Effect of Bacillus megaterium bacteria on geopolymer concrete as self-healing agent in repairing cracks of bridge structure

¹ Politeknik Negeri Bandung, Civil Engineering Department, 40514 Bandung, Indonesia
² PT. Vexcolt Indonesia Pratama, Technical Department, 16820 Bogor, Indonesia
³ PT. Hissan Trading Indonesia, Technical Department, 12520 Jakarta, Indonesia

^* Corresponding author: luthfi-mm@polban.ac.id

Abstract

Concrete production accounts for up to 10% of total global CO2 emissions, prompting the replacement of cement with environmentally friendly alternatives that have properties equivalent to conventional concrete, such as geopolymer concrete, which consists of a binder (fly ash) combined with an alkali activator (NaOH, Na₂SiO₃), filler or aggregate, water, and other additives. However, geopolymer concrete is not immune to cracking, so its necessary for self-healing technology using microorganisms such as Bacillus Megaterium bacteria which can survive inside concrete. The production of 15x30 cm test specimens began with bacterial inoculation, the crushing of test specimen waste into RCA, and the testing of material physical properties. The research results showed that the compressive strength was 30.35 MPa, while the compressive strength of geopolymer concrete and self-healing geopolymer concrete was 24.17 and 24.21 MPa, respectively. However, geopolymer concrete did not exhibit self-healing due to the 10M alkaline activator solution with a pH > 14. Although the compressive strength may exceed that of ordinary geopolymer concrete, the strong alkaline environment is not a suitable pH for Bacillus Megaterium bacteria.