Concrete finishing....all you want to know.

[DDA52]

Originally Posted by jer29_11_13

This is the part I'm having difficulty with... that's why I was going to set interior 2x4 forms to screed to and then remove as I move along as you have explained in the next paragraph. Do you have a pictures of this aspect?

Nope, I sure don't. We don't ever do it that way due to cost. It just isn't the best way to do it for us. We would rather run wet lines and go full blast with that. I can take pics of that process on Thurs. We will be pouring that slab then.


This may sound dumb but I didn't realize I can walk in the concrete , I guess I need to get a pair of boots, you should add these to the essential tools list

You can walk all you want before the screeding is done. After, only to bugg it or fix something. Otherwise it is best to wait. It really messes up the grades. I figured boots were a given....I'll fix it later.



Thank you very much Don for explaining everything!

Yer Velcome

[DDA52]

Originally Posted by jer29_11_13

When using the knee boards is the 1/4" footprint depth the same test to know if you can walk on the slab?


No..the 1/4 is for the machine. It weighs a lot more than you do...or at least it should. I believe, with boards, you can get on it with a 1/2...maybe 3/8 footyprint. The main thing is not to sink too much. That will make a heck of a crater to have to fix. It also will displace the concrete around that spot making a ripple you won't necessarily see, but will still need to get out. When doing it by hand, it takes loads longer, so timing is essential. You need to get on as soon as possible...WITHOUT making a mess.

Not being familiar with a trowel machine, how do you adjust the blade angle?
Also how do you fine just finishers, the companies I've spoken to want to do the whole job?
Thank you Don!

Trowel machines have two type of pitch adjusters. The twist type and lever type. Mine is twist. Look at the handle in the pics. There will be a knob in the middle at the top by the operator...me. That is the adjuster. Twist clockwise to raise...counter to lower. Very easy. The lever types will be located in the same general area. Most pull back to raise and push foreward to lower.

Hired guns...good question. I would not ask the companies. Go find a finish crew working somewhere and ask them. They will know for sure. Who knows, they may even be the ones you are looking for. There are more hired guns working residential than commercial. So, find a new subdivision or house oing in and ask. If they are all wearing uniforms, don't bother. They are employees.

[hammertime]

My new home is constructed with ICF, which i feel is the way to go. So if in your area requires footings, using ICF forms is the way to go. Then you can add hydronic tubing into you floor for heating, and your well insulated from the elements.
Other things to thing about are frost heaving and stress relief. A good idea is to put down insulation under your pour to reduce heaving. Renting a concrete saw to cut the concrete to control cracks.
Exposed aggregete is kind of cold way to finish walk ways and patios and a good option.
My shop floor I didn't go with the super smooth finish because of problems i had with slippery problems.

Thanks

[mccutter]

Download the .doc file below for a "printer-freindly" version of Don's Most Excellent Concrete Finishing Procedures and Tips listed above. They are in Word 97 Format. Word Viewer can be found at Microsoft.com.

Note that the smileys had to be removed to get it to the SFT-acceptable file size...

Thanks, Don!

PS: don't forget to download the very descriptive pictures from above, as well.

[jer29_11_13]

Originally Posted by mccutter

Download the .doc file below for a "printer-freindly" version of Don's Most Excellent Concrete Finishing Procedures and Tips listed above. They are in Word 97 Format. Word Viewer can be found at Microsoft.com.

Thanks McCutter this is great!

[DDA52]

Mccutter, that is cool...and yer velcome.

Hammertime, valid points for up north maybe, but then I ain't there. I also did this thread to discuss concrete finishing. That is design, etc. Design and such are too area specific. What works in one will not in another and so on. Some of the basic principles will work, but as a rule, maybe not. That is why I stay away from that topic when possible.

As to exposed agg.....I would hesitate to tell a beginner to do it, but it can be done. If need be I can walk anyone through it. It takes some experience in reading concrete to do it well. One scew up or mis read and you have literally seconds to fix it before it is too late....or hours of acid scrubbing, depending on whether too early or too late.

[DDA52]

Ok, as promised, I did pour the slab yesterday and I got some more pics that will help I hope.

First up...Wet Screedumacation.

On this slab, I have a form set on both sides for the end of the porches. The middle was over 22' wide. My mag screeds are 16' long. So to get a line in the middle, we set two stakes with a grade nail near the middle. We then will flatten out the concrete flush with the nail. That is now our grade point. The mag screed is then used to even out the concrete from the form to the point in the middle about two feet wide in this case. We then turned 90° and used that line and the porch form to screed from.

Edit: BTW, those stakes will stay in place until they strike it off right up to them. This is a safety net deal. If the line should get off, they can always go back and reset it with the grade nail.

Two guys were raking excess and filling holes behind the board. The one man is holding the board on the form, while the other uses the wet line to go by. That line has to be held just right. If you press too har, it will dig. If you are too light, the screed will ride up over the line. Either way, your grade will be off.

In this case, they screeded off 3/4 of the slab. The concrete was then ready for the jitterbug and immediately after the bull float and hand work along the perimeter.

You may notice that we are screeding it off although it is not fully poured out. This is what you want to do. Screed off at truck intervals when possible. This was done here at two trucks down. That gave us enough to work easily and also complete the maximum while waiting for the next one. Had the second truck not been there, we would have screeded the one off and waited. Never let the stuff sit toolong, esp in hot weather. It can get away from you if you wait too long. It was not too hot yesterday..about 94°. Too long in this case would be an hour with this mix. Other mixes and conditions will change that figure, so don't use it as a rule...use this: Don't wait too long..get it done asap.

[DDA52]

Ok, I also have some pics of hand finishing examples.

First up, we finished the porches completely by hand. The guys got out on it about the time they would leave a 1/4 inch footptint. They used knee boards and hit the whole porch with the float and immediately after with a trowel. They also edged the perimeter as they went. You will notice the 3 1/2" drop on the right side. The man next to it used some of the cream he was floating up to put in the holes and imperfections on the face of the drop. ( It is legal to steal cream from one point to fill holes and imperfections at another. We do this all the time. Concrete by nature, is spotty when it dries. It is very common for some spots to dry faster than others. Sometimes when that happens, rock holes will appear due to the finishing process. If that area is too dry to fill it, get some that isn't as dry from elsewhere and fill er up. )That was later scrubbed with a sponge to leave a sandy looking finish. This was done just before or right after the porch was broomed...in other words...as it was done and done for.

The last pic shows the end result. This was the first and second hit in one fell swoop. The porch took one more trowel hit and was then broomed shortly after. Since it was a broom finish, it didn't need as much work as the smooth finish areas. It could have been smooth finished in this manner, but is risky for the inexperienced to do. When it is setting up, it can dry rapidly after the trowel hit. If you are unacustomed to reading the drying speed, it can get tough.

[DDA52]

Next up are some hand finish examples of completed steps.

Pic one is of the edge at the second hit. It is well formed and no holes should be left. It is still kinda rough and textured. The last or next hit should be progressively and markedly smoother.

Pic two is of a finished edge. It is smooth, with no imperfections or extremely slight ones. This is going under the plate of the wall, so it will never be seen. You canget away with some imperfections in this case, but I won't get into that habit. Lots of guys do and it becomes second nature....then when you are finishing an exposed edge, they have troubles getting it nice looking because they were lazy in the previous steps. Just my opinion of course.

Pic three is a pulled back view of the second. I did this to show how far in Rogelio hit with the trowel. It is hard to see because of the shadow, but in the middle, near the pipes, you can see the shiny spot...that is how far he reached in on the whole wall. The concrete inside still needs several more hits, but the edge is finished. Now, he doesn't have to go that close to the edge with the machine.

Pic four is of my main finishing tools. These are my basictools and my mainstays. L to R...6x6x1/4 stainless edger, 22" float, 16" bullet trowel and 24" finish trowel. I use others, but these are the ones that get used the most. I can do 95% of my work with just these four.

[jer29_11_13]

Once again Don a BIG THANK YOU!

Its funny that you can buy some very good videos to learn to weld, operate a lathe or mill, etc. but I've not seen one for pouring a large slab with all the steps that you have shown us here...perhaps someday you could create one...I certainly would buy it!

Fred