The Hidden Nation of Cement
By Justin Lindemann, NC State Master of International Studies student
What surrounds us quite often, keeps us upright, yet adds instability to our lives, all at the same time?
Cement.
Shocking, right? Though the title gave it away.
Often interchanged with concrete, cement is used to create the water-added paste that combines with various aggregates (sand and rock) and mixed together into the universal material. With cement having been first incorporated in buildings dating back to southern Syria and northern Jordan around 6500 BC, the concrete ingredient has been around for ages. But, the environmental impacts have been largely swept under the rug, with more of the focus dedicated to other sources of greenhouse gases.
Surprising to many, the construction component is 8% of the world's total carbon dioxide emissions, and if labeled a country the cement industry would be the third-largest emitter, behind China and the US. In other words the volume of cement used for concrete is so large, that in a day the global building industry uses enough concrete to construct something that is almost the size of China’s Three Gorges Dam -- the largest dam in the world.
Three Gorges Dam, China. Credit: Le Grand Portage, Wikipedia
We may have even crossed the line at which concrete’s total carbon mass outweighs every single tree, bush, shrub, or other greenery on this planet. Outlining exactly how massive cement’s use has gotten.
The emissions from cement stem from a myriad of factors. One of them being the traditionally-used cement making process, involving heating up limestone that then creates lime and CO2-waste -- this results in half of the emissions that cement produces.
Further 40% of emissions comes from burning fossil fuels to heat up the limestone, with the remaining 10% coming from fuels used to mine and transport the required raw materials.
Other environmental damages transpire from the landscape degradation, dust, noise, and loss of agricultural land to the extraction process. As well as the amount of water used to wash away aggregates, reduce the severity of dust, and in several other parts of the manufacturing process.
In terms of the water consumption used in creating the concrete mixture, a study in Nature quantified that in 2012 global concrete production was responsible for 9% of global industrial water withdrawals. While predicting that in 2050, 75% of the water demand for the production process will most likely occur in regions that will experience the severity of the planet’s water stress.
As for the United States and its relationship with cement, the biggest historical emitter is ranked at number four in the world for its cement production. Production is predicted to increase as the US is following the global trend of increased urbanization, with the US possibly seeing almost 88% of its population living in urban areas by 2050. Spiking the need for housing and construction, as more and more people flock to those heavily cemented areas.
North Carolina has also seen a progressive growth in urbanization, as around 57% (5.9 million people) live in urban areas. With ⅔’s of NC growth projected to take place in the Triangle and Charlotte -- the two regions of NC make up 40% of the state’s top ten most populated cities. If those populations were to increase -- something that is very likely -- the number of construction sites are sure to go up as well to meet the demand. Currently, there are already signs of a prosperous population influx in the decades to come, deriving from the recent release of the 2020 census data. Showing an almost 1 million population increase in NC since 2010, which was enough for the state to gain one additional Congressional seat.
Charter Square South construction in Raleigh, NC in 2014. Construction ended in 2015. Credit: James Willamor, Flickr
As for the consequences of cement’s pollutants, the environmental justice impacts stemming from the discriminatory placement of domestic cement plants are quite evident. With parts of the US, including NC, knowing very well what this looks like.
Nationally, Texas is home to the largest number of plants in the nation, with Harris County, having the most in the state. It is in State House District 140, that we see one of the many examples of the motions of environmental racism take place. The district’s community makeup represents around 83% Hispanic, 9% Black, 6% White, and 2% Asian residents, making this a prime target for predatory polluters. With Harris County having at least 188 of these production plants, much of the pollution impacts have grappled communities, as dust from the concrete plants cover their property, infect their lungs, and even creates a muddy build up that traces through the community. Sadly, the effects of nearby concrete batch plants don’t just stop there, as the aforementioned lung infections have created a disproportionate health storm from the associated particular matter creation in the production process of concrete. The pollutant is linked to reduced lung development in children, and higher rates of asthma, bronchitis, heart disease, and even cancer. In the nearby Houston area (which is also part of the State House District 140), a 2015 study of satellite imagery and other data sources, linked 5,200 premature deaths in the city to particulate matter. The Texas metropolis has also been found to have almost ⅓ of its batch plants just a short walk away from a school or daycare.
In NC, a similarly disastrous choice was almost made, as a proposed asphalt/concrete plant was paused by Carolina Sunrock LLC in the Anderson area of Caswell County -- Northern NC, alongside the Virginia border -- in proximity to the majority populated Black community on Hughes Mill Road. Thankfully, the North Carolina Department of Environmental Quality’s Division of Air Quality (DAQ) denied a permit for the facility.
However, lifesaving choices like this don’t happen in all areas in the US -- as shown by Harris County, TX. Showcasing the specific paths that concrete firms and corporations take when looking to pollute freely.
Abandoned cement plant located near Castle Hayne, NC, 15 min. outside Wilmington. It is also a Superfund site, due to the mercury leaching from the fire bricks used inside the kilns. Credit: leep, Flickr.
Nevertheless, with all the downsides of continued cement usage and concrete production, there are possible solutions in the mix, specifically ones that promote circular thinking and longstanding reusability. Seeing as though cement production will continue to be prevalent alongside our seismic population and economic growth, it is important to offer less-damaging alternatives to cement’s age old formula. Fortunately, newer recipes for the centuries old mixture are in the works.
One of them is from CarbonCure Technologies in Halifax, Nova Scotia, where a process of injecting liquid CO2 into the concrete mixing process is used to keep the well-known greenhouse gas from entering the atmosphere. It strengthens the concrete created, all the while reducing the amount of cement used. Though the carbon reduction has only been a small 5-7%, there is enough room to innovate and grow the process to achieve a higher emission decrease.
Other corporations involved in the business of efficient cement mixing and low-carbon concrete include Blue Planet -- based in Los Gatos, CA -- as they use CO2 from the exhaust stacks of a power plant to synthetically produce limestone, substituting the sand and gravel that is normally incorporated into concrete. The pilot technology has been used at the San Francisco International Airport.
Another revolutionary of the construction industry is RTP based firm, BioMason, which uses a carbon-calcium combination to produce biocement for its biologically formed bioLITH technology. The precast product is made up of 15% biocement and 85% granite, and captures carbon similarly to nature, instead of the traditional release of carbon. The new concrete construction is three times stronger than a regular concrete block, completely reusable and recyclable, CO2 neutral.
All in all, just this one ingredient of concrete, has a massive global impact on our environment and emissions trajectory. Along with the environmental racism and injustices corresponding to its production, the loss of life, and possibly fatal health problems associated with its pollutants. Of course, there is a way out, as numerous ingenuities and technical solutions that could lessen the impact of cement and its concrete products are on the move. Each ensuring a more circular paradigm in the construction sector, while still allowing humans to keep the sturdiness that the long-used cement-water mixture has given us. But, with population growth demanding more space to create and cement’s bigger future endangering the planet’s critical goal of zero emissions, applying these fixes and many others needs to happen as soon as yesterday. Fortunately, today still gives us a chance to do better, and the innovation mentioned will help us reach another tomorrow -- a circular one that is.