ASTM C939 - Flow Cone Test

[KBVT]

I am editing a specification section for Auger Cast Piles. I am unsure what flow cone test parameters I should be issuing to the contractor. The subsurface soils on the site are very poor, basically extremely soft silt & clays to a depth of 65-70 feet. We are using 16" diameter ACIP piles with 4000 psi grout, with depths in excess of 100 feet.

The base spec indicates a 21 second minimum requirement for the flow cone test, but the specialty subcontractor has already asked to relax the requirement to 16 sec. I am also unsure if the standard test is applicable or if the flow cone can be modified by removal of the 1/2" orifice allowing grout to pass through the 3/4" hole in the bottom of the cone. It would seem that the removal of the 1/2" orifice would allow the grout to flow out of the cone faster, decreasing the test time.

For my background, I am a building structural engineer, and a little out of my element in the intricasies of ACIP. I would appreciate any help. Thanks.

 

[KBVT]

Due to the lack of traffic in the forum, I have gone ahead and posted the question in the Structural Engineering Other Topics Forum. Please disregard this thread and I apologize for the cross-posting.

 

[dirtydude]

I have never seen a flow cone with only a 1/2 inch orifice. All ACP flow cone tests I have performed have been donw with the 3/4" orifice and the standard has called for 15 to 18 seconds. Hope that helps.

 

[GeoPaveTraffic]

I have always used the 3/4" opening for ACP.

As for allowable flow time, as long as the grout can reach the required structural strength, there should be no problem no matter how fast the grout flows.

Installation technic is VERY important with ACP. I always require full time observation by a trained professional, preferably and engineer.