Pressure washing is widely believed to be the single most useful process that you can look into if you want to clean a house that has been left to rot for so long that you have a hard time perceiving a future in which it would actually look presentable. However, it would be erroneous for us to say that pressure washing is a complete package in and of itself. While you would need to pressure wash concrete surfaces at some point or another during your lifetime, suffice it to say that treating the surface afterwards is an oft ignored crucial aspect of the process without a shadow of a doubt.
One thing that you should always keep at the forefront of your mind is that concrete needs to be sealed after you power wash at this current point in time. Concrete is usually sealed to prevent moisture from entering into the holes that are microscopic but still large enough to absorb some water in drips and drabs. Pressure washing naturally strips this sealant off, and as a result of the fact that this is the case you need to apply a new layer or the concrete would start to crack before too long.
In order to seal your concrete, you need a bucket of sealant which you can mix together to incorporate it into a single fluid. You can then use a simple paint roller to apply the first, second and third layers. Make sure that you let the layer of sealant dry before you start to apply the next layer because it might start to break off in pieces if it has not been allowed to harden.