Evaluation of Mechanical Parameters of Bacterial Concrete

Abstract

Conventional concrete is prone to cracking under tensile load, despite its good compressive strength. Recently, biological agents have been applied to heal the cracks in concrete, making concrete structures more serviceable. This paper mainly attempts to evaluate the mechanical properties of bacteria-based self-healing concrete. Two bacteria were selected as the bioagents in concrete, namely, Bacillus subtilis and Bacillus halodurans. The concentration of the bioagents were set to 10 5~1 0 7 cell/mL in water. Then, the two bacteria were applied to cracked concrete to cure the cracks. After curing for several days, the bacteria-based self-healing concrete was subjected to compressive and flexural tests to estimate its mechanical parameters. The results show that the self-healing concretes cured for 14d and 28d had a 7% and 18% higher compressive strength than conventional concrete, respectively; the self-healing concretes cured for 14d and 28d had a 11% and 28% higher flexural strength than the conventional concrete, respectively. Thus, the bioagents could effectively heal the surface cracks on concrete, and make the concrete imperviable.

Bacterial Self-Healing of Concrete: A Scoping Review

“…Bacterial mixtures with chitosan incorporation at 0, 0.5, 1.0 and 1.5% increased strength by 1.97%, 3.44%, 13.79% and 1.48% with respect to the control mixture (Dolomite-sandcement-water-superplasticizer) [47]. In another study, it was found that at 28 days the concrete with B. halodurans with solutions of 10 5 CFU/mL reached the highest strength, being superior to the mixture with B. subtilis at the same concentration [53]. In addition, by using a genetically improved strain (B. subtilis T), a significant increase in resistance was achieved [30].…”

“…An important aspect of this type of studies is to evaluate the mechanical properties of selfrepairing concrete considering the type of bacteria and the concentration of bioagents, thus, it has been identified that at 28 days of curing, mixtures with B. halodurans and B. subtilis are superior to conventional concrete (7% and 18% higher, respectively) [53]. Likewise, several studies report the use of other types of bacteria that improve compressive strength over conventional strength, among them we have: B. sphaericus (15.95%), B. cohnii (11.45%), and B. megaterium MTCC 1684 (16%) [54]; B. megaterium MTCC 1684 (14.8%), and Lysinibacillus sp.…”

Self-Healing Cement: A Review

“…The compressive strength of cement is satisfactory, but its tensile strength is different [42]. As we have expressed in the previous discussion, a method of healing cracks via bacteria offers a change in concrete structures.…”

Crack healing and flexural behaviour of self-healing concrete influenced by different bacillus species

“…All the prepared concrete samples are cured in normal water for 28 days before testing. The surface cracks are formed using 65% and 75% stress level concentrations [16]. To evaluate the healing ability of bacterial agents, three different curing conditions are adopted, namely water, calcium lactate, and air (i.e., ambient curing).…”

“…Self-healing concrete is the one that heals itself when it comes into air, water and produces lime on the outer layer of the concrete. The self-healing process can be broadly classified into two types, i.e., autogenous self-healing and autonomous self-healing and the healing methods are shown in Fig 1 . The healing can be done with many materials like biological agents [14][15][16][17][18][19], chemical agents, superabsorbent polymers, crystalline materials, pozzolanic materials [20][21][22] and mineral admixtures that are added and replaced with cement in order to arrest the cracks of concrete which shortens their production.…”