Q. How many days should we wait before beginning to drive piling near a newly placed concrete retaining wall? The wall is 15 feet high and 3 feet thick at the base. The piling work will be about 12 feet from the base of the wall. If the test cube strength achieves 90% on the fifth day, can piling works commence then?

A. The strength of the concrete in this retaining wall is only one small piece of the larger puzzle. Soil conditions play a large role in how much of the vibration energy reaches the wall. The water content of the soil also can have a large effect on the interaction of the various elements in the system.

I can’t tell you at what point in time the concrete strength is no longer the limiting factor. But my best guess is that waiting until the fifth day or the 90% indicator should be sufficient to have passed that point.