Feasibility of lactate derivative based agent as additive for concrete for regain of crack water tightness by bacterial metabolism

Abstract

Lactate, produced by fermentation of e.g. cane or corn residues, can serve as a carbon source in bacterial healing for cement-based materials such as concrete. Bacterial spores, activation nutrients and a carbon source are mixed in with dry concrete or mortar constituents upon material production. Upon cracking of the concrete matrix and ingress of water, an active bacterial colony forms and starts to convert the included carbon source to CO₂. In the alkaline surrounding of concrete carbonates form and deposit as minerals on the crack surface, sealing the entrance to further ingress. In this work a lactate derivative based healing agent containing bacteria and activation nutrients is added to a commercial mortar, exerting negligible effect on the mortar strength development. Functionality of the agent is indicated by oxygen consumption under aerobic conditions and shown by regain of crack water tightness beyond the autogenous healing capacity in a permeability test. In order to indicate feasibility for healing agent application in a commercial setting, the environmental burden is discussed and a competitive production price is estimated.