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September 2023

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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.

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The Value of SRWs vs Alternate Reinforcement Systems
10/5/23, 2/22/24

Segmental Retaining Wall Design
Sign up: 10/12/23, 2/29/24

Best Practices for SRW Design
Sign up: 10/19/23, 3/7/24

AB Walls 3D+Terraces Basic Tutorial
Sign up: 10/26/23, 3/14/24

Water Management and AB Walls 3D+Terraces
Sign up: 11/2/23, 3/21/24

SRW Inspectors Presentation
Sign up: 11/9/23, 3/28/24

Terraces and Global Stability in AB Walls 3D+Terraces
Sign up: 11/16/23, 4/4/24

Seismic Consideration and Above Wall Considerations in AB Walls 3D+Terraces
Sign up: 12/7/23, 4/11/24

Complex Composite Structures and No-Fines Concrete with AB Walls 3D+Terraces
Sign up: 12/14/23, 4/18/24

SRW Architectural Presentation
Sign up: 1/11, 4/25

GRS/IBS Application
Sign up: 1/18, 5/2

Submittals and 3D Modeling in AB Walls 3D+Terraces
Sign up: 1/25, 5/9

AB CADD within the AB Walls Design Software
Sign up: 2/8, 5/16

AB Fence Design and Installation
Sign up: 2/15/, 5/23

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In this Issue:

Certified the most New Contractors

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Allan Block Workshop Videos
Reference Document
Design Professionals

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Case Study: Level Surface for Candelas Medical Development

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In Arvada, Colorado a new medical center is being built to accommodate the increasing population due to numerous new residential developments. With the location for the Candelas Master Development plan consisting of rolling hills, a retaining wall was necessary to create buildable land.

CTL Thompson was the engineering firm working on the layout and design of the required retaining wall. The final layout that CTL Thompson came up with consisted of multiple walls in a terraced application that reached upwards of 35 ft (10.7 m) following Best Practices recommendations.

The construction was done by Miller Wall Company, an Allan Block Certified Installer, who has been installing large and complex commercial retaining walls since 1984. With the scale of the project, the biggest hurdle they faced was the logistics of the earthwork.

Check out the full Level Surface for Candelas Medical Development case study for more in-depth information.

Zero Section

Engineer Talk: The Importance of Good Soils in Tall Walls

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Engineering tall Allan Block Retaining walls demands meticulous attention to detail, especially when it comes to the soil being used. Allan Block Retaining walls have earned their reputation in engineering due to their modular design, aesthetic appeal, and versatility. Yet, the foundation on which these remarkable structures stand—the soil—often remains in the shadows. Let's bring it to the forefront.

Not every wall of the same height is equal in the eyes of engineering. The concept of "tall walls" comes into play when structures reach heights of 10 – 15 ft (3 – 4.5 m) and over. Factors like site conditions and additional surcharges, such as slopes or structures above the wall, influence this definition.

The foundational pillar of a tall segmental retaining wall’s (SRW) stability and performance is the quality of the underlying soil. Good soils are characterized by:

Tall Wall

  • Adequate Cohesion: The soil possesses the necessary "stick-togetherness" to resist shearing forces, helping to keep the wall stable.
  • Appropriate Friction Angles: The soil has the right balance of interlocking particles to resist sliding, which is crucial for maintaining the wall's stability. The best soil is wall rock or select/structural fill with less than 10% fines, to the limits of the geogrid lengths.
  • Sufficient Bearing Capacity: The soil can withstand the expected loads from the SRW without compromising the wall's structural integrity.

These will provide a solid and reliable base for the wall structure. Engineers rely on these soil properties to design the wall to withstand the anticipated loads and external forces effectively. Refer to Chapter 6 in Best Practices for more on Soil & Compaction.

Benefits of using good soils:

  • A stable foundation minimizes the risk of wall movement, cracking, or deformation.
  • Good soil ensures that the bearing capacity of the foundation is sufficient to handle these loads without compromising the wall's integrity. Insufficient bearing capacity can lead to settling, tilting, or even catastrophic failure of the wall.
  • With good soil as the foundation, engineers can better control and predict settlement rates. Properly compacted and stable soils reduce the risk of excessive settlement, which can negatively impact the performance and aesthetics of the SRW.

The quality of soil beneath a tall segmental retaining wall is a critical factor that directly impacts its stability, load-bearing capacity, longevity, and overall performance. Engineers must prioritize soil analysis and ensure that the chosen site possesses good soils to create safe, durable, and reliable SRWs that meet the demands of complex engineering projects and provide long-lasting benefits to the communities they serve. For more information on Designing Tall Walls, refer to Chapter 8 in Best Practices.

Tools: For Fast Quick Designs, Use the Zero Section in AB Walls

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At Allan Block we strive to be ‘Always Better’ as our motto says. With the addition of terrace design to AB Walls Design Software, a new tool was added to aid in segmental retaining wall design for these complicated projects. Being able to create a full design within the software speeds up the process from start to finish. But what if you just want to show an example to convey a concept or quickly check an idea for feasibility?

Use the Zero Section in combination with terrace design to create cross sections with ease. All the features available when creating a full wall design are available within this module as well.

Zero Section

To learn how to use the Zero Section with terrace design check out the AB Walls Reference Document for Designers or reach out to the engineering department for a full tutorial at either or call 800-899-5309.

Contractor Talk: Terraced Wall Compaction

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Allan Block has learned many lessons over 30 years in business. One of those is the importance of compaction when building segmental retaining walls. As new lands open to development, large grade changes are becoming the norm. One of the easiest ways to solve aesthetic challenges on these sites is to create tiered retaining walls, which help to soften abrupt changes in elevation.


Achieving proper compaction is just as important when designing and building a retaining wall. The soils being supported by the lower walls end up becoming the foundations for the upper walls. Ensure that compaction testing procedures and requirements are supplied by the designer and followed by the installation team. Communication is key to a successful project. Refer to Allan Block’s Best Practices Chapter 6 for Compaction Guidelines and Responsibilities.

No matter if your project is big or small, pay close attention to the transition areas where a wall splits and becomes two. If sufficient compaction is not achieved differential settlement can occur over time and cause aesthetic concerns.

For further inquiries please reach out to the Allan Block Engineering department at or call 800-899-5309.


Hot Topic: Proper Embedment for when there is Toe Slope

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When designing and estimating a retaining wall, the toe slope is often a key component of the design that can be overlooked. The embedment of the segmental retaining wall into the ground helps provide a stable base for the wall. It can be easily missed on a bid or project design and has the potential to make a significant impact on the overall success of the project.

To design and calculate a toe slope below the wall, the engineer must always consider the stability of the slope. Even a relatively short slope can be a problem if the wall is not embedded deep enough into the slope. The reduction in stability is directly related to the reduction of shear resistance along the failure surface and the weight of soil stabilizing the structure.

The recommendation for block embedment with a toe slope is to bury enough blocks so that from the toe of the wall a 5 -7ft (1.5-2.1m) horizontal bench to daylight is created.


For example, a 2:1 slope below a 6 ft (1.8m) wall, creates a horizontal 5 ft bench, with 3 ft (0.9 m) of embedment. See below for details:

Embedment Equation

After the wall is complete, the level area can be backfilled to continue the appearance of the continuous slope. Depending on the soil type and slope, a global stability analysis may be necessary to model those grade changes in slopes.

Feel free to reach out to Allan Block’s Engineering Department at or call 800-899-5309 for preliminary global analysis or assistance.

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