Asphalt driveways are typically less expensive than concrete, costing a minimum of about $2.50 per square foot. An asphalt driveway might last just 20 years; however, while a concrete driveway can last more than 30.
Semipermeable membrane. The diffusion of water through a selectively permeable membrane is called osmosis.This allows only certain particles to go through including water and leaving behind the solutes including salt and other contaminants. In the process of reverse osmosis, thin film composite membranes (TFC or TFM) are used.
Note that a semipermeable membrane is not the same as a selectively permeable membrane. Semipermeable membrane describes a membrane that allows some particles to pass through (by size), whereas the selectively permeable membrane chooses what passes through (size is not a factor).