Making an Exposed Aggregate Concrete Path

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Introduction: Making an Exposed Aggregate Concrete Path

I love working with concrete because it's tough and versatile and relatively cost effective.

In this instructable I'll be jazzing up a new footpath by exposing the aggregate.

There are a few ways to do this, and many commercial operators use a high pressure spray to blast off the top surface of cement.

The method I will show you doesn't require any special tools other than what you would use when mixing and laying concrete...it doesn't use any surface disruptors or acid, nor does it use a water blaster.

So if you can lay concrete, you can do this.

If you're concerned about committing to a large project, you may want to do a test run of the method by making some pavers or tiles on a small scale. Then when you're comfortable with the process you can create your large project.

Supplies:

Aggregate (pebbles) around 12-22 mm in diameter.

Trowel

Screed (board or straight edged box aluminium)

Bucket (for pebbles)

Garden hose and water supply

Brush or broom - medium firm bristles

Helpers (the more the better, especially about an hour in...you'll be pleased you had them!)

Edging tool (optional but nice)

Step 1: Box; Mix; Pour; Lay; Screed; Trowel

We mixed our own concrete onsite but this method will work with premix concrete that has a normal cure time. A rapid set concrete should not be used.

I won't go through the specifics of the above steps, but so you know...

- box the area

- mix the concrete

- pour the concrete

- lay and screed the concrete

- trowel the concrete smooth

Pro tip

Curve your path...it's much nicer to the eye and can be easier to create than a straight edge.

Step 2: Seed the Pebbles

The pebbles are scattered or sprinkled onto the surface of the concrete. Do this by the handful, and have a good supply of pebbles on hand.

The concrete needs to be firm enough so the pebbles do not sink out of sight, but not so firm as to be difficult to push the pebbles into the concrete. You'll have to make a judgement call on this but I was able to seed the pebbles soon after trowelling the concrete smooth.

Pro tip: Wash the pebbles to remove any twigs etc.

Step 3: Push the Pebbles Into the Concrete

When you have a good covering of pebbles, begin to push them into the concrete with a trowel. You can see in the video that the concrete is still quite pliable. Take care not to push dents into your concrete...keep your tapping pressure consistent and trowel it smooth keeping the surface flat.

Finish the process by trowelling the concrete to a smooth finish. You'll know this is done when you see only a faint outline of the pebbles as shown in the last photo. A thin cement slurry will have covered all of the pebbles.

Step 4: Continue Seeding and Trowelling

It pays to have help! There is a point in this process where concrete has been laid and seeded, while at the other end, concrete is still being made and laid. Then it becomes apparent that the concrete is beginning to firm up and it needs to be seeded...while elsewhere the seeded stones need to be pushed down. It can be hectic!

So, have a few pairs of hands available...I had my family all working on this project and I was thankful for their effort!

Continue to trowel-in the seeded pebbles while someone else is seeding the new concrete further along the path. It will be a moving front of lay-screed-trowel-seed-trowel, lay-screed-trowel-seed-trowel, interspersed with cries of help as you realize the concrete is going off somewhere! See below for definition of 'going off'.

The last photo shows the concurrent stages of seeding concrete...empty boxing; fresh concrete; screed concrete; trowelled concrete; seeded concrete; trowelled seeded concrete. Whew!

Pro tip

Use an edging tool to create a nice edge to your path, using the tool while the concrete is still easy to work.

Glossary

'going off' in this instance is Kiwi slang for the concrete setting or firming up.

In different circumstances it can mean:

"Streuth mate, you better get that 3 week old lasagna out of the fridge 'cos it's going off big time."

"I'd stay away from the neighbor for an hour or two. Someone egged his house and he's royally going off."

Step 5: Last of the Seeding

We made it! Nice work everyone.

Finishing off the path, the final pebbles are being pushed into the concrete and trowelled off.

Now you have time to go and eat the cold toasted sandwich that was made for you an hour ago.

The next step takes place when the concrete has firmed up.

Step 6: Wait for the Concrete to Firm Up

It was about 8 hours on a warm day until I was ready to expose the aggregate.

Setting time will depend on many factors so you'll need to use your judgement, but as a guide the concrete won't stick to your finger when touched, and you can scratch your fingernail into the surface of the cement. You can also gently walk on the concrete...but don't twist your foot as you may loosen or tear out your precious pebbles!

Step 7: Time to Expose Your Aggregate

This is the best part!

Using a brush and light spray of water, begin to gently brush and wash away the top layer of cement to expose your pebbles. Keep your brushing light and water to a minimum...but you'll get a feel for it and can increase both as you continue.

Take your time and don't brush out too much cement as you risk the pebble coming out. Constant watering will reveal your progress.

Step 8: Your Path Is Complete

If it's all gone to plan, you should have a beautiful exposed aggregate path. You've never appreciated a footpath like the one you've just finished!

One final optional step is to apply a concrete finish coating to the path. You'll need to leave your path for 28 days or more to cure, but the coating will add luster to your path as well as seeping into the concrete and 'locking in' the pebbles.

I used a brush and roller to apply the coating to the path. It looks magnificent!

I hope you have success with your exposed aggregate projects.

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    36 Discussions

    0
    terrefirma
    terrefirma

    Question 1 year ago

    did you remove the wood forms?

    0
    Minnear Knives
    Minnear Knives

    Answer 11 months ago

    Yes, I removed the wood a week after it was laid.

    4
    sharpstick
    sharpstick

    1 year ago

    I think a section of concrete that long should have expansion joints.

    0
    Minnear Knives
    Minnear Knives

    Reply 1 year ago

    It's about 8 m long and could have expansion joints cut in. Thanks for your comment.

    0
    berryjp
    berryjp

    Reply 11 months ago

    You want your hard work to last. An expansion joint is a flexible asphalt strip used when a slab is butted against other materials/structures (concrete expands/contracts greatly from heat and cold). Control joints are saw cut or finished tooled depressions that defines where the concretes cracks, as all slabs will crack. Wire mesh/rebar will keeps it together after it cracks. Finished edges prevent edge chipping. Use compacted properly sized aggregate base material of sufficient depth for stability and drainage. Slow, damp covered curing improves strength. Bake a good cake before you add the frosting.

    0
    cfuse
    cfuse

    Reply 1 year ago

    What about rebar? Every large chunk of concrete I've seen done has rebar in it.

    0
    Minnear Knives
    Minnear Knives

    Reply 1 year ago

    The concrete is quite thick and it's handling only foot traffic.

    1
    FlorinJ
    FlorinJ

    Reply 1 year ago

    It lays flat on the ground and doesn't have anything on top that should make it act like a 3D structure. It will behave like a foil - very tough foil, but still a foil, that will be eventually torn apart by the ground moving underneath with seasonal temperature changes.

    0
    Minnear Knives
    Minnear Knives

    Reply 1 year ago

    There are many concrete paths around here that are coping well in this climate. Thanks for your thoughts.

    0
    DavidS1383
    DavidS1383

    Reply 1 year ago

    Pros who did my concrete front driveway and walk (area subject to winter freezing) used wire mesh, not rebar which would be overkill. They placed expansion joints in driveway every 10’.... which was expected. But to avoid expansion joints that would ruin the look of the walkway, I slow cured it... kept lightly watered for first month, and now in process of burying gravel with weedblock fabric along perimeter of walkway for water management / freeze control... to avoid stress from irregular lifting in a hard freeze.

    Anyway, great-looking aggregate walkway... so much nicer than standard concrete!

    0
    SusanP170
    SusanP170

    1 year ago

    It looks great! ..... A lot of helpful hints along the way were really appreciated.... I will definitely be trying this once I research what a Canadian winter might do to it, or what additional steps may be required.... Thank you!

    0
    beamer.smith
    beamer.smith

    Reply 1 year ago

    as long as the equator of each pebble is submerged in the cement, it should be fine (freeze/thaw pop-out wise) Added bonus, you can still walk on it after freezing rain as the pebbles will break up the ice when you walk on it

    0
    SusanP170
    SusanP170

    Reply 1 year ago

    Thank you xx

    0
    Minnear Knives
    Minnear Knives

    Reply 1 year ago

    Looking forward to a progress report. All the best in Canada from New Zealand.

    0
    panzer1
    panzer1

    1 year ago

    good job !

    0
    gcai_fwb
    gcai_fwb

    1 year ago

    Nice job! and it looks great - just the idea I need for finishing a planned 'stepping' stone walkway using one of these https://www.quikrete.com/athome/walkmaker.asp - I'm going to use the "country stone" pattern.
    ps. nice touch with the Kiwi slang - I'll have to dig out and reread my old Footrot Flats graphic 'novels' again

    0
    dragon flyer
    dragon flyer

    1 year ago

    That looks great! Does the finish coat make it slippery when it's wet?
    I've been wanting for years to make some hypertufa planters; I wonder if I could use this technique on them...

    1
    Minnear Knives
    Minnear Knives

    Reply 1 year ago

    It's not slippery due to the texture of the pebbles coming through. If it was smooth concrete, yes it would be slippery when wet.

    1
    Kink Jarfold
    Kink Jarfold

    1 year ago on Step 8

    Fantastically beautiful walk. Very appealing. Very artsy. Great job.

    1
    gerryveldkamp
    gerryveldkamp

    1 year ago

    one tip from one who has don it many times before, mix a pound of sugar with a bucket of lukewarm water put it in a garden weed sprayer and gently wet the surface just before it goes off then let it set. Ones set you can gently rinse of the concrete as the sugar has killed the surface layer of cement