Performance of pore-lining impregnants in concrete protection by unidirectional salt-ponding test (U-SPT)

Until recently, solvent-based forms of monomeric alkyl (isobutyl) trialkoxy silane, produced under various trade names, were exclusively used in the United Kingdom for concrete protection of transportation structures and other structures subject to surface salt contamination. Reflecting the move toward more sustainable construction and with increasing demand for less-hazardous materials, alternative protective treatments that are based on various aqueous formulations have emerged. These treatments include dual-purpose materials for protection and concrete coloration. At the same time, developments in nanomaterials have resulted in the availability of a low-hazard pure silane that is neither water nor solvent based. This investigation evaluated the performance of this material and three water-based materials with respect to their resistance to water and salt solution absorption and chloride ion penetration. A comparative investigation assessed the possibility of using convenient concrete cubes rather than larger-scale slabs for chloride contamination testing by the salt-ponding method. The results of the study are particularly relevant to older reinforced concrete structures, which frequently suffer low concrete cover to their steel-reinforcing bars.