Before any aggregate pier system is approved for full-scale construction, the smart money is on verification. That’s where a modulus test comes in-a full-scale field test designed to confirm the pier’s stiffness in the actual ground conditions of the site.

At Garbin GeoStructural Group, we view modulus testing as more than a compliance box- it’s an engineering opportunity. A properly executed test reveals how the ground responds under load, validates design assumptions, and ensures the aggregate piers will perform as intended once the structure is in place. It’s data-driven assurance that the improvement system is working with the soil, not against it.

During testing, a reaction frame is set up, a test pier is loaded incrementally, and deflection is measured at each load step. The resulting load- displacement curve allows us to determine the composite stiffness of the pier. That data informs design refinements and provides the owner and engineer with confidence in both performance and cost-effectiveness.

Aggregate piers are often used to support heavily loaded slabs, tanks, embankments, or light foundations over weak soils. Without a modulus test, design is theory. With it, design becomes verified performance- and that’s the difference between building on numbers versus building on knowledge.

Planning a ground improvement project? Contact Garbin GeoStructural Group to discuss testing and verification options for your site