Waterproofing concrete - the simple way to reduce the environmental impact of buildings and concrete structures
Posted by Albert Berenguel - 08 March, 2021
“With the new target to cut EU greenhouse gas emissions by at least 55% by 2030, we will lead the way to a cleaner planet and a green recovery.”
“The European Green Deal is our new growth strategy. It will help us cut emissions while creating jobs.”
Ursula von der Leyen, President of the European Commission
We all agree that climate change and environmental degradation are a serious threat to our planet. Reducing the carbon footprint of buildings, transportation or our lifestyle is a challenge we all face every day. To overcome these challenges, Europe is engaged in ambitious plans to make its economy more sustainable, as Ursula von der Leyen, President of the European Commission, states.
Buildings and construction together account for 36% of global final energy use and 39% of energy-related carbon dioxide (CO2) emissions when upstream power generation is included. (1) Concrete is one of the biggest contributors to the carbon footprint of buildings and infrastructure:
- Every year, more than 10 billion tons of concrete are used, which makes it
the second-most consumed substance in the earth after water. (2)
- Every year, more than 4 billion tons of cement are produced, accounting
for around 8% of all CO2 emissions worldwide. (2)
- Despite improvements in processes and control measures, the manufacture
of concrete still emits between 70 and 90 kg of CO₂ per ton. (3)
The main environmental impact of concrete occurs during manufacture, especially the production of cementitious binder, reinforcing steel, mining and transport of aggregates, and, not to forget, the energy used to transport the concrete to the job site.
Reducing the impact of concrete and the construction industry will become even more important in coming years as rapid urbanization and economic development increases demand for new buildings and, thus, for concrete and cement. Concrete is also the most commonly used material for infrastructure, helping to provide clean water, sanitation, energy and transportation, wind farms and hydroelectric dams, with demand for renewable energy infrastructure is set to increase due to clean energy commitments from countries and organizations.
With this is mind, it does not come as a surprise that cement, concrete and chemicals producers are developing several initiatives to reduce the environmental impact of concrete. The development of “green concrete”, with reduced environmental impact, is an important step towards a sustainable construction industry.
Reduction of energy consumption and fossil fuels used to heat the cement kilns to achieve the reaction temperatures.
CO2 captured by breaking down calcium carbonate into calcium oxide during cement production.
Use of industrial by-products (e.g. blast furnace slag or fly ash) as cement replacements.
Use of admixtures to produce concrete that has higher mechanical strength, reduced shrinkage, faster hardening, or easier placement, reducing installation mistakes, etc.
Use of recycled aggregates from construction and demolition waste (C&DW) that could save up to ten times more CO2 emissions than virgin aggregates.
But what about existing concrete structures? Is there a way to reduce their environmental impact?
The answer is YES.
The International Concrete Repair Institute (ICRI) Committee 160 in the document “Sustainability for repairing and maintaining concrete and masonry buildings”, outlines the two most important ways to lower the carbon footprint of concrete construction:
“Much of the life-cycle cost and comparatively low environmental impact of concrete are due to its longevity, and extension of that longevity further enhances these benefits”
“Protective measures during construction and proactive maintenance can prevent the need for repairs and are ultimately the most sustainable approach.”
Extend the lifetime as much as possible.
In my previous post “4 + 1 cases where concrete structures need MasterSeal waterproofing solutions”, we could see that there are at least 5 cases where even the best concrete mix will require additional waterproofing and protection with surface membranes or other waterproofing systems.
Water must be present for most of the degradation processes that affect reinforced concrete (carbonation, acids, sulphates, chlorides…) and, apart from meeting functional requirements for structures, this is why waterproofing membranes have an important contribution to the durability of concrete, preventing water and aggressive substances from penetrating into the concrete matrix.
Extending the service life of a concrete structure using protective waterproofing membranes, combined with inspection and maintenance programs, makes sense because:
- It has much lower economical cost than refurbishment, repair or eventually replacement of concrete.
In our blog “A little goes long way: Why diligent maintenance makes a difference.” Dr. Engin Seyhan explains this with the Law of Fives, published by Dr. De Sitter in 1984:
“When maintenance is neglected, repairs, when they become essential, will generally equal five times the maintenance costs. If repairs are not carried out, rehabilitation costs will be five times the repair costs.”
It has lower environmental impact, compared to repair of concrete:
An interesting paper from the Norwegian University of Science and Technology shows that:
“… from an ecological point of view, it appears to be a very good strategy to carry out preventive maintenance of a concrete structure before a stage is reached where patch repairs may be necessary”.(2)
Even if we consider that the patch repair is only necessary on a limited part of the surface and that protection is always applied to the whole surface, the difference in the ecological impact is so huge that preventive protection remains the best option.
It has a minimal environmental impact compared to the demolition of the structure and the construction of a new one… even if low environmental impact concrete could be used.
This graph was extracted from an Eco Efficiency analysis to evaluate the environmental performance and costs of an outdoor water reservoir for a period of 25 years in Europe (dimensions 40m*40m*5m). It shows that the carbon cost of waterproofing the concrete is negligible compared to the total cost of producing the concrete.
This means that it is environmentally much more sustainable to protect the concrete in the reservoir rather than to build a new one, even if demolition waste could be re-used.
- And finally, by selecting the right waterproofing and protection product, we can also minimize the impact of the waterproofing operation. The graph shows the results of an Eco Efficiency analysis conducted to compare the environmental performance of five different waterproofing membranes applied to the reservoir, as detailed above, over the 25-year period. The results of this analysis show that cementitious waterproofing membrane MasterSeal 6100 FX has a significant advantage in its environmental impacts compared to the other four alternatives considered.
MasterSeal 6100 FX is a sustainable, one component, highly elastic cementitious waterproofing membrane with low consumption that needs only 1.85 kg of powder product to achieve 2 mm applied thickness It provides high performance properties including resistance to 5 bar of water pressure and A4 class crack bridging capacity.
To find out more about MasterSeal 6100 FX and sustainability:
MasterSeal 6100FX product page including technical data sheets, declaration of performance
Sustainability website of Master Builders Solutions with best practices of different building types
3 Aspects of Green Buildings, recommended blog post highlighting the opportunities in the construction industry to contribute to the rise of sustainable construction
1mio m² waterproofed concrete - saving 1,7 mio kg CO2eq, long-term success story of MasterSeal 6100 FX achieving a major milestone in making concrete structures more sustainable
(1) UN Environment and International Energy Agency (2017): “Towards a zero-emission, efficient, and resilient buildings and construction sector. Global Status Report 2017.”
(2) J. Lehne, F. Preston. “Making Concrete Change. Innovation in Low-carbon Cement and Concrete”. Energy, Environment and Resources Department. Chatham House report. June 2018.
(3) MPA The Concrete Centre. “Concrete Industry Sustainability Performance Report”. 12th report: 2018 performance data. www.sustainableconcrete.org.uk.
(4) Vemund Årskog (Ålesund College, Norway), Sverre Fossdal (Norwegian Building Research Institute, Norway) and Odd E. Gjørv (Norwegian University of Science and Technology, Norway). “Life Cycle Assessment of repair and maintenance systems for concrete structures”. International Workshop on Sustainable Development and Concrete Technology. 2004