The Science Behind Direct Displacement Micropiles: A Comprehensive Guide

by | Dec 7, 2023 | News, Stelcor®, Stelcor® Historic Preservation

Thanks to the unique advantages of  STELCOR DDMs, they consistently produce better results than projected in the design process. 

Here’s why… 

Our internationally patented STELCOR Drilled-In Displacement Micropile produces ZERO spoils and installs quickly using highly mobile, quiet and vibrationless equipment. 

And while STELCOR is our proprietary and internationally patented product, it’s been developed from tried and tested technology.

Steel and grout have been used together for structural reinforcement in the construction industry for more than 100 years.

Simply put, we engineered a way to use these same two elements more effectively.  The result is STELCOR. The internationally patented STELCOR DDM, which produces ZERO spoils or vibration, and installs quickly using highly mobile and relatively quiet equipment. 


In some ways, the key elements of STELCOR seem deceptively simple. The drive plate enters the ground, followed by the deformation structure, a lateral displacement plate and a reverse auger/reinforcing steel auger that runs the length of the pile. 

Using hydraulic-powered rotary equipment, STELCOR DDMs are turned into the ground while crowd or downward pressure is exerted on the steel core. Simultaneously, a continuous flow of grout is provided to the top of the pile. Reverse flighting welded to the steel core draws the grout into the annulus created by a displacement head located near the tip of the steel core.

The soil is displaced and not removed. The end result is greater loads at lesser depths. The STELCOR pile is embedded into the improved soil with a unique corrugated weave of grout which greatly enhances the soil bond and load transfer capacity.

We place grout ports every 5’ along the length of the pile, ensuring a grout supply to lower sections. This takes care of any concerns around the unlikely event of soil collapsing on the shaft in a particular zone. 


We recommend a grout mix of 0.44 water to cement (W/C) using Type I/II Portland cement.

It’s essential to use a high-shear/colloidal mixer.



STELCOR 1200 – 0.38 Cubic ft. per lineal foot

STELCOR 1400 – 0.44 Cubic ft. per lineal foot

STELCOR 1600 – 0.67 Cubic ft. per lineal foot

STELCOR 1800 – 0.88 Cubic ft. per lineal foot

STELCOR 2000 – 1.15 Cubic ft. per lineal foot

*Note: 1200 = 12” Corrugated Grout Column, 1400 = 14” Corrugated column.


The STELCOR pile takes advantage of the strengths of steel and grout, uses relatively small installation equipment, produces no spoils and consistently produces better results than were projected in design.

Continuous Steel Core

  • Pipe to Pipe compressive load transfer
  • Lateral Capacity at connection greater than the pipe
  • STELCOR’s steel profile and placement yields greater lateral capacity and buckling resistance 
  • Interior confined grout column increases axial compression capacity and pile stiffness, allowing for increased lateral capacity.

From structural, geotechnical, mechanical, and installation standpoints, STELCOR just makes sense, and the load test results prove it.

Central Steel Pile Shaft

  • 3.5”O.D – 7”O.D 80KSI Tube
  • A primary load-carrying element

Max Test loads Per Pile

  • 325 Ton (650kips) Compression
  • 325 Ton (650kips) Tension

Because STELCOR DDMs need minimal installation equipment and no spoils need to be removed from site, you can make significant savings.

STELCOR is the perfect solution when the objective is to provide a deep foundation solution in extremely poor soils at comparatively shallow depths, repeatedly delivering higher-than-expected load test results in compression, tension, and lateral applications.


The benefits of STELCOR DDMs are many and clear. We’ve distilled the key benefits down to our top six:

  • Highly reliable and repeatable
  • Higher capacity and less depth in poor soils
  • Increased installation speed
  • ZERO spoils
  • No vibration
  • Low mobilization costs

Flying Excavators and STELCOR DDMs at a Paper Mill in Duluth, MN

A new paper-making machine necessitated the installation of a new deep foundation, but the project faced multiple challenges: there was no clear access, a 9-12 inch concrete slab spanned the install area, and spoils would be difficult and costly to manage. 

Find out how STELCOR excelled at Duluth Paper Mill

Discover how STELCOR DDMs could be the perfect solution for your next deep foundation project: just ask our IDEAL team! 

We provide general and installation contractors with free design support, value-added deep foundation engineering designs and redesigns that can deliver significant savings to your bottom line.  

You can also rely on our commitment to manufacturing high-quality, American-made helical piles that are competitively priced. 

Use the chat or text function on our website to get in touch, or fill out this form to get a quote.