Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Basement Floor Slab on Piled Foundation

Basement Floor Slab on Piled Foundation

Basement Floor Slab on Piled Foundation

I am currently designing a 3 storey reinforced concrete structure over basement on a very loose sand/silt sub-grade. The Geotechnical Investigation Report recommends bored piles for the foundations.
The basement of this building will be subjected to ground water ingress so I wish to tank the external walls and floor structure below grade. My main concerns are as follows:

If I design the basement floor slab as an overall pile cap for the concrete bored piles, how can I effectively tank the underside of the basement slab where it adjoins the bored piles?

Should I design independent pile caps for the pile groups and pour an independent floor slab over the top. This method would allow me to fully tank the underside of the basement slab.

In the above approaches I am assuming that the basement slab acts as a raft foundation for the reinforced concrete support columns of the building.

I would appreciate your feedback.



RE: Basement Floor Slab on Piled Foundation


I would go for the second proposal of using independant pile caps with the floor slab sitting over.  Trying to seal the connection between the pile and the slab will be frought with problems because you do not cast the pile and the floor slab in the same pour.  Also, you cannot cast the waterbar into the pile concrete to form a good seal because of the nature of pile construction and the need to break off the top metre of concrete of the pile where the contaminated concrete is located.

Servicised and other similar sealant manufacturers do produce pile cap waterbar but this is designed to seal between individual pile caps and the overlying slab (so you are back to option 2 again!!).



RE: Basement Floor Slab on Piled Foundation

Have you considered "watertight" concrete as an option. The cost of concrete increase by the addition of the admixture but there is construction programme saving as well as saving on the water proofing membranes. "Caltite" is one product that is used in the UK. Pudlo Concrete is another option.

RE: Basement Floor Slab on Piled Foundation

Thanks SuqlainUK and Andy for your comments. I think I will be going with Option 2. I have considered "watertight" concrete but because of the occupancy of the proposed basement area I will go with the fully tanked option to ensure no water leaks.



Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close