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The issue of chloride induced corrosion of reinforced concrete is a serious problem affecting infrastructure globally and causing huge economic losses. As such this issue has gained a considerable attention in the scientific community in the recent past. Layered Double Hydroxides (LDHs) have recently emerged as a new class of concrete-additives with a potential to increase the chloride resistance of concrete and mitigate corrosion. LDHs are clay like structures consisting of positively charged layers of cations with associated hydroxides and exchangeable anions in between the layers. Due to this charge balanced structure, LDHs possess the property of encapsulating an anion from the environment and replacing it with an exchangeable anion present in its layers. Potential applications include chloride entrapment in concrete and delivery of corrosion inhibiting anions. However, many versatile compositions of LDHs can be easily synthesized and their application as cement additives reach far beyond corrosion mitigation in concrete. This review presents a summary of recent advances on the applications of LDH in concrete. An extensive set of recently published literature has been critically reviewed and trends have been identified.

This work investigated the use of ZnAl-layered double hydroxide (LDH) intercalated with nitrate or nitrite ions for controlling the corrosion of steel in reinforced concrete. The work started by analyzing the stability of the powder in the 1-14 pH range and the capacity for capturing chloride ions in aqueous solutions of different pH. The effect of the ZnAl-LDH on the corrosion of steel was studied in aqueous 0.05 M NaCl solution and in mortars immersed in 3.5% NaCl. It was found that the LDH powders dissolved partially at pH > 12. The LDH was able to capture chloride ions from the external solution, but the process was pH-dependent and stopped at high pH due to the partial dissolution of LDH and the preferential exchange of OHions. These results seemed to imply that ZnAl-LDH would not work in the alkaline environment inside the concrete. Nonetheless, preliminary results with mortars containing ZnAl-LDH showed lower penetration of chloride ions and higher corrosion resistance of the steel rebars. dioxide leads to the carbonation of concrete, which is accompanied by a decrease in pH. When the front of low pH reaches the steel surface, the passivity is lost and uniform corrosion starts. Chloride ions, on the other hand, can disrupt the passive layer even at high pH, if a threshold concentration is surpassed [5]. In these conditions, the corrosion is localized in the form of pitting, crevice, or stress corrosion cracking. The iron corrosion products are more voluminous than steel, which creates expansive stresses, leading to cracking at first and spallation of the concrete cover at the end. After that, steel becomes directly exposed to the atmospheric environment, and corrosion proceeds at a much faster rate.Since the corrosion of steel rebars dramatically limits the service life of reinforced concrete, many forms of corrosion control are being explored [2][3][4]6,7], including the use of stainless steel or galvanized steel rebars, application of epoxy coating on steel rebars, cathodic protection, and addition of corrosion inhibitors to concrete (e.g., calcium nitrite, sodium benzoate, chromates, phosphates, polyphosphates, silicates, polycarboxylic acids, fatty acids emulsions, and alkanolamines). Corrosion can also be delayed by painting the surface of the concrete structure or using a thicker layer of concrete, separating the rebars and the environment. Less porous concrete (lower water/cement ratio), high quality cement, and the use of water and aggregates without soluble salts also contribute to extending the durability of the structure.The direct addition of corrosion inhibitors to concrete may affect the curing process or the mechanical properties of the hardened material. Because of this possibility, the encapsulation of inhibitors in nano-or micro-reservoirs to be released only when needed (either with the onset of corrosion or in the presence of aggressive species) is a line of investigation worth pursuing.Layered double hydroxides (LDHs) are one example of such nanostructured reservoirs. The LDH structure...

A multiscale modelling framework, especially for corrosion modelling, requires not only robust computational tools but also an efficient datacentric architecture for handling information exchange at different modelling scales. Different computational solvers require and produce data in different programming languages and specific formats signifying a strong non-uniformity for an easy nexus with other solvers. This non-uniformity has created a need to focus on intermittent state-of-the-art datacentric software tools which aim to bridge data exchange heterogeneity across diverse set of solvers. Data organization in the form of metadata structures are presented as a standard for a coherent information representation regardless of the diverse nature of data formats specific to a scientific discipline. This fundamental work presents the concept, underlying terminology and working mechanism of a datacentric architecture tool SOFT5 for exchanging and interfacing data-flow between solvers and its present application to a concrete technology multiscale simulation network as a potential application.