marshalls keybond,i used it for the first time today,you mix it 6 to 1 with water and put on block with can,it makes your sand joints go rock hard,i poop myself at first as it goes down like emulsion paint but it had dried in in about an hour and the joints were solid,i was told it will keep weeds and ants away longer,i was impressed,lots of people are offering it instead of sealing to save future headaches,it cost £33 for 5 litres( £6.50 a litre) and i charged £50 extra on job as i only used 3 litres (£19.50 cost),it does you a favour so i think its worth being cheap so custy has it