. The results showed that the explosion caused by HVPD using copper wires increased the crack width by more than 34.8% compared to that caused by the electrohydraulic effect. After 10 explosions caused by HVPD using copper wires, the single-layer reinforced concrete slab was split into several slabs by cracks to achieve the crushing effect. The single discharge energy, i.e., discharge voltage, had a significant effect on the crushing of concrete slabs, and the width of concrete cracks produced by a 100 kV discharge was more than twice that of a 40 kV discharge. The increase in concrete strength acted as a crack arrestor for the slabs, and the crack width of C20 concrete slabs increased by approximately 10% to 25% compared to C40 concrete slabs. The increase in crack width with increasing number of discharged copper wires decreased with increasing discharge voltage. The width of concrete cracks produced by the explosion of 60 copper wires compared to 30 copper wires increased by approximately 10% at 100 kV and by approximately 20% from 60 to 80 kV. The crack width of concrete slabs with discharge holes of diameter 40 mm increased by approximately 5% to 15% compared to concrete slabs with holes of 50 mm. Expressions for the relationships between the damage degree of the concrete slab (i.e., the width of the concrete cracks around the holes on the outside of the slab) and the key parameters such as the output voltage, the number of discharged copper wires, and the strength grade of the concrete were established based on the experimental results.

Effect of 3D laser point spacing on cement concrete crack width measurement

The objective of this paper is to examine the reliability of three-dimensional (3D) laser detection technology data density for crack width detection results of cement slabs. Four groups of cement concrete crack elevation data with a laser data density of 0.5–1.5 mm were obtained using an indoor 3D laser detection system, and 3D models were established. The nonlinear least squares method was applied to fit the fracture section, and the crack width was determined by the peak value analysis. The results demonstrate that the lateral spacing of laser points exerts a large impact on the mean and discrete degrees of cement concrete crack width detection results. The laser point spacing is positively correlated with crack identification errors. Insufficient laser accuracy leads to an overestimation of crack severity level and affects the accuracy of pavement damage condition evaluation. High-precision laser equipment exhibits certain reliability for detecting cement concrete crack width above 3 mm. In the actual pavement crack width detection process, the appropriate transverse spacing of laser points can be selected according to different error limit requirements to fulfill the requirements of both detection reliability and data processing efficiency. Suggestions for future research include expanding the experimental conditions, increasing the 3D laser point spacings, and selecting more road lanes and pavement materials to further examine the influential factors of pavement crack width measurement.

Calibrating a Physics-Based Corrosion Model with Field-Based Bridge Condition Data

This paper presents a novel method for calibrating a physics-based corrosion prediction model using a deterioration curve derived from field-based bridge condition assessments. The corrosion model used in this study considers inputs such as corrosion rate to predict outputs such as concrete crack width. Deterioration curves that present bridge element condition versus time are converted into crack width versus time using inspection guidance from transportation agencies. Input parameters of the corrosion model are calibrated by matching the crack widths predicted by the corrosion model with those predicted by the deterioration curves. The calibration method is demonstrated for a reinforced concrete bridge column in this article. The corrosion rate before cracking, the pitting factor, and the ratio of corrosion rates at critical crack width and before cracking significantly influenced the model results and were calibrated. Postcalibration input parameter ranges were narrower than but within the ranges reported in the literature. A physics-based corrosion model thus calibrated using field inspection data can potentially improve the predictions of future structural health and aid in asset management.

Concrete Crack Width Measurement Using a Laser Beam and Image Processing Algorithms

The presence of concrete cracks in structures indicates possible structural deterioration, but it is quite difficult to measure crack width accurately. While much research has been conducted on crack detection using image processing, there is a gap in the accurate quantification of crack width in millimeters. Current methods either measure in pixels or require the attachment of scales or markers onto a measured surface, which can pose safety hazards in hard-to-reach areas. This paper addresses these issues by proposing a novel image-based method for measuring concrete crack width in millimeters using a laser beam and image processing. The proposed method was validated in the laboratory by capturing images of concrete cracks with two cameras of different resolutions, each attached with lasers. The lasers projected a circular laser beam onto the surface of the concrete under inspection. The images were then pre-processed, segmented, and skeletonized for crack width measurement in pixels. The relationship between the laser diameter and camera distance from the surface was used to convert the measured crack width from pixels to millimeters. The method was performed with high accuracy, as indicated by the absolute error. The largest absolute error was 0.57 mm, while the smallest absolute error was 0.02 mm. The proposed method allows real-world interpretation of results in millimeters. As a result, measured crack widths can easily be compared to allowable limits in international standards, which are typically expressed in metric or SI units. The proposed method can also promote safer inspections in areas of low accessibility by attaching the laser to devices such as drones.

鉄筋腐食に伴うコンクリート内部に進展するひび割れが表面ひび割れ性状に与える影響

Concrete structure is usually inspected by appearance at the periodical inspection. However, highly skilled engineers are necessary for this preliminary and qualitative inspection. Considering decrease in expert and increase in deteriorated concrete structures, more quantified inspection method is needed to evaluate the performance more accurately and easily. Previous researches have presented the relationship between corrosion mass loss of reinforcing steel bar in concrete and surface crack width. These studies were often conducted by using reinforced concrete specimen which includes single longitudinal rebar. On the other hand, on-site structures include not only longitudinal rebar also transverse rebar which is located with larger cover thickness. For this reason, the accelerated corrosion test using the specimens and inspection at an on-site corroded structure were conducted to evaluate the effect of the transverse rebar and its corrosion on the behavior of surface crack. As a result, it was revealed that internally propagated crack would have a large influence on the surface crack and the index of the surface crack density could bring more accurate evaluation of the corrosion mass loss of rebar than only the crack width.

Structural performance of buried reinforced concrete pipelines under deep embankment soil

Purpose Buried pipelines under various soil embankment heights are cost-effective alternatives to transporting liquid products. This paper aims to assist pipeline architects and professionals in selecting the most cost-effective buried reinforced concrete pipelines under deep embankment soil with minor structural reinforcement while meeting shear stress requirements, safety and reliability constraints. Design/methodology/approach It is unfeasible to experimentally assess pipeline efficiency with high soil fill depth. Thus, to fill this gap, this research uses a dependable finite element analysis (FEA) to conduct a parametric study and carry out such an issue. This research considered reinforced concrete pipes with diameters of 25, 50, 75, 100, 125 and 150 cm at depths of 5, 10, 15 and 20 m. Findings According to this research, the proposed best pipeline diameter-to-thickness (D/T) proportions for soil embankment heights 5, 10, 15 and 20 m are 8.75, 4.8, 3.5 and 3.1, correspondingly. The cost-effective reinforced concrete (RC) pipeline thickness dramatically rises if the soil embankment reaches 20 m, indicating that the soil embankment depth highly influences it. Most of the analyzed reinforced concrete pipelines had a maximum deflection value of less than 1 cm, telling that the FEA accurately identified the pipeline width, needed flexural steel reinforcement, and concrete crack width while avoiding significant distortion. Originality/value The cost-effective thickness for the analyzed structured concrete pipes was calculated by considering the lowest required value of steel reinforcement. An algorithm was developed based on the parametric scientific findings to predict the ideal pipeline D/T ratio. A construction case study was also shown to assist architects and professionals in determining the best reinforced concrete pipeline geometry for a specific soil embankment height.

EIS based assessment of electrodeposition effect of concrete cracks: Experiment and equivalent model

In this study, the electrochemical impedance spectrum (EIS) is proposed to evaluate the effectiveness of concrete cracks repaired through electrodeposition. The EIS responses of the concrete cracking and electrodeposition repairing processes are investigated. The obtained results show that the impedance of concrete decreases with increasing crack width. The impedance of concrete increases gradually during the electrodeposition process. In order to characterize and forecast the EIS responses during the concrete cracking and electrodeposition repairing processes, a new equivalent circuit model is proposed. The crack repairing rates are defined in terms of the crack resistance and total impedance of concrete. After 14 days of electrodeposition repairing, the crack repairing rates can eventually reach 79.35% and 77.81% in terms of crack resistance and total impedance, respectively. In addition, the influences of the w/c ratio, crack width, and crack tortuosity of concrete on the EIS responses of concrete repaired by the electrodeposition process are calculated and discussed.

Practical Application of Digital Image Processing in Measuring Concrete Crack Widths in Field Studies

Cracking in concrete structures is a ubiquitous problem and affects the serviceability of such structures. In many cases, it is imperative to properly measure and monitor a crack’s size to identify locations for repair and rehabilitation. This paper describes two field studies that used digital image processing to measure the width of cracks in concrete structures. The first field study compared crack measurements from digital image processing, a handheld microscope, and a crack gauge card. In the second field study, digital image processing was used to measure end region cracks in precast pretensioned concrete girders. Guidance is provided for engineers who wish to use digital image processing in field studies. Conditions where digital image processing may lead to errors are identified, and limitations of the methods are discussed. In general, the studies demonstrate that image processing methods can efficiently measure the size of cracks in concrete structures in field settings and that image-based measurements are comparable to microscope measurements.

Durability degradation simulation of RC structure based on gamma process considering two-dimensional chloride diffusion and life probabilistic prediction

In this paper, based on the gamma process, a new method for predicting the life of reinforced concrete (RC) structures eroded by chloride is presented considering two-dimensional (2D) chloride diffusion. First, according to the chloride diffusion theory, an analytical model and a finite difference numerical model considering 2D chloride diffusion under the action of multiple factors were established. Based on this, the Monte Carlo method and method proposed in this study were employed to predict the initial rust time of RC structures eroded by chloride. Histograms of the initial rust time and probability density function obtained using the two methods mentioned above were compared and analyzed to verify the validity of the proposed method. Finally, the life prediction model of the RC structure considering the initial rust time T1, rust expansion cracking time T2, and time when the concrete surface crack width reaches the limit crack width T3 was established, and its applicability was verified through an analysis of an engineering example. The research indicates that the gamma process-based probability models can approximately predict the time required for rebar corrosion of an RC structure eroded by chloride considering 2D diffusion.

Design formulae for Long-Term responses of continuous Steel-Recycled aggregate concrete composite slabs

The steel-recycled aggregate concrete (RAC) composite slab is a low-carbon structural member with higher constructional efficiency. However, no design method has been established for the serviceability limit state evaluation of such members accounting for long-term effects. The non-uniform shrinkage peculiar to composite slabs significantly deteriorates the long-term responses of slabs, which would be more significant when using RAC. Previous studies only focused on the long-term responses of simply-supported composite slabs using NAC. The investigated responses include member deflection and stress in steel decking. No research attention has been paid to the continuous composite slabs, in which non-uniform shrinkage further induces possible yielding of the negative reinforcement and the limit exceeding of concrete crack width in the negative moment zone. Furthermore, the recycled aggregate influence has not been accounted for in the long-term design of the composite RAC slabs. In this context, this study aims to establish simplified explicit design formulae for the long-term responses of continuous RAC composite slabs accounting for the non-uniform shrinkage effects and the recycled aggregate influence. The target long-term responses include deflection, steel decking stress, negative reinforcement stress, and the concrete crack width in the negative moment zone. The simplified explicit formulae were derived from cross-sectional analysis results with some variables reasonably simplified into constant values based on collected data from real applications. The validation results have shown that the proposed formulae are capable of predicting the long-term responses of continuous RAC composite slabs, with the prediction accuracy similar to the code formulae for reinforced concrete slabs.

Experiment Study on Residual Flexural Capacity of Prestressed Concrete Deck Slab Under Fatigue Loading

The deterioration of a concrete deck damaged by repeated traffic loads could directly affect its performance. Two full-scale specimens modified from a precast, prestressed concrete (PC) deck slab on a 12.65-m-wide composite bridge with twin I-girders spaced at 7.05 m were tested to study the degradation of mechanical performance of the slabs under fatigue loading. The depth of the slabs was 30 cm at the midspan and 40 cm at the two supports. One specimen was 3.0 m wide and conducted a three-stage fatigue loading before the static destructive loading, the other was 1.5 m wide and performed a static load test to failure only. The ultimate strength of specimens was obtained, and the variation of deflection, reinforcing strain, and cracks were discussed. The test results showed that the failure mode of the PC slabs was flexure subjected to static load. Fatigue loading significantly degenerated the stiffness of the slab, and the maximum stiffness reduction was about 35.2 %. The distribution scale of cracks was expanded about twice as much at the same load level under the fatigue loading. It could be deduced that the fatigue loading could enlarge the crack width, by comparing the measured results of concrete crack widths of the two specimens, however, the design provisions did not take this into account. A comparison between the transformed flexural capacity of the two specimens showed the residual flexural capacity was reduced by 7.8 %. Moreover, an analysis model was developed to predict the residual flexural capacity of PC slabs.

Experimental study of post-installed anchor embedded in concrete under simulated seismic and wind loads

In this study, experimental protocol to simulate wind-induced vibration of post-installed anchor embedded in concrete was developed. The proposed loading protocol was based on the ratio of deformation due to seismic load and dynamic wind load of anchors in the connection between the sign structure and the concrete building. Then, based on ACI 355.2 and the developed protocol, numerous experimental tests were conducted to evaluate the performance of anchor under simulated seismic and wind loads. In simulated seismic test, crack width of concrete did not affect the performance of anchor. Their maximum force as well as residual capacity showed practically the same value. Moreover, anchor used in this experiment satisfied the condition to be rated as full capacity for seismic performance. In simulated wind test, the crack width did not cause any difference in performance of the anchor in tension test. Though, in simulated wind shear test, there was a major difference for the anchor residual capacity. Additionally, the performance of anchor in simulated wind test did not satisfy the criteria to be rated as full capacity.

Lifetime reliability analysis of concrete columns damaged by reinforcement corrosion

Rebar corrosion caused by chloride ion ingression is a critical factor leading to performance deterioration of in-service reinforced concrete (RC) structures exposed to aggressive environments. This paper presents a new method to evaluate the concrete crack growth, the bearing capacity degradation and the lifetime performance deterioration for the corroded RC columns under small eccentric compression. By analyzing the material degradation mechanism of the corroded RC structures, an effective method is proposed to predict the concrete crack growth and to estimate the residual bearing capacity of the corroding eccentrically loaded RC columns. Then, the concrete crack width and the load-bearing capacity deterioration rate are selected as structural performance indicators to assess the lifetime performance of the corroding RC columns. The stochastic gamma process is adopted for simulating the evolution of structural performance indicators and estimating lifetime failure probability and the remaining useful life of the corroding structures. Finally, a numerical example is given to demonstrate the effectiveness of the proposed methods for the lifetime performance assessment of the corroding columns. The obtained results show that the residual bearing capacity and the lifetime performance of the corroding RC columns can be significantly affected by rebar corrosion level, load condition and in-service environments.