The Materials Book

Invasive Plant, Innovative Aggregate: Removing eucalyptus trees provides employment and a building material Concrete is usually made by combining cement with aggregates such as sand and gravel. In South Africa, an alternative aggregate is wood chips from invasive species, which offers environmental benefits that go far beyond the building sector. The wood comes from non-native plants, such as eucalyptus trees, that threaten the local flora, consume an outsize share of scarce water resources, and fuel wildfires. Locals are hired to cut the plants and grind them into wood chips, which are then mixed on-site using low- cement binder. The wood-chip formula offers sufficient strength to build multilevel structures and has a three-hour fire rating—triple the level of conventional building materials. Example: Light House Invasive-wood-chip aggregate, developed by the Department of Environmental Affairs of the Republic of South Africa, South Africa Contributed by: Stephen Lamb, South Africa 312