Masonry remediation and protection by aqueous silane/siloxane macroemulsions incorporating colloidal titanium dioxide and zinc oxide nanoparticulates: Mechanisms, performance and benefits

In this study the influence of metal oxide nanoparticulates on aqueous silane/siloxane pore lining facade remediation treatments is presented. Pre-treatment attributes including stability and rheological properties were investigated. Colloidal titanium dioxide and zinc oxide nanoparticulates were incorporated into the novel silane/siloxane o/w emulsions and characteristics of such systems were then assessed in terms of thermal stability and rheological modification. Post-treatment attributes including water repellence, sorptivity and aesthetical alteration were also assessed. Enhanced emulsion properties were found to be dependent upon the extent of aggregation which was attributed to the morphology and size of the particulates. Excess of colloidal medium did reduce viscosity, however a significant stabilization was achieved regardless. Post-treatment results showed that a improved water repellence could be achieved with negligible visible alteration to substrate aesthetics; a novel benefit of such treatments for retrofit and remediation products combined with zero VOC emissions, complying to new EU directives. Findings undoubtedly confirm the potential for nanoparticulates to be used as effective emulsifiers in similar emulsion systems while being commercially and practically viable for facade remediation due to the small concentrations required.