aspect ratio for concrete slab on grade for drainage channel

huangyhg

aspect ratio for concrete slab on grade for drainage channel
i need some information on the aspect ratio, ie width of channel and spacing of contraction joint(for concrete slab on grade).  i was suggested by a public agency that i should have 2:1 aspect ratio.  for 25'-0" wide channel, i shall place cotraction joints at 50'-0" on center and expansion joint at 150'-0" oc.  could anyone out there lead me to a source where i can find some info. on aspect ratio ? thanks.