I need to dig up about 2m^2 area of floor to about 25mm; hard brittle
asphalt, concrete screed, concrete raft. From recalling brick courses
elsewhere I am suspicious the asphalt & screed could be as little as
25mm, although 30mm seems more likely.

What is the best tool?
Ubiquitous angle grinder with diamond saw, 8kg SDS+, 18kg breaker?

How long?
I recall a kango removes 350kg/30min, so 0.05m^3 is 120kg or 10mins?
Is the screed likely to fracture off the concrete surface or what?

Before anyone asks, partitioned off with stud & polythene and
extractors. Backhoe & bucket would be quicker, but TNP is not a
neighbour...

On May 11, 10:34*pm, "js.b1" wrote:
I need to dig up about 2m^2 area of floor to about 25mm; hard brittle
asphalt, concrete screed, concrete raft. From recalling brick courses
elsewhere I am suspicious the asphalt & screed could be as little as
25mm, although 30mm seems more likely.

What is the best tool?
Ubiquitous angle grinder with diamond saw, 8kg SDS+, 18kg breaker?

How long?
I recall a kango removes 350kg/30min, so 0.05m^3 is 120kg or 10mins?
Is the screed likely to fracture off the concrete surface or what?

Before anyone asks, partitioned off with stud & polythene and
extractors. Backhoe & bucket would be quicker, but TNP is not a
neighbour...


Drill a test hole before you start so you know what you're dealing
with.

On May 12, 6:30*am, harry wrote:
Drill a test hole before you start so you know what you're dealing
with.

I think that is the only solution, thanks.

I found an old photograph showing the bottom of an internal load
bearing wall.

From the brick height & dimensions...
a) No screed, just 20-25mm of brittle flooring grade asphalt poured
against shuttering boards later removed to create a gap filled by
skirting board.
b) Screed 70-72mm, with 20-25mm brittle flooring grade asphalt over
the top.

Only way to know is a test hole... got some smaller diamond core bits.

If I do need to take 10mm out of the concrete, what is the best way?
Armeg scutch chisel and 3.2J SDS do not sound like they could handle
2x1m area?

On May 12, 1:07*pm, "js.b1" wrote:
If I do need to take 10mm out of the concrete, what is the best way?
Armeg scutch chisel and 3.2J SDS do not sound like they could handle
2x1m area?

Looks like I have a scale of removal...
- Marcrist BF750 diamond disc slot, try breakout with 5J SDS
- Marcrist CCU850X core stitch drill, try breakout with 5J SDS
- Apply 40J electric breaker
- Apply diesel, fertiliser, aluminium powder

Can not get there to do a test hole yet.

On Saturday, May 12, 2012 7:57:59 PM UTC+1, js.b1 wrote:
On May 12, 1:07*pm, "js.b1" wrote:
If I do need to take 10mm out of the concrete, what is the best way?
Armeg scutch chisel and 3.2J SDS do not sound like they could handle
2x1m area?

Looks like I have a scale of removal...
- Marcrist BF750 diamond disc slot, try breakout with 5J SDS
- Marcrist CCU850X core stitch drill, try breakout with 5J SDS
- Apply 40J electric breaker
- Apply diesel, fertiliser, aluminium powder

Can not get there to do a test hole yet.

It depends what the concrete is like really. Some is like cheese, some is like metal. Unfortunately for me, one set of previous owners of my house were navvys who worked on, amongst other things, the Thames Barrier. I have come across quite a lot of the iron stuff in the wrong places.

The TCT toothed SDS blades in particular can be pretty effective on their own if it is softer stuff. With the hard stuff then, like you suggest, slotting it is best. Its vulnerability is brittleness so slotting should be enough, I can't see the core drill stitching helping really, hit it at the root of the slot and long chunks will fracture off after a bit.

On May 12, 11:19*pm, wrote:
It depends what the concrete is like really. *Some is like cheese,
some is like metal. *Unfortunately for me, one set of previous owners
of my house were navvys who worked on, amongst other things, the
Thames Barrier. *I have come across quite a lot of the iron stuff in
the wrong places.

Who was under it? :-)

The TCT toothed SDS blades in particular can be pretty effective
on their own if it is softer stuff. *With the hard stuff then, like you
suggest, slotting it is best. *Its vulnerability is brittleness so slotting
should be enough, I can't see the core drill stitching helping really,
hit it at the root of the slot and long chunks will fracture off after a bit.

Thanks.

Now you mention it concrete is weak in tension, like cast iron baths,
so "has to give" once slotted & whacked from the side.

In message
,
js.b1 writes
On May 12, 6:30*am, harry wrote:
Drill a test hole before you start so you know what you're dealing
with.

I think that is the only solution, thanks.

I found an old photograph showing the bottom of an internal load
bearing wall.

From the brick height & dimensions...
a) No screed, just 20-25mm of brittle flooring grade asphalt poured
against shuttering boards later removed to create a gap filled by
skirting board.
b) Screed 70-72mm, with 20-25mm brittle flooring grade asphalt over
the top.

Only way to know is a test hole... got some smaller diamond core bits.

If I do need to take 10mm out of the concrete, what is the best way?
Armeg scutch chisel and 3.2J SDS do not sound like they could handle
2x1m area?

I am trepidating over a similar issue here. Drilled exploratory hole
seems simple until you start worrying about the location of buried CH
pipework:-)

My current idea is to carefully measure up from where a soil pipe (laid
on the oversite) exits the house, through a convenient window and back
to the floor. My interest is the overall thickness of screed plus
insulation.

regards

--
Tim Lamb