Condition Evolution in Bridge Management Systems and Corrosion-Induced Deterioration

The majority of works in the field of chloride-indued corrosion of steel in concrete are focused on the cracks formed by the corrosion products. However, the number of studies on the influence of cracks (pre-cracked concrete) on corrosion is limited. Cracks create preferential/free paths for the penetration of chlorides, water, and oxygen into concrete; thus, the presence of cracks in concrete can intensify chloride-induced corrosion of steel reinforcement. This paper presents a review of the effects of cracking on the corrosion of steel in concrete. It was widely reported in the reviewed papers that cracks have a negative impact on concrete durability. They influence the chloride penetration and the chloride-induced corrosion of reinforcement in terms of the initiation and propagation stages. This influence is a complex function of many factors, including mix design, exposure conditions, crack frequency, crack orientation, crack width, and cover depth. Although there is a general agreement on the effects of cracks on the initiation of corrosion, the role of cracks and their widths on the propagation of corrosion in the long term is still under debate.

Time-dependent fragility analysis of a nuclear containment structure under internal pressure and chloride-induced corrosion

This paper reports the results of a study conducted to investigate the influence of sulphate concentration and associated cation type on chloride-induced reinforcement corrosion in blended cement concretes. Reinforced concrete specimens were exposed to chloride plus sulphate solutions for a period of 1200 days. The exposure solutions contained a fixed concentration of 5% sodium chloride and the sulphate concentration was varied from 0 to 4% SO42−. The effect of cation type associated with sulphate ions, namely Na+ and Mg++, on chloride-induced reinforcement corrosion was also evaluated. Reinforcement corrosion was assessed by measuring corrosion potentials and corrosion current density at regular intervals. The results indicated that the presence of sulphate ions in the chloride solution increased the corrosion current density, but no significant effect on the time to initiation of reinforcement corrosion was noted. Further, the corrosion current density increased with increasing sulphate concentration and the period of exposure. The corrosion current density on steel in the blended cement concrete specimens was much less than that in the plain cement concrete specimens, indicating that the corrosion resistance of blended cements was much better than that of plain cements. The cation type associated with sulphate ions did not significantly influence either the initiation or rate of reinforcement corrosion.

The chloride-induced corrosion of steel reinforcement is one of the main causes of deterioration of reinforced concrete structures. Cathodic protection (CP) of steel in concrete is a widely accepted repair technique to reduce, or completely stop, reinforcement corrosion. One possible method of cathodic protection is through the use of embedded galvanic (sacrificial) anodes, consisting of a zinc metal core surrounded by a precast alkali-activated cementitious mortar. The design of a CP system based on embedded galvanic anodes is based on the required amount of zinc material and the throwing power of the anode (i.e., radius around the anode in which the steel achieves sufficient protection). In this research, the protection of steel reinforcement in concrete surrounding an embedded galvanic anode was evaluated through depolarisation measurements with internal and external reference electrodes. Based on these measurements, the throwing power of the galvanic anode was determined, taking into account the 100 mV depolarisation criterium (cf. EN ISO 12696:2016). Additionally, the influence of the degree of chloride contamination of the concrete and relative humidity and temperature of the environment on the throwing power was evaluated. The results show a strong influence of chloride contamination on the throwing power of the galvanic anodes, in the sense that a higher chloride concentration in the concrete matrix leads to a reduction in the throwing power. This reduction can be related to the more negative potential of corroding steel reinforcement compared to passive steel, thus leading to a lower driving potential for the galvanic reaction. Especially when the chloride concentration is higher than 1 m% vs. cement mass, the throwing power is greatly reduced. Additionally, it was found that a higher relative humidity (RH) of the environment (and consequently, a higher RH of the concrete) resulted in a higher throwing power.

This experimental work estimates the corrosion behavior in a sodium-chloride environment of steel reinforcements in mortar specimens with 0, 15, and 30% Greek natural pozzolan, cured either for 1, 7, or 28 days. The corrosion resistance was evaluated by measuring the corrosion potential development of steel rebars, their gravimetric mass loss, their anodic potentio-dynamic behavior, and the total- and free-chloride content of the mortars. Additionally, their mineralogical composition was determined by X-ray diffraction (XRD) analysis. The increase of curing time, as well as the addition of the Greek natural pozzolan, for both percentages tested, improved the corrosion behavior. The combination of the pozzolan addition with longer curing time reduces the steel rebars mass loss up to a level of about 40% after five months of exposure.

Experimental study on cyclic flexural behaviour of GFRP-reinforced seawater sea-sand concrete slabs with synthetic fibres

The minimum cement content requirement given in codes of practice over the years to ensure durability of concrete is being increasingly questioned. Of all the durability problems related to concrete structures, corrosion of reinforcing steel is the single most prevalent deteriorating process. This paper describes a study undertaken to determine the influence of variation in cement (binder) content at fixed water/cement ratio on carbonation- and chloride-induced reinforcement corrosion. Cement (binder) content was varied above and below the limits given in current European standards in the tests. The fines content (particles < 75 μm) of some cement-reduced mixes was maintained with the inclusion of a limestone filler as part of the sand content. The results indicate that cement reduction below the given minimum cement contents in current standards has insignificant influence on the overall carbonation-induced reinforcement corrosion process. Moreover, cement content has very little influence on the overall chloride-induced reinforcement corrosion process except the possible better performance of cement-reduced concrete with filler. It is suggested that the attention traditionally given to minimum cement content in determining reinforcement corrosion resistance may be disproportionate to the effective influence of this parameter.

Chloride-induced reinforcement corrosion and concrete cracking simulation

Predicting bridge deterioration is essential to an effective bridge management. Understanding the evolution of bridge performance in specific periods is fundamental to anticipating future needs and planning appropriate interventions. In this context, this paper aims to analyze Bridge Management Systems (BMS) that use deterioration prediction models and the methods employed. To perform this analysis, 12 BMSs from 12 countries were selected, considering the number of publications and citations related to the subject of “Bridge Management System” in each country. When examining the information from these systems, the significant importance of predictive models is evident. More than half of the systems (67%) use some type of deterioration prediction model, 25% do not use prediction models, and 8% did not obtain any information. Moreover, it is common to observe the countries that collaborate the most in BMS research adopt these models in their systems. Among the systems that employ deterioration prediction models, three main types were identified: physical, deterministic, and probabilistic models. In analyzing the bridge prediction models, it was found that 67% of them are based on probabilistic approaches using Markov chains, 11% are deterministic, 11% are physical models, and in 11% of the cases it was impossible to obtain information. These results highlight the preference for probabilistic approaches in modeling bridge deterioration, considering the uncertainty associated with the process. Such predictive models perform a crucial role in effectively managing bridges, enabling the anticipation of maintenance needs and the proper allocation of resources. In summary, the implementation of bridge deterioration prediction models is widely adopted in management systems worldwide, with probabilistic models based on Markov matrices being the most widely used. Understanding these models and their application can provide valuable insights for developing efficient and sustainable management strategies for bridge maintenance.

<p>Bridge Management Systems (BMSs) are sophisticated software tools, widely used for managing bridges. Comprising a centralized database of all relevant information for the entire bridge stock and analytics to forecast bridges’ condition and maintenance cost, BMSs are irreplaceable tools, used by all the National Road Authorities (NRAs) around the world. These powerful tools, although different from one another, all lack adequate visualization of bridges. Recently, numerous researcher proposed using the Building Information Models (BIMs) to address this issue.</p><p>This paper presents the geometric approach of introducing BIM to BMS. Rather than trying to thoroughly connect these two robust systems on the object definition level, this approach focuses on geometry. The paper firstly shows how all the inventory information from BMS can be associated with corresponding BIM objects. Afterward, the ways to include the condition assessment data into BIM are proposed. Once the basics of the geometric approach are explained, the example of connecting BIM with BMS is presented. The example is based on KUBA, the Swiss BMS.</p><p>Finally, the feasibility, as well as the challenges of the presented approach are analyzed. The analysis focused on two important questions. Firstly, it considered if BIM is capable of making workflow changes in the Infrastructure Asset Management (IAM) the same way it did it in the construction industry. Secondly, it evaluated the BIM capability to describe all the condition assessment information relevant to IAM.</p>

This paper presents a robust reliability analysis method for systems of multimodular redundant (MMR) controllers using the method of partitioning and parallel processing of a Markov chain (PPMC). A Markov chain is formulated to represent the N distinct states of the MMR controllers. Such a Markov chain has N2 directed edges, and each edge corresponds to a transition probability between a pair of start and end states. Because N can be easily increased substantially, the system reliability analysis may require large computational resources, such as the central processing unit usage and memory occupation. By the PPMC, a Markov chain's transition probability matrix can be partitioned and reordered, such that the system reliability can be evaluated through only the diagonal submatrices of the transition probability matrix. In addition, calculations regarding the submatrices are independent of each other and thus can be conducted in parallel to assure the efficiency. The simulation results show that, compared with the sequential method applied to an intact Markov chain, the proposed PPMC can improve the performance and produce allowable accuracy for the reliability analysis on large-scale systems of MMR controllers.

The main objective of this study was to analyze the influence that the addition of finely ground hydrated lime has on chloride-induced reinforcement corrosion in eco-efficient concrete made with 50% cement replacement by fly ash. Six tests were carried out: mercury intrusion porosimetry, chloride migration, accelerated chloride penetration, electrical resistivity, and corrosion rate. The results show that the addition of 10–20% of lime to fly ash concrete did not affect its resistance to chloride penetration. However, the cementitious matrix density is increased by the pozzolanic reaction between the fly ash and added lime. As a result, the porosity and the electrical resistivity improved (of the order of 10% and 40%, respectively), giving rise to a lower corrosion rate (iCORR) of the rebars and, therefore, an increase in durability. In fact, after subjecting specimens to wetting–drying cycles in a 0.5 M sodium chloride solution for 630 days, corrosion is considered negligible in fly ash concrete with 10% or 20% lime (iCORR less than 0.2 µA/cm2), while in fly ash concrete without lime, corrosion was low (iCORR of the order of 0.3 µA/cm2) and in the reference concrete made with Portland cement, only the corrosion was high (iCORR between 2 and 3 µA/cm2).

The paper is devoted to studies of regularly and singularly perturbed Markov chains with damping component. In such models, a matrix of transition probabilities is regularised by adding a special damping matrix multiplied by a small damping (perturbation) parameter ε. We perform a detailed perturbation analysis for such Markov chains, particularly, give effective upper bounds for the rate of approximation for stationary distributions of unperturbed Markov chains by stationary distributions of perturbed Markov chains with regularised matrices of transition probabilities, asymptotic expansions for approximating stationary distributions with respect to damping parameter, explicit coupling type upper bounds for the rate of convergence in ergodic theorems for n-step transition probabilities, as well as ergodic theorems in triangular array mode.

Increasing stocks of public infrastructure and the serious deterioration of infrastructure systems in many countries present great financial, safety, technical and operational challenges to government organisations responsible for their development and management. This paper proposes a performance-based life-cycle cost management model for reinforced concrete bridge structures with regard to chloride-induced reinforcement corrosion. The model comprises four aspects: a chloride-induced corrosion deterioration model; performance-based management of concrete structures; the cost-effectiveness of management actions measured by the performance improvement per unit of money spent; a life-cycle cost model, which includes construction cost, inspection cost, maintenance cost, repair cost and failure cost. Two examples of chloride-induced reinforcement corrosion are provided to demonstrate the use of the proposed performance-based management strategy.

Modelling the impact of climat change on a novel Irish Concrete Bridge