Cement building materials, such as concrete, mortar and masonry, easily absorb water due to their pores and capillary structure. In order to prevent damage due to moisture absorption, the absorption of the material can be reduced by applying a waterproof sealant.

Silane and siloxane are the two most common water-repellent agents, both derived from silicone molecules. Silicone is a common name for various polymer chains built around the molecular skeleton of silicon-oxygen-silicon. Despite the close relationship, silane and siloxane have significant performance differences, which will be explained below. But first, this is the general similarity between silane and silicone sealants:

Both are penetrating sealers.
Both allow the substrate to breathe, allowing moisture to escape and at the same time repelling water from the outside.
There is almost no change in the appearance of the coated substrate-the surface is not shiny.
When used, the silane hydrophobic agent will penetrate into the substrate and react with calcium hydroxide to form a hydrophobic hydrophobic resin in the pores and on the surface. In order for this chemical reaction to occur, the substrate must be alkaline (high pH). It must contain calcium hydroxide. Therefore, silanes formulated for concrete and masonry are ineffective in sealing other substrates (such as natural stone, clay bricks, or wood).

Unlike silanes, siloxanes do not depend on substrate pH to react. Siloxane can react with moisture in the atmosphere and any moisture in the substrate to form a hydrophobic resin. Therefore, silicone is very suitable for the treatment of non-cemented building materials, such as brick, plaster and stone.

Because silanes are composed of smaller molecules than siloxanes, they usually penetrate deeper than siloxanes and therefore perform better on dense surfaces such as cast-in-place concrete and precast concrete. However, the result of this small molecular size is that the silane is very volatile. Therefore, the solid content of the silane waterproofing agent should be high enough to compensate for the evaporation of reactive materials during application and curing.

Siloxane has a slightly larger molecular structure and is somewhat effective on medium porosity (medium weight), heavy weight, smooth surface concrete blocks and other substrates. Unlike silane, their chemical composition does not promote rapid evaporation. Therefore, their solid content is usually less than silane.

 Silway specializes in modified silicones and formulation technology. The product line covers agricultural silicone adjuvant ,   silicone water repellent    ,    Innovative Silicone   ，cosmetic silicones, sealants and additives, modified silicones for die casting, etc.   https://www.silways.com/product/silicone-water-repellent.html