Repair Seawalls without major excavation and without replacing tie-backs
Backfill loss is one of the leading causes of seawall distress. Water enters through joints, cracks, tieback penetrations, and damaged sections of the wall, gradually washing soil away and creating hidden voids behind the structure.
These voids can lead to settlement, sinkholes, loss of support, and costly structural repairs.
Cellular Foam Concrete (CFC) offers a practical alternative to extensive excavation. Pumped through small access holes, CFC flows long distances and fills hidden voids and washouts behind seawalls. Once cured, it provides uniform support while helping reduce future backfill migration.
Benefits of Cellular Foam Concrete include:
• Flows into irregular voids and washouts
• Self-compacting with no mechanical compaction required
• Lightweight, reducing loads on existing structures
• Pumpable over long distances
• Minimal excavation and disruption
• Available in permeable and non-permeable formulations
• Compatible with existing seawall repair methods
Typical applications include seawall backfill repair, sinkholes behind seawalls, void filling, tieback stabilization, bulkhead rehabilitation, and marine structure repair. Sinkhole and void filling means CFC can be used for many rehabilitation projects in waterfront areas.
To learn more about Cellular Foam Concrete and Richway CreteFoamer systems, contact us using the form below.
Call us: 319 596 5941 email directly to [email protected] Richway Solutions LLC Janesville, Iowa, USA
Cellular foam concrete has a decades-long track record on large commercial retaining walls, road sub-bases, and slab-on-grade construction, void filling, and many other uses. The same advantages that make it the engineer’s choice on those demand-ing projects — no compaction required, reduced lateral wall pressure, self-leveling placement — make it a game-changer for foundation repair and related uses. And it is why an increasing number of foundation repair contractors are already using CFC to solve problems and provide a wider and better range of ser-
vices to their customers.
Richway equipment is already in the hands of contractors throughout North America doing exactly these large-scale applications with equipment producing up to 100 cubic yards an hour of cellular concrete. Now Richway is bringing that proven technology within reach of foundation repair contractors with the LV Series Cretefoamers, as low as 3 cu yds/hr continuous production rate.
CFC is a lightweight concrete made by adding air to a Portland cement and water slurry. The air is added by using an detergent type foam to precisely control the density and other properties. It can be made to be very flowable to fill even the smallest void and be made either self-leveling or stiffer to stay where it is placed. It is always self compacting and when cured behaves like full density concrete, but at a lower density and strength
TECHNICAL INFORMATION: Use of Cellular Foam Concrete for Seawall Backfill Construction and Repair
For seawall backfill repair and rehabilitation, Cellular Foam Concrete (CFC) offers several advantages that are difficult to achieve with conventional sand, stone, grout, or flowable fill. (CLSM)
1. Fills Voids Completely
The most common seawall problem is loss of backfill through joints, tie-rod penetrations, cracks, and weep holes.
Because CFC is highly fluid during placement, it can:
- Flow into irregular voids and washed-out areas
- Fill spaces beneath slabs, sidewalks, docks, and pool decks
- Reach locations that excavation cannot access, can be pumped up to several hundred feet
- Create complete contact with existing soils and structures
This is often the single greatest advantage of CFC.
2. Extremely Low Lateral Pressure After Cure
Unlike sand or stone, cured CFC behaves as a low-density solid.
Benefits include:
- Does not continue to exert active earth pressure
- Eliminates settlement of loose backfill
- Reduces future movement behind the wall
- Helps stabilize compromised seawall sections
For older seawalls with questionable structural capacity, this can be very important.
3. Lightweight Fill
Typical seawall backfill materials:
| Material | Approx. Unit Weight |
| Sand | 110-125 pcf |
| CLSM | 120-140 pcf |
| Soil | 95-130 pcf |
| CFC | 25-90 pcf (Adjustable by the amount of foam added) |
Using 30 to 40 pcf CFC can reduce dead load by roughly 75% or more compared to conventional fills.
This is valuable where:
- Tiebacks are overstressed
- Wall movement has already occurred
- Underlying soils are weak
- Additional loading could accelerate failure
4. Can Be Installed Through Small Holes
Most seawall repairs are performed from the landside.
When necessary CFC can often be pumped through:
- 1.5″ to 3″ injection holes
- Existing access openings
- Small core holes in slabs or decks
This minimizes:
- Demolition
- Landscape damage
- Dock removal
- Concrete replacement
5. Self-Compacting
No vibration or mechanical compaction is required.
The material:
- Flows around obstructions
- Fills beneath utilities
- Encapsulates tie rods
- Produces uniform support
This eliminates many problems associated with compacting soil in confined areas.
6. Reduces Future Settlement
Once cured, CFC becomes a monolithic mass.
Unlike sand backfill, it:
- Does not wash away
- Does not migrate
- Does not require re-compaction
- Does not develop large settlement voids
This helps protect:
- Decks
- Sidewalks
- Pools
- Landscaping
- Structures near the seawall
7. Pumpability Over Long Distances
CFC can be pumped hundreds of feet from a staging area.
This allows contractors to:
- Keep equipment away from sensitive landscaping
- Work in limited-access waterfront sites
- Repair long seawall sections efficiently
8. Can Be Designed as Permeable or Non-Permeable
Depending on the project objectives:
Low-permeability CFC
- Limits water movement
- Reduces soil migration
- Creates a stable backfill mass
Permeable CFC
- Allows controlled drainage
- Reduces hydrostatic pressure buildup
- Can function as a drainage layer
- Suitable for use in tidal areas
This flexibility is unique compared with conventional fills.
9. Provides Structural Support
Higher-density CFC can provide meaningful compressive strength while remaining lightweight.
This can support:
- Pool decks
- Patios
- Walkways
- Driveways
- Building slabs near seawalls
while simultaneously filling voids beneath them.
10. Complements Existing Seawall Technologies
CFC is not usually a replacement for:
- Tiebacks
- Deadmen anchors
- Helical anchors
- Vinyl panels
- Concrete panel replacement
Instead, it works alongside those systems by addressing the washed-out backfill that often caused the problem in the first place.
Summary
For seawall rehabilitation, CFC’s biggest advantages are:
- Complete void filling.
- Lightweight loading on weakened walls and soils.
- Pumpability with minimal disruption.
- Self-compaction.
- Resistance to future washout and settlement.
- Ability to be engineered as either permeable or non-permeable.
- Compatibility with virtually every existing seawall repair method.
- Can be easily excavated if necessary using hand tools or light power tools
For many seawall projects, the most compelling advantage of CFC for the property owner is: It restores lost backfill, stabilizes the area behind the wall, and supports overlying structures without excavation and without adding the weight of traditional fill materials.
We believe in transparency! The single most important disadvantage of using CFC in seawall repair is material cost. It is more expensive than sand or soil backfill. Sand or soil is cheaper, but they are also the materials that disappeared in the first place.
CFC is usually somewhat less expensive than CLSM and is more flowable and pumpable. CFC is considerably less expensive than poly foam and as a backfill CFC provides considerably more lateral force reduction against the seawall. CFC may be made more dense than water to displace water.
For many seawall projects, the most compelling advantage of CFC for the property owner is: It restores lost backfill, stabilizes the area behind the wall, and supports overlying structures without excavation and without adding the weight of traditional fill materials.
What the property owner wants is:
- Reduced future settlement
- Reduced void formation
- Better support for decks, sidewalks, pools, and landscaping
- Less likelihood of repeat repairs
