Me VS Concrete Slab - Slab is Winning - Bigger (Jack) Hammer or Other Strategies?

So I've moved ahead with the relocation of some plumbing under my master bathroom's slab. I had previously done some exploratory investigation near my existing toilet flange, and found 1) my hydronic radiant floor PEX tubing is about 1.5" under the surface, a good thing 2) I've got insulation under my 4" slab and 3) rebar and mesh in the slab 4) my existing toilet plumbing does a near 180º turn under itself to get to my main drain. I also punctured the PEX in the slab and puncture my toilet vent, which in hindsight actually meant the floor in this area was a little thinner that it might be other places...

After meeting with a plumber who agreed to do the rough-in work and telling me where I should cut and trench the slab, I got to work. 

First, I cut the slab with a diamond segmented blade about 2" penetration. 

Then I took a 7lbs sledge and gave it a few good swings to see what would happen. Nothing happened. Barely a dent. Hmmm...

Then I took my 7lbs rotary hammer in hammer mode and attacked the cut sections with it. Again, very slow going, barely a dent. 

Then I rented a 35lbs jackhammer for 3 hours, and I got 4" into the slab...and the slab...continued. 

Basically I've determined that in this area where I don't have the radiant heat lines, for whatever reason I also don't have under-slab insulation, but I do have nearly 8" thick slab. 

Now, my slab is reinforced with aforementioned rebar every 24" square, and wire mesh, but also fiber in the concrete. Together, I don't so much "break up" the slab, and need to pulverize it into gravel. I can't seem to get any "chunks" bigger than a few inches around. 

How can I make this easier? 

I plan on renting a 75lbs jackhammer for the remaining section of trench I need remove (10" x 3') but I've also wondered if I might be better off drilling holes around in the perimeter and creating "break lines" for the jackhammer to actually remove chunks.

Any suggestions?

I hate jackhammering slabs out, I charge by the hour and it's usually very expensive.

7 lb isn't really a sledgehammer, it's the thing I use to drive stakes. 20lb is minimum for concrete break up.

A 35lb jackhammer is pretty much nothing either.

Rent the biggest jackhammer you can get and attack it at an angle, not straight up and down. It will take 10 times longer than you think too

Jackhammers are not my friend. I'd rent a saw and cut a perimeter and some break lines. Much easier and faster than drilling holes. Messier too. Big saw. Big mess. 
This will give you nicer edges to meet when new concrete goes in too. 
 

I hate concrete work. Passionately. 

Also, you can drill holes or score it more too, do another line down the center if you'd like.

You really want to take it out in big pieces so don't do a bunch of scoring. The bigger jackhammer will help immensely

When we pull out pieces of floor at work we cut with a concrete saw and the. Put floor anchors in and lift them out in large chunks, it's less work and cleaner than jackhammer. We use a forklift but you could use an engine hoist of the chunks are the right size. 

Work from an edge or corner. If you don't have either, then the first piece will be very difficult. Once you create a space for the piece you want to break off to move toward, it will break away better. 

I don't want to be running a big gas powered saw indoors. 

There are some benefits to not having clean cut lines too - better adherence of new concrete to old. 

I'm thinking I may need to install some dowels, not many, but some, and therefore the big SDS-Max drill bit would have a dual purpose.  

One thing I don't want to do is rent an even bigger, heavier jackhammer, work at it for another 3 hours, and still not have it be complete. I feel like the bigger machine should be easier, not harder! 

pheller said:

I don't want to be running a big gas powered saw indoors.

Neither do we, we rent electric walk behinds with a water system. it is really clean. 

3 foot by 10 inches, reinforced, with the rebar still attached? That can be a whole day with the big jack hammer. 

Drill lots and lots of holes all around the perimeter and inside, you might get down to a half day with a big hammer and a flat chisel bit instead of a pin. 

Concrete sucks and it's extremely time consuming. I dread the work I know I'm going to have to do here in the future. 

I would hire a farm boy and say "make that go away".

That's a serious slab.

Concrete gets harder with age. We closed in mom and dads porch that the concrete was 19 years cured in the Indiana climate. Drilling the base for tapcons sucked donkey d..... it was terrible.

Dynamite? :)

The time doesn't bother me too much, and despite being dirty, loud work that is more cleanup than anything else, it's not "hard" work (except for the concrete haha). 

My main thing is down time. When it comes time to trench the area around the existing toilet, I want to be done with it ASAP so the plumber can be back out the next day installing the new line so I can start worrying about the next steps of filling it all back in again. 

I'd sooner drill a bunch of holes if that'll speed up the process because I can still use the toilet with the surrounding area full of holes, even if it does trip my wife's Trypophobia. 

Everything you are doing is a silica risk. Drilling, cutting, jackhammering.  Seriously. Rethink. Cancer sucks. 
 

The best way to cut that is with a wet saw. Eliminate silica.  Why did you stop at 2"?  Cut as deep as you can. A good sized wet saw can cut 6-8", including the rebar.
 

There are electric wet saws. 
 

If water is not an option, then you should have a Hepa filter vacuum system attached to the saw.

The best option I can offer is to hire a Sawcutting company. They will cut it with a wet hydraulic saw, and be done in less than an hour. No dust.  Concrete debris will be in a neat little pile outside.  By the time you rent all that stuff, you'd probably save money.  Those guys know how to do only one thing, and they do it really well. 
 

This is one of those times it's best to not screw with DIYing.

... and there are no advantages to broken rough edges.  It's too easy to dowel stuff back together. 
 

The broken edges are starting points for future cracks to develop in your slab. 

ICS makes a concrete saw that is a chain saw and its hydraulic. See if you can find one of them to rent. Go all the way through the slab, get the biggest jack hammer you can find and let it do the work. You want a Bosch Brute or similar Hitachi, 75-80lb class machine. You'll be done in 4 hrs.

If you can find an ICS saw cut as far through as you can with whatever saw you can find. Bigger hammer is the key, you've been using Playskool stuff so far.  Start out straight vertical and as the tool starts to bite you lay it back about 15 degrees. Chunks will pop off.

I've been aware of the silica. I've been wearing a respirator, closing up that side of the house,  I've got a fan in the window trying to push dust outside and cleaning up with a water-vac and wetting down the bathroom every time I work. I've been wetting the blades and worksurface as much as possible while cutting, as well as running a vacuum right at the cut sight. 

I'm not sure if we have a local sawcut company. Even if we did everyone is so goddamn busy I'd be waiting for months. 

The cuts I made were with a grinder and 7" circular saw.  In the area where the slab is thicker, yea, 2" is nearly worthless. Over in the thinner area, it's a bit better. 

Is it worth trying to find a specialist for a few more feet of work? 

SVreX (Forum Supporter) said:

... and there are no advantages to broken rough edges.  It's too easy to dowel stuff back together. 
 

The broken edges are starting points for future cracks to develop in your slab. 

This is exactly correct. Pretty much anytime you have any corner at all, concrete will crack

pheller said:

The time doesn't bother me too much, and despite being dirty, loud work that is more cleanup than anything else, it's not "hard" work (except for the concrete haha). 

My main thing is down time. When it comes time to trench the area around the existing toilet, I want to be done with it ASAP so the plumber can be back out the next day installing the new line so I can start worrying about the next steps of filling it all back in again. 

I'd sooner drill a bunch of holes if that'll speed up the process because I can still use the toilet with the surrounding area full of holes, even if it does trip my wife's Trypophobia. 

 

 

If it's downtime you are worried about you need the biggest jackhammer you can get. You up to this point have been lightly touching the concrete with with a rubber mallet basically.

A big jackhammer is the thing you need above all else

In reply to pheller :

A respirator is better than nothing, but it shouldn't be necessary. Wet cutting doesn't make dust, and hepa vac is very minimal.  
 

You're using the wrong equipment. 
 

Is it worth finding a specialist?  It's worth a phone call. Sawcutting guys are rarely scheduled very far in advance. It's like roto-rooter. They don't get the call until there is an issue. 
 

For me?  Damned right it's worth getting a specialist.  And it's worth not exposing my kids to that E36 M3.  YMMV. 

If you have to do it yourself, then like AntiHero said- get the biggest jackhammer you can get. 
 

And make sure the kids are away from the house for the entire time all the way through cleanup,  plus a few hours. 

Kids have been away while I was working, and luckily on opposite side of the house when they are inside.

Downside is that I'm working next to our bedroom, and we're still using the bathroom in question.

That spurred me to do an additional wipe down of the bathroom, as well travel paths and surfaces in our bedroom. 

While I probably could do the rest myself, I like the idea that a company could do it more quickly. 

I only found one local company who advertises doing "sawcutting" and concrete coring, so I'm going to call them, and I called two local concrete places, one said they aren't even doing residential quotes because they are so busy. 

The concrete backpour is super easy- anyone could do it. You don't need a concrete guy.

For Sawcutting it might be a little hard to google them.  They generally will not have a web presence.  Call ready mix concrete companies and ask for a referral, or maybe a commercial plumber or large equipment rental company. 
 

Good luck!

...or a large commercial contractor. Like one who does roads and bridges. They use the Sawcutting companies frequently. 

I told my wife about this. She works for a ready mix and material supply company that also does roads and bridges. She just laughed and said "he's seriously trying to do it himself? Just call a pro!" Then she started going on about in-floor radiant and sealed systems and I had to change the subject.