Technical News

Exclusively for Allan Block Design Professionals

March 2022

Join us:

# # # # # #

More Technical Newsletters

Allan Block

ABU Online

Our Design Professional ABU Online events were created to help you with your retaining wall needs. Our local production and sales partners will be happy to schedule in person training on any topics you see below (call us if you are looking for those individuals) but feel free to use these to help with immediate needs.

training opportunities

Signup for our Webinars

All eligible for 0.1 CEU/1.0 PDH
60 minute sessions

Held at:
8AM, 11AM, 1PM or 4PM CDT
on the date listed

Submittals and AB Walls 3D+Terraces
Thursday 3/17

3D Modeling and AB Walls 3D+Terraces
Tuesday 3/22

Water Management and AB Walls 3D+Terraces
Thursday 3/24

Best Practices for SRW Design
Tuesday 3/29

AB Walls 3D+Terraces
Thursday 3/31

Segmental Retaining Wall Design
Thursday 4/7

SRW Inspectors Presentation
Thursday 4/14

SRW Architectural Presentation
Thursday 4/21

AB CADD Tutorials
Thursday 4/28

Complex Composite Structures (CCS) and AB Walls 3D+Terraces
Thursday 5/5

No-Fines Concrete and AB Walls
Thursday 5/12

Terraces and Global Stability in AB Walls 3D+Terraces
Thursday 5/19

AB Fence and Installation
Thursday 5/26

Above Wall Considerations in AB Walls 3D+Terraces
Thursday 6/2

Seismic Consideration in AB Walls
Thursday 6/9

Go To Webinar


Once registered for an ABU Online event, you will receive an email notification with a calendar invite attached. Simply open that calendar invite and save it to your calendar for easy access in the future. In addition, you should receive 2-3 email reminders about the event.

Be sure to follow us on LinkedIn to see all our great announcements and upcoming trainings.

Inspiring Project Ideas













In this Issue:

Vintage at SLO, San Luis Obispo, CA

Back to Top

Vintage at SLO is a luxury apartment complex located just two miles southeast of downtown San Luis Obispo, CA; offering its residents luxury living without sacrificing convenience. When the developer was designing this community, they realized they needed a solution to create the required parking spaces. Creating this parking area would prove to be quite the challenge though; an adjacent road 15 ft (4.5 m) above the proposed parking lot elevation was being widened to accommodate increased traffic loads. The developers originally looked at a cast-in-place retaining wall to create usable land but when faced with exorbitant costs, they turned to Allan Block for a better solution.

Bus Stop

This area is geologically difficult to build on due to the poor clay soils, high seismic risk, tight space limitations and utility lines. The developers did not think a segmental retaining wall would even be an option on this project because the geogrid reinforcement would encroach the property lines and the excavation would have disturbed the roadway. The Allan Block Engineering team proposed a design using No-Fines Concrete (NFC) to reduce the overall structure depth. The estimated cost of the completed Allan Block retaining wall using NFC came out to be much less than the cast-in-place wall. The cast-in-place wall footing alone was about the same price as the whole Allan Block wall. Without the use of NFC and the support from Allan Block’s engineering team, the developers would have been limited to a cast-in-place wall, essentially doubling their expenses.

Check out the full case study on our entire case study library.

Tools: AB Walls exports to ReSSA for Global Stability

Back to Top

At Allan Block, we pride ourselves on being able to provide a product that gives customers more usable land. However, not all reclaimed land is the same. You may have situations where slopes are at the top and bottom of the wall, poor site soils, and groundwater present. Or even a combination of conditions that could impact the overall stability. Internal Compound Stability (ICS), which is included within AB Walls, performs a modified Bishop’s slip arc analysis looking at an envelope 2x the height of the wall back from the wall facing. This analysis should be not used as a replacement for a true global stability analysis, but Allan Block has a solution.

There are several software applications commercially available for performing global stability analysis calculations. Although the AB Walls Design Software does not perform global stability analysis, the software does allow designers to export cross sections directly into the ReSSA global stability analysis program. With a few simple clicks, designers can quickly create a file for any of their designed cross sections. This can save designers hours of time modeling their design in a global stability software application.


The designer can then open the file within ReSSA and run the analysis to ensure their design will not be impacted by slip arcs running underneath the wall or outside the wall envelope.

If you have questions on a project or need assistance to run the global stability analysis feel free to reach out to our engineering department at or call 800-899-5309.

Complex Composite Structures as a Solution for tricky sites!

Back to Top

How many projects have you seen that a standard retaining wall design did not fit the requirements of the site? Think about the times when you would like the economical solution an Allan Block retaining wall can provide, but you have one or more of the following:

  • Utilities directly behind the wall in the reinforcement zone
  • Property line close to the back of wall
  • Excavation limitations (Bedrock, existing structures above wall, etc.)
  • Fences above

You may still use an Allan Block wall, but do you know about Complex Composite Structures (CCS)?

Geogrid Wall Structures

CCS are walls that are designed as a single wall section with two distinctly different Structures positioned one on top of the other. These are identified as complex because they are structures that are a combination of more than one uniform structure. They are composite structures because they rely on multiple materials to resist driving forces to create a safe and effective retaining wall solutions.

What are some scenarios that CCS could be a solution?

  • Geogrid Wall above or below
  • No-Fines on top or bottom of Geogrid Wall Structure

If you have a project that follows one of the above listed criteria or have a complicated site, check out our AB Engineering Manual Chapter 7 for more information on CCS.

We also provide tutorials on how to apply CCS in our AB Walls Design Software. Email us at to setup one up.

Contractor Talk: Corners in Retaining Walls

Back to Top

Though Allan Block strongly recommends designing AB segmental retaining walls (SRW’s) using curves in lieu of corners, there are indeed options for incorporating corners into projects. Certain application steps, aspects, and regulations should be implemented for successful execution.


Corner design type – Is it an inside or outside variation? Inside corners require removing part of the section of the top lip from the first black making the lip line up with the adjoining block. This will allow the opposite wall to adjoin and subsequent courses to lay flush. Outside corners incorporate the AB Corner, with no need to cut blocks as the wall progresses.

Geogrid considerations – Placement and usage of geogrid is important with SRW corner design. Inside corners require alternating courses that extend the grid past 25% of completed height of the wall. Simply divide by four, use the result for the additional grid, and account for it in your planning. Outside corner grid applications require that each side is reinforced independently from each other. Also consider that geogrid should never be placed directly on top of each other when laying each segment.

Geogrid Outside corner

Capping – With either option, cutting AB Capstones at a 45° angle will finish corners seamlessly.

Keep these considerations in mind when planning and designing walls with corners. Contact us at if you need preliminary assistance with corners, or give us a call at 800-899-5309 at ex. 3.

Hot Topic: Segmental Retaining Walls (SRW) or Cast-in-Place – Which is Better?

Back to Top

For decades, commercial site developments have commonly constructed cast-in-place reinforced concrete walls to retain soil. However, since the mid 1980’s, segmental retaining walls (SRW’s) like Allan Block have provided a better solution to these rigid walls. Some of the advantages SRW’s have compared to cast-in-place walls include the following:

  • Lower installation cost (30-70%)
  • Limited excavation for footing preparation since frost depth is not a factor
  • Faster installation
  • Easier to design elements to fit site conditions
  • Better aesthetics options
  • More reinforcement options (e.g. geogrid, no-fines concrete, wall anchors, etc.)
  • Flexible vs. rigid system




Aside from all the advantages listed above, what is often missed is the fact that SRW’s can also out-perform rigid walls, particularly in the most aggressive circumstances possible, such as during an earthquake. SRW’s ability to withstand seismic loading conditions has been proven in both the laboratory and the real world.

Allan Block’s full-scale seismic testing documented that SRW’s can withstand large seismic forces. The testing subjected the test walls to forces up to 0.8g and all experienced only minimal deflection and/or settlement. The tests showed the block facing, soil mass and geosynthetic reinforcement all moved together as a unit, in phase with the earthquake induced forces. It was suggested by Dr. Hoe Ling from the Columbia University that these structures, that are both flexible and coherent, are ideal for seismic conditions (AB Seismic Research Summary, Reference Document #R0505, August 2003).

In today's world, with Segmental Retaining Walls being tried and true for more than 30 years, there isn’t much of a market for traditional cast in place walls anymore. The next time you think you must use a cast in place wall on a project, just call Allan Block’s Engineering Department, 800-899-5309 x3, for a second set of eyes to see how we can find the most efficient design.

Engineer Spotlight: Jeff Schwindt - Harper Houf Peterson Righellis Inc.

Back to Top

This time around for our engineer spotlight, we are highlighting Jeff Schwindt, a great wall engineer out of Portland, Oregon. Jeff started his engineering career at the University of Portland and graduated in 2004 with a degree in engineering. After college, Jeff worked for about a year for a Washington DOT structural and materials testing lab. Jeff was first introduced to segmental retaining wall design when he moved to a multidisciplinary firm doing structural design. After a few years, Jeff found himself at his current company, Harper Houf Peterson Righellis Inc., which specialized in civil design work. Jeff wanted to create his own firm after the 2008 market crash, but then decided to approach the company to create a partnership. Ever since then, Jeff has been a proud associate partner of Harper Houf Peterson Righellis Inc.


When asked, how has Allan Block contributed to his success, Jeff praises the support and literature supplied by Allan Block. Several of our older resources have been a great help year after year for him. For example, Jeff will consistently reference one of the technical newsletters on fences above retaining walls. For him, it has been an invaluable resource to help explain to DOT employees why we take a certain design approach or why extra reinforcement is needed. It is one thing when he tells the DOT employees, but it is another if he can provide a document from the block manufacturer that backs up his position. AB Walls has also been a great tool for him and his team. Jeff said that in comparison to other SRW design tools out there, AB walls is the easiest program to make quick adjustments as well as incredible flexibility. From geogrid reinforced walls to no fines concrete retaining walls, the availability of these options gives him the choice to choose which option he would like to design with.

Jeff had some advice to new engineers starting out in the retaining wall design industry: get your hands dirty. Jeff praises Allan Block’s Contractor Certification Class because it is one of the best opportunities to get a better understanding of the installation process, which helps speed up installation and reduce headaches when designed properly. It is one thing to understand the math behind the design equations, but it is another when you can see the principles in practice. Jeff has found that his hands on experience has provided him with the knowledge necessary to work as a team along with the contractors.

Did We Miss Someone? If you know someone at your company who doesn't want to miss out on this amazing newsletter, send them this email so they can sign-up for the AB Technical Newsletter here!

Allan Block Corporation
7424 W. 78th Street, Bloomington, MN 55439
Help & Support Center: (800) 899-5309
You have received this email because you are an Allan Block Design Professional or are otherwise affiliated with Allan Block. If you have no more interest in receiving emails from us, please unsubscribe.