Thicker layers of flowable mortar sound logical when ironwork fails. But if the material cracks under load, does using more of it fix the underlying problem – or just repeat it?
There is a growing trend within the highways and civil engineering sectors towards the use of increased thicknesses of flowable mortars and similar materials when installing and reinstating ironwork.
On the face of it, the logic is understandable. If a traditional installation has failed, perhaps the answer is to use more material. A thicker layer should, in theory, provide greater strength, increased support and a more robust installation.
But is more mortar really the answer?
SHIMPAC® believes the industry needs to take a step back and consider a fundamental question. If a material is already susceptible to cracking, shrinkage or failure under certain conditions, does increasing the amount of that material genuinely address the underlying problem – or does it simply provide more of the same?
This is not an argument against flowable mortars or any individual product. Mortar has an important role to play across the construction and highways industries and has been used successfully for decades.
The question is whether the industry should continue to rely increasingly heavily on mortar-based solutions to deliver the compressive and structural performance required of modern, heavily trafficked ironwork.
The answer may lie in rethinking the system itself.
The Changing Demands on the Network
The roads of today are not operating under the same conditions as those of previous generations.
Traffic volumes have increased. Heavy goods vehicles are heavier. In 2022, the maximum permitted weight of certain HGVs increased to 48 tonnes, placing additional demands on road infrastructure and the assets installed within it.
Ironwork seating systems must therefore withstand enormous forces generated every day by vehicles travelling over access covers, manholes and gully gratings.
At the same time, the UK is dealing with increasingly unpredictable weather, from prolonged rainfall to extreme temperature fluctuations and repeated freeze-thaw cycles. Water ingress, movement, poor installation and deterioration can all contribute to failure.
Against this backdrop, the question of how ironwork is seated and supported is becoming increasingly important.
Simply putting more material into the void and waiting for it to harden may not be enough.
The Problem With Doing More of the Same
There is an old definition of insanity often attributed to Albert Einstein – doing the same thing repeatedly and expecting a different result.
The highways industry should perhaps ask itself whether this principle has relevance when it comes to ironwork installation.
If a traditional installation fails because the supporting material has cracked, deteriorated or lost its integrity, then simply increasing the thickness of that same type of material may not necessarily solve the fundamental issue.
There are countless reasons why mortar-based installations can deteriorate. Shrinkage, cracking, water ingress, temperature fluctuations, poor preparation, movement and the stresses created by modern traffic can all play a part. The quality of installation and site conditions can also have a significant influence on performance.
The result is that a material intended to provide strength and support can ultimately become the weakest point in the installation.
When that happens, the consequences extend beyond the ironwork itself.
Movement can create gaps between the ironwork and the surrounding carriageway. Water can find its way into these gaps, penetrating beneath the road surface. Once water enters the structure, freeze-thaw cycles can accelerate deterioration, while repeated traffic loading continues to apply shear and compression forces.
Eventually, the cycle begins again.
A failed installation leads to a repair. The repair requires another road closure. Traffic management is reinstated. Operatives return to the carriageway. Materials are used. Budgets are spent.
A Different Approach to Ironwork Seating
SHIMPAC® takes a fundamentally different approach.
Rather than relying on increasing quantities of mortar to provide the primary seating and levelling solution, SHIMPAC® is a fully engineered system designed specifically to provide precise and durable support for ironwork.
The system uses ROADSHIMS® to achieve millimetre precision, allowing ironwork to be accurately positioned and aligned with the surrounding road surface.
An ironwork cover that is correctly aligned with the carriageway is not simply a matter of aesthetics. It is about ensuring that the forces generated by traffic are properly managed and that the installation is not subjected to unnecessary movement.
SHIMPAC® is engineered to provide long-term performance under the shear and compression forces generated by modern road traffic, helping to maintain the integrity of the installation throughout the life of the asset.
Less Reliance on Material – More Reliance on Engineering
The future of sustainable infrastructure cannot simply be about using more materials.
It must be about using the right materials in the right way, reducing waste and designing systems that last longer.
Every failed ironwork installation has a wider environmental and economic impact. Materials must be manufactured and transported. Traffic management must be installed. Vehicles must travel to site. Operatives must return to the carriageway. Further materials must be used to complete the repair.
The cycle continues.
SHIMPAC®’s approach is designed to break that cycle by providing an engineered system that is built for long-term performance.
When installed correctly, the system has demonstrated exceptional longevity, with the earliest installations now more than 35 years old and no reported failures. That is a very different proposition to a maintenance model that anticipates repeated intervention throughout the life of an asset.
The Real Measure of Sustainability
Sustainability is often discussed in terms of the materials used during an installation. But true sustainability should also consider how long that installation lasts.
A product that requires less material but fails repeatedly may ultimately have a greater environmental impact than a system that delivers long-term performance from the outset.
The same applies economically.
A cheaper installation that requires repeated maintenance may ultimately cost significantly more over its lifecycle than an engineered solution that lasts.
SHIMPAC® therefore believes the industry should be looking beyond the initial installation and considering the whole-life impact of ironwork seating, posing questions like:
- How many times will the site need to be revisited?
- How many times will traffic management need to be installed?
- How many additional vehicles will need to travel to the location?
- How many additional tonnes of material will be required?
- How much labour will be spent repairing something that could have been engineered to last in the first place?
These, they believe are the questions that should shape the future of highway maintenance.
A Long-Term Solution for a Long-Term Problem
The highways industry needs solutions that reflect the realities of modern roads.
Increasing traffic loads, heavier vehicles, unpredictable weather and growing pressure on local authority budgets all demand a more considered approach to infrastructure maintenance.
SHIMPAC® does not suggest that mortar has no place in highway construction. Instead, it challenges the assumption that the answer to ironwork failure is always to use more of it.
Sometimes, the solution is not more material. It is better engineering.
Ultimately, if the industry continues to repair failed installations in the same way, using increasingly substantial quantities of materials that can themselves be vulnerable to cracking and deterioration, it should not be surprising when the same problems return.
The definition of insanity may be doing the same thing repeatedly and expecting a different result.
Perhaps the future of ironwork seating lies in doing something different.
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