“Concrete structures are deteriorating at a much faster rate than expected, resulting in a massive need for repairs and premature replacement that costs billions of dollars annually.”
If you are in charge of concrete structure maintenance – particularly if you are required to administer a limited budget – these words will ring true for you. It’s all too common for concrete infrastructure to show signs of deterioration well before its planned service life.
THE SIX CAUSES OF CRACKING
There are 6 underlying causes of cracking. Actually it’s not quite that simple, as more than one cause can be present in a structure simultaneously. But these are the basics:
- Shrinkage cracking at curing stage.
- Thermal stresses (e.g. freeze-thaw cycle).
- Chemical reactions (e.g. ASR).
- Corrosion or low cover.
- Design defects or load stresses.
Lately, of course, there has been increased focus on the various impacts of climate change. It’s not our intention to ignore this discussion but we believe the various effects fall under the same basics as seen in the past – except accelerated or aggravated.
“Atmospheric CO2 is a major cause of reinforcement corrosion in bridges, buildings, wharves, and other concrete infrastructure in Australia… The increase in CO2 levels associated with global warming will increase the likelihood of carbonation-induced corrosion.”
THE DETERIORATION CYCLE
Minor cracking in itself isn’t enough to bring a structure down. There would be few concrete structures or slabs that don’t exhibit some form of micro-cracking or worse.
The concern is the way cracks contribute to longer-term deterioration. Cracks are gateways into the concrete, for reactive contaminants – carried by moisture and moisture vapour.
For example, moisture-borne chlorides can enter the concrete via shrinkage cracks, and penetrate to the reinforcing zone. The chlorides then break down the natural passivity of the concrete, setting up corrosion of the steel. At once, instead of one cause of cracking, you have three – the original shrinkage; the chemical reaction of the chlorides; and the expansion of the corroding steel.
Small cracks lead to larger cracks. Larger cracks lead to delamination and spalling. You can see where this is heading. Next stage is you are assessing the repair or replacement cost of the structure.
ACT EARLY TO REDUCE THE RISK!
It is not intelligent to conduct a ‘reactive’ maintenance program – acting only when deterioration is evident. This is an expensive approach, and its effectiveness can be debatable.
“Cost-competent maintenance and management of civil infrastructure requires balanced consideration of both the structure performance and the total cost accrued over the entire life-cycle.”
Weigh up your overall costs, and consider the benefits of being ‘pro-active’ with your maintenance program. If you could apply a treatment early in the life of the structure, which would reduce the risk of cracking, and guarantee or even extend the planned service life, you are effectively saving costs. (Remember the ‘Rule of Fives’?)
AN ADVANCED, EFFECTIVE TREATMENT
Just now we commented that the cracks are gateways for moisture-borne contaminants. The movement of moisture is the key. Concrete in truly dry atmospheres, such as central Australia, does not deteriorate anything like as quickly as coastal concrete. But New Zealand is an island country! Moisture-borne contamination is an unavoidable factor.
So we need to immobilise the moisture. Prevent the entrance of the contaminants. Prevent their movement and action within the porosity of the concrete.
This can be done! AQURON treatment penetrates deep into the concrete, converting free limes and existing moisture into a HYDROGEL within the porosity of the concrete. It’s not easy to believe such a simple and cost-effective treatment can provide so many benefits and such a high degree of long-term protection.
Intrigued? Get in touch with us for case studies, test results, and project referrals.
OTHER BENEFITS OF AQURON
- Nil VOC, and certified for potable water – can be used in environmentally sensitive areas.
- Minimal downtime – treated structures are trafficable about an hour after application.
- Colourless, and leaves no residue or coating – will not affect the appearance or finish of the structure.
2 Climate Change Impact and Risks of Concrete Infrastructure Deterioration, Mark G Stewart et al [ONLINE] Available at: https://publications.csiro.au/rpr/download?pid=csiro:EP101172&dsid=DS1 [Accessed 04 April 2018]
3 Maintenance and management of civil infrastructure based on condition, safety, optimization, and life-cycle cost*, Prof. Dan M Frangopol, Prof of Civil Engineering, Lehigh University [ONLINE] Available at: https://www.tandfonline.com/doi/abs/10.1080/15732470500253164 [Accessed 04 April 2018]