When looking for a concrete sealer, you have to narrow down your choices from the initial level of surface versus penetrating sealers. Next, if you choose penetrating sealers, you must choose between silicate-, siliconate-, or silane/siloxane-based concrete sealers. If you decide to use a silane/siloxane sealer, you finally need to choose which of those you want to use.
Silanes and siloxanes are both derived from the silicone family. Despite being very closely related, they have significant performance differences. Because silanes are made up of smaller molecules than siloxanes, they typically will obtain deeper penetration than siloxanes. As a result, silanes perform well under abrasion and weathering conditions. A consequence, however, of this small molecular size is that silanes are relatively volatile. Therefore, the solids content of a silane product should be high enough to compensate for the loss of reactive material through evaporation during application and cure. Siloxanes, because they are less volatile, generally offer good water repellent performance at lower costs. However, for concrete surfaces subjected to abrasive wear, treatment with a silane sealer will provide longer lasting protection. In regard to surface texture and color, treatment with silane sealers typically cannot be detected visually. Siloxane products may slightly darken the treated surface.
Manufacturers have since realized that the disadvantages can be mitigated with a special blend of the two. While there are many poorly blended silane/siloxanes on the market, there are some high-quality ones that offer a unique blend of penetrating and surface protection.
When choosing a silane/siloxane sealer, you want to look for a product that is water-based with a low VOC content. These will be easier and safer to apply, with fewer fumes and less flammability. You also want to use a product that is water repellent, such that the water will bead on the surface of your concrete. If the water doesn’t bead, then you can’t know if the siloxane part of the blend is properly working. If it is not properly working, it means the manufacturer has likely messed up the blend.