Selection of Nutrient Used in Biogenic Healing Agent for Cementitious Materials

Abstract

Biogenic self-healing cementitious materials target on the closure of micro-cracks with precipitated inorganic minerals originating from bacterial metabolic activity. Dormant bacterial spores and organic mineral compounds often constitute a biogenic healing agent. The current paper focuses on the investigation of the most appropriate organic carbon source to be used as component of a biogenic healing agent. It is of great importance to use an appropriate organic source, since it will first ensure an optimal bacterial performance in terms of metabolic activity, while it should, second, affect the least the properties of the cementitious matrix. The selection is made among three different organic compounds, namely calcium lactate (CaL), calcium acetate (CaA), and sodium gluconate (NaG). The methodology that was used for the research was based on continuous and non-continuous oxygen consumption measurements of washed bacterial cultures and on compressive strength tests on mortar cubes. The oxygen consumption investigation revealed a preference for CaL and CaA, but an indifferent behavior for NaG. The compressive strength on mortar cubes with different amounts of either CaL or CaA (up to 2.24% per cement weight) was not or it was positively affected when the compounds were dissolved in the mixing water. In fact, for CaL, the increase in compressive strength reached 8%, while for CaA, the maximum strength increase was 13.4%.

A Review of Self‐Healing Concrete for Damage Management of Structures

“…In two recent studies, the effect of organic calcium salts, which can act as calcium carbonate mineral precursor compounds (calcium and sodium gluconate, calcium acetate and calcium lactate), were investigated for potential to heal cracks in mortar specimens, and it was found that calcium gluconate and calcium lactate enhance the self‐healing kinetics for large cracks, and that the compressive strength of mortar cubes increased with 8% for calcium lactate and with 13.4% for calcium acetate …”

Stimuli-responsive engineered living materials

“…Several strategies have been described that utilize bacteria as a self-healing agent capable of surviving the harsh environment of concrete mixing. [245][246][247][248][249][250] These strategies typically utilize concrete matrices mixed with immobilized bacterial strains. Bacteria are capable of converting calcium lactate into calcium carbonate by using external oxygen.…”

High throughput production of microcapsules using microfluidics for self-healing of cementitious materials

“…3 This leads to recovery in transport properties and hence durability performance and, to some extent, to recovery in mechanical properties. Several methodologies have been applied to achieve such self-healing, including the enhancement in the autogenous capacity of cementitious materials to heal their own cracks through the addition of minerals, 4,5 fibres, 6 superabsorbent polymers (SAPs), 7 ; and autonomic healing through vascular systems, 8,9 bacteria [10][11][12] and shape memory polymers. 13 However, the addition of these materials may lead to unwanted variations in the rheology during mixing and/or laborious changes to include the system during casting.…”