The Secret to Finishing Concrete Ep.84

[Music] now if you have watched any of my concrete videos you're going to know that i am all about preparing the subgrade it is probably the single most important factor to the overall success and the lifespan really of the work you're doing compacted fill filter fabric vapor barriers all of it it's important if your concrete slab is sitting on expansive or saturated or uncompacted fill or dirt the finish doesn't really matter much because that slab's going to crack or heave and you're going to have much larger problems on your hands than any other mistake you could make remember that your concrete will never be any more stable than whatever it is that it's sitting on now coincidentally this might be just about one of the most well prepared subgrades i've ever poured on top of there's about 20 inches of two inch rock well compacted then a layer of filter fabric then about 12 inches of one inch minus rock with a vapor barrier layered in there someplace and yes this is overkill but it just worked out this way after all the excavation we did and with the finished grade we wanted you get the idea [Music] do do [Music] do [Music] [Applause] do now we've done several other videos about concrete flat work maybe you've seen them on the channel and so the details around rebar placement and grades and slopes and mix designs have probably been covered in those other videos and i may not hit on them too intensively in this video one of the first things that makes this pour somewhat different is that it is part of an overall poor strategy with the flat work that's going to go in and around this building the garage floor needed to go first so that we could secure the building can't very well put a garage door in until the floor is in for the guys to set the door on i mean we could but it builds in work and makes the garage door vulnerable to concrete work that sort of thing so in order to get a nice secure work area that'll remain protected from the elements under the roof we feel very confident that it's time to put the garage floor in one mistake that's really easy to make with pouring concrete particularly flat work scattered around and inside of a building is biting off more than you can chew there's a perfectly normal impulse to sense you're mobilizing a pump and a truck and a place and finish crew that you might as well just get all that you can and that's true as long as you are able to realistically project just how fast that chemical reaction is going to happen and how much time is going to have to be spent getting the finished product that you and more importantly the client is going to be happy with [Applause] oddly enough i think and it's a hip shot but the 50 yards of rock that we put under this concrete is going to end up being more expensive and take more time than the eight yards of concrete that we're going to put on top of it now it doesn't always work like that and costs like that are not always predictable but you may be interested to know that we do have and will have the costs for everything that we do here put up on a page for our supporters and you can check out the information about how to how to access those costs in the notes below the video all of that being said and most of that being true concrete poor days are exciting and besides that they're fun to watch i even like watching these guys do what they do concrete's going to be here in an hour got lots of time and we're all ready but before this is covered up forever there's a couple things i want to point out the first of them is that i really don't want this to crack much now it's undoubtedly going to crack some but i intend to control the cracking and force it to crack in the bottom of saw cuts i've not put any slip dowels out here in this mat because the concrete is going to shrink in this space it's going to pull away from all four sides and so with that in mind i'm putting extra cuts in i'm going to create squares that are about six and a half feet by seven and a half feet but the thing that could really bite me is the inside corners that are created by the foundation here's an example of an inside corner the concrete will pour up against this angle iron frame and the inside corner concentrates the stress of the concrete shrinkage the concrete's pulling back and it creates i'm going to call this i don't think this is quite right but it creates the effect of a weakened plane joint and the crack is going to want to crawl out of here someplace so one of the saw cuts that we're going to put in is running from this corner over to that doorway hopefully it'll capture that one the other inside corner that i'm concerned about is right over here where the door goes into the house now this corner is about only i think 38 degrees or so but it's still a corner and the concrete is going to want to break in some direction so i put this little piece of eighth inch plate about an inch and a half below grade and then we're going to come over the top of this with a saw cut so essentially the concrete slab will be cut severed all the way through top to bottom held together with these three pieces four pieces of number three bar so you don't get any shifting i mean it can't lift at the break but it's going to force this crack to come this direction so it will look intentional the rest of this is garden variety right a lot of rock moisten the subgrade it's about four and a half inches thick maybe average is about almost five inches thick so there's lots of coverage over the top of two half inch bars got this little angle iron frame that's going to receive the trap door down into the crawl space this is just garden variety flat work under a roof in the shade on a beautiful spring day how can you beat that [Music] i'm going to let you just watch this pour and i'll talk about a few of the things that are going on but i'm not going to tell you what i think the big secret is to finishing concrete like a pro until the very end i want to see if you can guess it after watching these guys do what they do [Music] the first thing to point out is this chalk line right along the stem wall i snapped this out very carefully on all three sides and it is our target for the finished elevation of the slab it slopes at about two percent or a quarter of an inch per foot towards the door and this is what jeff is looking at as he pumps his way around the perimeter of the garage now it's easy enough to see and match this line on the stem wall but out in the field in the middle of the floor it gets a lot tougher to estimate the grade and that's what this board in the center of the garage is for this is known as a top screed and it's installed to match the finish grade of the slab as it slopes towards the door opening [Music] oh [Music] [Music] [Music] [Music] so [Music] now floating concrete is simultaneously pushing down the rocks pulling up the cream and cutting the mud to exactly the right height in one process rich is carefully floating the edge to grade because as you can see there is no top screed or form for dustin to rest the screen rod on as he pulls the concrete to grade he's got to maintain the correct height with his arms with his back with his legs using that soft mud as a reference and believe me it's a lot harder than it looks rich can rest his end of the board on the top screed so his job right now is a lot easier to get right [Music] do [Music] do [Music] on the other side of the garage now it's rich that has the hard job of wet screeding wet rotting the simplest task here is actually in the hands of the guy in the middle the mucker the mud cutter who in this case is me i'm adding and removing mud as needed so the guys are not pulling any more than necessary and like everything else it's easy to do and hard to do right if they're moving too much mud with the rod or if there's not enough mud in the right place at the right time things start getting out of whack quickly and progress will slow way way down [Music] so dustin is screeding a little extra slope right at the front of the slab in front of where the garage door will come to rest this creates sort of a threshold just like you would see at any other exterior door [Applause] now to ensure proper cracking dustin pushes a trowel right down through the joint which will almost guarantee that the crack will form right [Music] here [Music] so [Music] so [Music] so [Music] so [Music] do [Music] [Applause] [Music] [Music] [Applause] [Music] oh [Music] [Applause] [Music] a power trial beats hand finishing in every single aspect on a finish like this and there's really only one thing that it can't do which is finish nice and tight up to the walls or the inside corners that's hand work nothing we can do about it today but out in the middle in the bulk of the floor in the field as it's called by keeping after the process with multiple passes spread out over the whole afternoon we're after what is called a burnished floor the repeated traveling passes with steeper and steeper trowel angles and higher speeds as the floor gets harder and harder and harder results in a finish that is as smooth as glass literally in fact it actually turns a dark charcoal gray color and you can literally see your reflection in it when you're through [Music] [Music] [Applause] [Music] hey man how's it going [Music] all right i'm up here we're getting ready to shoot sealer and i'm going to saw cutting about 30. [Music] all right i'm at the very top very end of it yes sir about two gallons oh yeah yeah somewhere around halfway it doesn't need that much but whatever you don't fill up with liquid you have to pump up a hand yeah yeah yeah it's easier to pour back in that's right the acrylic cure and seal we're putting on here is doing at least two things number one it traps moisture inside the concrete so that it continues to harden for a longer period of time this is known as curing and results in a harder slab and number two the same seal that keeps the moisture in for curing will help keep future things out concrete is very porous and can be stained by chemicals oils paints acids you name it almost anything can seep into the slab and so a cure and seal helps the slab keep clean or clean looking for much longer think of it like a coat of varnish okay the time has come for me to lay out there what i think is the secret to finishing concrete and boiled down to one word the answer has to be timing everything you watched dustin and rich and jeff do was carefully organized and timed so that the individual processes were happening at the proper moment in the concrete hydration process this video cannot convey the sense of urgency in the laying down process the relaxing break that happened after it was floated the horse race the rich had trying to trial the edges by hand as they went off the time spent waiting in between power trial passes testing the hardness of the concrete with fingers and fingernails looking at a watch timing the minutes and the hours and maybe the most obvious thing is understanding the best moment the ideal moment to hit the slab with the sealer wait till it dries and then walk out there and cut it great concrete finishers understand the correct timing of when to float when to fresno when to edge how to modify a concrete order or the mix design based on temperatures or site conditions because they know that the mix will affect the timing of the hydration process they understand when to wait and let the concrete catch up and when to panic and call for help to make sure the finished product is going to match expectations these dynamics around timing fluctuate and change immensely depending on the type of the finish the location of the pour the time of the year the size of the crew the site access frankly the time of the day also i mean think of it if the poor isn't going to start until 3 p.m and there's only four or five or even six hours of daylight the finisher is taking that into account both when he orders the mix design and when he schedules the crew and when he decides how much time to spend on each part of the place and finish process you know as i think about this i gotta say that finishing concrete is something everyone should attempt and get a little experience with because it's an ancient technology right it's deeply connected with civilization and human flourishing it's scary it's fun it's permanent and it can be really satisfying when something comes out nice my advice though is to start small before you attempt something even remotely this size and if at all possible you've got to get some good help until you really understand what it is you're up against because a chemical reaction my friends is a wonderful and a miraculous and a brutally relentless thing thank you for watching essential craftsman and keep up the good work [Music] [Music] [Music] [Music] you

Channel: Essential Craftsman

Views: 956,527

Rating: 4.915916 out of 5

Keywords: anvil, forge, blacksmith, forging, craftsman, mentor, trades, tradesman, career, smith, carpetner, builder, wisdom, workbench, fabricate, tools, tool, tips, trick, hacks, protip, concrete, concrete driveway, cement garage floor, concrete finishing, concrete preparation, cement prep

Id: Q9UrR31RGVI

Length: 26min 23sec (1583 seconds)

Published: Tue Aug 11 2020