Exposed Aggregate Oxenford

Exposed Surrounds Oxenford

Project Description

Location: Oxenford
Project Size: 122sqm

Our clients here got onto us through Facebook which is nice for a change. We priced up this job a few months ago, got given the go ahead but had to wait a while for a few things to be sorted on our clients end with landscaping and a few other things.

With our dates locked in for a few months, we got around to starting perfectly on time (for a change), and didn’t take long before making a good dent in the work load ahead.

We began with our machine excavation and sub-grade of the areas, removing approximately 4m.cub of fill from the patio section, re-using that fill near the water tank to raise levels, then of course removing the grass and sub-grading the rest of the pathways adjoining.

Returning a few days later, we formed everything up, placed in all the steel and booked everything needed for a Saturday pour. On the Saturday we started off by chairing up all the steel, along with the typical other fittings such as Abel Flex and re-entry bars, then began letting the pump do it’s thing on the 50Lm push ahead of it.

This of course is a long push for exposed aggregate, so the going at first was relatively slow, but as we crept back and lines where taken off, the pump started getting in front and away we went with the screeding and finishing behind ourselves.

A few trowels and some raw sugar later (possibly a beer or two as well), the concrete was all ready for a wash off to reveal our nice, new Salt and Pepper Aggregate beneath.

Such an easy project this one, not only from having the right men on the job, but also a larger, flat(ish) block was nice to work on, along with fantastic clients and we were left wondering why every project can’t be the same.

We’re now straight on from this one on a dirty refurbishment project just around the corner where we’ve been pushing shit up hill for a week now, but that as well is all ready to finish off. It’s nice to have a run of work getting results, especially on good quality projects that myself and the boys can be proud of.

Exposed Aggregate Oxenford
Exposed Aggregate Oxenford
Exposed Aggregate Oxenford
Exposed Aggregate Oxenford
Exposed Aggregate Oxenford
Exposed Aggregate Oxenford
Exposed Aggregate Oxenford
Exposed Aggregate Oxenford
Exposed Aggregate Concrete

No High Rise Concreters!

I remember seeing an ad in the paper years ago for a residential exposed aggregate contractor in need of a good finisher. At the end of the advert stated the words very specifically, “no high rise concreters”.

I giggled a little reading it at the time, knowing very well exactly what they meant. Over time as well, I’ve seen many more occasions where these words have rang true for unsuspecting clients choosing the wrong contractor for their exposed aggregate. The contractor has come in and has plenty of experience on house slabs for instance, but very little time on exposed aggregate and gets a little lost when installing the work.

On one such occasion quite recently, I was called out to a driveway that had been completed by another concreter. The home owner was stuck for options as the concrete that had been placed look fairly terrible. The installer was contracting primarily to builders doing house slabs and clearly hadn’t completed much exposed aggregate work. The contractor had made sure the levels were all ok, I could also see that he/she was not bad on a screed for levels as it all appeared relatively flat, but it’s the finer details of placing exposed aggregate properly that really make the job look great.

Now this of course wasn’t much of a problem, even though the aggregate was poorly finished there are still options we have for resurfacing. But, if you’re having your driveway done in exposed aggregate, choosing the wrong contractor can often lead to a fairly ordinary finish of which you then need to spend more money on to get it right.

Here are a few special steps we follow to ensure a good exposed aggregate concrete installation that isn’t¬†typical for normal plain concrete installation.

1: Not filling boot holes back in with aggregates
When the installers are placing your concrete, as you can imagine it’s all hands on deck in the concrete, shoveling it, raking it, mag troweling and of course screeding it off. Now this especially rings true for the person on the screed. As we move around and back through the concrete we of course leave boot holes in the surface. I’ve personally watched many concreters simply screed back over these boot holes and hope for the best. Now most of the time, they’ll be fine with new aggregate filling the holes and making sure it’s spaced out properly. But a good installer will always take the bit of extra time to fill each boot holes in properly with new and good amounts of the exposed aggregate stone. It only takes a few seconds extra and is an assurance worth sweating for.

2: Leaving screed lines in the surface
Screed lines are a tricky one as you can’t actually see them really until you wash off the surface matrix revealing the stones, along with the lines. Basically screed lines are long straight lines caused by, you guessed it, the screeding process. You’ll often see a good exposed aggregate screeder using more of a pulling motion through the concrete, as opposed to the usual cutting motion on normal plain concrete. The cutting technique will often cause the sharp edge of the screed to dig in, in turn leaving a line where there is no stone because it has been pushing too far down into the concrete in that area. A good screeder will also use lots of pressure with back blading making sure theyre almost “floating” the concrete with the screed to finish off each run.

3: Over working the troweling
Once your boot holes have been filled in, the screeder has been extra careful with the leveling and all the floating has been done, it’s time to finish the surface typically as we would for normal plain concrete. However once the initial steps have been completed, there is no need to over work the surface. A good finisher for exposed only really needs to work the surface 2-3 times making sure the stone is flattened properly within the concrete and taking out any bad cement lines that may be there. Keep in mind, this surface is only going to be washed off again, so making it perfect like a polish finish is not required, also keeping in mind the more you work the surface, the more chances there are of making a mistake and having the trowel dig in, also leaving bare patches after you wash off.

4: Retarding the surface
Once the concrete has been placed and troweled to a satisfactory level, a retarding agent is then used on the surface to slow down the setting to allow ample time to wash it off properly without too much difficulty. There are chemical products that you can use, but the tried and tested age old raw sugar is always a fan favourite. This section is all about timing. If your contractor puts the sugar on too early, it will penetrate too far into the surface, then when it is washed off, will over exposed the aggregate leaving the stones coming out then and there, and of course over time as the concrete gets older. If it’s applied too late, it will not penetrate far enough making it difficult to keep the expose even over the entire project. There are a few simple ways a good installer will tell when the timing is right, some just by looking at the surface, others by dragging a finger lightly and others by lightly pressing down. I won’t give away what we’re looking for as not all secrets need to be shared, rather learned through on the job training.

From there, if everything has been completed right, your contractor should have a nice easy time on the hose and brooms removing the surface of your concrete, hopefully exposing a lovely, even blend of chosen stones with no boot holes and screen lines.

These steps I’ve discussed here are the simple ways exposed aggregate is placed different to plain or coloured concrete. Although they might not seem like much, if your contractor hasn’t had their boots in exposed aggregate enough, they will be found a little lacking in these steps and often bring up a finish that leaves a lot to be desired.

If you’ve got a new exposed aggregate project in mind, give us a call today. Not only will we be more than happy to pop out and run through your project, but we’ll also provide multiple job sites of our completed work for you to see the quality of our finish first hand.

We look forward to hearing from you.