Consolidation of artificial decayed portland cement mortars with an alkoxysilane-based impregnation treatment and its influence on mineralogy and pore structure

Abstract

Surface treatments, especially hydrophobic agents to prevent water ingress and consolidants able to fill decay- induced cracks, are often proposed as a method for preserving stone cultural heritage, however its use to pro- tect concrete heritage is much less common. New products, specifically designed for concrete, have been developed. These products are based on alkoxysilanes that interact directly with the products of portland cement (OPC) hydration (essentially Ca(OH)2 and C-S-H) to generate additional C-S-H gel. This study assesses the effect of an impregnation treatment, based on alkosysilanes, on artificially decayed cement mortars, in terms of product penetration depth, changes in the porosity of mortars and changes in its mechanical strengths. Reduced porosity and enhanced mechanical strength attested to treatment efficacy. Substrate porosity and pore size distribution were not the only factors found to condition treatment effectiveness, however, mineralogical changes caused by the deterioration processes (such as the presence or absence of portlandite, or the presence of salts) modify the sol gelling time and the substrate surface energy, impacting treatment penetration depth.