February 08, 2022
Over the last three years I have taken notice of the small sand bar that sits near the bridge across the Arkansas River that I travel going north to work. The sand is held together by the grass and trees that have managed to take a hold. The size of the sand bar varies depending on the height and velocity of the river’s current. This section of the river is part of the US river navigation system, and there is a sand plant nearby that will occasionally dredge the river bottom to remove the excess silt and sand that accumulates. The sand bar sits out of the main channel, so it has continued to survive.
When I looked online, I found that sand is a granular material composed of finely divided rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. The composition of sand varies on local rock sources and conditions. The most common sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. The second most common type of sand is Calcium carbonate (CaCO3), which has been created over the past 500 million years by various forms of coral and shellfish. More rarely, sand may be composed of calcium sulfate (CaSO4), such as gypsum and selenite, found in places like White Sands National Park and Salt Plains National Wildlife Refuge in the US. Sand is a non-renewable resource over human timescales, and sand suitable for making concrete is in high demand. Fifty billion tons of beach sand and fossil sand is used each year for construction.
Sand is the second most-consumed natural resource on the planet besides water. The concrete used to construct shopping malls, offices, and apartment blocks is primarily made of sand. The concrete or asphalt used to build the roads that connect these structures are largely made of sand. The glass in every window, windshield, and smart phone screen is made of melted sand. Even the silicon chips inside our phones, computers, and nearly every other piece of electronic equipment are made from sand. The plentiful desert sand is useless for building as it is eroded by wind rather than water, forming a smooth surface that does not adhere well in concrete. The more angular grains of sand are found in the beds, banks, and floodplains of rivers, and in lakes and on seashores. The demand is so intense that riverbeds and beaches are being stripped and farmlands and forests are torn up to get the sand.
Thoughts: The demand for sand has spawned criminal gangs who capitalize on the trade of black-market sand. This has resulted in a wave of violence during the 21st century around the struggle for construction sand, and our addiction to sand is growing. Scientists are working on ways to replace sand in concrete with other materials (including shredded plastic) and developing concrete that requires less sand. Other researchers are looking at more effective ways to grind down and recycle concrete. Many Western countries have begun to phase out river sand mining but getting the rest of the world to this restriction will be tough. The West has abused the planet’s resources for 500 years, and now expects underdeveloped countries to limit progress to preserve the environment. This will not happen unless developed countries are willing to take the first (and several) steps in our own reduction. Follow the science. Change is coming and it starts with you.