Innovative Gel Method: Sustainable Crack Healing in Ceramic Geopolymer Mortars via Marine Actinomycetes and Bioactivated Carriers


Koseoglu S., Kubat M., Uysal M., Aydogdu E. O. A., Aygun B. F., Canpolat O.

CASE STUDIES IN CONSTRUCTION MATERIALS, cilt.23, sa.e04954, ss.1-67, 2025 (SCI-Expanded)

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 23 Sayı: e04954
  • Basım Tarihi: 2025
  • Doi Numarası: 10.1016/j.cscm.2025.e04954
  • Dergi Adı: CASE STUDIES IN CONSTRUCTION MATERIALS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, Directory of Open Access Journals
  • Sayfa Sayıları: ss.1-67
  • Yıldız Teknik Üniversitesi Adresli: Evet

Özet

This study addresses the urgent need for efficient self-healing methods in geopolymer mortars (GMs), which, with their favorable low-carbon character, are still vulnerable to microcracking and ongoing durability loss. GMs made of 50 % ceramic powder (CP) and 50 % granulated blast furnace slag (GBFS), synthesized with sodium hydroxide (2–12 M) and sodium silicate (Na₂SiO₃/NaOH = 1.0–2.0) at an initial sand-to-binder ratio of 2.5, were cured at temperatures of 40°C to 100°C. Artificial microcracks with diameters of 0.2 mm and 0.6 mm were created before applying liquid (+S) and gel-like (+J) formulations of S. pasteurii and marine actinomycetes isolated from Marmara Sea sediments for 90-day treatments. Compressive and flexural strength, water absorption, ultrasonic pulse velocity (UPV), and microstructural analyses via SEM/EDS, XRD, and FTIR were considered methods for assessing healing performance. The S1 +S group showed the best mechanical recovery, with compressive and flexural strengths of 42.92 MPa and 8.98 MPa, respectively, while S26 +S showed the best UPV value of 3245.44 m/s, attesting to effective internal consolidation. S13 +S showed the most balanced improvement in acetate-decomposing strains, with compressive strength of 37.20 MPa, flexural strength of 5.63 MPa, and minimized water absorption (7.44 %). Preservation of calcite precipitation and crystalline geopolymeric phases were confirmed via XRD. At the same time, increased carbonate and Si–O–Al bonding in FTIR indicated that the microbe-induced and inorganic polymerized structures occurred simultaneously. EDS also supported these findings, where increased Ca and C contents asserted localized CaCO₃ accumulation and increased peaks for Si and Al confirmed the unstable geopolymerization. All these findings place marine actinomycetes—especially acetate-decomposing strains—at the forefront of prospects for self-sustaining crack healing and structural reinforcement in green GMs.