The base material, wall rock, and drainage stone all require a quarried backfill. Although you could use different materials for each, I recommend sticking with just one material for all three zones. This should be a clean crushed rock, like a #57 or #78 stone, 3/4″ crushed rock, or clean crushed limestone.
While some walls only need soil, compacted gravel backfill is the go-to for applications requiring durability and drainage. ✨ Why gravel backfill works: ✔️ Adds structure and stability. ✔️ Prevents water buildup with proper drainage. ✔️ Improves the longevity of your retaining wall. #RetainingWall #RetainingWallBlock.
Poured concrete is the cheapest type of retaining wall, in terms of materials. Pressure-treated pine is next, and wood retaining walls are becoming more popular now. If you prefer stone, granite is generally the least expensive option.
Crushed sedimentary limestone is an excellent material for backfill. In fact, where I work, it is the only high quality material available at a reasonable price. It has excellent properties and compacts well. It is suitable as the base for buildings, roads, railroads, etc... and we use it for all of those applications.
When building a retaining wall, the normal build practice is to use 3/4 inch drain rock behind the wall, in order to facilitate drainage down the hill that you are holding back with the wall. If you want to use a retaining wall just as a decoration on a raised bed that is two feet by 30 feet long,...
Properly constructed retaining walls require a specified backfill material and drainage requirements in order to relieve any hydrostatic pressure that may build up over time. Retaining walls experience a surcharge which is the pressure that the wall experiences from behind it caused by static and dynamic loads.
Absolutely! Even a 2-foot retaining wall needs an effective drainage system. Without it, water can build up behind the wall, leading to pressure that might cause the wall to lean or even collapse. All walls need systems to manage water effectively, preventing damage over time.
For cost effective materials outside of building envelopes look for fill/overburden or sand fill.
Compacted Stone
It is a highly stable and predictable material for backfilling. In many situations, compacted stone is a preferred choice for foundation backfill. It provides excellent drainage, minimizes the risk of settlement, and offers superior load-bearing capacity for supporting the structure.
Fractured rock is often the preferred choice for the drainage layer of retaining walls. Unlike rounded pebbles, fractured rock has angular edges, which help to create a more stable structure that locks together well.
Sometimes retaining walls are designed as cantilevers. These typically include reinforcement and rely on the combined strength of the concrete and reinforcement to resist bending at the base of the wall. In that case, plan on waiting seven days before placing the full depth of backfill.
Controlling the Height of the Wall
Adjusting the height of the retaining wall can lead to significant cost savings. In scenarios where it's feasible, reducing the height of the wall while allowing for a gentle slope can decrease the amount of materials needed and thus the overall expenses.
Filled Wall Blocks Promote More Efficient Drainage
You may end up with entire sections of a retaining wall that need replacing. You can avoid a situation like that entirely by filling your hollow blocks with gravel or other stones.
One major thing to avoid when building your retaining wall is lining the back of your wall with plastic sheeting as this will surely result in the pooling of water behind the wall.
While many types of solid and durable retaining walls exist, concrete and stone are easily the best options. These materials are long-lasting, rigid, durable, extremely strong, and can easily support your site.
Leca® LWA has remarkable properties which ensure its versatility for use in a vast number of structural and geotechnical applications. When used against retaining walls, Leca® LWA will reduce the weight acting on the rear of the structure by at least 75%, in comparison to traditional fill materials.
Fine-graded soils, including sand, are popular choices for backfilling due to their compaction characteristics and ability to maintain a stable foundation. These materials facilitate effective compaction and minimise settlement, providing a solid support system for the structure.
Fill sand is recommended if your project requires a backfill material.
Type A backfill material shall be stone, recycled portland cement concrete, flowable fill, or RAP. Type B backfill materials are selected soils. Where Type B backfill materials are called for, Type A backfill materials may be substituted.
Backfill the wall with gravel or sand. If you use sand, first cover the backside of the retaining wall with landscape fabric. This will keep the sand from seeping between the blocks. If you're backfilling with gravel, you can pour the gravel after every course you lay.
The backfill material must be appropriately compacted to provide a stable foundation. Hand tampers, plate compactors, or roller compactors can be used for this process. The equipment used for compacting differs based on the material's size and type.
Don't Skimp on Gravel Amount
Add an angular aggregate — clean, crushed stone or gravel between 1/2- and 3/4-in. — as a base under the retaining wall and as back fill behind it.
Base thickness = 1/8 of the height of the wall but not less than 12 inches. Stem thickness = 6 inches + ¼ inch for each foot of wall height.
Weep holes are a crucial component of retaining walls. The common function of retaining walls is to create a difference in level between the ground at the top and the area in front of the wall by supporting a height of retained soil.