Concrete and the Environment
As we move into the 21st Century there is increasing concern about the environmental impact of Portland concrete production. Inclusive of carbon dioxide (CO2) emissions, the handling of kiln dust (CKD), the emission of trace metals including mercury, as well as smaller quantities of other greenhouse gases such as Nitrous Oxide (NOx), Sulfur compounds, and the Methane Gas being released into the atmosphere. The production of 1-ton of limestone-bonded Portland concrete is reported to emit approximately 0.87 tons of CO2 into the atmosphere, along with other harmful emissions. (https://en.wikipedia.org/wiki/Environmental_impact_of_concrete)
CO2 emissions emanate from the calcination (high heat firing) of limestone. While additional toxic emissions are due to the combustion of the fossil fuels. In the United States the production of Portland concrete accounts for more than a hundred million tons of waste carbon dioxide, about 2% of our manmade CO2 emissions. Globally, the Portland concrete industry produces approx. 1.6 billion tons of CO2 – exceeding 8% of the total CO2 emissions from all human activities. Due to increased awareness of these facts, it's also important to note that the world concrete industries seriously want to reduce all forms of toxic, earth polluting emissions.
While useful results have been limited, to date the most ambitious attempt to reduce CO2 emissions occurred when world governments provided carbon credit financial rewards that were welcomed by non-carbon polluting industries. In this context, our global government supported CO2 reduction strategies are focused on reducing rather than eliminating harmful Portland concrete emissions. While these financial incentives have not significantly reduced our atmospheric pollution issues.
Current concrete industry reduction strategies include installing more fuel-efficient kiln technologies, substituting non-carbonate sources of calcium oxide within the kiln-firing of raw materials, and using recycled aggregates. Valiantly trying to overcome the adverse production / end-user problems due to the corrosive, acid susceptible, low strength realities inherent within the alkali-based chemistry that occurs when calcined limestone is blended with gypsum, toxic fly ash, various mineral aggregates, and exothermally water-activated into artificial stone. The basis of traditional Portland concrete was invented in Leeds, England by Joseph Aspdin in 1824 using limestone obtained from the near-by Isle of Portland.
At that time Aspdin’s kitchen calcined (fired) limestone concrete was impressive. It was relatively easy to produce and use as a water-activated, artificial rock material that could be slurried, hand stirred, and formed into multiple construction / building products. To overcome the low compression / flexural strength metal rebar was inserted, allowing Aspdin and later on his son William's Portland concrete inventions to create the foundations of our modern world.
From that historic perspective, over the past two-hundred years limestone-bonded Portland concrete has revealed a litany of infrastructure, construction, building, metal rebar corrosion problems. Primarily due to the limestone-bonded, alkali chemistry inherent in traditional Portland concrete admixtures. While the concrete / construction industries have spent decades and $100’s of millions seriously trying to improve traditional Portland concrete; the crumbling, cracking, durability problems remain a serious problem.
Inclusive of Portland concrete material safety data sheets (MSDS) listing a range of health hazards. Including the caustic, alkali chemistry being detrimental to wildlife. With fish and aquatic creatures especially vulnerable to the caustic pH water changes from the toxic runoff that emanates from road building/repair and construction operations. While the obvious solutions to remove concrete pollution include (1) reducing the use of limestone-bonded Portland concrete, which is impractical given the massive worldwide need, (2) improving Portland concrete chemistry into non-toxic, eco-safe formulas, and (3) recycling CO2 emissions into carbon activated energy systems. With numerous carbon capture projects currently in advanced stages of development. https://www.climatecentral.org/news/first-commercial-co2-capture-plant-live-21494
Inclusive of another factual-based reality: traditional Portland concrete formulas are not going to go away anytime soon. Therefore, it's essential that the raw materials used in Portland concrete be replaced by eco-friendly, non-toxic versions. In studying these issues, a variety of chemistry issues underpin Portland concrete’s environment related issues. While the Portland concrete industry has supported decades of research to improve limestone-bonded concrete, unfortunately few if any worthwhile results have been achieved. While these earnestly enacted research efforts have convinced the competitive concrete industry that it has done and continues to do all it can do to improve Portland concrete. Inclusive of lauding the use of ‘coal-fired’ fly ash as a “recycled green material"? In spite of the fact coal-fired fly ash contains numerous toxins, including radioactive ingredients. As referenced in this link (https://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/).
With these concrete facts shared, environmental issues will continue to be a serious issue for the global concrete industries. With the Earth Summits in Rio de Janeiro, Brazil, Japan, and Germany in the 1990’s emphatically agreeing the continuing release of concrete produced greenhouse gases was no longer environmentally and socially acceptable. With the 2015 Paris Accord initiating a variety of protective concrete industry regulations to reduce harmful atmospheric emissions. While said regulations have not provided any significant, provable benefits other than increasing public awareness of these earth-threatening issues.
While the noble object of these environment protection policies was to significantly reduce CO2 related greenhouse gas emissions by the year 2030, as 2023 unfolds there has been little to no conclusive evidence of improvement. As the production of Portland concrete is vital to our global building, construction needs the massive use of traditional Portland concrete will remain a major environmental concern. All of which illustrates the need for the government agencies charged with reducing concrete pollutants to widen the scope of their investigations to include the superior quality, eco-friendly, durable benefits of the chemically-bonded ceramic concrete formulas that have emerged in recent times.
Significantly improved versions of Portland concrete conveniently produced and applied using conventional Portland concrete technologies. Providing water-activated, user-friendly, non-toxic, science validated concrete repair, construction, home building, decorative, radiation shielding solutions. With this information shared, due to the on-going global need for concrete the CO2, toxic runoff, environmental problems inherent in traditional Portland concrete will remain problematic into the foreseeable future.
With the noted exception of the chemically-bonded ceramic concrete formulas this report identifies 'seriously' being recognized and valued by the world concrete industries as the long awaited, evolved, readily available, eco-safe, user-friendly, 21st Century versions of Portland concrete. Not to replace and instead improve the use of Portland concrete by widening the earth-friendly scope of our local / global concrete needs. With decades of U.S. government / academic studies confirming that chemically-bonded PortlandCeramic concrete improves, protects, and removes the toxic-laden problems inherent in limestone-bonded Portland concrete.