This study compares Enzyme-Induced Calcium Carbonate Precipitation (EICP) and Microbially Induced Calcium Carbonate Precipitation (MICP) for repairing external cracks in cement-based materials. Cracks in cement-base members can compromise structural integrity and increase maintenance costs. Thus, cement-base specimens with controlled cracks were treated using EICPs and MICP, with organic and non-organic additives to enhance calcium carbonate formation. Results show that both methods were effective in sealing cracks smaller than 0.35 mm. While incorporated additives improved the overall precipitation effectiveness, influence the crystallite size and altern the morphology of precipitated calcium carbonate. MICP generated more consistent crystal structures, while EICPs resulted in diverse crystal shapes influenced by enzyme sources and additives. Both methods offer promising, sustainable solutions for crack repair, with EICP providing greater flexibility and easier preparation. Presented research gives the comprehensive insights into the field of crack repair via bio-based methods reveals its potential in this area.

We have characterized the dynamics of the polar nanoregions in Pb (Mg _1/3 Nb_2/3)O₃ through high-resolution neutron-backscattering and spin-echo measurements of the diffuse-scattering cross section. We find that the diffuse-scattering intensity consists of both static and dynamic components. The static component first appears at the Curie temperature Θ∼400 K while the dynamic component freezes completely at the temperature T_f ∼200 K; together, these components account for all of the observed spectral weight contributing to the diffuse-scattering cross section. The integrated intensity of the dynamic component peaks near the temperature at which the frequency-dependent dielectric constant reaches a maximum (T_max) when measured at 1 GHz, i.e., on a time scale of ∼1 ns. Our neutron-scattering results can thus be directly related to dielectric and infrared measurements of the polar nanoregions. Finally, the global temperature dependence of the diffuse scattering can be understood in terms of just two temperature scales, which is consistent with random-field models.