In the last decade, there has been an increase in research related to green corrosion inhibitors for conservation of metals cultural heritage to help promote sustainable practices in the field that are safe, environmentally friendly, and ecologically acceptable. The most common are organic substances derived either from natural and/or biological sources: plant extracts and oils, amino acids, microorganisms, and biopolymers. The chapter will provide a review of these substances as corrosion inhibitors for metals conservation, by discussing the state-of-the-art research to date, with a special focus on cysteine. Most of the research has focused on the examination of such inhibitors on metal coupons with or without corrosion products using electrochemical techniques or weight-loss measurements to determine their effectiveness. Some of these studies have also considered the conservation principles for practice, i.e., reversibility of the treatment and the visual aspect of the modification of the treated metal surface. However, before such green inhibitors can be routinely applied by conservators, more research is required on their application to real artefacts/monuments using in situ corrosion measurements. Furthermore, given that the composition of a green inhibitor is highly dependent on its extraction process, research must also involve identifying the specific adsorption models and involved mechanisms to ensure reproducibility of results.

In this paper examines the improving durability of different limestone cement and effects of the use of corrosion inhibitor. The target is to experimentally investigate the effect of different types of cement in corrosion of reinforcement in presents of corrosion inhibitors and without it. Three types of cement have been used: CEM II, LC1 and LC2. For this purpose constructed mortar specimens, containing 4 reinforcements, with or without corrosion inhibitors for each group, these exhibited to partial immersion in sodium chloride in 3.5% w.t NaCl solution. The methods, with which the corrosion of reinforcement in concrete was tested, were measurements of corrosion potential, corrosion current and mass loss of reinforcement. The mortars with CEM II cement have better durability than that with limestone cement. The use of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with CEM II cement upper 50%. On the other hand, the addition of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with limestone cement 30% or lower.

According to currently enforced Eurocode 2 for the design of reinforced concrete structures, it is essential to protect steel reinforcements from corrosion and concrete from degradation under aggressive environmental conditions such as marine, urban, industrial environments and soils, to which these are normally exposed. In this context, this experimental study investigates the enhancement of the physico-mechanical properties of common cement-based mortars and the electro-chemical properties of reinforcing steel, through the addition of nanomaterials in the mix. For the experimental set-up, cylindrical, prismatic, and cubic specimens of different dimensions were cast and were partially immersed in sodium chloride solution for eight months. To evaluate the corrosion of steel rebars, cylindrical cement mortar specimens were used in order to induce a constant cover between exposure and the reinforcement; the physical and the mechanical tests were carried out on standardized shape cubes and prisms, respectively. Two groups were considered: cement-based mortar composites with 0.5 wt.% CNTs addition and plain (reference) specimens without any addition of nanomaterials, for comparison. The influence of adding CNTs on chloride penetration resistance was subsequently evaluated using standardized and non-standardized testing techniques: tests such as flexural strength and porosity, mass loss of steel, electrochemical measurements (corrosion current, HCP) and total chloride content calculation. The test results showed that using CNTs as an addition in mortar production led to the protection of steel rebars against pitting corrosion; moreover, an improvement (almost 9% at 120 days) in flexural strength and reduced porosity of mortars was also observed compared to the reference specimens without CNTs.

Although reinforced concrete structures are able to withstand towards a variety of adverse environmental conditions, reinforcement corrosion could lead to concrete structure deterioration. The present study examines four different ways of using corrosion inhibitors against pitting corrosion. In particular, it was investigated the chloride penetration resistance of reinforced cement mortars using corrosion inhibitor applied in three different ways. The corrosion behavior of the specimens was evaluated by electrochemical methods such as Linear Polarization Resistance and Half-cell Potential Resistance. In addition, the mass loss of steel rebars against time of partially immersion in sodium chloride (NaCl) solution was carried out in the lab. The experimental results showed that the corrosion systems examined in the study provide anticorrosion protection on steel rebars against chlorides comparing with the reference group.

Corrosion of reinforced concrete is the most important cause of concrete structure deterioration. In the present study, the protective effect of the reinforcement mortars against corrosion is examined. In particular, the chloride penetration resistance on reinforced cement mortars using organic coating as additive containing was studied. The aforementioned additive consists of corrosion inhibitor for protection of steel rebars against pitting corrosion. For the experimental procedure, four (4) different types of reinforced mortars were prepared. The corrosion protection of the additive was evaluated by electrochemical methods, (linear polarization resistance, Half-cell Potential Resistance and Electrochemical Impedance Spectroscopy). In addition, the mass loss of steel rebars against time of partially immersed in NaCl solution was carried out in the lab. The experimental results showed that in all examined cases the organic coating provides anticorrosion protection on steel rebars against chlorides.