Carbon-capturing Bituminous Pavement: A Sustainable Approach to CO2 Sequestration in Road Infrastructure Using Bacillus subtilis and TiO2 for Carbon Sequestration
J. Environ. Nanotechnol., Volume 15, No 3 (September 2026) pp. 809-817
Abstract
The escalating atmospheric CO₂ concentration necessitates sustainable infrastructure solutions. This laboratory-scale study investigates a Carbon-Capturing Bituminous Pavement (CCBP) incorporating a bio-enhanced layer comprising Bacillus subtilis, hydrated lime, and titanium dioxide (TiO₂). The carbon-capture mechanism relies on urease-producing B. subtilis to hydrolyze urea, generating carbonate ions that react with Ca²⁺ from hydrated lime to precipitate CaCO₃. TiO₂ nanoparticles (synthesized via sol-gel) were characterized by XRD (anatase, crystallite size 18±4 nm), TEM (spherical, 22±6 nm), and EDS (Ti/O elemental distribution). The pavement design followed IRC:37-2018 procedures; full compliance was not verified. Controls included a conventional pavement and formulations lacking bacteria, TiO₂, or lime. CO₂ capture efficiency (η) was defined as the ratio of experimentally measured carbonate (by acid-base titration) to the stoichiometric maximum based on lime content, corrected for background carbonates. This laboratory efficiency is not equivalent to atmospheric CO₂ sequestration, and a complete carbon mass balance was not performed. η reached 56.27% by Day 7 under controlled laboratory exposure. Sequestration capacity (g CO₂/m² = moles carbonate × 44 / exposed area 0.045 m²) increased from 12.9±1.1 to 104.8±8.1 g CO₂/m² over 28 days. Dynamic modulus (n=6) was 2444±118 MPa for CCBP vs 2235±96 MPa for conventional (p=0.032), a 9.35% improvement. SEM with complementary XRD/FTIR confirmed calcite precipitates; EDS showed Ca (8.7±0.5 wt%) and Ti (3.2±0.3 wt%), consistent with elemental composition but not proof of photocatalytic function. These results indicate potential for carbonate formation and enhanced stiffness under controlled conditions. Future work will include direct photocatalytic tests, long-term field validation, a complete carbon mass balance, and a full life-cycle assessment before atmospheric sequestration claims can be made.
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Reference
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