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.

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.  

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.