The stains found on paving and patios are generally a result of overspill from pointing the joints with cement mortar. Sometimes brick walls etc will have been built on the slabs of a concrete drive leaving big lumps of mortar.
Firstly, any lumps need to be removed using a hammer and bolster chisel. This needs to be done carefully actually banging down on the mortar rather than trying to get the chisel under it. Click on any of the images below to buy.
Once all the lumps are up and you are just left with a stain on the paving or concrete, you can use a brick or patio cleaner to finish off. Make sure you have all the appropriate safety clothing, including a mask and protective glasses and follow the instructions on the container. Click on the images below to buy. For particularly stubborn stains you can scrub with a wire brush or wire wool.
Some stains can be removed using a power washer so take a look at our project called power washing decking