Dig an area around 2 feet wider all around than you want the barbecue pit to be. Make this area 2 inches deeper than the thickness of your pavers. Level the area and check that it is all even with the level.
Dig your pit, around 1 1/2 feet deep. Make sure the sides are straight, and the ground in the pit is even.
Lay an inch of gravel over the inside of the pit and the surrounding dug-out area. Lay another inch of sand over the gravel, only in the pit at this point. Dry-lay a base of bricks, tightly packed, on the bottom of the pit.
Mix the mortar as per the manufacturer's instructions. Coat the sides, ends and bottom of a brick, then gently tap it onto the base of the pit, along the wall. Lay a complete row along the wall. Keep laying bricks, mortaring as you go and staggering the joints until you are two bricks' height over the top of the pit.
Lay a second two rows adjacent to the two rows above the pit wall, to create a thick, sturdy top for your barbecue pit.
Mix the surface bonding cement as per the manufacturer’s instructions. Apply a ¼ inch layer all over the brick work in your barbecue pit, smoothing it over with the ends of the trowel. This is not essential for the structure, but creates a uniform and aesthetically pleasing finish to your pit. Let cure for three days.
Lay an inch of sand over the remaining gravel around the pit—this can be done while the pit is curing. Place your pavers, around ¼ inch apart, around the dug-out area. Apply more sand over the top, then sweep it into the paver joints with the broom. Wet down the sand after the barbecue pit has cured and apply more where necessary, brushing it into the joints and wetting again.
Place three or four evenly spaced bricks into the bottom of the pit, and rest the metal grate on top—this is for the barbecue coals, so allow ventilation space underneath. Place the metal grill plate over the top of the barbecue pit opening, and your open pit barbecue is ready for action.