Pouring a concrete ramp

[Stan in Oly, WA]

I've got to build a ramp between two concrete retaining walls. I don't have much experience pouring concrete with slope to it. When I've had to do it in the past, I've gotten it done somehow, but without ever feeling that I was totally on top of the situation.

The ramp will be 48" wide. It has to rise 30" in 18' which works out to 1.67" rise per foot. The bottom half of the ramp will be directly on undisturbed hard clay soil. I will remove the loose topsoil down to the clay layer for the top half and bring up the level to pouring height with crushed rock.

I'll be mixing the concrete with a mixer. I'd like to get some experienced help but I probably won't be able to. Anyway, I prefer to work alone. I don't have to do the whole pour in one day.

What can anyone tell me that will make this go better? I like concrete work a lot when I know what I'm doing, and I don't like it at all when I'm making it up as I go.

Thanks, Stan

 

[Jim Will]

Oly Wa.
Good morning.
When pouring your ramp, snap a chalk line down each side at the level you want to finish the cement. When you mix the cement just don.t add too much water. Don't make it too dry either or it will be too hard to work. Then wheel barrow the mixture up the ramp and dump some on each side being careful not to dump on your chalk line or it will disappear. Just hand float some cement on each side up to the line for 3 ft or so then fill in the middle, rake and screed it off using the height of the cement you placed along the walls as your guide. Then continue on 3 - 4 ft at a time.Crushed rock is a poor sub base for immediately under the cement as all the water and cream in the cement will quickly run out the bottom. Use your crush for base then a few inches of mulch and compact well. good luck . Jim Will

 

[Anonymous-0]

Another way would be to use two chalk lines.
One at floor level another 3 1/2" up. Then when
you pour you can rough it in with bottom line
and then use 2x4 screed board to level with. Just
line up the top of 2x4 with the top line (2x4
goes under top line) that way you don't have to
worry about losing your floor height line. Fred

 

[Anonymous-0]

That is a tough one to do alone. I would use a road type sub-base (called item #4 here) subgrade well compacted and hopefully well drained, then the crushed stone with enough of the various composite aggregate sizes to compact well, too many voids in clean crushed stone for a slab, I agree on that, might lose the water. I'd want a stiff mix for this, workable for finishing, but minimal water, stay close to what the bag calls for water/cementitious material (water/cement ratio)


One thing that would make this easier is a ready mix truck, 4' x 18' x 4" thick slab is about .88 of a cubic yard, so 1, 1.25 cubic yard(s) would do if the form dimensions are true. Though access and being a real short load, can see why you are mixing bags, we have small quantity batch trucks that deliver here, mix what you need on site, not sure if you have seen those trucks, they're completely different from the regular trucks, real noisy too.

If you are abutting existing concrete, might want to consider where to put expansion joints using an asphalt impregnated fiberous material or similar that can be recessed in the joint and sealed with caulk. especially if you have to do this in sections. Consider the sides along the existing walls as well.

Maintain at least a 4" thickness at each end of the ramp, you don't want thin areas there. Also make sure that the transition to and from the ramp at the ends will be smooth, other than that, not much different than doing a sidewalk.

Reinforcing - 6" x 6" woven wire mesh will do, I've used heavier gauge wire livestock fence too, make sure to pull up on it with a hook while placing the concrete to make sure it is in the middle of the slab thickness, not bowed downward into the sub-base.

 

[bc]

I'm kinda with Billy on this. I'm not sure if this ramp has the retaining walls from side to side or end to end so I don't know if you will have forms on the sides or just the ends. If this is a wheel chair ramp, I believe ADA requires no more than a 1" to a foot slope minimum.

Consider some 1/2" rebar drilled into the present concrete at 1 foot intervals or at least 4" to 6" deep and sticking out about a foot.

I wouldn't put concrete directly on clay. Though hard it will shift and swell. A few inches of fill sand under the concrete will help.

Use a lower slump concrete/not to much water with your slope. Have an inside end board available along with your screed board so that way you can have a moving end form while you move your way up the slope. Then dump your mixer batch in and use the end form so you can screed each load as you go.(don't need a perfect flat end each time and can't becaue of the remesh but just be able to screed up close to the end board) With an all day, one man job, be ready to float it every so often with a hand float since you won't get a bull float in there. Same for any hand trowling or edging. Have your straw broom ready so you can go down and do your brush finish side to side as it sets up while you are working your way up. Every 4', more or less, (or on an even spacing of your 18') you will want to tool in a groove or else come back and cut one later with saw about an inch deep.

Good luck.

I guess you are going to borrow or rent a mixer, then have have a load of sand and a load of gravel brought in and dumped on the ground and then leave a big mess to clean up in the mixer area. BTDT. Around here you can get a minimum of 1/2 yard before they charge a minimum. Even the extra $50 they may charge for a short load is nothing compared to the hassle and work involved in hand mixing. To get a load of sand brought in costs as much as the concrete with the trucking. Same for the gravel. Then shovel it in to the mixer by hand. Even if you haul your own sand and gravel you still have your gas costs plus having to shovel it a second time and that depends upon how far away the pits are. Then the trip to home cheapo for the concrete and carry it around. Mixer cleanup and return is time and money.

I've found it is either a quikcrete/sakcrete job or else bring in a bulk truck. They do these small jobs all the time and especially on weekends. Tell them what you are doing and the slope and they will adjust the slump.(it's the same process used in curb & street gutters, just pile it up with a shovel/rake and come along with a curb shaped piece of plywood for a screed form to make the curb while scraping along the excess and using a trowel to fill a void) Most people using a mixer or by hand make concrete too soupy which may account for your past problems. They can always add water at the truck if needed. Depending upon how hot it is, they may not want to put anything in it that will make it set up to quick on you. Have some forms premade for pavers, etc if you want to use any of the excess. I'd even pay another $50 if they had a time charge cause you take an hour or so to wheel barrow it in and stop every so ofter to rake it into place and screed it. Sometimes the driver may jump in and help screed if he knows it will get him out quicker or he is nice.

A good investment is a double wheeled poly wheelbarrow. Even my wife can move around a load of sand without it tipping. She could probably run a screed board too. The poly is quieter when pulling a hoe mixing quikcrete without those fingernail scratching sounds on a metal one. Sams has them between $50 & $60.

Stan, be advised that I'm not trying to talk you out of doing all that physical labor. Maybe your back needs the exercise. But sometimes when you put a pencil to cost, time, and labor saving you may find you are not really saving any money or enough money for all the hassle. Your back going out while shoveling into a mixer in the middle of a job can be quite a mess.

 

[Anonymous-0]

Mulch?? I worked on construction for 33 years and I've never heard of placing mulch under a concrete pour. Could you explain this theory some more, or maybe it's a misprint?

We always wanted any type of vegetation removed, earth compacted, crushed dirty limestone fill compacted again, and wet the sub-base before the pour to prevent wicking moisture out of the mix. We never used reinforcing in sidewalk, but intended only for foot traffic. Expansion material is needed for trapped areas. Vibrate or "spud" the mix to consolidate it for greater strength. Lay out your joints to control cracking, and to give you a quitting spot for the day. Throw an end form in at a joint and you won't see the stopping point on the finished product. Don't let anyone step from the wet mix to the dried area, but if they do, clean up the "slobbers" before they dry. Plan what kind of finish you want by what's already been done nearby. Because of the slope, it will be hard to keep the finished surface wet for good curing. You could cover it with white plastic to cure it for a few days. They make spray-on curing compound, but probably not cost effective for a small situation unless you know someone in the business and then you might not want it on the surrounding concrete. Ready-mix would be easier, but around here they charge like the dickens for short loads. Don't kill yourself in the heat!!!

 

[Stan in Oly, WA]

Hi bc,

Thanks for the long, informative response. This ramp and the retaining walls that run alongside it (which also don't exist yet) are part of a large amount of concrete work and brick masonry that I intend to do this summer and fall. This will include hundreds of sq. ft of sidewalks, patios, stairways, brick planter boxes, brick flowerbed borders (1 ft high), and a brick wall facing for my 100'X 36" retaining wall.

One way to do it would be to form up everything that will be poured, then get it all pumped at one time. The main trouble with that method, to my mind, is that there's no way I could stay on top of that much concrete that needed finishing without hiring a skilled crew and paying them a large a part of what what they'd charge to do the whole job, anyway.

Another consideration is that if I could do the whole project at one time, my wife and I would have to live with it however it came out, however close or far it was to the way we had imagined it. Of course, that's the way it is for most people in a similar situation, and it's not the end of the world if you don't get exactly what you hoped for. But doing it piecework the way I am, any element can be changed if it's not what we had in mind. This ramp, for instance, was envisioned as a stairway and sidewalk until two days ago.

I'll look into getting a short load when it's time to pour this. What you have to say about it makes a lot of sense.

Thanks, Stan

 

[Stan in Oly, WA]

Hi Billy,

Thanks for the response. Lots of valuable information, as usual. This is starting to seem more intense than I imagined when my wife said, "How about a ramp instead of a stairway?" and I immediately responded, "Sure, no problem."

I'm good at stairs, and not too crazy about OJT on a project that is to be something of a showpiece on my own property (or anywhere, really.) I'm already intending to build three 10'X 40" X 24" high brick planter boxes (on poured foundations that I've completed) to see if I can get the brickwork pretty enough to make me feel that I could take on the job of a brick facing wall in front of my 100'X 36" retaining wall. It was intended to be our splurge project that I'd get an expert to do, but the bids came in about 50% higher than what we considered to be all we could spend---even splurging.

I'll undoubtedly be asking more advice on related subjects over the next several months.

Thanks again, Stan

 

[Anonymous-0]

Sounds like a neat home project, you'll probably want to also get familiar with masonry details, drainage for all these comnponents and I'd recommend speaking/consulting with a landscape architect maybe have em review your designs, to expose any problems or possibly value engineer same. Smart move to take bids first and see what prices are off the street, contractors are expensive, kind of a luxury to be able to hire one in today's economy. Once you have a firm design that can be constructed, things can get easier, though with changes, contractors prices are also subject to change.

Another thought is to kind of value engineer a little here, can you get anything in precast that will be of use, can you alter the design to allow smaller pours that will coordinate with the other components and still make it cost effective to purchase ready mix saving you some hard labor. Sounds like what you are building will take a fair quantity of material, so if you can divide it up into sizeable but managable portions, might help. Not everything that is designed can be constructed cost effectively, it's wise to review any design and see what can be done to streamline it without detracting from its original intent.


Make sure those walls are drained, if you have cavity walls, (brick veneer on face with annular space between brick and concrete) make sure to use the correct masonry accessories, cavity has to be well drained with weeps and you can't let the mortar fall in while constructing, can easily block the weep tubes.

Keep in mind to also dowel in and stub up, and or out of the concrete with deformed reinforcing bars (rebar) where needed, where makes sense to do so etc., easier to embed than to drill, epoxy and dowel in later.

Attached link to Hohmann-Barnard, take a look in there, all kinds of masonry accessories and details to help you design something, also weep accessories, tie backs, masonry reinforcing, all kinds of good products, I've done a lot of jobs where they specified H-B products, not allowing an as equal or equivalent by another manufacturer.

Link will take you to the products page, look carefully, there are a lot of products in there, as well as 3D models illustrating their use.
Hohmann Barnard

 

[bc]

Stan, do it in sections and you can keep up. Dig and pour your footing with rebar going lengthways for the wall all at once. Get your string lines laid out and even a cheap laser level helps. Just need get a basic level with a float and stick a 2by4 on edge into it for a key way. Then stick in your rebar for your wall or stick it in the dirt before you pour. No real forming and no real concrete work other than some floating with a wood float. You want to use a 2by on one or both sides or something to form up and keep your brick ledge level which depends upon your yard level.

Do your walls in sections of whatever amount of osb plywood and 2by's that you want to buy. 6 sheets of plywood will give you 24' of wall at a time. You could put the 12" leftovers nailed to 2bys to make another 8'. Once all the bracing is done, then no real finishing since you are just filling the forms. Put a keyway in the end. To avoid a lot of extra bracing, drill the forms for wire ties to keep them from blowing out like they do with basement forms. I haven't dealt with walls for brick in a long time but maybe you cut some slits in the forms for inserting brick ties into the concrete at the appropriate height.

Do about 24' or so at a time. use some extra plywood strips to do more. Poke some rebar into the sides before it dries completely to tie into the next section.

Same for sidewalk and and your ramp. keep it to no more than 24' sections and you can screed it, float it, edge it, cut your joints, and give it a brush finish. One guy could handle that although it would be nice to have someone run a screed while you dump from the truck trough and rake it around to where it needs to go. A big crew really helps if you are doing a lot of flatwork and slab work such as a building floor where you need 2 to screed or run the power screed and then have a lot of trowling to do and depending upon how hot and dry it is which causes it to set up fast. My grandpa and uncle used to be able to do it and then come back and power trowl when ready for that. If we did use the mixer, one guy mixed full time, one guy ran the wheel barrow and helped screed, and one did the concrete work until it finished.

You have enough work going here without having to mix the concrete too. It's nice to have a helper to clean trowls, forms, help remove forms, etc. Makes for a very long day to do all this and still shovel into a mixer. Save the mixer for mortar but you may be better off using a mortar box or wheelbarrow since you may be working slow with the brick. I always did the mortar mixing for my grandpa and uncle who did the actual bricklaying but I would like to do it sometime. Use storypoles with string lines to keep everything straight and level.

Given a choice between a ramp or stairs, I take a ramp anytime except when icy. 1.67 isn't ada but should be passable by a power wheel chair or someone used to pushing.

Well to repeat what your wife has been telling you, "you better get crackin", "When are you going to be done?", "Are you done yet?", "The summer is half over and you haven't started yet!", and there are others wives are known to say with these honeydo jobs. Good luck.

 

[Stan in Oly, WA]

Hi Fred,

Great idea, and simple too. A working chalk line the height of a 2X4 above the finish line is exactly the kind of detail that can make a ton of difference, but I can never seem to come up with when I'm hot into the job. There's something to be said for learning from someone who knows what they're doing. I seem to spend an incredible amount of time trying to reinvent the wheel on just about every job I do. It used to be a source of pride until I figured out that I'm actually not that good at it. A couple of years ago my wife said to me in exasperation, "Why can't you just do things the way other people do? What would be wrong with that?" Pretty late for that, is what I thought. What I said was, "Good point."

All the best, Stan

 

[Sid]

If I may add to the advice already given, my experience has been that you will have less problem working down the slope rather up the slope. I find it easier to work bent over facing up slope rather than bent over facing down slope. It is just plain easier to go down hill, it seems to eliminate several little annoying things that add up to make a job aggravating.

 

[Stan in Oly, WA]

Hi Jim,

I appreciate your clear description of the actual process of putting the mud in place. Things like that make a big difference. A few weeks ago a friend stopped by while I was moving ten yards of top soil with a wheelbarrow and a shovel. I've probably moved more material in a wheelbarrow than practically anyone who's finished high school, but my friend was able to point out a couple of things I could do differently to make it easier on my back. He was right, too.

Thanks for the advice about not using crushed rock directly under the concrete. Like PJH, I've never heard of using mulch, either. What is it, exactly? How about using sand directly over the crushed, and then soaking it good just before the pour? Sand is something I've got plenty of.

All the best, Stan

 

[Anonymous-0]

I will probably take a few hits on this one, but anyone living in a cold / hot zone needs to understand one very important thing about frost. I'm refering to rebar being drilled into any wall. No one in this world believes in rebar more than me. That being said I will assume the walls are below the frost line, if that is the case you can not tie into those walls. You need to drill the walls and pin it AT GRADE LEVEL. NOT into your ramp. The reason is frost will lift your ramp, and nothing in this world will stop it. You must keep it from setteling down, so pin it at the bottom of the concrete line so the frost can lift, but the rebar will keep it from ever going down. If you try to pin it to the concrete it WILL bust off the edges of your ramp. Look around some recent pours and watch what happens when winter sets in. Sidewalks that are pined to concrete walls bust even sections of a concrete wall. This can be a better situation if you have very good drainage however or you are just lucky.

Another point I would suggest is concrete does indeed run downhill better, but you get alot of cupping behind the screed, thus we usualy pour uphill so the concrete stays in place when screeding. The last note is not a big deal either way however, but the pinning of rebar is a major problem in alot of cases. I would even suggest expansion joint on both sides, but must be water tight.

 

[Stan in Oly, WA]

Hi PJH,

No heat here to kill me. Western Washington has had the coolest spring since they started keeping records in the late 1800's, and there's no letup in sight. Most days are in the mid 60's and we've only had a handful of days with temperatures into the 70's since April. I'm sorry for everybody who's not getting their summer vacation weather, but you really can't beat it for outdoor work.

Thanks for the step-by-step on how to proceed with the project. You're right about the cost of ready mix for a small job, but that's not the real reason I don't want to do it that way. The fact is, I've never been involved in a concrete pour involving a truck that didn't have an element of Chinese fire drill about it---no matter how well prepared, no matter how many able bodies standing by. If the size of the project doesn't make the use of a mixer either impossible or ridiculous, then using a good mixer, a wheelbarrow, and one other good worker is my favorite way to pour concrete. It's a lot more work, but that's never bothered me too much, and I really appreciate the feeling of always being in control of the process. To each their own, I guess.

All the best, Stan

 

[Anonymous-0]

3" thickness is usual for pedestrian traffic but put reo[about 3 mil] in it because that is what gives concrete strength otherwise it will crack in odd places. if you have all your supplies down the bottom then I would start the pour at the top, providing the mix is about 60 slump it won't flow down hill.I would use "B" grade crushed rock{with fines} for the fill...compacted.or you could use "no fines" [crushed rock coated with cement] which would set hard also act as a water drain.

 

[Stan in Oly, WA]

I've read your advice several times and I still don't think I understand it completely. When you say I should "drill the walls and pin it AT GRADE LEVEL. NOT into your ramp", does that mean that the rebar gets drilled into the bases of the walls and tied together from wall to wall on top of the fill (crushed rock, or whatever) and then the concrete poured on top of it? Or does it go in or under the crushed rock so that it won't contact the concrete at all?

I'd like to do whatever I can, within reason, to prevent future problems. I'm sure that local codes here address issues of frost line and snow loads, even though our winters are so mild that most of us forget to consider those possibilities. When we think of winter weather, we think of rain.

Thanks for the advice.

All the best, Stan

 

[Stan in Oly, WA]

Thanks, Sid. That's a great tip. I wouldn't have thought of it, either.

All the best, Stan

 

[Anonymous-0]

Sorry my computer is acting up and shutting down without reason. At the bottom of the concrete is what I'm intending to say for the short pins only. The other rebar for your ramp should tie together the ramp concrete only. Rebar are usualy in the bottom 1/3 of a slab. Use plastic clip chairs with what they call 1 1/2 inch cover. They simply snap over the rebar and hold it 1 1/2 inches from your crushed rock fill. Alot of rebar gets stepped down and do little if any to hold the slab together.

The small pins into your walls need no chairs as it should be at the top of the crushed rock--and at the very bottom of the concrete in the ramp / slab. When the concrete tries to settle the short pins hold it up, and the frost can heave it up without damaging the concrete in the slab / ramp or the walls.

Sorry I don't explain things so well. I wish the good Lord would have made me a little smarter instead of so darn good looking! I can hear everyone laughing under their breath on that one!

I will try to keep in contact here, but the computer is acting up.

As far as tieing the wall together I have no idea of the way they were constructed so I will assume they are ok. If there is any question by all means drill clear thru and cable / redi bolt them together. Keeping the water out is always good.

On a related note the last rebar I got was over nine dollars for a 20 ft stick ==1/2 in no grade bendable. And when you add on the 4,000# reverse mix at 100 dollars---you get a head ache real fast.

I also would like to tread water---We always pour uphill, but we use a power screed, otherwise it probably would be easy to pull it downward. It kinda makes a differance if everyone at the job site knows what their part in the program is before the truck delivers it. A well experianced crew makes it fun, or at least little stress.

We are blessed with good truck drivers that know what I want before I ever ask them. We treat them with kindness and harvest it as well. The man on the chute has to just know--no exceptions to this rule. We always coment that it is better to smack a chute man with a shovel as it is to shovel extra cement around.

Don't get into a big hurry to order the cement--get it ready first so you can do a quality job. A concrete mess can get hard to jack hammer out.