Semi Lightweight Concrete

[lutein]

I am working on a renovation project on a 1969 building. It is a 2 way flat slab structure. The Record Drawing's General Notes specify "SEMI-Lightweight" concrete for the slab with 4000 psi strength.

Questions:
1. What is the unit weight of "SEMI"-lightweight concrete?
2. What kind of reduction for shear (lambda factor in ACI) for "SEMI"-lightweight concrete?

Your help would be very much appreciated.

Thanks.

 

[shin25]

I think, semi light weight concrete may have unit weight ranging from 120 to 130 pcf. To use a lamda value, you may have to find out if it was a sand light weight or some thing else. If you are not sure, then using the lowest value may be most appropriate.

 

[hokie66]

Most likely lightweight coarse aggregate and regular sand fine aggregate.