<p>Cracking in earth-based construction materials poses significant durability challenges, necessitating sustainable solutions. 3D printing offers efficient, scalable construction with earthen materials, but requires durable, eco-friendly matrices. This study explores enzymatic-induced carbonate precipitation (EICP) using urease to improve water resistance and self-healing in earthen-based 3D printed elements containing cement and rice husk fibers. Urease catalyzes urea hydrolysis, forming calcium carbonate (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">${\text {CaCO}}_{3}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mtext>CaCO</mtext> <mn>3</mn> </msub> </math></EquationSource> </InlineEquation>) to fill pores and seal cracks. EICP was applied as a soil additive for water resistance and as a surface treatment for crack repair. The optimized formulation (1 M <InlineEquation ID="IEq2"> <EquationSource Format="TEX">${\text {CaCl}}_{2}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mtext>CaCl</mtext> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>-urea 4 U/L urease, Mod. B1-E4) achieved 25.5% less mass loss than 24. 7% for nonenzymatic controls after 60 min of immersion in water and sealed cracks up to 0.45 mm wide within 48 h. SEM, EDS, and XRD analysis confirmed a reduction in porosity 15% through <InlineEquation ID="IEq3"> <EquationSource Format="TEX">${\text {CaCO}}_{3}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mtext>CaCO</mtext> <mn>3</mn> </msub> </math></EquationSource> </InlineEquation> formation, which improved resistance to erosion. The formulation yielded 0.75 g of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">${\text {CaCO}}_{3}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mtext>CaCO</mtext> <mn>3</mn> </msub> </math></EquationSource> </InlineEquation> per reaction cycle, demonstrating efficient biocementation. EICP offers a low carbon alternative for improving the durability of 3D printed earthen structures as a pore-filler and crack-sealer, with potential for sustainable and scalable repairs in construction.</p>

Improved resistance to water erosion and self-healing capacity of earthen-based 3D printed elements using enzyme-induced carbonate precipitation (EICP)

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2026年3月30日

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Omar Rojas,
Javier Nakamatsu,
Rafael Aguilar,
Robert Ñañez,
Guido Silva,
Suyeon Kim

摘要

Cracking in earth-based construction materials poses significant durability challenges, necessitating sustainable solutions. 3D printing offers efficient, scalable construction with earthen materials, but requires durable, eco-friendly matrices. This study explores enzymatic-induced carbonate precipitation (EICP) using urease to improve water resistance and self-healing in earthen-based 3D printed elements containing cement and rice husk fibers. Urease catalyzes urea hydrolysis, forming calcium carbonate ( ${\text {CaCO}}_{3}$ ${CaCO}_{3}$ ) to fill pores and seal cracks. EICP was applied as a soil additive for water resistance and as a surface treatment for crack repair. The optimized formulation (1 M ${\text {CaCl}}_{2}$ ${CaCl}_{2}$ -urea 4 U/L urease, Mod. B1-E4) achieved 25.5% less mass loss than 24. 7% for nonenzymatic controls after 60 min of immersion in water and sealed cracks up to 0.45 mm wide within 48 h. SEM, EDS, and XRD analysis confirmed a reduction in porosity 15% through ${\text {CaCO}}_{3}$ ${CaCO}_{3}$ formation, which improved resistance to erosion. The formulation yielded 0.75 g of ${\text {CaCO}}_{3}$ ${CaCO}_{3}$ per reaction cycle, demonstrating efficient biocementation. EICP offers a low carbon alternative for improving the durability of 3D printed earthen structures as a pore-filler and crack-sealer, with potential for sustainable and scalable repairs in construction.