The increased use of secondary (i.e. recycled) and renewable resources will likely be key in achieving sustainable materials use. Unfortunately, these strategies share a common barrier to economical implementation—increased quality variation compared to their primary and synthetic counterparts.
With this project, we are working to reduce energy use and greenhouse gas emissions associated with the construction industry by introducing alternative materials derived from unused or currently under-utilized industrial waste.
Beneficial Use of Non‐hazardous Industrial Byproducts in Building Materials
Industrial activity leads to significant environmental impact in the form of energy use and emissions to air, land, and water. The construction industry is one of the largest consumers of natural resources and one of the largest sources of greenhouse gas emissions.
With growing industrialization and urbanization in the developing world, and the impacts of global climate change becoming ever more apparent, it is imperative that we work together to find alternatives to many industrial status quo practices. To that end, we are developing new construction materials based primarily on industrial byproducts to address both the environmental impact of the byproduct generation and the impact of resource use in the built environment. Our approach combines expertise in materials science, environmental and economic assessment, architecture, and civil engineering.
Current Focus: Masonry from Industrial Boiler Ash
Our primary focus so far has been on alkali-activation of boiler ash derived from partial combustion of agricultural waste products (e.g., rice husk, bagasse, and wood chips). In India, as with much of the developing world, standard industrial practice is to produce electricity locally due to unreliability of the electric grid. While large plants primarily burn coal, small and medium-sized paper, rice, and sugar mills burn the cheapest agricultural wastes available to them, producing upwards of 20 tons of ash per day. Agricultural waste production varies by season and locale, yielding ash that is similarly variable. Due to this variability, boiler ash generally ends up in nearby landfills instead of being utilized, as with more homogeneous fly ash stemming from coal combustion.
Alkali-activation—the reaction of aluminosilicate precursors, such as ash and clay, with alkali hydroxides—affords us the opportunity not only to divert ash from landfills, but also to reduce India’s reliance on red bricks as a building material. Red bricks must be cured at temperatures around 1000oC, with demand leading producers to dig deep into and erode topsoil clay, which could otherwise be used as arable land. Alkali activated materials and geopolymers achieve appreciable strength after only days of curing at room temperature, illustrating their promise as an alternative to many current building technologies, red bricks included.