Siloxanes in concrete: from manual application of water-proofing treatments to mix-design addition for concrete hydrophobicity

Manually applied waterproofing treatments with siloxane based emulsions are quite common for slabs exposed to rain and/or ponding water. This study has started first of all with the assessment of such a manually applied treatment, employing a commercially available siloxane based product. Reference has been made to capacity of such a treatment to reduce capillary absorption of water both in the case of un-cracked and cracked normal strength concrete specimens. The study has further evolved showing the potential of the siloxane based emulsion, when added into the mix as a partial replacement of the total mixing water (10% by weight in this case) to create a hydrophobic concrete, featuring highly reduced values of capillary absorption of water, even without the manual application of any surface treatment. The obtained results are interesting and very promising and pave the way to spread the use of such a simple technology for improving the durability characteristics of the concrete imperviousness, which would be no longer subjected e.g. to the UV light induced aging and deterioration of the manually applied films.