Key Points for the Repair Slabs
1. Determine if the apron and walls of the
latrine are strong enough to hold a slab. If
the apron and walls are strong enough
chisel into the apron for the placement of
the rectangular steel tubes. This may
require removing the back portion of the
apron to ensure the rectangular steel
tubes have enough bearing.
2. If the walls are not strong enough they
may need to be rebuilt. The masons are
not to touch the waste in the rebuilding
process. Use lime and stepping stones if
necessary. Rebuild the portion of the wall
that is unstable.
3. Cut the rectangular tubing to allow for 20
-25 cm (minimum) of bearing on both
side walls.
4. Place the rectangular steel tubing (40mm
x 60mm) at even intervals. The first piece
of rectangular tubing should be placed
next to the existing slab.
5. Level and secure the rectangular steel
tubing and create a base for the
galvanized roof sheets.
6. Place roofing sheets on the rectangular
steel tubing.
7. Create rebar mesh using 12mm (or 10
mm) rebar. Rebar lengths should be
approximately 10 cm less than concrete
slab dimensions. Long rebar lengths
should be spaced at 12mm intervals.
Short, cross pieces should be placed at 20
mm intervals.
8. Place the rebar mesh on the roofing
sheets. Add 2 cm sections of 2.5” pipe
“spacers” as required in the dip of the
roofing sheet to hold up the rebar. Limit
the number of spacers.
9. If necessary, build wooden form for
outside edge of concrete slab. There
should be a 3-7 cm gap between the wood
form for the slab and the rebar ends.
Between the existing slab and the rebar
there should be a 2-3 cm gap.
10. Mix concrete for slab. Do not use
excessive water! Mix proportion is 1:2:3
(Cement: Sand: Gravel). Use only small
gravel for layer under rebar. Use 2 parts
large gravel and 1 part small gravel for
the remainder.
11. Keep concrete moist and covered for 5
days.