Beyond Whole Lifecycle Costing

When key infrastructure is disrupted, the true financial, societal and environmental costs can multiply direct costs by orders of magnitude. Here, Wayne Zakers, General Manager for Electrochemistry at Fosroc, considers the need to go beyond whole lifecycle costing for key infrastructure developments to avoid creation of future liabilities.

The expansion of the European Union creates many opportunities and challenges for all member states. Accordingly, the Cohesion Policy seeks to address the disparities in wealth between regions and countries, and to bring about sustainable growth across the whole Union.

Of the €308 billion Structural and Cohesion Funds for 2007–2013, 78 percent is to be targeted at lifting regions and countries out of relative poverty. Historically, countries such as Ireland and Spain have demonstrated an ability to create stronger local economies to the benefit of the wider region. However, the pace of expansion with the recent inclusion of 10 accession countries is raising questions about budget levels and the ability to create high impact with thinly spread funds. Over 90 percent of the population of the 10 accession countries live in regions with a per capita GDP below 75 percent of the EU average.

In a period of reduced growth and increased unemployment across the Union, and against a backdrop of unrelenting globalisation, it is critical that this investment is used wisely to create sustainable development and avoid creation of future liabilities.

When the whole annual budget can be consumed with one major cross-border infrastructure project, the temptation is to attempt to please as many people as possible, do as much as possible as cheaply as possible. The reality is that inevitable shortcuts and compromises on quality in design and construction, stores up future problems and considerable costs. Despite the development of an increasing awareness of the concept of whole-lifecycle-costing within some member countries, the analysis that sits behind such calculations in all but the most sophisticated cases, falls short of a full assessment of the true costs.

Sufficient consideration of the historical costs of maintaining a typical structure or structural component can enable accurate forecasting of direct maintenance costs. The true financial, societal and environmental costs of disruption to key infrastructure can multiply the direct costs by orders of magnitude.

Many estimates have been made of the commercial costs of traffic congestion, which run into billions of euros each year. A significant proportion of this is due to reduced road capacity, caused by essential road and bridge maintenance activities. The longer-term costs of the public health and environmental impacts of this maintenance-driven congestion, are more difficult to calculate and are rarely considered.

The low influence of those in need of social housing, and the need to fast track these projects, lead to low design and construction standards. Design lives specified are almost always considerably shorter than the periods over which they are actually required to provide shelter for society’s most vulnerable, and the structural problems hidden behind decorative facades ultimately manifest themselves in hazardous defects. As significant as the direct repair costs can be the indirect expenses associated with providing temporary, often unplanned, housing for large numbers of tenants. Eventual wholesale demolition and replacement require political decisions to be taken with a time horizon, which is considerably longer than political tenures.

Inland waterway and coastal port infrastructure is particularly sensitive to disruption, due to the high volume throughputs they normally provide. Inability to import and export goods within the Union and with international partners have significant effect on local and extended business communities. In such cases, as in other sectors, loss of income to the owner or operator from key revenue generating infrastructure can considerably exceed the actual repair cost. Every repair required on a structure during its life requires input and transport of labour, materials and waste products. This increases the overall, effective carbon loading of that structure, where this could be avoided by sustainable development. For energy-intensive construction materials such as concrete and steels, the wider environmental effects of such repairs are therefore considerable.

When structural funds are limited and demands are great, delivering high value, sustainable solutions in a cost-efficient manner is essential. The difficulty in delivering practical harmonisation of construction standards across the Union brings further challenges in product sourcing. Even though EN standards exist across the industry, the legacy of local requirements provide an additional layer of bureaucracy, add costs for cross-European suppliers, and act as an historical barrier to free trade. The effect is to limit market forces, increase costs, restrict innovation and delay uptake of advanced technologies. Such technology can be seen as expensive options at the tender stage, when indeed it may be they that create the real value through obviation of future downtime, disruption, pollution and waste generation.

The reality for many, who would leave lasting legacies at the end of their tenures, is that they unwittingly trade their vision for minor short-term benefits. These decision-makers are able to avoid this by asking just a few questions with only limited subject knowledge.

It is clear that decisions made at the conceptual and design stage need to consider not only the future direct expenses, but also the wider financial, societal and environmental costs. Only such an approach can prevent today’s financial support becoming tomorrow’s liabilities in key items of infrastructure that support cross-border commerce.

Defining concrete Issues

Reinforced concrete is a ubiquitous medium for the construction of key infrastructure for good reason, its beneficial properties including design versatility, strength, fire resistance, and thermal and noise insulation. However, failure to understand the material’s limitations and particular susceptibilities can lead to spiralling maintenance expense and accompanying wider, consequential costs to commerce and the environment.

Principle agents for attack of key items of reinforced concrete infrastructure include carbonation and chlorides. In the former case, carbon dioxide in the atmosphere migrates into the porous concrete structure, eventually reaching the steel reinforcement, where it changes the pH conditions sufficiently to permit onset of generalised corrosion. With attack by chloride ions, normally sourced from road salts, marine splash or marine and estuarine atmospheres, chloride contaminated aggregates, or the use of chemical treatments (e.g. in swimming pools anti-legionella treatments), the effects tend to be more localised and more rapid. Localised corrosion of the reinforcement can lead to material weakening of the structure with relatively low external symptoms.

Specialist surveying engineers can carry out quantitative analysis of a structure to determine the level of the problem. Unfortunately, surveyors are often called in when the condition is already quite advanced, and only when the owner or operator has become aware of an obvious problem. Early signs, such as cracking, staining and initial break up of the surface, caused by expansive corrosion materials, often go ignored. The costs and benefits of preventative maintenance schedules are normally avoided in order to minimise and defer operating expenses. The resistance of the structure to attack is best addressed at the design and construction phase, where spend leverage is greatest.

Constructive solutions

At the construction phase, chemical additives (admixtures) for precast and in-situ cast concrete are used to modify the setting and physical properties, to create a material most suitable for the design intent and to provide resistance to future damage. Admixtures may be specified to minimise the porosity of the concrete, reducing the rate of ingress of carbon dioxide, chloride, or other agents. Effective physical coatings can also provide a barrier to these external agents, though these coatings are specialist in nature, since simple paints are ineffective.

Tailoring of sealants and water barriers in key areas of the structure can prevent water ingress, especially where this is likely to contain chlorides. For example, sealant failure at bridge joints leads to characteristic visible wetting and staining, where surface water run off occurs via the easiest route. Road salts within this run off are concentrated at these points and create highly active corrosion sites, usually at the most highly stressed structural areas. Selection of cheap, multi-purpose sealants therefore saves insignificant levels of funds at construction, but creates highly expensive and complex repairs later. These difficult repairs inevitably force closure of the road, rail or waterway intersections with associated disruption.

A final approach to extend the structure’s life is to anticipate the corrosion issue and to install pre-emptive measures at the construction phase to prevent, inhibit, defer or reduce the corrosion. As this corrosion is an electrochemical process, wherein the corrosion site is anodic and the passive areas cathodic, prevention and inhibition can be achieved using well-proven cathodic protection technology, first demonstrated by Sir Humphrey Davy to protect ship’s hulls as far back as the 1820s. Two key technology options exist to make the reinforcement steel cathodic, each with distinct benefits as well as their common advantages.

Impressed current cathodic protection (iccp) uses external, regulated, power supplies to provide a current flow through the concrete. Careful selection of anode design and appropriate system monitoring and maintenance extends structural longevity by several decades, and provides reassurance against the dangers of hidden corrosion.

Galvanic systems are self-powered and self-limiting, and are therefore particularly suitable for pre- or post stressed concrete where embrittlement might be of concern. Although it is possible to monitor their performance on a regular or continuous basis, they are particularly well suited for remote areas, for regions where monitoring competency is limited, and where their “fit and forget” nature is otherwise desirable.

As well as providing ongoing protection in case of carbonation or chloride ingress, inclusion of properly specified iccp or galvanic systems during construction also has the effect of raising the chloride concentration required to initiate this aggressive mechanism of corrosion. Though both forms are covered by an EN standard, and have been used for concrete protection for several decades, use can still be limited through lack of owner and operator awareness, and through prejudicial comments by organisations interested in ongoing repair programmes.

At the initial design and construction stage then, it is important to question the degree to which the engineer’s recommendations and their supplier’s product offer can be truly tailored to the client’s actual needs and constraints. Proposals should be based upon sound, proven technical principles, and evidenced by truly independent assessments. Only a full range of quality admixtures, coatings and sealants provides the necessary choice to limit post-construction ingress of corrosion-inducing agents into the concrete structure.

Escalating maintenance

Lack of awareness amongst the owner-operator community, and understandable focus on economics, lead to repeat repairs over ever-shorter cycles.

Patch repair of damaged concrete can set up accelerated corrosion in adjacent areas, the so-called ‘incipient anode effect’, and leads to further, larger repair requirements with increased frequency. For non-critical structures, which are easily accessible without wider disruptive effects, and for which short life expectations are required, this may be of little concern. Of course, the removal of spoils usually to landfill, the manufacture of repair materials, and the energy expended in carrying out the work all contribute negatively on the environmental impact of that structure during its lifetime.

For more important structures, particularly where access is difficult or the area requires to be isolated, the closure periods, the scale of work required and its wider impacts all spiral until full replacement, however unpalatable, must be considered.

For repair applications, including remediation during new construction, a supplier of the broadest range of technical solutions such as quality repair mortars, carbon fibre support, iccp and galvanic systems, coatings, and injection resins, has an ability to liaise fully with structural engineers and surveyors on the efficacy of possible repair options. The supplier can avoid biasing proposals to any single product area, and instead advise on the correct approach for the given application, considering all local environmental, commercial and disruptive factors. The success of investment in EU enlargement could be measured as the short-term ability to complete as many projects as possible.

The reality is that future generations of citizens will judge our wisdom in the durability of projects we complete, and the longer-term economic, societal and environmental costs that we leave as our legacy.

For more information please visit www.fosroc.com