By Johan van Wyk (MICT), N.Dip Civil Engineering, Penetron Africa

Fact: Concrete structures deteriorate over time, and even more so when durability is not paid attention to by everybody in the value chain, from structural design, mix design and construction to maintenance and repair. This leads to lower return on investment and higher cost of ownership.

Concrete durability (and by implication the structure’s durability) is defined as its ability to resist modes of deterioration and retain its original quality and serviceability. When we consider that the primary function of concrete in a reinforced structure is to take up compressive forces and protect the reinforcing steel, the service life of the structure is determined by the time it takes for the concrete to deteriorate to a point where the reinforcing steel is no longer protected from water ingress. It is at this point where the steel starts to corrode and becomes evident in spalling.

The Limitations of Conventional Thinking

The current modus operandi to increase service life is to increase the cover to steel or use higher contents of cement and lower C/W ratios in the mix design. This leads to heavier and more costly structures, but because the concrete still deteriorates over time, it only delays the inevitable failure.

The solution is to design the concrete with improving performance in durability, for the lifespan of the structure.

The True Cost of Concrete Failure

The cost of failure or signifi cant deterioration can be obvious, but also hidden or delayed. In my experience working across multiple infrastructure projects, these costs include:

Initial Underperformance and Defects

Poor mix design, inadequate cover and cracks show in the structure as early as the construction phase. This leads to a reduction in service life and even safety concerns.

Maintenance and Repair Cycles

The need for maintenance and repair become evident throughout the life of the structure and more frequent as deterioration accelerates. Fixing spalled concrete and reapplying coatings leads to costs in labour and materials and time-related costs due to loss of service.

Operational Downtime and Disruption

Operational downtime and disruption occur when structures have to be taken offl ine, which causes inconvenience and a cost to reputation. I’ve seen projects where this alone has cost clients millions in lost productivity.

Accelerated Replacement

Accelerated replacement before the design life might be needed when repairs become uneconomical and will incur capital cost and an increase in the carbon footprint.

Environmental and Social Costs

In the case of catastrophic failure, environmental and social costs will have an impact on communities and expose owners to liability.

Opportunity Cost and Financing Costs

Opportunity cost and financing costs reduce funds available for other infrastructure or services, because they tie up money in repeated repairs and maintenance.

It is clear that the cost of failure tends to escalate nonlinearly. If defects or early deterioration are not addressed, repair costs are moderate. But once corrosion and damage become widespread, costs multiply (labour, materials, shutting down operations, possibly legal and regulatory penalties).

De Sitter’s Rule of Five: A Critical Insight

According to De Sitter’s Rule of Five, R1 invested during the design and construction of concrete structures is equivalent to:

• R5 after the structure has been built, but corrosion is not yet evident
• R25 when corrosion has started at some areas
• R125 when corrosion has become widespread, and rehabilitation is required

This principle highlights the profound economic advantage of early durability investment. In my work with municipal and private sector clients, I’ve watched this play out exactly as De Sitter predicted.

Durability-Driven Design: A Smarter Economic Strategy

Durability-driven design and considering life-cycle costing are strategies to avoid or reduce concrete failure. Their power lies in shifting the design and thinking to the long term.

This strategy includes:

Designing for Durability

Specifying concrete mixes, cover, crack width and admixtures so that common degradation mechanisms are prevented.

Use of Integral Crystalline Protection

Using integral crystalline protection, like Penetron Admix, that becomes part of the concrete matrix, self-seals micro-cracks and reduces permeability. This will also effectively dematerialise the structure from high carbon footprint coatings and membranes.

Reduced Maintenance and Repair Cycles

With better initial design, there are less frequent repairs and less need to completely rebuild surfaces or membranes.

Optimised Timing of Interventions

Doing interventions when cost is lowest and avoiding letting damage reach a threshold where repair is extremely expensive.

Environmental, Regulatory and Social Considerations

Considering environmental, regulatory and social concerns like carbon footprint and community impact over the long run.

Instead of just comparing initial capital cost, cost of ownership over the lifespan of the structure needs to be considered, including design and construction, plus maintenance, operational downtime and replacement needs, discounted to present value. This often shifts choices toward more durable, slightly more expensive upfront options that save many multiples over time.

Case Studies: Durability in Action

Babylonstoren Wine Cellar, Western Cape, South Africa

These strategies were considered at Babylonstoren Wine Cellar in the Western Cape. The client specifi ed a cellar with an exposed aggregate roof slab, without high carbon footprint coatings and waterproofi ng membranes and maintaining the aesthetic value. This was achieved by using Penetron Admix as an integral crystalline waterproofer and durability enhancer, in addition to Penebar SW-55 swellable waterstop to seal construction joints.

Outcomes:

• Construction timelines reduced by 25%
• Because of the durability and self-healing ability of the concrete, maintenance cycles were limited to a minimum
• Concrete was not covered, which made it possible to inspect and plan for maintenance, if needed
• Estimated savings in time cost, dematerialisation and maintenance cycles amount to more than 25% over the lifespan of the structure

Kigali Finance Centre, Rwanda

Kigali Finance Centre in Rwanda is a mixed-use development with three below-grade basements, plus pools and pump rooms. The high exposure to chemical attack, tight timelines and budgets ruled traditional waterproofi ng and membranes out of the equation. Penetron Admix was used for advanced crystalline waterproofi ng, self-healing, enhanced abrasion resistance, chemical durability (pH 3-11) and reduced drying shrinkage.

Benefits:

• Reduced material and labour expenses by streamlining waterproofing
• Saved time via less scaffolding and immediate backfilling instead of waiting for coatings to be applied

Investing in Durability Pays Dividends

The true cost of concrete failure is much more than the cost of repairing concrete. It includes water loss, disruption, shorter usable life, environmental cost, reputation and regulatory risk.

Life-cycle costing and durability-driven design often require slightly higher upfront investment but yield large savings over decades in maintenance, replacement and downtime.

The Penetron projects illustrate real cases where integrating waterproofi ng into the concrete, using crystalline technologies, repairing early, and avoiding membranes or coatings have delivered signifi cant time saved, lower maintenance, extended lifespan, and sustainability advantages.

For governments and developers that manage many such structures (reservoirs, parks, commercial buildings), adopting durability as a core requirement can save millions over time, not just per project, but across portfolios.

Throughout my career, I’ve seen how early investment in durability, good design practice and advanced materials ultimately delivers exceptional value over the extended lifespan of a concrete structure.

About the Author

Johan van Wyk holds a National Diploma in Civil Engineering and is a Member of the Institute of Concrete Technology (MICT). He serves as a technical specialist at Penetron Africa, where he focuses on durability engineering, life-cycle costing, and sustainable infrastructure solutions across the African continent.