With the proportion of Africans living in cities expected to climb from 18 percent in 1950 to 56 percent by 2030, building materials will be in greater demand than ever. Rising to the task are two recent studies reporting new ways to make bricks from common materials, including mining waste and desert sand. Although more research is needed to ensure the innovative bricks can withstand extreme weather and won’t pose health risks, initial tests are promising. Photo by Marc Falardeau (Flickr | Creative Commons)