Preparing the Site
In most cases, the Hello Hub will be build on top of a small concrete slab. The concrete slab provides a stable base for the Hello Hub structure to attach to, as well as a foundation for the benches to be built upon.
The slab is a simple 4" reinforced concrete slab. The process, in most cases, of building the slab is:
- Stake out the slab area
- Clear grass and excavate 4 inches of topsoil
- Place and compact 2 inches of 1" gravel or equivalent
- Build forms
- Mix concrete
- Pour and level
- Float and smooth
Staking out the slab area
Stake out an area that is 6' wide by 9' long. Check the square by checking the diagonal measurement both ways (they should be the same.)
Clear and Excavate
Using shovels and hoes, remove the grass and top 4 inches of soil in the marked slab area, and extend out 4 inches past the staked area.
Compacted Gravel Base
Place gravel and use a tamper to compact, up to 2 inches in the whole excavated area.
Using 4" wide scrap lumber with at least one straight edge, build the forms 6' wide by 9' long. Place on the excavated area, square using the same method above and stake the outside of the forms to reinforce.
Using the ratio 1-2-3, mix small batches of gravel (aggregate), sand and portland cement. Depending on local practices, this can be mixed on the ground in larger quantities or in a wheelbarrow in smaller quantities. Pour each mixed batch into the formed area, use a shovel or trowel to agetate the poured mix to make sure the concrete fills all the voids. Level by moving a long straight board back and forth accross the slab as you move from one end to the other.
Float and smooth
One the slab has been poured, a thin layer of water will form on top of the mix. Wait for this water to be absorbed before you do a final smooth with a float or trowel.
Cover the slab with plastic sheeting or a tarp and wait at least 24 hours before continuing the work.