Cement

It’s time to redefine our relationship with one of the world’s most consumed materials: concrete. Favored by builders in urban and rural development for its durability, affordability, and widespread availability since its invention in the early 19th century, concrete now covers over .8% of the earth's surface and is the source of more than 8% of CO2 emissions globally. Concrete also vastly contributes to the urban heat island effect, exacerbating heat waves in cities across the globe, and contributing to soil pollution and urban flooding. So, what’s to be done about our concrete problem?

As designers, builders, and city planners, we can reduce the amount of virgin concrete used for the construction of new buildings and infrastructure by utilizing deliberate and economical design strategies. By weighing concrete’s material benefits against its high environmental and social costs, we can learn to treat concrete as a valuable resource regardless of its availability or price point. Utilizing regionally appropriate and diversified building materials can also aid in taking the strain off concrete as a primary building material. 

We can also choose cement alternatives--also known as supplemental cementitious materials or SCMs--whenever possible and promote the diversification of SCMs sourced from regional material supply chains. Cement, the key binding agent used in most standard concrete, is produced using processes of “chemical and thermal combustion,” which are primarily responsible for concrete’s carbon footprint. Portland Lime Cement is the standard binder used in concrete--its replacement can significantly reduce the carbon footprint of cement. A variety of notable SCMs already exist: Fly Ash, a by-product of coal production, has been utilized as a primary SCM since the 1920s, though it may become increasingly scarce as coal power plants continue to shut down. Glass pozzolan (GGP) is another SCM derived by grinding up recycled glass. GGP contains high amounts of silica but requires that 'waste' glass is carefully sorted from contaminants such as paper, a time-consuming and costly process. Other SCMs are more niche due to challenges of cost and scale, but offer significant beneficial outcomes. The mineral olivine, which absorbs atmospheric carbon, can be utilized as an SCM to create carbon negative concrete. As SCMs become increasingly accessible and diversified, be sure to utilize alternatives to Portland Cement whenever possible. 

Mini article: Regionally Native vs. Native plant gardens

Many of us understand the benefits of selecting native plant species for our gardens, but little emphasis is placed on selecting plants that are regionally native… And yes, there is a difference! 

The composition of regionally native plant species surrounding your home is likely considerably different from the composition of native plant species even just a few miles away.

To help preserve the balance and biological diversity of native plants and animal species in your region, make sure to do your research and plant native species only within their native range. 

For example, a plant species which is regionally native to one area of CA might not be regionally native in nearby regions. A native species from one region of CA could become invasive in a different region of CA when planted outside of its native region.  

Planting regionally native species ensures that your garden is most resilient and water efficient in your unique climate.

Planting regionally native species also aids in preserving the diversity of native animals and pollinators such as native bugs, bees, and birds. Many native plants and pollinators form highly specialized interdependent relationships, in which a pollinator is specialized to pollinate one plant species and a plant is specialized to attract a single pollinator species. If either species disappears, plant or animal, both species will perish. Help to preserve delicate interspecies relationships by planting regionally native!