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Protect your marine concrete structures

Sustainability for Concrete Marine Structures

Protect your marine concrete structures
24 October 2019 Posted in ,

Are you trying to protect your marine concrete structures from corrosion and trying to reduce high maintenance costs?

If you are an engineer, developer or asset manager don’t let your concrete structures suffer the same fate as many other structures in and around the harsh marine environment.

 

Read on to learn:

  • How concrete is not unconquerable on its own – and how you can enhance/protect it especially around the marine environment
  • The effects of moisture and contaminant migration through concrete – and how to stop it
  • How to reduce your maintenance costs – and how $1 spent in construction saves $125 in maintenance

 

Concrete is not unconquerable on its own – Here’s how you can protect it

Many people run into the problem when dealing with concrete, thinking that concrete is a non-destructive material and don’t do anything to protect it from the effects of deterioration over time.

 

Concrete is naturally durable – but not entirely. All concrete is slightly porous, due to micro-pores formed during curing. This means that moisture, and moisture-borne contaminants, can enter the concrete.

 

Contaminants include chlorides, nitrates, and other reactive substances, which break down the concrete’s natural durability and speed up deterioration.

 

Marine concrete is especially at risk.

Seawater contains high concentrations of chlorides, in particular, along with other reactants. Due to the high level of ambient moisture, these contaminants are easily carried into the concrete and attack both the concrete and the reinforcing steel, causing a cycle of deterioration.

 

How do you protect your concrete?

Coatings are not enough. They are easily abraded, cannot guarantee complete coverage, and cannot prevent moisture movement between uncoated abutting surfaces.

 

Crystalline technology is inadequate. Crystalline formations within the concrete are a one-shot application, susceptible to slight movements of the structure, and are not reactive to ambient moisture vacillation.

 

So if coatings and crystalline technology are not the answer – how do you protect your concrete?

 

By using an advanced, colloidal silica hydrogel concrete durability and waterproofing admixture.

 

A C-S-H hydrogel can be produced within the concrete by applying nano-particle colloidal silica. This reacts with free moisture and calcium within the concrete. The resulting ‘gel’ formation immobilises moisture, preventing entry and movement of the contaminants which are carried by that moisture (and moisture vapour).

Why use a hydrogel admixture?

  • Firstly, the concrete delivered to your site is already waterproofed, throughout the mix. No need to wait for moisture ingress to active it like other products.
  • Secondly, hydration is improved, reducing shrinkage; compressive and flexural strengths are enhanced, for long-term durability.
  • Then there’s improved workability, ease of placement, and environmental safety.
  • And the steel reinforcement is protected from day one.

Even The Roman Empire Utilised Silica

Roman concrete used ‘pozzolana’ wherever possible. This was volcano dust and had high alumina and silica content. This silica content contributed to the concrete becoming resistant to cracking, and robust in seawater.

 

Read more about concrete admixtures for waterproofing and durability in marine structures

 

 

Moisture migration is killing your concrete

Moisture migration is killing your concrete

Again – any concrete around the marine environment is especially at risk. Seawater contains high concentrations of chlorides, in particular, along with other reactants. Due to the high level of ambient moisture, these contaminants are easily carried into the concrete and attack both the concrete and the reinforcing steel.

 

Concrete within the splash zone is especially prone to early deterioration. This is due to the aggressive movement of moisture and rapidly varying moisture levels.

 

The effects of moisture and contaminant migration through concrete.

Moisture is the vehicle for contaminants. Reactants such as chloride and nitrate ions are carried in solution by moisture and moisture vapour. These can react with the concrete itself, or reach the steel reinforcing and cause corrosion.

 

Unwanted concrete reactions and steel corrosion cause significant cracking, opening the way to more contamination, and so into a cycle of deterioration.

 

How to stop moisture from slowly but surely destroying your concrete?

Immobilise the moisture! 

 

A specialised catalytic silica treatment can be applied, inducing a hydrogel within the porosity of the concrete. This hydrogel binds up the free moisture within the concrete, preventing the entrance or movement of moisture-borne contaminants.

 

Topical coatings are often specified for remediation but these have serious drawbacks: they can be worn away over time; they do not penetrate into the reinforcement zone, and they cannot stop moisture moving between abutting uncoated surfaces.

 

Some remediation treatments utilise crystalline technology. This is insufficient for the long term, a one-shot application which does not remain reactive to ambient moisture vacillation.

 

Crystalline admixture is dependent on the initial moisture of the concrete for its reactivity. Once the reaction has run its course, there is no further activity through the life of the concrete. 

 

Hydogel technology, on the other hand, remains sensitive to ambient moisture levels, which means it stays ‘live’ and active within the concrete.

 

Read more about conquering chlorides in concrete

 

 

Wharf maintenance

How to save $125 in maintenance costs with $1 spent at construction

$1 spent in construction saves $125

Wolter Reinold de Sitter, a part-time professor in the design of structures in concrete at the Eindhoven University of Technology, proposed a Law of Fives for structural concrete maintenance.

There are various English versions extant, but fundamentally the law reads as follows:

  • The life of a concrete structure, with respect to durability, can be divided into four phases:
    • Phase A: Design, construction and concrete curing
    • Phase B: Corrosion initiation processes are underway, but the propagation of damage has not yet begun
    • Phase C: Propagating deterioration has just begun
    • Phase D: Propagation of corrosion is advanced, with extensive damage manifesting
  • $1 extra spent at Phase A is equivalent to saving $5 at Phase B, $25 at Phase C, or $125 at Phase D.

Now think about that – a little extra investment at the design, construction and curing phase will reduce long-term expenses.

 

So what you can do to reduce your maintenance costs?

To arrest the deterioration cycle, ACT EARLY!

 

Concrete hydrogels, introduced as catalytic silica admixture, will prevent the movement or ingress of moisture-borne contamination. This arrests the deterioration cycle.

 

By arresting and delaying this deterioration, the service life of the structure will be increased, and overall maintenance costs significantly reduced.

 

Read more about protecting new concrete

 

 

 

In Conclusion

So a quick recap on protecting your marine concrete structures and reducing your maintenance costs:

  • Concrete is not bulletproof on its own.
  • You need to be stopping the effects of moisture and contaminant migration through concrete.
  • You should be protecting it from within by using an advanced colloidal silica hydrogel admixture.
  • By adding an admixture at the construction stage, you can save you approx. $125 in maintenance.
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