Concrete protection – the context
Concrete is often viewed as a solid, impermeable material. In reality, it contains a network of microscopic pores and capillaries that allow water and dissolved contaminants to move through the concrete matrix. This movement of moisture is responsible for many of the deterioration mechanisms that shorten the service life of concrete structures.
Chlorides carried by water can initiate reinforcement corrosion. Sulphates can attack the cement paste. Carbon dioxide can enter concrete and contribute to carbonation. In colder climates, freeze-thaw cycles can cause progressive damage. While these mechanisms differ, most have one thing in common: they depend on moisture movement through concrete.
- Colloidal silica technology in action: Nyrstar Smelter acid tanks
That’s why many durability specifications today focus on limiting permeability. Once contaminants have reached reinforcement, repair options become more expensive and disruptive.
One technology attracting interest from asset owners and engineers is colloidal silica, particularly where long design life and reduced maintenance are priorities.
What Is Colloidal Silica?
Colloidal silica is a stable suspension of extremely small silica particles dispersed in water. These particles are measured in nanometres, making them many times smaller than those in conventional cementitious materials.
Although colloidal silica and silica fume are both silica-based materials, they behave differently. Silica fume is supplied as a dry pozzolanic material and functions primarily as a supplementary cementitious material. Colloidal silica, by contrast, consists of nano-sized particles already suspended in liquid form. This enables it to penetrate and interact with the concrete matrix in ways that traditional pozzolans cannot.
The exceptionally small particle size provides a very high surface area, creating opportunities for chemical reactions and microstructural modification throughout the concrete pore network.
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How Does Colloidal Silica Work?
To understand the role of colloidal silica, it helps to look at what happens inside concrete after hydration.
When cement reacts with water, it produces calcium silicate hydrate (C-S-H), the primary compound responsible for concrete strength. It also produces calcium hydroxide, which contributes comparatively little to durability.
Colloidal silica reacts with calcium hydroxide produced during cement hydration. In simple terms, this reaction creates additional C-S-H gel, helping fill microscopic pathways through which water would otherwise travel. These reactions occur within the pore structure of the concrete.
In practical terms, fewer connected capillaries means fewer opportunities for water and dissolved contaminants to move through the concrete.
Rather than functioning as a surface barrier, colloidal silica works from within the concrete itself. Its effect is distributed throughout the treated zone, altering the microstructure and reducing permeability at a microscopic level.
Why Reducing Moisture Movement Matters
Most durability problems begin when water carries aggressive substances into concrete.
In a marine wharf, that may mean chlorides reaching reinforcing steel.
In a wastewater treatment plant, the system may be subject to chemical attack from aggressive environments.
Different structures face different threats, but moisture transport is the common pathway.
Chlorides entering marine structures, bridge decks or industrial facilities can reach reinforcing steel and initiate corrosion. Sulphate-rich environments can attack cementitious materials. Carbonation progresses more readily when moisture and carbon dioxide are present. Even concrete exposed to wetting and drying cycles experiences gradual deterioration as moisture repeatedly moves through the pore network.
By reducing permeability, colloidal silica helps limit the transport processes that drive these forms of deterioration. The goal is to stop contaminants from entering the concrete, rather than repairing damage later. Rather than repairing damage after contaminants have entered the structure, the objective is to reduce their ability to penetrate in the first place.
- Tested on site: Geraldton Wharf Berth
Key Benefits for Concrete Structures
For asset owners, this can translate into several practical benefits
- Extend service life.
- Reduce long-term maintenance costs.
- Improved resistance to contaminants.
- Enhanced waterproofing performance.
- Improved curing efficiency.
- Increased durability in aggressive environments.
These benefits are particularly valuable for critical infrastructure, where long-term performance and reduced maintenance costs are major project objectives.
How MARKHAM Uses Colloidal Silica
Colloidal silica for concrete is the core technology that MARKHAM has used for over 30 years. We have a range of admixtures to incorporate protection into the mix during concrete production. It can also be introduced through spray-applied treatment for both new and existing concrete.
This versatility allows the technology to be applied in both new construction and remediation projects. Whether the objective is to improve durability from the outset or to extend the life of an existing asset, colloidal silica modifies the concrete matrix itself rather than simply protecting the surface.
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Typical Applications
Because of its many benefits affects a wide range of structures, MARKHAM uses colloidal silica technology across numerous sectors, including:
- Marine and coastal infrastructure
- Water and wastewater facilities
- Structural waterproofing
- Warehouses and factories
- Data centres
- Transportation infrastructure and bridges
In each of these environments, durability and waterproofing is closely linked to controlling the movement of water and contaminants through concrete.
Looking Beyond Strength
Concrete durability is often assessed by compressive strength, but strength alone does not guarantee long-term performance. The ability of concrete to resist moisture ingress is equally important in determining how well a structure withstands service over decades.
Colloidal silica offers a proactive approach to durability by working within the concrete matrix to refine the pore structure, reduce moisture transport, and support a longer service life.
The challenge for designers and asset owners is no longer simply achieving strength targets. It ensures concrete can resist the causes of deterioration over decades of service. Colloidal silica provides a multi-benefit tool for achieving that outcome.
Interested in reducing permeability and extending the service life of your concrete structures? Talk to MARKHAM about colloidal silica technologies and long-term durability solutions.
On-demand webinar: “Risk Reduction in Concrete Construction“.
