The Environmental Impacts of Concrete
The US, and the world, have a concrete problem. Concrete as a substance is a very porous material (20-30% of the cement phase). Over time, oxygen, moisture, chlorides, and carbon dioxide leech into the pores of the concrete and penetrate deep into the material, sometimes even reaching the rebar. This porosity leaves it prone to damage.
WHAT’S THE CONCRETE PROBLEM?
As contaminants leech deeper into the concrete, the passivating film on the steel surface breaks down and steel begins to rust. As the steel rusts, it expands from the forming of rust oxide, which puts an immense amount of stress on the surrounding concrete (<20,000psi) which leads to cracking, spalling, and failed concrete. Even if damage to the concrete is detected before contaminants have reached the rebar, the concrete is still affected. Carbon dioxide, chlorides, acids, and other chemicals still enter the gel pores in the concrete. Once they enter, they reduce the pH of the concrete and the chlorides deposit themselves into the chemical structure of the concrete.
CONCRETE AND THE ENVIRONMENT
So where does this problem lead us? After water, cement, the main component of concrete is the most consumed substance on earth. Approximately 8% of all global emissions are directly attributed to the production of concrete.* And an even more alarming fact? In the time it takes you to read this sentence, the global building industry will have poured more than 19,000 bathtubs of concrete.**
And it is not just the production of concrete that has the Earth in trouble. An equally devastating aspect of concrete is the waste created by removal and replace techniques of concrete repair. One of the largest concrete industry, besides new construction, is the replacement of failing concrete structures. In 2018, 600 million tons of Construction & Demolition (C&D) debris were generated in the U.S., more than twice the amount of generated municipal solid waste.*
Looking at the graph to the right, you can see just how high of a percentage concrete accounts for in C&D debris. Even if you add all other categories, concrete still outranks them. Demolition represents more than 90 percent of total C&D debris generation. That means that demolition is a huge area that generates waste.
What does that really mean? It means that there is 405 MILLION TONS of concrete that is removed and thrown into waste. And how long does it take for concrete to decompose back into the Earth? Well, there are still structures from the late 1800’s which foundations remain, which means that we are looking at at least 200 years, if not more.
RIP AND REPLACE ALTERNATIVES
Rip and replace is when materials that need repair are ripped out and replaced with new materials in order to repair the structure. With concrete, this means that the concrete is ripped out and new concrete is poured / installed in it’s place.
A study performed by the US Department of Transportation, Federal Highway Administration in 2017 on the difference in cost between repairing and replacing SD bridges (Structurally Deficient) in both the NHS (National Highway System) and non-NHS (under local jurisdictions). The study found that taxpayers saved 32% by extending the service life of the structure.
Let’s break this graph down. This graph has totaled the amounts that it would take to fully replace the total number of structurally deficient bridges and compared it to the amount it would take to rehabilitate the bridges instead, which through compiling actual cases of repair vs replace in bridges, they have found to be 68% of the cost to replace. They have also found there to be a total of 54,560 structurally deficient bridges in the US, a total of National Highway System bridges and Non National Highway System bridges.
After that, they figure the cost per square foot for replacement of the bridges, which comes to $232 for NHS bridges and $199 for non-NHS bridges. Using all of this data they found the totals of each type of actions, for all of the bridges combined. The savings was a staggering 32% or $15,600,647,050.
HOW DOES SURTREAT® HELP?
Concrete is formed through the chemical process of hydration and curing. Conversely, concrete deteriorates largely by chemical means by carbonation/loss of pH or the presence of aggressive and hostile chemicals. the corrosion of reinforcing steel (rebar) is the most common cause of failure in reinforced concrete structures. In fresh new concrete, rebar is protected by high pH and low contamination levels. Concrete is inherently porous which allows a variety of contaminants to penetrate it. When water and oxygen are present it creates an electrochemical reaction between segments of a single piece of rebar, which causes the steel to rust. When it rusts, steel must expand, causing the rigid concrete to crack and fail.
The SURTREAT® process is based on the fact that the deterioration of Portland cement concrete is largely a chemical process which can be inhibited or reversed! Our process is proven to be the most environmentally friendly and cost effective way to restore deteriorating concrete and to offer long-term protection to surfaces exposed to extreme elements. This process will result in significantly reducing ongoing maintenance costs and eliminating future deterioration and corrosion of concrete structures.
SURTREAT® provides turnkey solutions to problems associated with concrete deterioration and corrosion. We provide solutions, not just products. The performance of our products can be measured by reduced chloride contamination and increased concrete resistance to attack by chemicals known to deteriorate concrete structures. Extensive testing is conducted before and after the solution is installed to confirm the results of the treatment. Ongoing testing allows our clients to evaluate the condition of their structure.
SURTREAT® AND THE ENVIRONMENT
Extending the life of a concrete structure makes economical and environmental sense for the owner and the environment. Application of SURTREAT® chemical treatments will slow or stop reinforced concrete from deteriorating. It will extend useable life indefinitely, and significantly reduce lifetime impact on the environment. SURTREAT® products are water-based and environmentally friendly.
The use of Surtreat will benefit the environment through:
- Surtreat Solutions restores, protects, and extends the life of concrete structures at all stages of its lifecycle.
- By increasing the lifespan of assets, Surtreat can be a major factor in budgetary and environmental savings significantly reducing both Co2 emissions and harmful Silica’s
- By decreasing the amount of traditional concrete removal and replacement Surtreat offers advantages towards the reduction of our carbon footprint.
- Surtreat TPS solutions are water based and safe for workers and the environment unlike other more traditional products containing harmful component’s
HOW SURTREAT® HELPS: COST
Below is a chart showing the direct cost savings that Surtreat Solutions provided on various projects. The alternative cost was traditional repair and replace methods. Surtreat Solutions was able to achieve this cost savings through:
- Indefinite extended service life
- Minimal concrete remove and replace
- Significantly less labor intensive
- One-time application
- Non-Destructive application allows continued operation of structure
- Prevents Corrosion from occurring if applied during new construction
Each of these projects were able to have Surtreat Solutions provide a custom, turn key solution that addressed the issue and would be able to provide similar, if not better, results than traditional rip and replace methods. Our average savings were 82% from alternative methods. That’s not only cost savings but below we will demonstrate the environmental savings gained from using a turn key system provided by Surtreat Solutions.
HOW SURTREAT® HELPS: ENVIRONMENT
In 1990, Surtreat Solutions provided Allright Parking Garage a turn key system that was able to rehabilitate their structure and repair the eight elevated levels (first mezzanine to fifth floor) have suffered damage due to the infusion of water and salt into the concrete, and what appears to have been
All of the elevated levels have suffered rebar corrosion, delamination, spalling and the loss of sections of concrete from the floor and roof. Previous restoration work has involved patching with asphalt, cement mortar, polymer concrete and polymer coatings. Besides Surtreat Solutions being able to provide a solution at 88% of the cost of alternative methods, which was demolishing and rebuilding the structure, we also were able to keep all of the original concrete from becoming waste product and prevented the need for new concrete to be created.
Given the state of the structure before Surtreat Solutions applied our turn key systems, life structure was extended by 25-30 years, and 4,888 cubic yards of concrete were maintained in service. This means that the parking garage, through our solution’s technology, was able to be not only repaired but strengthen enough to last another 30 years WITHOUT any removal of current concrete.
In terms of thermal pollution, maintaining the existing structure prevented the release of 12,000 MMBtu (12,660 GJ) of heat into the environment. This prevented the release of 1221 tons of CO2 and 48 tons (48,000 kg) of acid rain constituents (SO2 and NOx ). This prevention of heat and CO2 into the environment is a combination of the energy saved from removal of the concrete, transportation of concrete to a proper waste facility, creation of new concrete materials, transportation of the new concrete materials, installation of the new concrete, and the various other activities that would need to be undergone to remove and replace the structure.