103d: Concrete Flatwork

Question 1

My sidewalk cured but isn’t level. What happened?

Answer 1

The original soil layer probably wasn’t leveled before being compacted

Question 2

I forgot my tamper at home, can we still finish our forms today?

Answer 2

Probably not. You HAVE to compact your sub-base layer before you’re ready for concrete

Question 3

The gravel truck didn’t show today, but my cousin has a duck load of sand…can I sub it in for my sub-base?

Answer 3

Yes.

Question 4

I ordered poly for my driveway, but I’m not so sure….

Answer 4

You don’t need damp proofing for a driveway since it will be exposed to the exterior anyways….pointless

Question 5

I apparently need a concrete column in my slab but we’re almost ready to pour. What can I do?

Answer 5

You can dig a hole and construct a space for extra concrete to thicken the slab where the column will go

Question 6

Is it ok for me to place my rebar on top of my concrete after I pour it? As long as it’s in the mix write?

Answer 6

No. It has to be placed in the bottom where tensile pressure is higest

Question 7

I pulled a reference line from my garage door to build my driveway…but don’t know how to extend that all the way to the sidewalk…

Answer 7

You need to pull a string line perpendicular to it down to the sidewalk, and check for square

Question 8

My driveway needs to be 8’ wide. Can I just measure my width at 8’ and stake my 2x6 form placement?

Answer 8

No. You have to account for the thickness of the 2x6, so you will actually set your stakes 8’3” apart

Question 9

The engineer says my driveway might move more than my house foundation, but I really wanted to pour the slab at the same time….

Answer 9

Build the forms with an isolation joint so the driveway can move freely from the house

Question 10

My sidewalk to my backyard has cracks all over it after the previous winter…what should I have done?

Answer 10

Cut control joints evenly spaced along the sidewalk to provide a safe place for cracks to form during freezing and thawing

Question 11

I gotta wrap up for the day but we aren’t quite done pouring our slab….

Answer 11

Install form work to act as a construction joint with a key way, so you can pick up again tomorrow

Question 12

My slab is lumpy on the surface; I think I missed a step!

Answer 12

You didn’t screed and level it after pouring it!

Question 13

I didn’t bring a long enough straight edge to screed, can I do something else?

Answer 13

Yes. You can measure the finished height of your slab and nail a long piece of dimensional lumber across the top to act as a screed

Question 14

My driveway is 20ft wide…I DON’T have a 20ft 2x6 to screed

Answer 14

No worries. Use the wet screed method and level your concrete in sections!

Question 15

It’s pouring rain out but I need to let my concrete cure…

Answer 15

Cover it to protect it from excess water absorption from the rain

Question 16

It’s supposed to hit 0deg overnight…can I still pour my driveway today?

Answer 16

Yes. But you must keep it at a consistent warm temperature to cure; try tarps and a diesel heater

Question 17

There’s a bunch of gravel stuck to my driveway surface that wasn’t there yesterday…

Answer 17

You should’ve floated the surface to pull up cement and push down and small aggregate. Now the chunks have cured to the surface, and it’s never going to be smooth