Nitrite producing bacteria inhibit reinforcement bar corrosion in cementitious materials

Abstract

Chemicals and synthetic coatings are widely used to protect steel against corrosion. Bio-based corrosion inhibition strategies can be an alternative in the arising bioeconomy era. To maintain the good state of steel reinforcement in cracked concrete, microbe-based self-healing cementitious composites (MSCC) have been developed. Yet, proposed strategies involve reasonably slow crack filling by biomineralization and thus risk the possible rebar corrosion during crack healing. Here we upgrade the rebar protection to a higher level by combining MSCC with microbial induced corrosion inhibition. Presented NO reducing bacterial granules inhibit rebar corrosion by producing the anodic corrosion inhibitor NO and meanwhile heal a 300-µm-wide crack in 28 days. During 120 days exposure to 0.5 M Cl solution, the rebars in cracked MSCC keep showing open circuit potentials above the critical value of -250 mV and they lose less than 2% of the total rebar material which corresponds to half the material loss in cracked plain mortar. Overall, the obtained rebar protection performance is comparable with that of uncracked mortar and mortar containing chemical inhibitor, hence the microbe-based system becomes an alternative to the traditional methods.

Production of concrete compatible biogranules for self-healing concrete applications

“…ACDC biogranules specifically granulated for concrete application were determined to be compatible with a cementitious matrix and are useful for crack healing in concrete at a bacteria dosage of 0.50% w/w cement [1,4]. Moreover, at the same dosage, ACDC granules simultaneously inhibit reinforcement bar corrosion, by producing the anodic corrosion inhibitor NO 2 − , and heal a 300-µm-wide crack in 28 days in marine-similar conditions [5]. The former provides a bio-based alternative to the use of chemical corrosion inhibitors and enhances the sustainability of the cementitious materials.…”

Durability of self-healing concrete

“…Microbial NO3reduction was investigated by using a non-axenic self-protected NO3reducing culture called ACDC, produced as described in [3]. In corrosion experiments, as a control culture, a self-protected nonaxenic ureolytic culture was used (CERUP, produced by Avecom NV, Belgium), with an effect on mortar properties similar to ACDC, while it can induce crack sealing through urea hydrolysis.…”

“…When corrosion inhibition occurred, the rebars lost less than 2% of the total material (average rebar mass 5.5±0.2 g, n=30) at the end of 120 days exposure to salt solution. More information can be found in [3].…”

“…OCP versus SHE for uncracked and cracked normal mortar (all graphs), uncracked and cracked positive control containing chemical nitrite as corrosion inhibitor (top), uncracked and cracked self-healing mortar with ureolytic CERUP (middle), uncracked and cracked self-healing mortar with denitrifying ACDC (bottom). Redrafted after[3].…”

The influence of SAPs on chloride ingress in cracked concrete

“…Most data can be found for encapsulated polymers: Maes et al [3], Van den Heede et al [4], and Van Belleghem et al [5] investigated the effect of adding glass capsules filled with polyurethane on chloride resistance. Erşan et al [6] studied the influence of nitrite producing bacteria on chloride ingress indirectly by investigating reinforcement bar corrosion.…”