Producing C-S-H gel by reaction between silica oligomers and portlandite: A promising approach to repair cementitious materials

• Published in: Cement and concrete research Vol. 130; p. 106008
• Main Authors: Zarzuela, Rafael, Luna, Manuel, Carrascosa, Luis M., Yeste, María P., Garcia-Lodeiro, Inés, Blanco-Varela, M. Teresa, Cauqui, Miguel A., Rodríguez-Izquierdo, José M., Mosquera, María J.
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01.04.2020; Elsevier BV
• Subjects: B. calcium-silicate-hydrate (C-S-H); Calcium silicate hydrate; Cement; Cement paste; Chemical compatibility; Concrete; Concrete construction; Concrete repairing; Concrete structures; Construction materials; D. Ca(OH)2; Degraded concrete; Impregnation; Impregnation treatment; NMR; Nuclear magnetic resonance; Oligomers; Porosity; Reaction products; Silica oligomer; Silicon dioxide; Sol-gel processes; Impregnation treatment; Degraded concrete; Silica oligomer; B. calcium-silicate-hydrate (C-S-H); D. Ca(OH)2; Concrete repairing
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2020.106008

Impregnation treatments are one of the alternatives to protect concrete-based building and monuments from weathering degradation. However, it is important to consider the chemical compatibility of the reaction products with the building material. The impregnation product studied here consists of a silica oligomer able to polymerize, by a simple sol-gel process, inside the pore structure of concrete. In this work, we investigate the ability of this impregnation treatment to produce C-S-H gel in contact with cement paste. A complete characterization of the reaction products demonstrated that the silanol groups from silica oligomers react with the portlandite present in the cement paste generating a material with the chemical, structural and morphological features of C-S-H gel. Simultaneously, the 29Si NMR results indicate that the SiO units are incorporated into the existing C-S-H, increasing its chain length. These results open the way for a simple concrete structures repairing procedure.