Recommended safety measures for the removal of hot cast asphalt screed

Hello everyone,

I need your advice / tips regarding the proper removal of hot asphalt screed (approx. 50 sqm area) in an apartment and the recommended protective measures.

I plan to remove this floor structure of about 2.5 cm myself using an 18kg demolition hammer and then dispose of it via a rented container. Now I am wondering if and how I need / should protect myself appropriately? Do I need special protective clothing, such as respiratory protection, overall, gloves, goggles, etc.? Should I set up a black-and-white zone, etc.?

The house was built in 1972, and the building application from that time states that cast asphalt should be installed. The floor covering in the rooms is only floating parquet or laminate.

Image 1 - is the test drilling.
Image 2 - is the screed drilling piece - I assume to see cast asphalt.
Image 3 - beneath the screed is a kind of loose insulation with coconut fibers?.



What do you think?

Thanks for the tips.

Best regards
Chippy

Hello "chippy".
When I look at the three photos even in enlarged view, I come to the conclusion:
Neither the lower nor the upper screed layer can be made of poured asphalt!
Poured asphalt has (regarding the lower screed layer) never been applied on loose rock but as a rule (!) always on a separating layer.
"Rule" means: only if the poured asphalt was also intended as waterproofing, it was applied in a composite over a bonding bridge and bituminous sealing layer.
The upper screed layer also cannot be poured asphalt.
On the one hand, it is far too thin for that, secondly it was also applied in composite (on the lower layer), and thirdly one can see pores in the cross-section.
This is impossible for poured asphalt!
For a concrete evaluation of what exactly is going on with the installed materials, I would need to hold the core sample in my hand.
In this context an additional note: one cannot take a core sample from poured asphalt with the dry drilling method.
The bitumen would smear due to the frictional heat generated between hollow drill and material wall during drilling and would overload the torque of any drilling machine.
To still answer your questions:
A dust mask is definitely necessary, during chipping work also safety goggles and gloves! However, one should not wear Sunday trousers during demolition.
If you always chip off pieces larger than plate-size, the demolition goes quite quickly.
All other considered protective measures can be done if you are bored or want to impress your neighbors.
They are certainly not necessary.
The next problem you will encounter (not asked about here, though) is the construction of the new floor.
You should discuss that with a specialist company (screed layer) and not do this step yourself.
There are always limits for laymen that they must recognize.
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Good luck: KlaRa

Hello KlaRa,

Thank you very much for the feedback.

What do you think the material of the screed is then? Possibly just cement screed? I’m only surprised that it is still somewhat blackish. Should I take a very close-up photo of the drill piece again? I was already worried that it might be mastic asphalt or something tar-containing. Then I will contact the disposal company again regarding the necessary container. So far, I have assumed disposal of mastic asphalt and cement screed.

Should I pay attention to any standard for the protective mask? I once looked at an online retailer. So at least FFP3 or can you possibly recommend a model that I could also use for other work?

Everything regarding the screed construction is already arranged. I just want to do the demolition and disposal myself. After that, a floor heating system including insulation will be installed on the raw floor. Then a new heated screed will be laid by the screed installer. :-)

Best regards
Chippy

For reassurance:
Mastic asphalt (the term is used in building construction, not in road construction) has never been made with the binder "tar," but always with bitumen.
Tar is a by-product of lignite or hard coal, whereas all types of bitumen commonly used in building construction come from petroleum refining.
Regarding the brownish residues on the core sample, it could be bitumen emulsion screed.
In the 1970s, in residential construction, whatever was available and cheap at the time was sometimes installed. Unfortunately!
In many cases, the installation method of what we might call a "load distribution layer" did not comply with the state of technology at that time.
During dismantling, a normal dust mask is sufficient. The dust particles are not so small that we would need to switch to FFP2 (mesh size approx. 0.8µ).
This mesh size is fully sufficient for dusts.
[Persönliche Anmerkung: bei Viren geht man von Größen zwischen 0,06µ bis 0,16µ aus; weswegen entsprechende Nicht-Verwendungshinweise auf den Umverpackungen zur Kenntnis genommen werden sollten]
What was ultimately installed in your house at that time could certainly and easily be clarified with corresponding analytical effort, but the fundamental question is whether this insight reflects an acceptable cost/benefit ratio.
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Regards

Now I have also sent the photos to a disposal company and they said that it is probably cast asphalt after all. Now I am uncertain.

I have now chiseled out more surface. Here are some photos of a larger piece. On top is a kind of gray leveling compound and underneath a kind of brown paper?
Disposal would of course be expensive then :-(

What do you think? What kind of floor material is it? Can I still safely chisel out the floor with the usual protective measures?

Thanks for the feedback.

Best regards

Hello "chippy". On 18.02.2021 I gave you my notes on the subject. Possibly - if you ask often and long enough - a response will eventually come from the "community" that it is a cast asphalt. From my point of view, it will still be a misjudgment, however one that goes against your preconceived opinion. Especially with your currently uploaded photos, the binder "Bitumen" is again not confirmed. Moreover, you yourself write about a "gray leveling compound". And cast asphalt has never been and is not a leveling compound. If you do not want to agree with my expert opinion, then that is your decision, which we must accept. At least do the burn test, which will probably convince you and put you on the right track: Hold a lighter flame for about 2 minutes to the building material you suspect to be "cast asphalt". If you do not see smoke clouds, do not smell anything that remotely resembles bitumen, then please decide whether you believe my explanations or continue to raise the same question in this or other forums until maybe someone agrees with your suspicion with a corresponding answer. I am not acting here missionarily, but purely informatively! The answers to your initial questions have already been given in this forum anyway! --------------------- Regards: KlaRa