Texas A&M scientists have developed a new 3D printed, local soil-based, load-bearing structure for greener housing purposes.
According to the project’s principal investigator. professor Sarbajit Banerjee. concrete remains the material of choice for many construction projects. It however has a large carbon footprint and this results in high waste and energy expenditure.
The construction industry has been of late showing some interest in build structures layer by layer with the help of additive manufacturing, saying it reduces waste.
However, the materials used in the process need to be sustainable as well, opines Banerjee, alluding to the yearly 7% of CO2 emissions caused by concrete manufacturing – which, to make matters worse, cannot be recycled.
“Historically, humans used to build with locally sourced materials, such as adobe, but the move to concrete has raised many environmental issues,” contends Aayushi Bajpayee, a graduate student in Banerjee’s lab.
“Our thought was to turn the clock back and find a way to adapt materials from our own backyards as a potential replacement for concrete.”
Using a material as abundant as local soil (clay) has many advantages; it doesn’t need to be manufactured and transported to the building site, and this helps reduce costs and damage done to the environment.
As part of their research, the scientists collected soil samples from a colleague’s backyard and tailored the material with a new environmentally friendly additive so that it would bind together and be easily extruded through the 3D printer.
Because soils vary greatly by location, their aim was to have a chemistry ‘toolkit’ that could transform any type of soil into printable building material.
From there Bajpayee built small-scale test structures, cubes measuring two inches on each side, to see how the material performed when extruded into stacked layers.
The next step was to ensure that the mixture is load bearing, meaning that it will stand up to the weight of the layers but also other materials used in construction such as rebar and insulation.
To help with this, the scientists strengthened the clay mixture by ‘zippering’ the microscopic layers on its surface to prevent it from absorbing water and expanding.
According to the scientists, this method is both resourceful and sturdy as it helps the new material to hold twice as much weight as the unmodified clay mixture.
Image and content: Aayushi Bajpayee/ACS