What about sand? The supply has no limit, right?

degrowth.de: "Globalization has had massive impacts on human life on Earth. Its sphere of influence extends from homogenization of cultural aspects such as clothes, food and language to even things like the concept of modernity. Today, one would expect similar infrastructure in cities that are either developed or rapidly developing. One sees a greater number of glass facades and skyscrapers as cities develop. It has become the norm to expect more and more roads, airports, bridges, ports, golf courses, parking lots in a modern country irrespective of terrain and geography. However, beneath this extraordinary growth lies an unexamined philosophy. Since ancient times, sand and other aggregates have always been used to create concrete. But the scale of construction has increased far beyond measure today and this increase in scale has spawned problems that few people in earlier generations could have imagined."