April 29, 2016

Why Do We Call it Wall Rock?

Wall Rock
Wall Rock is defined as well graded rock with less than 10% fines.  Many quarries refer to it as drain or sewer rock because it has no fine grained material in its makeup which allows water to pass easily through it.  

W
Block Connection
all Rock is very important to any segmental retaining wall (SRW) no matter how tall.  Some people might claim that the primary function of Wall Rock in an Segmental Retaining Wall (SRW) is to promote drainage but that is not true.  

Incidental Water Drainage
Wall Rock’s primary function in an SRW is to aid in the compaction in and around the facing.  Its second primary function ties directly to the first and is to aid in connection between the facing units and the geogrid layers.  Its other, less primary, function is to allow incidental water that may get into the wall structure to drain freely down to the drain pipe at the bottom of the wall facing and route the water out of the wall, keeping the facing dry.


So please do not refer to this material as drain rock because now you know drainage is not its primary function.

April 22, 2016

Where is the Water Going?

Improper water management is a leading cause of wall failures.  To help mitigate this potential problem, proper water management is critical throughout the life of your retaining wall.  In an earlier post, we touched upon the planning that must be done in order to direct water away from your retaining wall using swales, berms, and other grading. 

In addition to these suggestions, the secondary line of defense is the minimum 1 ft (0.3 m) of clean stone behind the wall.  This drainage column allows incidental water to migrate downward to the base of the wall.  Once the water makes it to the base of the wall, it enters the drain pipe.  The water is then expelled to daylight through a vent.  As noted on the Water Management page of the Allan Block website, the details require a toe drain for walls over 4 feet (1.2 m) tall.

Once the wall is built correctly with proper drainage, the owner must assume responsibility for the water management for the life of the structure.  If future site improvements involve grading the site differently, keep in mind how water may flow and ensure that it does not flow directly toward the wall.  If new gutters are put on the house, or a new sprinkler system is installed, avoid having this water pool near the top of the wall.  Taking care to avoid water management issues will prolong the life of the retaining wall and keep it maintenance free.


April 15, 2016

Patterned Retaining Wall - Putting a Puzzle Together

As I was putting the finishing touches on my retaining wall I had a huge sense of accomplishment.  Similar to the feeling of finishing one of those 1000+ piece puzzles and don’t even get me started on the 3D puzzles.  However, that is exactly what I had done.

I loved the clean, crisp lines the AB Ashlar Pattern provided when I used the AB Collection by Allan Block.  The dealer did provide some instruction and did say that the pattern installation would take a little more time.  He did provide a few patterns for me to use.  Now these patterns were nice during the installation, but I found them more useful as I was trying to figure out how much material to order.  Obviously, I had a budget and simply overestimating block was not going to fly with my wife.  However, my local dealer had an estimating tool on his counter computer, which I later found on Allan Block’s website and confirmed the estimate. 


The project was a great success and the pattern did create the look I was going for.  It was just like putting a puzzle together, but easier because the pattern was the road map.

April 8, 2016

Special Retaining Wall Conditions

I just wrapped up helping an engineer with his design and thought to myself “this is a great wall to blog about.”  The wall was nothing spectacular, in fact, it was quite ordinary.  All too often we get excited about those monster walls and forget that most of the walls built are less than 10 ft (3 m) tall.  What made this wall interesting was the slope below the wall, a parking lot above the wall, and a very tight job site.  For a detailed look at some of the conditions you need to watch for, see the Conditions page on the Allan Block website. 

Slope Below a Wall
The first thing we addressed was the slope below the wall.  A general rule of thumb is to bury additional block when there is a slope below the wall so you have a minimum level area, or bench, of 5 ft (1.5 m) extending from the toe of the wall horizontally to daylight. 

Global Stability
In relation to this slope below the wall, we discussed the potential for a global stability problem.  A global stability failure can be defined as the entire hillside slipping and sliding to the bottom of the slope which would obviously take the Allan Block wall with it.  Global stability can also be a concern when building terraced walls, working in poor soil conditions, or building near water.

Next, we discussed the location of the wall on the jobsite.  The wall’s setback was a critical factor in determining what type of block would be used.  Segmental walls have a setback, or batter, and as you can see in this picture, as the wall height increases the wall setback from vertical also increases.  We determined that the AB Stones, with an approximate 12-degree setback, would not fit in the proposed location.  Because of this, the engineer chose to use the AB Classic block with a rough setback of 6-degrees.

Surcharge
Finally we discussed the surcharge from the parking lot.  A surcharge can range from a sidewalk for a walking path, to a major freeway carrying thousands of vehicles per day.  The wall design will be influenced by the expected load of this surcharge and its location in respect to the wall.  When the engineer designed the wall in AB Walls Design Software, he was sure to include the load from the commercial parking lot on the retaining wall.

Once the local engineer had the wall designed, he used the new “Send Info” button in AB Walls Design Software to send a preliminary material estimate to his local AB Sales Representative.  In no time, the sales rep contacted the engineer with a couple AB Certified Contractors that were interested in bidding the job.


As I mentioned, this was by no means a monster wall, but it did demonstrate a few of the conditions that need to be considered when designing your retaining wall.  For additional information, please visit allanblock.com or your local engineering professional.

April 1, 2016

Decorating your Retaining Wall


Have you already installed a retaining wall at your home? Did the pictures in the brochures look different than how your wall looks? If so, you may be missing flowers and shrubs that can bring your entire project to that final aesthetic appeal that you were missing.

If you are like most homeowners, you might not have been able to pay for a complete installation and landscaping in a single phase. By now, you have already had installed a retaining wall and completed your seeding to give you more green space or to add appeal to your yard. Whether you planted grass and it doesn't grow thick enough or you planned on adding plantings after the fact, it might be time to plan, design, and install flowers in the final phase of your project.

By using the Internet or visiting a local nursery, you can receive design help for which flowers and plantings to use. Make sure you ask about the amount of sunlight, how much maintenance is required, required distance between plantings, and how deep the root ball is required to be placed.  These may be only a few of the many questions you might have, but are a good starting point during the planning portion.


Once you have the design completed and the flowers ordered, installation is the final step. Plant each flower and shrub according to the installation process.

Now that the flowers and plants are installed...finish off the area with a mulch that fits the color scheme and step back to review the transformation that just took place. Flowers can add even more appeal to the new space and allow you to tie everything together.


Make sure you take pictures throughout the year as your flowers begin to bloom so you can capture the overall transformation while giving you bragging rights at how great your landscaping project came together!