Many Contractors Still Do Not Know How to Repair a Seawall
Before the advent of advanced seawall repair materials such as SW-RP1, contractors often attempted to fill voids behind seawalls with cement (which cures into concrete). Unfortunately, there are still inexperienced contractors out there who are using this outdated method.
The Disadvantages of Filling Seawall Voids with Cement
Concrete Puts Unnecessary Pressure on the Seawall and Surrounding Soil: Concrete weighs a lot. Filling a void behind a seawall with cement creates additional lateral load pressure on the seawall. The heavy concrete also further destabilizes the soil over time.
Concrete Displaces Supporting Soil and Breaks Apart Over Time: Unlike our SW-RP1 seawall repair material, cement does not permeate and stabilize loose soil surrounding a void. Instead, cement just displaces the surrounding soil. This leaves open the possibility of further erosion and void formations below and around the cured concrete. Once the surrounding soil begins to give way, the concrete will often break into pieces over time (see the featured photo in this blog post for an example).
Concrete in the Soil Impedes Advanced Seawall Repair Methods: Since void-fill with cement is not a lasting solution for seawall-supporting soil, proper repair with advanced materials such as SW-RP1 will eventually be required. Unfortunately, concrete in the soil surrounding the wall just makes this process slower and more expensive. Concrete in the soil obstructs advanced seawall stabilization methods such as installing repair material via injection rods and installing an anchoring system. In a case like this, additional time and resources would be required to excavate and dump the old void-fill concrete, then replace it with fresh fill soil before beginning the repair process.
So consider yourself warned if a contractor proposes filling the voids behind your seawall with cement. What once (long ago) may have seemed like a common-sense solution has been repeatedly proven to make the situation worse over time.