How to Work with Concrete
Tool and Material Checklist:
Concrete mix, Garden hose, Level, Float, Hatchet, Tiling
spade, Groover, Long 2x4's for screed, Line, Brush or
broom, Concrete hoe, Pail, 2x4's and other material for
forms, Edger, Rubber boots, Line level, Reinforcing mesh,
Determining How to Secure your Concrete
Concrete can be secured in many forms. Ready mix concrete,
which requires only the addition of water, is the simplest
to use. It is ideal for small jobs but becomes quite
expensive when big projects are undertaken. Transit-mix
concrete is delivered to you in revolving barrel trucks.
This is the simplest and easiest way to buy concrete for
large projects. However, you obviously have to pay for the
delivery of the concrete and the convenience of premixing.
Check local sources for prices on concrete of this type.
You-Haul concrete can be purchased in some areas. In this
case you buy the concrete and rent a You-Haul trailer
mixer for taking the concrete to the job behind your car.
Again, you have to pay for the premixing and the rental of
the trailer. Check locally for prices on concrete of this
No doubt the cheapest way to secure concrete for large
projects is buying the dry ingredients and mixing them
yourself. Of course, this requires a lot of work and the
rental or purchase of the necessary mixers and other
equipment. Figure the amount of concrete needed and make
local comparisons of prices to determine which approach to
purchasing concrete is best for you.
Making your Own Concrete
There are four basic elements in any concrete. These are
Portland cement, fine aggregate such as sand, coarse
aggregate such as crushed rock or gravel and water. The
aggregates (sand and gravel) usually makeup fro 2/3 to 3/4
of the volume of any finished concrete. All aggregates
used should be clean and free of organic matter. Water
used for making concrete should be clean, free of acids,
alkalis, oils and sulfates.
Although the ingredients in concrete are always the same,
the results depend largely on the proper mix of these four
elements. The intended use of the concrete you are pouring
will determine the amount of water and other ingredients
used in each mix.
For foundations or retaining walls, about 6-1/4 gallons of
water will be used for each sack of cement if the sand is
damp. However, if the sand is wet, 5-1/2 gallons of water
will easily do the job. Concrete mixed for pouring
sidewalks, stepping stones, slabs, etc. will require about
5-3/4 gallons of water per sack of cement if the sand is
damp; approximately 5 gallons of water if the sand is wet.
If you are pouring heavy footings for walls where
waterproofing is not a factor, you mix can consist of 1
part cement, 3 parts sand and 4 parts gravel. If you are
pouring sidewalks, steps, driveways, etc. use 1 part
Portland cement to 2 parts sand and 3 parts gravel.
You can measure the ingredients on small jobs by using an
ordinary galvanized or plastic pail. A wooden box
measuring 12 in. x 12 in. x 12 in. can be made to give you
an accurate measurement for 1 cubic foot of sand or
A 3/8 in. half round can be nailed on one side of the box
at carefully measured points. This will enable you to
measure 1/4, 1/2 or 3/4 of a cubic foot. Always follow the
mixing instructions on the bag when mixing any concrete.
Estimated Materials Needed
The following is a table giving the number of cubic yards
of concrete required to pour slabs of different size and
thickness. To use this table, multiply the length by the
width of the area you plan to concrete. This will give you
the square footage in the area.
Thickness in Inches
Cubic yards of concrete
in slabs of various thickness
For example, suppose you are
planning to pour a patio 10 in. x 14 in.. This is a total
of 140 square feet. Suppose you plan to pour the slab 5
in. thick. by using the table you find that 100 square
feet of a slab this thick would require 1.5 cubic yards
and an additional 50 square feet would require .77 cubic
yards. Adding these two together you would find you will
need 2.27 cubic yards of concrete to do the job.
Building the Forms for Pouring
Almost any concrete job will require some type of form. In
some cases, forms are built above ground. In other cases,
digging is required. Dig down to the desired level and
build the forms to the necessary shape and size for the
concrete job you are starting.
Use a few temporary posts to establish the proper grade or
slope of the concrete to be poured. Nail the stakes
lightly to the forms used or the forms can be temporarily
clamped to the stakes with a C-clamp. Use a level to get
the proper grade or slope of the concrete form. After the
proper grade has been set, permanent stakes can be driven
and the form nailed to them.
After the forms are set, spray the entire area within the
form lightly with a garden hose and pour in the concrete.
After the form is filled, tamp the freshly poured concrete
to compact it. This can be done either with a tamper or by
putting on rubber boots and walking around the poured
concrete area to make sure it is compacted around the
Small concrete areas can be compacted with a 2x4. For
larger areas, roller tampers can be rented. After the
concrete in the form has been thoroughly tamped, use a
straight edged 2x4 (used as a screed) for leveling the
concrete. Work the 2x3 back and forth, saw fashion, to
level the concrete at all points. A magnesium concrete
rake with an extension handle can be purchased to reach
concrete in hard to get at places.
When the concrete has set up sufficiently to support a 2x8
plank, use the plank as a straight edge to guide a
groover to cut contraction joints. Contraction joints are
necessary to allow the hardened concrete to expand and
contract in extreme temperatures. On sidewalks or other
narrow concrete areas, such contraction joints should be
cut every 4 ft.. to 6 ft.
On patios or other large concrete areas, expansion joints
should be cut in each direction about every 4 ft. to 6
ft.. This can be done by using two lengths of beveled
clapboard.A nail should be driven into the top of one
board and both boards painted with motor oil They should
then be embedded in the concrete.
After the concrete begins to set, the board with the nail
in the top can be removed leaving the second board hidden.
The removal of the first board provides an adequate
contraction joint for a large expanse of concrete.
In some cases, concrete needs reinforcing with steel mesh.
Regular fencing material with 2x4 or 2x6 mesh can be used.
If the pressure on the concrete is to come from the top of
the slab, the reinforcing should be laid deep near the
bottom of the slab. If the strong point in the slab is at
the center and the pressure will come one either end, the
reinforcing should be laid as near the top of the slab as
Different Ways to Finish
Concrete can be given a smooth finish with a trowel and a
float. The float is used to smooth out the concrete on the
first rubbing. A trowel is used to five the concrete a
finishing touch. A light, swirled pattern can be created
by holding a steel trowel flat against the surface of the
slab and moving it around in a swirling motion, on the
last troweling of the concrete.
For a heavier swirling imprint, use a wood float instead
of a trowel and do the swirling while the concrete is till
fairly wet. A soft pattern of parallel lines can be
created by dragging a soft brush straight across a
moderately wet surface. To achieve heavy lines, drag the
soft brush across while the surface is still wet.
To achieve light texture lines of the same pattern, trowel
the concrete and allow it to dry slightly before dragging
the brush across. A very attractive and practical pattern
can be placed in concrete by using an ordinary broom as a
brush. Such brushing provides a rough finish that makes
the surface of the concrete much safer when wet.
All brush strokes can be made in the same direction or
each block between contraction joints can be brushed in
opposite directions for a very desirable effect. An
ordinary garage floor brush can be used to create
extremely attractive wavy patterns, in newly laid
concrete. The wavy patterns add to the appearance and make
the surface sager when wet.
A flagstone pattern can be created by tolling the concrete
after it has been leveled off with a float. A tool for
creating the flagstone pattern can be made by cutting an
18 in. length of 1/2 in. or 3/4 in. copper pipe and
bending it slightly.
The surface of the concrete should be troweled lightly and
brushed after the flagstone pattern has been
placed in the wet concrete. Fossil like effects can be
created along the edge of newly laid concrete by first
troweling the surface and then pressing leaves into the
freshly troweled surface along the edge.
Completely embed the leaves but do not cover them. Remove
the leaves when the concrete is stiff. Brush away bits of
concrete as the leaves are removed. Attractive ring
patterns can be created by pressing tin cans or glasses of
different sizes into the freshly laid surface.
The pattern can be created at random or specific designs
can be followed. Keep rim of can or glass wet as designs
are pressed into the freshly poured concrete.
Letting the Concrete Cure
All concrete must be given time to cure. During this
curing period, the concrete surface should be kept wet
down by repeated hosing with a fine mist. Such a hosing
down process should be done at least twice during any 24
hour period for about three days. Concrete poured in a
basement, garage or other under-cover area can be left
exposed. However, a guard rail should be placed around it
to keep any child or animal from walking on the surface
until it is dry.
Concrete laid in the open air or direct sun should be
covered with burlap, roofing felt or building paper during
the curing period. This protective covering should be
removed before the concrete is wet down. Never attempt a
big concrete job on an extremely hot day. Concrete will
set up extremely fast in direct sunshine. It is always
better to wait until mid-afternoon even if this means
working late in the evening.