How To Lay A Concrete Path
For a long-lasting path with a smooth finish, concrete is a great option. It is made by mixing one part cement, two parts sand and four parts gravel, then gradually adding water.
To work out how much concrete you’ll need, multiply the area of the path by the desired thickness, round up to the nearest cubic metre and add an extra 0.2m3 to account for errors.
Mix the concrete in a wheelbarrow, or hire a concrete mixer for bigger jobs, for about $65 a day. Combine the sand and gravel, collectively called aggregate, with the cement and add an oxide powder for colour, if desired.
Carefully add water until the mixture is creamy but not runny.
Dry concrete mix can be purchased in bags with cement and aggregate already combined in the correct proportions. Simply add water to the mix according to the instructions.
TIP Always wear protective gloves, long pants and gumboots, as concrete can burn exposed skin.
Order premixed concrete for larger jobs, choosing N20/10. The N stands for normal concrete, 20 is its strength in megapascals, and 10 is the aggregate size in millimetres.
Install steel mesh with the edges at least 50mm from the formwork and control joints, and with equally thick layers of concrete above and below.
Set out a curve by building one side of the formwork using plywood, then use a timber gauge board with spacers beneath to position the other side.
Avoid hot days as the concrete will set faster and be more prone to cracking. Temperatures below 30°C are best.
Install drainage at a suitable low point to direct runoff into the stormwater system.
Step 1. Build the formwork
To install curved formwork, use 12mm plywood with 50 x 50mm hardwood pegs spaced 500mm apart. Secure the formwork to the pegs using 40mm bullethead nails. Brace the pegs with a kicker, if the formwork extends more than 150mm above the ground.
Step 2. Pack the base
Use a plate compactor to pack the ground, lay 100mm of roadbase material, then pack again. Spread a 20mm layer of sand to eliminate friction between the concrete and base. TIP Large plate compactors can be hired for about $60 per day.
Step 3. Pour the concrete
Fill the formwork with concrete and spread it evenly using a rake or shovel. Lift the steel mesh off the ground to centre it in the concrete, then tap the sides with a hammer to eliminate trapped air pockets. Pack concrete along the edges with a float.
Step 4. Screed the surface
Use a timber screed to level the concrete with a sawing action. Smooth the surface with a hand float in both directions to bring the cement cream to the top for a smooth surface. TIP Use a steel float for a smooth finish or timber for a slip-free, rougher result.
Step 5. Cut control joints
Use a straightedge and a concrete groover to cut control joints in the surface of the concrete at intervals equal to the path’s width. Cracks that occur as the concrete dries will form along the joints. Drag a stiff-bristled broom over to hide any imperfections.
Step 6. Let it harden
Once the concrete is hard enough that your finger doesn’t leave an indent, cover with plastic sheeting and weight down. Keep it damp for three days, sprinkling water over areas that dry too fast. Let it harden for a further two days, then remove the formwork.
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