concrete walkway project

[jmt1271]

I am trying to build an exposed aggregate concrete walkway joined to an existing driveway. The driveway slopes on one angle, and the walkway will have to share that slope as well as slope(on another plane) away from the house. I am trying to figure out the best way to make this look great. I would love to find a site with directions, and especially pictures. Any suggestions on the whole project as well as websites?

 

[machmeter62]

I am trying to build an exposed aggregate concrete walkway joined to an existing driveway. The driveway slopes on one angle, and the walkway will have to share that slope as well as slope(on another plane) away from the house. I am trying to figure out the best way to make this look great. I would love to find a site with directions, and especially pictures. Any suggestions on the whole project as well as websites?

To gain experience, I would buy or get a thin sheet of masonite at a building supply. It's inexpensive. Cut a 3.5" piece off the 4' or 8' length, unless you already have some. Bend it in a complete circle off the 4' end or 8' length, and fasten the ends together with nails or screws with adequate overlap. Get small bags of ready mix to test your skills! Pour the mixed ready mix into your circle form, on a hard surface, let it set up for a little while based on temperature. You also don't want "too loose" of concrete. Seed the aggregate, grade it level to your form. Don't trowel below the surface if you want to walk barefoot on it? Again, let it set up longer this time because you will be exposing the aggregate with a garden house! Go with very lightly spraying at surface level, barely exposing the aggregate! As it starts to dry harder, and you want more exposure, spray lightly again. It may take you several tries, but the knowledge builds fast. If you are doing it by yourself on the sidewalk, I would just try one section per expansion joint, until the confidence builds? Also those round practice slabs won't go to waste; they can be used in gardens, etc. You can practice with different amounts of seeding for your satisfaction. Hope this helps?

 

[machmeter62]

JMT1271: You can also use the remaining masonite for special turns for landscaping purposes, etc. on your new sidewalk? Use adequate stakes so it doesn't deform however!!

 

[jmt1271]

Not having a lot of luck looking for step by step directions online. From what I gather, I basically need to just keep working the forms until they are right and then go to town, right? One end is lower than the other, should I start the pour on the low end and go to the high end?

 

[machmeter62]

Not having a lot of luck looking for step by step directions online. From what I gather, I basically need to just keep working the forms until they are right and then go to town, right? One end is lower than the other, should I start the pour on the low end and go to the high end?

You may want to invest in a good masonary book from Home Depot or Lowes; the books include a lot of expert advice.

I would set the mixer up at a convenient location, and decide from there; the start and finish point to make it easy on yourself, the slope shouldn't be a factor. Are you mixing the concrete, or is this a redi-mix truck? Transporting concrete is a back breaking job with a wheelbarrow! Also I would recommend some 3/8" rebar for added strength!

How long and wide will the sidewalk be? Is the pour going to be done completely in one day? Slope on the side for rain runoff can be 1/4" per foot to prevent standing water.

 

[crbr]

I am trying to build an exposed aggregate concrete walkway joined to an existing driveway. The driveway slopes on one angle, and the walkway will have to share that slope as well as slope(on another plane) away from the house. I am trying to figure out the best way to make this look great. I would love to find a site with directions, and especially pictures. Any suggestions on the whole project as well as websites?

$0.02

There's a little more to this than meets the eye.

I worked for a life-long concrete / brick mason for a few summers during college. I learned a few tips from him that have never failed me with exposed aggregate finishes.

Tip of most importance (in my opinion) is predicting (planning) the finish.

That said, once the forms are erected and if you plan on having any horizontal surfaces to be exposed, spray the face of the form with a curing retardant (not a curing sealer). Use the retardant on the surface and the forms. Spray the forms as close to time before the concrete hits them so that it doesn't dry on the form.

Also upon finishing the placement, place your expansion joints while wet. Once you have the surface finished, spray the retardant on the surface. Spray liberally.

This allows the subsurface to hydrate to a point of a more solid mass, leaving the surface in a retarded condition, allowing for the water to remove the surface concrete, exposing the aggregate. Spray lightly until you get a feel for the exposure.

Predicting ahead is the key. Know your humidity and temps and anticipate a slow or faster hydration process. Once it goes, you should be ready to spray the surface.

As the other poster stated, practice would be beneficial but every day will be different in conditions for hydration.

Know in advance that you will want the subsurface to set a bit more than what the surface will appear to be set (with the retardant chemical). Without the retardant, you'll get a portion of the aggregate exposed properly and the rest of the placement will set up.

And again, spray the horizontal form surfaces as well, for the same useful methodology and concluding results. Took me the better part of three summers of work to get this down to a practice.

It's not difficult, by just knowing what you have pre-planned with use of a retardant. It won't hurt the concrete and will assist in slowing the evaporation of moisture, which is a good thing.


Your mileage may vary. Others here will have different opinions but this has worked well for me over the years.

 

[jmt1271]

You may want to invest in a good masonary book from Home Depot or Lowes; the books include a lot of expert advice.

I would set the mixer up at a convenient location, and decide from there; the start and finish point to make it easy on yourself, the slope shouldn't be a factor. Are you mixing the concrete, or is this a redi-mix truck? Transporting concrete is a back breaking job with a wheelbarrow! Also I would recommend some 3/8" rebar for added strength!

How long and wide will the sidewalk be? Is the pour going to be done completely in one day? Slope on the side for rain runoff can be 1/4" per foot to prevent standing water.

I will be having a truck deliver around 3 yds, plus a little since you never get it all out of the truck. The dimensions are 50 ft long by 4 ft wide. There will be radiused turns on both ends with straight sides. I wasnt intending on reinforcing the crete as it is just for foot traffic. My current problem is trying to figure out just how level the bottom surface(under the crete) needs to be. I wanted to maintain 4" thickness throughout, but the lay of the land makes me want to consider allowing it to vary between 3" and 4" to minimize ground prep. Is this okay?

 

[crbr]

I will be having a truck deliver around 3 yds, plus a little since you never get it all out of the truck. The dimensions are 50 ft long by 4 ft wide. There will be radiused turns on both ends with straight sides. I wasnt intending on reinforcing the crete as it is just for foot traffic. My current problem is trying to figure out just how level the bottom surface(under the crete) needs to be. I wanted to maintain 4" thickness throughout, but the lay of the land makes me want to consider allowing it to vary between 3" and 4" to minimize ground prep. Is this okay?

Thank you for the input.

 

[Bigboyskioti]

Reinfore it! Foot traffic won't break it the shifting of the ground will! Rebar won't stop it from breaking it'll keep it together. My opinion is 2 bars the entire length with some from side to side, about every 3' apart. make the rebar look like train tracks with crossties. Either way it's a must.

 

[machmeter62]

I will be having a truck deliver around 3 yds, plus a little since you never get it all out of the truck. The dimensions are 50 ft long by 4 ft wide. There will be radiused turns on both ends with straight sides. I wasnt intending on reinforcing the crete as it is just for foot traffic. My current problem is trying to figure out just how level the bottom surface(under the crete) needs to be. I wanted to maintain 4" thickness throughout, but the lay of the land makes me want to consider allowing it to vary between 3" and 4" to minimize ground prep. Is this okay?

If you are having a redi-mix truck deliver 3 yds of concrete; they will not pour the concrete out of the truck at your convenience without holding financial costs! You will need experienced help for a nice job too; or the following week you will be renting a "jackhammer" and starting the project over!! The seeding, expansion joints, and finishing job requires extra time too, and doing the job solo will result in a disaster; this is my opinion only!

The thickness can vary, depending on the compaction of the soil. Rebar will help prevent cracking there, and how much future weight may go on the walkway?

 

[jmt1271]

The guys around here dont mind delivering 3-4 yards and pouring it as you need it. I will have help. Calm down a bit, you are scaring the children

 

[sandman2234]

I worked for a company that made the precast slabs of the Pensacola wastewater treatment plant just west of downtown, over 30 years ago. They were exposed aggragate and we used a retarding spray to keep the concrete from setting up. However, almost everything we poured the aggragate was exposed on the bottom, and we lifted it out of the forms and erected it on the building. Been too long for me to be of much help, plus the overall process is different.
I have always liked the exposed aggregate concrete, and now that Pensacola is trying to move that plant away from the bay, I bet they skip that part.
David from jax

 

[MarkV]

I am glad you will have some help with the pour. Three yards on a fifty foot run will be more work to keep up with than expected if you are new to concrete work. I would suggest at least four hardy workers. It will really help if the concrete truck can get close enough to shoot the concrete on the whole run instead of moving it by wheel barrow or tractor FEL. That takes time and with exposed aggregate timing is important.

When setting your forms remove all vegetation where the concrete will be poured and see that any fill material used is well compacted. Some variation in depth is alright and on sidewalks most 4” pours are closer to 31/2” so 1x4’s can be used as forms. The curved sections are normally formed with masonite as mentioned above. Use plenty of stakes to hold the forms in place against the weight of the concrete. Also make sure the stakes are set below the top of the form so they will be clear when screeding the concrete level. I would use rebar or the 6x6 concrete wire to prevent cracking. It is important to get the rebar or wire to the middle of the concrete when it is poured. Just before the pour the forms should be coated with a release agent so the forms do not stick to the concrete. There are many commercial release agents but diesel fuel and a pump sprayer works pretty well.

Start the pour at the farthest point from the truck. Pour and rough the mud to the tops of the forms. Screed the mud with a straight 2x4 across the top of the forms by doing a sawing motion with the screed board and filling any voids. Have someone ready to start floating the screeded area while the others work the next section of the pour. It would help to rent a Bull Float for this part (Wide trowel on a long handle) although it can be done by hand with on four foot wide walk with a hand float.

I my opinion this will be the critical part of the pour for you. The floating process is to bring the “cream” or Portland part of the mix to the surface while forcing the aggregate down below the surface. You need the cream on the top to hold your decorative aggregate and the rough aggregate has to be down so it will not be exposed on the finish surface. Timing is everything. The mud can’t be to soupy when you start floating or it will not force the aggregate down into the mix. It also can not be to stiff or it will not bring up the cream. The timing can vary greatly depending on the mix and weather conditions. I’d suggest you work like mad men to get the concrete in the forms so all hands will be available when the concrete is ready to work.

Once floated with the cream on top and the rough aggregate forced into the mix it is time to broadcast your decorative aggregate. Put it on nice and even, then refloat everything to force it into the mix. If everything has gone well to this point you will probably have time for a beer. You are now waiting for the concrete to set up enough to start using a steel trowel for your finishing. You want to trowel to a smooth finish where you can barely see if at all the decorative aggregate. Once the mix has set up pretty well you will use a garden hose with a fine spray fitting to MIST the concrete exposing your decorative aggregate. You only want to wash enough concrete off to expose about a ¼ of the decorative aggregate. If you expose much more than that it will come loose from the surface in year to come. After several days of curing you can wash the walk down with a light solution of Miratic acid to clean the remaining gray film on the aggregate.

I would also suggest you go see the concrete supplier and explain your project to them. They can offer suggestions and supply a mix that will be the most forgiving for what you are doing.

Good luck,
MarkV

PS. We will want photos of the finished project.

 

[jmt1271]

Mark-

Thanks a LOT for that well articulated response. I appreciate it. I have done basically exactly what you described. I have the forms(2X4) set and staked every 1 to 2 feet. The stakes are below the tops of the forms. I used masonite for the radiused corners. The depth varies between 3 and 6-7 inches. I am waiting on weather to pour. Again, thanks alot for taking the time to reply as well as you did.

 

[shaley]

These guys don't even use a screed board they just fill the section and hand trowel. The key to cracking is the hydration rate or curing rate. I cover mine in plastic for 7 days and keep it wet. Very slow cure.

 

[MarkV]

Mark-

Thanks a LOT for that well articulated response. I appreciate it. I have done basically exactly what you described. I have the forms(2X4) set and staked every 1 to 2 feet. The stakes are below the tops of the forms. I used masonite for the radiused corners. The depth varies between 3 and 6-7 inches. I am waiting on weather to pour. Again, thanks alot for taking the time to reply as well as you did.

Glad I could help some. Sounds like you are off to a good start. On your areas that are too deep sand is much cheaper than concrete.

MarkV