# Slab on Grade question



## kenny911 (Apr 6, 2012)

I'm doing my final review and I'm looking at the syllabus and it mentions "Slab on Grade". What possible questions are they referring too for Geotech AM? Thanks in advance


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## BAZ20 (Apr 6, 2012)

Thanks for asking the question... I was also wondering about this... I hope senior members can share their experience...


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## treyjay (Apr 7, 2012)

you will need to know things like slabs are floors. that they are usally placed on a crushed aggregate, but they can be poured straight on the dirt in a pinch. also you can put rebar in them or maybe wwf. be sure that you know that slabs are made of concete....that is highly likely to be a test question.

I wish I could tell you more, but you can always try calling NCEES and asking them, because they write the exam and would know better than anyone.


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## YMZ PE (Apr 7, 2012)

Also they might ask if the slab on grade SHOULD be poured on-grade or if there will be any issues with doing so. If the soil is highly expansive, the subgrade needs to be R&amp;R'd as non-expansive fill or base course, or else the slab may deform due to shrinkage cracks or expansion of the clay.


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## BAZ20 (Apr 7, 2012)

Thanks treyjay and Myra... :wave2:


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## ptatohed (Apr 8, 2012)

kenny911 said:


> I'm doing my final review and I'm looking at the syllabus and it mentions "Slab on Grade". What possible questions are they referring too for Geotech AM? Thanks in advance


k9,

This is a good question and, honestly, I totally skipped the slab on grade topic in my studies (fyi, I do not recall a slab question on the exam). I looked in CERM and All In One and, while these books do contain discussion about slabs, I didn't see anything about slabs on grade. Some important parameters for the slab might be the concrete type/strength, thickness, reinforced/not reinforced, joint spacing, etc. but since this 'slab on grade' topic is under the Geotechnical AM discipline, my guess is you'd be more likely to be asked about the underlying soil parameters. Like Myra said, you want the direct underlying layer to be "select fill" (relatively permeable and non-expansive), compacted correctly, etc. Also of importance is to ensure positive drainage away from the slab. You might want to check out the Shallow Foundations section in CERM too. Good luck.


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## kenny911 (Apr 8, 2012)

I really appreciate it. Going to write this stuff down in my binder.


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## terzaghi83 (Apr 10, 2012)

Yes, slab on grade on expansive fill= bad.


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