Concrete stone flags have been used on driveways for years. They have historically been laid as 3ft by 2ft flags, however in recent years due to health and safety laws it is increasingly difficult to use this type of flag, so most installations are 2 ft by 2ft flags. They are easier to bed and certainly weigh alot less.
The problems we encounter are:
Once the sub base is worn away under the flag then due to the rigid design of the product they begin to wobble. After abit more rain and the passing of a season, then even more of the sub base is worn away. The flags wobble more and begin to affect surrounding flags, as the car drives over them they then crack thus worsening the problem further... it then becomes a downward spiral.
Overtime it is also likey that the pointing comes out of the joints of the flags, some people refer to this as the grouting. This generally happens because of the passing of seasons, water seeps into the gaps and in a cold spell freezes and pops the cement thus causing it to flake and crumble. However once the pointing has been weakend, to much direct power washing can cause further damage.
Often we also find that indian stone flags or natural stone flags require cleaning on a regular basis, generally this comes down to the foilage surrounding the area. You will often notice that once algae takes a grip on your lovely indian stone it soon becomes green, slimey and slippery. By cleaning the area down and using special preventative measures, Paving Shield will help keep these areas looking cleaner for longer.