May 27, 2016

Running Bond and Retaining Walls Are Vertical Lines Required?

Running Bond
We here at Allan Block often get installation questions.  The one that always is interesting is when the installer is trying to keep the blocks in a perfect running bond pattern.  You will notice a running bond pattern because most brick and block walls that use concrete and mortar are evenly spaced to have the edges of the following course is directly in the middle of the block below it.  Because of this familiarity with the look and aesthetics associated with these walls, there are many installers that believe that all block walls should have a true running bond. 

You can certainly install Allan Block in this manner and this is very to achieve if your wall is straight.  However, when your project has curves and corners the running bond installation gets to be more complicated.  The beautiful thing with Allan Block is that it is not required.  Let me explain:

  •          The structural integrity of your wall is maintained as long as the blocks are overlapped by at least ¼ of a block.  The front lip provides the connection between the units and this overlap is all that is required.
  • The vertical seams or running bond is difficult in curves because the setback of the wall actually changes the length of each course.  That is why the vertical seams appear to change as you stack the courses around a curve.
  • Think about the pattern walls.  Vertical and horizontal seams can be part of the wall face and not impact the stability.
  • The set back of a wall creates the strong horizontal lines within the wall’s appearance which means the smaller vertical lines are not as noticeable.  If you don’t believe me, start looking close at all of the Allan Block pictures on our website and literature.

So our answer when installers ask us about the running bond requirements…just make sure you have a few inches of overlap and that is all you need.

May 20, 2016

Retaining Walls for Water Applications

Retaining Wall for Water?  Why Not?

Live near a beach, a lake, river or stream?  Then you probably know a little something about erosion, flooding and potential water damage to your home.  One way to help remove these potential problems from around your home is to build a retaining wall.  These “water” retaining walls are built to withstand the water and will help preserve, maintain and divert water away from the areas you want to protect – your home.  Allan Block works well in this type of environment but these walls may need a bit more planning and design than a “standard” retaining wall.  Check out the information they have on Water Applications before you get started – then maybe an engineer.   

If a “water” retaining wall is what you need, then go with Allan Block – they have all the answers.

May 13, 2016

Why is Compaction Necessary When Building a Retaining Wall?

Compaction is often overlooked in residential wall projects and sometimes under considered in commercial projects.  Whether you are building a small landscape wall or a large commercial or DOT project compaction is essential to the success of the project.

Wall rock is always placed in the cores of the segmental retaining wall (SRW) units and directly behind the facing to aid in the compaction in and around the facing.  Every Segmental Retaining Wall (SRW) manufacturer’s specification tell the installer to build and compact their wall project in no more than 8 inch lifts.  What does this mean?  It means that when you stack one course of 8 inch block you must place and compact the wall rock and the infill soils behind the facing fully before stacking the next course of block.

It is very simple, NO SRW manufacturer allows any installer to stack 2 or 3 courses of block and then place the wall rock and infill soils.  Doing this WILL NOT allow for proper compaction levels.  The most common compaction level for commercial projects is 95% of standard proctor which we will not define here.

Typically compaction is done using a walk behind vibratory plate compactor or in small landscape project a simple hand tamper.

The results of improper or poor compaction is most often unwanted settlements at the top of the wall over time.  This settlement can cause ponding of water that will eventually work its way into the wall structure and potentially cause stability problems down the road.  Settlement can also cause down-drag forces on the geogrid layers that over time can cause damage to the geogrid and in some cases cause the geogrid layers to rupture.  Improper compaction can also cause wall bulging due to settlements behind the wall that drags the upper portion of the wall backwards into the settled area and pushes out the lower portions causing the bulge.

May 6, 2016

Outside Corners for Retaining Walls

Outside 90 degree corners on Allan Block walls are relatively simple to construct, but there are some tips that help improve the aesthetics of the completed wall.  When we look at a retaining wall we always look at the edges of the wall and details in the center of the face are overlooked.  When the wall has an outside 90 degree corner then, our eyes are naturally drawn to the corner.  Most professional contractors understand this and they typically will start construction of the wall at these corners and work away from them.

What happens when you have two outside corners then?  Most contractors will start at both corners and work inwards.  The two corners however may not always land at a half-block distance apart.  If the locations of the corners don’t fall at that precise half block interval then some odd length blocks may need to be cut for the corners to fit in the correct location.  This is not a problem for a skilled contractor.  If there are odd length cuts that are needed, they will randomly hide them towards the middle of the wall.  As we discussed before our eyes naturally look to the corners.  By hiding the odd cuts at random locations towards the middle they blend in to the background and only a trained eye might spot them.