Pavement covers about one-third of a typical city in the United States and the concrete expansion rate is over 250,000 million acres a year.

The Pantheon in Rome - almost 2,000 years old and built from concrete.

Today we use more concrete than any substance, other than water. That means it accounts for about 8% of the carbon dioxide (CO2) we emit into the atmosphere. That is substantially more than the aviation industry, which makes up about 2.5% of emissions.

While the word "concrete" is used to mean something solid and foundational there are widening cracks around the world, including more recently the drama and tragedy of falling high rises and as Beiser reports in Wired around 20,000 bridges made of concrete are structurally unsound. .

More concrete will be used to meet the needs of inevitable urban growth. According to the United Nations Department of Economic and Social Affairs around 55% of the world's population reside in urban areas. This is projected to be 68% by 2050. Other reports puts the figure at 75%. As people migrate to cities the use of concrete is projected to significantly increase. The projection is an addition of 230 million (l2.5 trillion square feet of buildings by 2060.

A number of the existing buildings are unstable due to siting, a problem with rusting rebar enhanced by salt corrosion as an example, poor concrete, inadequate building practices, or ignored repairs with aging.

In addition, urban growth based on traditional city planning means more concrete for roadways and therefore a larger impact from vehicles which means an increasing cycle of damage and waste and more repairs.

Even with technological advances in its production, concrete takes a heavy toll on the environment.

Concrete consumes vast amounts of valuable water, requires high energy use in its production, and replaces valuable soils.

According to the UN report the projected equivalent of building with concrete is an entire New York City to the planet every 34 days for the next 40 years, which is around the time span 0f 20 to 40 years when repairs will be due. This represents not only enormous energy consumption but also increased air pollution.

Concrete can contain a range of toxic materials including radioactive contamination that affects air quality, particularly during demolitions and natural diasters. Some concrete materials naturally emit radon and uranium.

It also contributes to higher temperatures. particularly during heat waves. The cement industry itself produces high amounts of greenhouse gas.

Concrete manufacturing is a source of heavy pollution and the dust from concrete represents an extreme hazard.

Concrete lasts longer than, for instance wood, but it also replaces valuable biologic resources such as soil.

 

Global industrialization and population growth increase atmospheric CO2 levels which results in greater carbonation progression into concrete structures.

Summarily concrete is a major contributor to climate change.

Building Back Better?

Currently, pavement covers about one-third of a typical U.S. city. The nation's concrete expansion rate is over 250,000 million acres per year. The Biden' Administration's plan for an infrastructure overhaul, (Building Back Better) is a study in contradictions. Green is an espoused value, yet the plan calls for a massive use of concrete.

In its favor the use of concrete is not all bad. Concrete acts as a barrier to natural disasters and it replaces the use of wood from carbon sequestering trees. Concrete supports vertical solutions to density; dealing with large influxes of people. Finally, concrete can be used to create beautiful forms in crafting public spaces and structure.

 

The Panethon in Rome - no rebar, 2000 years strong Jubilee Church in Rome (architect: Richard Meier), double-curved elements in precast concrete uses metal mesh instead of rebar. Torre de Especialidadesis mitigates CO2 in its surroundings

Can concrete buildings become living buildings that produce more resources than they consume? The exploration into better concrete is one aspect of the rubric "intelligent design."

\When it comes to tall buildings, various methods to reduce lateral load and to ensure stronger foundations have been at play since the late 1960s. Today there are global concrete companies that more or less look for alternatives to the current production of concrete. Some solutions are already in play. Others are more futurist.

Green concrete has been a focus of attention by companies in terms of production and sustainability. This includes making concrete more reactive to the environment in positive rather than negative ways.

Citu is building its headquarters in Leeds from a new low-carbon concrete that it says cuts CO2 emissions by 50% compared to traditional concrete.

The engineering firm Arup planned to build a zero carbon city in Dongan China. The company produced a report envisioning a "dynamic network of feedback loops" which can be depicted as a nervous sytem. In its report, It's Alive the firm shared its vision of a building powered by renewable energy such as external walls coated with photovoltic paint, micro-wind turbines and an algae facade to produce biofuels. A nano membrane captures waste carbon and converts it to oxygen. However, says Brubaker "planners failed to adequately consult with the community and adopt a “locally guided process,” a lapse common to nascent eco-cities".

Some companies use of recyled fly ash in the production of green cement as a method to reduce the use of natural resources. Other companies seek formulas that reverse the negative effects of concrete through production methods that contain additives that allow the sequestering carbon pollutants over long periods of time.

One proposal borrows from studies of water availability on the Moon which include the use of sulfar based "waterless concrete" as opposed to hyraulic cement to reduce natural resource use.

Among other innovations, Italcementi, founded in 1864 in Bergamo Italy, introduced a cement that retains smog with a transparent cement produced by using thermoplastic polymer resin. and a new cement that retains cement with enhanced titanium dioxyde. that is activated in sunlight. Pollutants that com in contact with the surface of the cement are oxidized.

Using less concrete is an optimal approach. The use of precast concrete using molds helps reduce production time and with less cement.

One company, Sirewell, is using rammed earth and hybrids that consist of some concrete. One building created in Pakistan is 100 feet tall and spreads out over .47 acres. The rammed earth technology proclaimed to be beautiful, shapely, more sustainable than concrete, great thermal capacity, with a natural array of colors, longer lasting, and it is even recyclable.

However, let's be clear, there is no magic bullet. For instance, rammed earth can produce elegant solutions however we are currently destroying soils around the world to an estimated loss of 30% of our subsoil in the last 200 years. In other words there are always tradeoffs and balances to consider. In the case of rammed earth, as an example, building a structure depends on local soils. But, ,an estimated 80% of carbon is stored in soils. Climate change and poor building and agricultural practices destroy this carbon storage and releases carbon into the atmosphere.

Regulations and incentives might that encourage using less cement. For instance, in 2019 Marin County CA established the nation’s first local building code that limits emissions from concrete used in public projects.

The New York State Assembly took another approach provided incentives in procurement selections of 5% add-on for companies that used concrete with reduced carbon emissions.

Telenor headquarters Islamabad using Rammed Earth

Equity and Community

Green concrete does not address the question of equity. To begin with poorer communities are not only more cemented over making their neighborhoods hotter and more susceptible to climate change, they also breath in air pollutants from concrete production and decay which are mostly located in their communities.

Communities have been destroyed as historically highway development broke up neighborhoods and cultures.
Remedies that address this inequity are in short supply.

For instance, Congress passed The National Environmental Policy Act (NEPA )in 1969, instructing governments and agencies at all levels to cooperate with public and private organizations “to create and maintain conditions under which man and nature can exist in productive harmony, and fulfill the social, economic, and other requirements of present and future generations..."

Today, NEPA seems to be a blunt instrument. But if refined and broadened enough to return to its roots NEPA could address the impact of proposed infrastructural changes to address inequities. The question of political will is a factor as to whether NEPA would be useful in that regard.

Alternatively, in an era of crumbling infrastructure some communities are fighting back. In the 1960s alliances were formed across racial and socioeconomic lines as part of a Freeway Revolt which was part of a multi-decade effort to protect communities against massive federal projects by deconstructing and reimagining better.

In Syracuse New York 1.4 miles of an aging 1-81 highway will be removed and a new community grid is planned to reconnect nighborhoods. Other cities are following suit, driven not only by the destruction of communities, but also because of the realization that it is now state funds, not federal, that have to pay for remediating decayed highways. Various approaches include replacing a highway with a boulevard (Octavia Boulevard), moving a main artery underground, (Boston), turning a portion of the highway into a surface street (Detroit MI), and developing a master plant to shape a former highway into pedestrian friendly access to a downtown area (Milwaukee MI).

In return, detractors who prefer to restore existing highways say removing highways will not dent racial injustice and removal will contribute to gentrification.

In almost all cases the mitigation of too much concrete and in the wrong places have happened not because of wise planning, but because of grassroots activism.

The back of the turtle

Let's return to Biden Administration's infrastructure proposal. It is difficult to discern where equity is a factor. It is as difficult to know how much innovation will actually occur.

There are a number of barriers to building in equity in infrastructural plans. The reality is the increasing density of urban areas, the challenge of vertical versus horizontal space, outdated building codes, values that determine infrastructure, the drive of private landowners to wait for price hikes, and, of course, politics as usual are all barriers. All in all it adds up to an incredible waste of urban space and antiquated transportation planning while many people remain homeless.

The use of concrete is not going to go away. However, what kind of concrete and for whom?

While phrases such as sustainable, intelligent design, housing for all, housing first, and green; are all at play with innovations on a global scale by private and public interests, they are words to consider carefully in terms of the actual accessibility in relation to low income housing. First, words such as "green"- are ideals, that, true or not, are easily co-opted. Secondly, notions of scarcity is a significant barrier to doing the right thing. This notion implies that technologies involved with "intelligent design" are too expensive in relation to low income housing, however defined, when in fact collectively speaking one could argue that the use of emerging technologies appropriately applied are less expensive options.

Concrete can be produced with greater efficiency and less environmental cost. Concrete can mitigate climate change. It can on a smaller scale be interwoven with technological advances in vertical and horizontal use of space for housing. It can meld with appropriate technologies as an infrastructural goal. It can be moved, reused and repurposed and used more sparingly. It can utilize technologies including the use of batteries. It can work in planning the right amount of green space. Concrete can be sustainable and a plus rather than a minus when it comes to climate change and the question of equity.