In Surrey we encounter a wide mix of subgrade materials that make compaction control anything but routine. From the dense glacial till over the upland plateaus of Fleetwood to the soft, compressible silts near the Serpentine and Nicomekl floodplains, every site tells a different story. We've seen beautifully graded gravel borrow turn to soup after a week of Lower Mainland rain, and stiff clay that looked perfect on the lab report but failed in the field because of hidden layering. That's why we run the sand cone density test per ASTM D1556 as our primary field check. It isn't the fastest method, but when the BC Building Code and the local authority ask for proof that your structural fill meets 95% or 98% of Standard Proctor, the sand cone gives an answer that stands up to scrutiny. Before we mobilize to site, we often review borehole logs from SPT drilling to understand what the native formation looks like at depth, so we're not just testing the fill but also confirming it's placed on competent ground.
The sand cone doesn't lie: if that last pass with the smooth drum didn't achieve spec, the numbers will show it before the next lift covers the problem.
