:::TECHNICAL HELP

12 Easy steps to DIY concreting!
*See Step 1c to calculate the Volume for your job.

For more information, click below:

STEP 1

Concrete is measured and purchased in cubic meters.
Follow these easy steps to work out the volume of
concrete required.

A Work out the area
Area in square meters = Length (m) x Width (m}. Using a
typical garage floor as an example: Area = 10m x 4m = 40m2

B Decide what thickness
This may depend on your excavation, but in any case minimum thickness should be:
Paths 75mm
Driveways 100mm
Garage Floors 125mm
For our example, thickness = 75mm

C Work out the volume
Read the volume required from this calculator.

For our example:
Area = 40m2
Thickness = 75mm = 0.075m
Volume = 3m3
Alternatively,
Volume in cubic meters = Area in m2 x thickness
For our example:
Volume required = 40 X 0.075 = 3m3

It is wise to add a little extra for wastage and
variations in depth. For
the example in
step A, B and C we would
order
3.2 m3.

CHECK
Do you need permission for your project from the local council?

STEP 2

STEP 3

If you don’t own the necessary equipment you can hire all the tools you need
from most plant hire organizations. It’s best to get some neighbours and
friends to help you. Not that it’s really hard work, but your .
project will proceed much smoother and faster if you have
the help of a few neighbours or friends. (We suggest a
minimum of six - two on barrows, two spreaders and
two screeders) This depends on the size of the job.

You’ll need:
•Timber for formwork and pegs.
• Builder’s barrows (with inflated rubber tyres)
  The number of barrows necessary is dependent on the quantity of concrete
 and the distance it is to be transported.
•One or two square-mouthed shovels.
• A screed board – (a smooth, heavy board about 900mm
wider than the formwork)
• A wooden float (a flat piece of wood with a handle) for
finishing the surface.
• A steel trowel, if needed.
• An edging tool for making cross-joints and edging
• A 15mm grooving tool for long sections of concreting
• A garden rake.
• A mallet or heavy hammer.
• Enough waterproof building paper, hessian, plastic
sheeting or sand to cover the areas to be concreted
• A spirit level.

STEP 4

Prepare the ground!
Hammer some pegs into the ground to mark out
the area you want to concrete. Use pegs long enough to be rigid when driven
into the ground. Then stretch a strong string, or twine,
between the pegs.
Next, decide how high you want the concrete in relation
to the ground around it. Remove turf or loose soil from
the marked-out area. If the ground is soft spread sand
over it to make a better base. You may have
to fill holes in the ground with stones, broken bricks or
any clean fill. Final leveling is best done with sand after
you’ve put in your formwork. When the whole area is flat,
compact it by rolling, walking or driving over it, and hosing
it lightly. The more it settles the better the foundation for
the concrete.

STEP 5

Cut and place the form work
“Formwork” is what we call the walls that support
concrete until it has set. It forms a mould. The best
material for formwork is timber at least 25mm thick, or metal c-section
with its width equal to the concrete thickness.

Structural plywood or hardboard can be used for paths.
For curved paths, hardboard or 7mm plywood is suitable
but requires more supporting pegs. The forms must be
strong, smooth on the top edge, and well supported with
stout pegs.

The formwork must be deep enough to hold the thickness
of concrete to be placed and to prevent slurry escaping
beneath.

Place the forms along the borders marked out with string,
and secure them in position with stout pegs driven into
the ground inside and outside the forms. The outside
pegs should be placed at more frequent intervals and
the forms nailed to them.

Hammer the pegs down to below the height of
the forms.

Coat the formwork lightly with some thin oil or
form oil from the hardware store to enable it to be
removed easily.

The ground and the forms should be thoroughly soaked
the night before the pour and dampened again before
the truck arrives. The ground should be
damp but not muddy.

STEP 6

Place reinforcement (if required)
Areas like garage floors require reinforcing. Local
building regulations, on occasions, demand the use of
reinforcement.

STEP 7

Check your measurements
Now that the formwork has been constructed, and all
other preparations are complete, have one final check
on the quantity of concrete required. You can use the calculator
to be sure of the quantity you will require.

Most important, check the THICKNESS. Remember that
if your slab has an average thickness of 10% more than
your original measurements you will need at least 10%
more concrete to complete your job.

STEP 8

Placing the concrete
If your job is level and the way is clear for the truck to drive
in and reach over your job with its chute, our truck can
discharge concrete directly into your formwork.

If your site can’t be reached by the truck, direct the driver
to discharge into the barrow, remember it’s easier to
move concrete on wheels in the first place than to move
it by shovel later. For a sloping site, tip your barrows
progressively up the slope - don’t start at the top.

A bit of teamwork will help you get the concrete placed
fairly quickly if you’re harrowing it to the forms. One or
two men can wheel and tip the concrete while another
can spread it.

If your job needs less than 2.4 m3 of concrete the truck
driver allows twenty minutes to unload it. Additional charge
applies if more than 20 to 30 minutes.

As the form is filled with concrete (fill to a little higher
than the formwork to allow for settling), remove the
inside pegs. Use shovels to spread the concrete fairly
evenly over the ground. Work a shovel up and down in
the concrete that’s just inside the formwork to give the
job a better finish at the edges. Compact the concrete
by working a shovel through it to remove air bubbles,
and to ensure that the concrete has filled right up to the
corners and sides of your formwork. Simply thrust the
shovel directly down into the concrete at spaces of 80 to
100mm in rows along your job. This is most important.

Remember, Minicretes will deliver small quantities
That’s ready when you are.

STEP 9

Smoothing out the concrete!
As the form is filled, take the screed board - one man at
each end - and, with each end of the board resting on the
formwork, move it back and forth across the surface of
the concrete, edging along from one end of the form to
the other. This will smooth the concrete and compact it
right up to the form.

It is quite normal for water to appear on the surface
of your concrete after this screeding process. Some of
this water will run off or evaporate, the rest of it will be
drawn back into the concrete when the “setting process”
commences.

STEP 10

Finishing the surface
If you want a smoother finish than the screeded surface,
use a wood float. “Floating” agitates the surface,
compacts the material, and brings enough mortar to
the surface to fill the voids. Use the flat with some light
pressure and tilted slightly upwards into the direction
you are pushing it. After floating, round off the edges
with an edging tool.

A rough texture can also be obtained with the wood float
by swirling the concrete, or by drawing a broom or a brush
over the surface.

If a very smooth finish is required, use a steel trowel after
the concrete has become quite stiff, taking care to avoid
bringing excess water and fine material to the surface. Start
trowelling as soon as the “shiny water sheen” disappears,
but while the concrete still looks damp. Do final edging
at this time. You can do final hard trowelling when the
concrete is nearly hard.

The time span between the screeding and finishing
process varies between summer and winter. On a hot
day, the time could be as little as an hour (in extreme
cases, less), but on a cold day as much as several hours.
Be patient - the water sheen is your guide. It is good
practice - especially in winter - to start your concreting
early in the morning.

Under no circumstances should you attempt to trowel
the concrete while water is lying on the surface.
This will make the surface weak, with dusting or
powdering likely to occur.

Where sections greater than three meters long are being
placed (such as a driveway or long path), evenly divided
grooves should be made across the concrete surface with
the grooving tool. The distance between grooves should
be no greater than three meters. The grooves aid in the
prevention of concrete cracking. Use the flat side of the
screed board as a support and guide when making the
grooves.

STEP 11

Cure the concrete
Concrete develops its strength by the reaction of water
with cement, so it should be prevented from drying out
too quickly, otherwise a weak, poor quality surface
may result.

As soon as the surface is hard enough to resist marking,
cover the concrete with plastic sheeting or waterproof
building paper and secure well, especially on the edges.
This will keep the moisture in.

STEP 12

Remove the form work
When the concrete has enough strength to support the
traffic it will take (usually after seven days of curing), strip
the forms away. Do not use metal tools to pry off forms
because they may cause damage. If you’ve used form
oil, the forms will be easier to remove and use for other
projects.

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