In this article you will learn how to clean moss and help prolong the time that it takes to reapear.
First if at all possible try removing any obstructions that can cause the loss of sun to shine on the concrete.then try scraping all the heavy build up with warm water in a light spraying motion, and a bristle brush to remove the moss
Some chemical solutions that can be used are laundry bleach and boiling water.You will want to use only a small amout of bleach as this can cause etching. The best thing to do is try it in an unconspicuous place thn move on to the other spots.
Another method is to use a solution of 1 part sodium pentachlorophenate to 8 parts water by volume. It should be applied so that the moss or other growth is thoroughly saturated. If the surface is exposed to rain within 24 hours following the application, some of the solution will be lost and a further application may be necessary. About one week after the pentachlorophenate solution has been applied, all vegetable growth should have been killed and the residue can be removed by brushing. The surface will usually retain sufficient weed killer in inhibit further growth for some time