The Concrete Underground

[Omphaloskeptic]

If I read your text and drawing correctly, this is to be your office wall? How the heck is the rebar tied into that form and the all thread?


P.S. - Congratulations on being back on site and in work!

 

[ConCretin]

If I read your text and drawing correctly, this is to be your office wall? How the heck is the rebar tied into that form and the all thread?

Thanks. You are correct about the location. Ironically, I was editing the post while you were typing to answer that very question. We'll drill & epoxy some bars into the foundation independent of the rods.

 

[ConCretin]

Question, where do you store the dock & gangway in the winter?

Thanks Nick. I tow the dock sections and gangway across the river to a marina that kindly permits me access. We pick them out of the water with a boom truck, load them onto a 40' trailer and haul them about 10 miles to my shop. I can see them from my office window waiting forlornly to go back into the water.

 

[NUTTSGT]

OMG, that has to be the longest pipe clamp I've ever see.


Glad to see you're back at it my friend.

 

[gooned]

OMG, that has to be the longest pipe clamp I've ever see.


Glad to see you're back at it my friend.

beauty work on those forms!

May I ask a quick question about a slab pour? I've got 6mil poly down and working on the rebar with mesh ontop inside my shop, working towards 1000ft2 of 4.5" concrete - what are the pros & cons of the water-reducer in the mix?

Also with a roof over it (no doors yet) any thoughts how cold can I still pour without blankets & heat?

now back to your scheduled program

 

[SiGmA_X]

I hope you'll take me at my word when I say that anybody who happens to be in the area and would like to stop by is more than welcome - although I might suggest a nice warm August day

I do sir. You seem like an amazingly nice gentleman, and a car nut, AND a master of the building profession. I've never had the chance to visit the east coast for more than a connecting flight to Europe or the Bahamas, and would love to take a small roadtrip/tour around the NE. Trust me, you'll be getting a message when the day comes

Well after a couple fits and starts we're officially back to work. If you recall, we were still fighting the weather on Monday but yesterday we were able to build this.
<snip>
It's fantastic to be back at it!

Lookin good! Man those look like some cold work conditions. We don't get much/any snow out here in Portland OR, at least not a routine thing. I do not envy working in those conditions! How warm to you heat the tent to?

I have a question - What type of tie is used that would leave a ~1" steel end exposed? Are those something you guys use in commercial where it is covered over by walling? I ask because I just noticed them sticking out the front of my neighbors new 'seawall' (river bank wall).

As always I am looking forward to your next updates LL!

 

[ConCretin]

:May I ask a quick question about a slab pour? I've got 6mil poly down and working on the rebar with mesh ontop inside my shop, working towards 1000ft2 of 4.5" concrete - what are the pros & cons of the water-reducer in the mix?

Also with a roof over it (no doors yet) any thoughts how cold can I still pour without blankets & heat?

Glad to help if i can gooned. If you go with a midrange water reducer there's really no downside. You get better concrete because there's less water but still get a very workable mix (typically 5-6" slump)

High range water reducers can provide a higher slump - which you don't usually want anyway - but can be tricky to work with.

We place slabs in the open at close to freezing but it makes for a long day and night. Hydration slows waaay down and it takes a long time for the concrete to set. Accelerators help as does placing in sunlight or on insulation. As long as you have the patience and the surface doesn't freeze you're fine

 

[ConCretin]

I have a question - What type of tie is used that would leave a ~1" steel end exposed? Are those something you guys use in commercial where it is covered over by walling? I ask because I just noticed them sticking out the front of my neighbors new 'seawall' (river bank wall).

Almost all ties are designed to 'break' or separate after the form panels are removed either by hammering or twisting. The 'break-back' can be as little as 1/4" or as long as a several inches. Some ties are tapered so they come out entirely and are reusable.

Typically you want any metal remaining to be deep enough to patch over and avoid rust and bleeding. With that said, when we blocked out our retaining walls for a future stone veneer, we moved the concrete surface in far enough to negate the tie's break-back. Now I have to go back and chip down, cut and patch.

I suspect your neighbor just hasn't got around to it or did something dumb like I did. Sorry you asked?

 

[BooUrns!]

I guess I'm coming in to comment on this a bit late. I've spent the last couple of days browsing through this thread. Very impressive work, I'm not sure I would have the patience to go the route you've taken.

Regarding the architectural finish you're going after right now, did you consider using self-consolidating concrete (SCC)? I'm not sure if the use of superplasticizer is a cost barrier you didn't want to cross but it would help produce the smooth finish you're after. I've seen LaFarge build some pretty impressive stuff with it in their pre-cast yard up here.

 

[Holedgr]

I can only imagine the great quality of your crew as ANY dent or nick from a accidentally dropped hammer or piece of rebar would translate into a timeless reminder of the event for you to enjoy every time you look at it.

I am amazed at this project and KNOW that the pictures show 1/100th of what it takes to achieve this level of quality. Keep up the inspiring work!

-Tony

 

[Modern Jess]

Really glad to see work underway again.

I needed my fix.

 

[ConCretin]

I had hoped to get our first architectural concrete wall placement off today but we had a few minor set backs and I didn't want to rush it. So it's all set for Monday at noon. I think we can make up for the lost time on the next placement since it's a carbon copy of this one. Structural steel is T minus 3 weeks.

So here's what things look like. This is the formwork on the back of the U shaped wall. Since this side of the wall won't show, I saved a few bucks and made some of the forms out of regular plywood.

One of the nice things about coil ties is that they can pass through one another, which comes in handy since they all pass through the same plane. I arranged the outside row of ties to hold the bulkheads at the ends of the wing walls.

Since concrete exerts pressure in all directions equally, we have to hold the bulkheads on the ends of our straight wall too. In this case we ran exterior ties in the form of coil thread.

You've heard me refer to ThermoMass quite often. Well, here it is;

It's essentially 2" rigid insulation that has been covered with a fiber reinforced film to increase its strength. The insulation is fitted with nylon spacers that hold it in the center of the wall during concrete placement.

In our case we cut the 4x8 sheets in half so they'd fit between our coil ties, which we turned on edge. Here's a shot of the Thermomass inside of a closed form. You can see that the spacers are slightly shorter than the wall thickness to facilitate a thin layer of paste to obscure them.

The nylon spacers have grooves cut into them to help hold the concrete on either side of the insulation together. The coil ties will assist with this as well. We'll also install some U bars at the top to tie the two sides together a bit more firmly.

Since one side of the wall actually bears on the floor slab and isn't really tied down, I felt like we needed a little more overturn resistance, especially in the short term when the wall is standing by itself and subject to wind loads. So I added some #5 bars to the end of the wall to tie it down.

A couple other formwork details; Yes those are biscuits. It's the only way we could figure out to adequately align the closing side of the form.

Can't forget the electrical rough in. There'll be a Lutron lighting controller on either side of the U wall to allow you to turn the lighting scenes in the main living space on or off as you pass by either side.

It's just a standard metal box I taped up to keep it from filling up with mud.

Well that's about it for now. All of the parts and pieces are now in for the ICF's so Monday, we'll start working two fronts. Did I mention that structural steel is now T minus 3 weeks?

 

[red]

Wow, I've poured a few yards (in my younger days) and you keep impressing me with how little I know. Do know all that attention to detail will pay off. Just very expensive because of all the extra time it takes.

 

[ConCretin]

Thanks to all for the positive comments.

Regarding the architectural finish you're going after right now, did you consider using self-consolidating concrete (SCC)? I'm not sure if the use of superplasticizer is a cost barrier you didn't want to cross but it would help produce the smooth finish you're after.

Good thoughts but SCC is still pretty new up here and requires very stout formwork. I considered a high range water reducer but I don't really feel like it's necessary and it would add another variable. We can a 5-6" slump out of a midrange, which should be fine.

I can only imagine the great quality of your crew as ANY dent or nick from a accidentally dropped hammer or piece of rebar would translate into a timeless reminder of the event for you to enjoy every time you look at it.

Thanks for giving me something else to worry about Tony. I'm going to reuse these panels 5 times so it would be the gift that keeps on giving.

 

[duggie]

You've heard me refer to ThermoMass quite often. Well, here it is;

I always understood that the concrete mass was more than enough to act as a heat sink. How much does the rigid insulation make a difference compared to a regular concrete mass wall ??



oh, and YOU **** !!! *had too be said, I'm jealous* ..

 

[NUTTSGT]

Can't forget the electrical rough in. There'll be a Lutron lighting controller on either side of the U wall to allow you to turn the lighting scenes in the main living space on or off as you pass by either side.

It's just a standard metal box I taped up to keep it from filling up with mud.

My guess the front of the box is flush against the wall with no hole cut in the wall. Is there any screws or anything used to hold the box in place so the mud doesn't push it off the the side or **** it one way or the other ?

 

[ConCretin]

I always understood that the concrete mass was more than enough to act as a heat sink. How much does the rigid insulation make a difference compared to a regular concrete mass wall ??

Thanks duggie. You're stretching my knowledge of thermodynamics with questions about heat sinks. I'm just installing the Thermomass to increase the R value of the concrete walls that separate heated spaces from the cold Maine winter.

My guess the front of the box is flush against the wall with no hole cut in the wall. Is there any screws or anything used to hold the box in place so the mud doesn't push it off the the side or **** it one way or the other ?

You got it Nutts. I just used machine screws thru the plywood into the holes in the boxes to hold them tight to the form. As long as we don't wack them with a ******** or forget to remove the screws before we yank the panels, it should hold well enough.

 

[Modern Jess]

You got it Nutts. I just used machine screws thru the plywood into the holes in the boxes to hold them tight to the form. As long as we don't wack them with a ******** or forget to remove the screws before we yank the panels, it should hold well be enough.

Continuing the discussion of the electrical box: I am notoriously paranoid about placement of electrical fixtures, so take this with a grain of salt: Are you absolutely certain that box is big enough for a Lutron lighting controller? They tend to be fairly large, and that box just doesn't look big enough to hold the controller and the wire nuts.

 

[ConCretin]

Continuing the discussion of the electrical box: I am notoriously paranoid about placement of electrical fixtures, so take this with a grain of salt: Are you absolutely certain that box is big enough for a Lutron lighting controller? They tend to be fairly large, and that box just doesn't look big enough to hold the controller and the wire nuts.

Well I was until you spoke up - now I'm freakin paranoid too.

My electrician tells me the Lutron controllers we are using are interchangeable with light switches and will fit in a standard box.

Given my newly induced paranoia, I'm going to call him and make absolutely sure. I only get one shot at this. It wouldn't be the first time someone on GJ saved my ****. Thanks!

 

[hpw]

Also, thinking out loud, the pvc going to the top of the electrical box, looks like

maybe an inch to the inside surface, will that be deep enough in the concrete?

Maybe bring a sweep to the back side of the electrical box if it isn't?? Or is this a non issue since it is pvc and not rebar and exposed to moisture?

 

[Oggy]

Can't forget the electrical rough in. There'll be a Lutron lighting controller on either side of the U wall to allow you to turn the lighting scenes in the main living space on or off as you pass by either side.

It's just a standard metal box I taped up to keep it from filling up with mud.

Well that's about it for now. All of the parts and pieces are now in for the ICF's so Monday, we'll start working two fronts. Did I mention that structural steel is now T minus 3 weeks?

Looking at this makes me think about how much planning you have to have done, Everything right down to the very location of your TVs and phones has to be pre-planned. I think having my wife that far into the planning stages would be enough to prevent me from taking on a project like this... She'd want TV and phone jacks at every outlet, living room, bedroom, bathroom, and kitchen. I would hope not in the hallways...

 

[Modern Jess]

Well I was until you spoke up - now I'm freakin paranoid too.

My electrician tells me the Lutron controllers we are using are interchangeable with light switches and will fit in a standard box.

Given my newly induced paranoia, I'm going to call him and make absolutely sure. I only get one shot at this. It wouldn't be the first time someone on GJ saved my ****. Thanks!

And it wouldn't be the first time that I induced unnecessary paranoia in someone else.

If your electrician says you're good, then I would certainly defer to him.

 

[Omphaloskeptic]

So I'm sitting here looking at your very detailed pics (thank you) of the form work with the Thermomass nestled within and thinking of the pressures involved when filling the forms. Is there a technique your guys use to prevent severe 'side-loading' of the Thermomass as the form is filled? I'm seeing the small but worrisome chance of the insulation being shifted/deflected one way or another enough as the form is filled that when the forms are pulled, those nylon spacers wind up showing on the finished surface as a nasty pattern of plastic 'dots' showing through the concrete finish. Just wondering if you will be using a pumper truck type of delivery and, if so, can the discharge be fitted with a 'dual spigot' so the mud is pumped to both sides of the Thermomass simultaneously during the fill? I hate to add 'one more thing' to your sense of paranoia; maybe I'm just seeing a problem where there is none. I imagine you are laying awake at night seeing the delivery date for the structural steel on your mental calendar, and at the same time worrying about every blessed detail of the form work trying to keep 'Mr. Murphy' off the job site.

 

[ConCretin]

Also, thinking out loud, the pvc going to the top of the electrical box, looks like maybe an inch to the inside surface, will that be deep enough in the concrete?

It's about an inch of cover at the narrowest, which should be fine. We only need enough room for the concrete to get in and fill the space. Since it's in an interior space the minimum cover for rebar is even less and and as you said, PVC won't rust anyway.

Looking at this makes me think about how much planning you have to have done

We have had to do a lot of planning but it may not be quite as bad as you think. We do need to build everything into the exposed concrete as we go but items in the ICF walls can be done after the fact. Plus there is a lot of drywall and cabinetry that can wired more traditionally. It's still a bear though.

Is there a technique your guys use to prevent severe 'side-loading' of the Thermomass as the form is filled? I'm seeing the small but worrisome chance of the insulation being shifted/deflected one way or another enough as the form is filled that when the forms are pulled, those nylon spacers wind up showing on the finished surface as a nasty pattern of plastic 'dots' showing through the concrete finish.

Nothing too elaborate - you just place the concrete in short lifts alternating side to side. The fiber reinforced film allows the insulation to support the weight of the concrete without breaking.

The color of the rods matches concrete pretty well and the concrete paste does tend to get between the rod and the surface. I'm hoping that my external form vibrators will increase this even more.

We've used the product in typical concrete walls and you couldn't see the 'dots' but we're shooting for a near perfect surface and I'm not 100% confident. That's why I started on this wall. The outside portion of the wall is covered with siding and won't show. I plan to fill the inside first to push the rods to that side. If it looks too bad, we'll have to re-evaluate how to go forward.

 

[KRZY1]

Glad to see you're back at it w/ the loan sorted out. Subscribing to keep up to date.

 

[onething]

In case you still need something else to worry about, the sky is falling in Russia

Thanks for the very detailed pictures and info.

Still subscribed.

 

[Motown 454]

I just read the whole thread. Wow what an amazing build! I can't wait to see more. I'm definitely subscribing. Wow!

 

[Omphaloskeptic]

" I'm hoping that my external form vibrators will increase this even more."


Since entrapped air is something you don't want for the architectural finish, it'll be worth every penny spent on the external form vibrators if they (hopefully) produce a bubble-blemish-free finished surface. Are they operational from the time the pour starts till hours (?) after the forms are top-troweled?

 

[ConCretin]

"Are they operational from the time the pour starts till hours (?) after the forms are top-troweled?

The external vibrators rattle your formwork pretty good so we don't plan to run them until the concrete is in place. We'll use internal vibrators first and then run the external units.

Each unit covers an area of about 4'x7' so for our 12' long walls, we'll use 3 per side After the first pass, we'll have to relocate each unit to cover the top of the wall.

We're experiencing very high winds here now so if I still have a tent, we'll be placing in a few hours and I'll have some pics of the units in action this evening. If not, we may get delayed a day

 

[ConCretin]

Despite a very windy night with gusts up to 50 mph, the tent was still there this morning. After fixing a little damage and taking care of a few last minute details, we were finally ready to place some concrete. It's been a while since we've seen of of these on site;

My conveyor truck is in the shop so I called my friendly neighborhood pump company and they sent me a nice little 38 m pump. We cut a slit in the roof and the tremie dropped right in.

The pump operator used his radio remote to control the pump, which allowed him to stay close to the action and see what was going on.

We placed the concrete in 4 foot lifts and used two internal vibrators to consolidate the concrete. We used a 2 1/4" head for the 8-10" sections and a 1" head around the ThermoMass.

Next we turned to our external ******** system. The heart of the system is this inverter, which if I have it right, converts the power from single phase 240V to 3 phase 42V.

The inverter can power four of these at a time. They clamp right on to the form with a wing nut.

I rented 9 units, which worked out pretty well. We'd use three to vibrate one face and then the other. The extra three allowed us to keep one row ahead.

To be honest, we've never used these before and I'm not sure what to expect. Even after we vibrated internally, there was a significant amount of air bubbling to the surface when we ran the external units. Hopefully this translates into a smooth surface.

The placement went quite well and I'm hopeful the results justify all the effort we put into the formwork. The next placement is significantly more complex. It incorporates a 70" linear gas fireplace, a recess for the TV and a cantilevered concrete hearth and mantle. Boy am I a glutton for punishment.

 

[Pluribus]

Wow, this is amazing! You probably have more work and material in your forms than the rest of us mere mortals have in our entire walls. It's a unique and fascinating project, and I love your setting there on the river. I will continue to enjoy watching its progress.

 

[1949 caddyman]

We placed the concrete in 4 foot lifts and used two internal vibrators to consolidate the concrete. We used a 2 1/4" head for the 8-10" sections and a 1" head around the ThermoMass.

What is "head"? (no jokes, I mean as in concrete pouring)

 

[KPSquared]

I seriously might have to come check your place out when it's done. That's just to freakin cool.

I'll bring Canadian beer. . .

 

[Omphaloskeptic]

My fingers are crossed for your pour! Hopefully, the upcoming macro-close-up pictures of the unveiled/unformed concrete surface with be as blemish free as a newborn baby's ****.

 

[ConCretin]

We spent the day in the shop building 'bucks' for the ICF walls and 'block-outs'
for the next U shaped concrete wall that gets the gas fireplace.

We'll start stripping yesterday's architectural concrete (AC from this point on) placement tomorrow. The concrete will have cured in 60 degree temps for at least 36 hours, which is an adequate protection period.

The next challenge is to bring the concrete temp down to ambient slowly to avoid thermal shock and 'gasp' cracking. We'll (hopefully) accomplish this by slowly reducing the heat in the tent and blanketing the concrete after we strip.

We placed the concrete in 4 foot lifts and used two internal vibrators to consolidate the concrete. We used a 2 1/4" head for the 8-10" sections and a 1" head around the ThermoMass. What is "head"? (no jokes, I mean as in concrete pouring)

It isn't really all that salacious. I was referring to the head diameter of the internal vibrators. That didn't really sound any better did it?

I seriously might have to come check your place out when it's done. That's just to freakin cool. I'll bring Canadian beer..

You show up with beer, you're gettin a tour.

My fingers are crossed for your pour! Hopefully, the upcoming macro-close-up pictures of the unveiled/unformed concrete surface with be as blemish free as a newborn baby's ****.

I'm right there with you brother. The likelihood of said photos is directly proportional to the quality of the finish. Just kidding, I'll post pics even if it looks like hell.

 

[NUTTSGT]

We're talking about the head diameter of vibrators, concrete, short sleeve shirts on a cold *** and windy day in February and I spy a floating step ladder.

This thread is so full of awesomeness.

 

[ConCretin]

We're talking about the head diameter of vibrators, concrete, short sleeve shirts on a cold *** and windy day in February and I spy a floating step ladder

 

[SiGmA_X]

That is a pretty badass step ladder I can't wait to see the wall stripped. Thanks for all the info as always. I had never seen nor heard of an external ******** prior, I'm looking forward to hearing your thoughts on the finish with it vs without. I expect its a little tricky to compare being you aren't pouring any AC's without them this time around.

 

[db2221]

sub...... scribeeeed

 

[ConCretin]

We started the day by 'unveiling' the concrete walls we placed Monday. The crew was a bit nervous, which I must admit was contagious.

After all the build up, expectations were high but I was not disappointed. There are some small air pockets but the overall surface is excellent. The pictures are a little deceiving because moisture on the surface exaggerates the imperfections.

As the surface dried the concrete looked better and better. By the time the color evens out completely, we'll have a nice uniform surface. It ain't plaster but that's not we were going for.

Even the corners came out nice. The boss didn't want chamfered corners, which raised the degree of difficulty.

Scott was the most nervous of all the guys when we started stripping but in the end he seemed happy with the result

After we stripped, we quickly blanketed the walls to allow the concrete temp to come down slowly and avoid thermal cracks

Here's where the next placement is going - have I mentioned how much I love winter construction in Maine.

If you're curious why I didn't post any photos of ThermoMass dots, it's because the damn things are completely invisible on both sides of the wall. Even though we knew where to look for them, we couldn't find any sign of them. I am pleasantly surprised and we'll stick with our original plan and use it in a couple more walls as planned.

Next up is the opposite U shaped wall and the wall to the right of the prep kitchen. We'll make a few adjustments to our methods and the mix to see of we can improve the surface even more.