Scientists Develop Lower-Carbon Cement Alternative From Recycled Glass and Construction Waste

In a new study, scientists have found a way to turn industrial waste, such as recycled glass and construction waste, into a soil solidifier that is cement-free. By cutting out the cement, the material serves as a lower-carbon material for green construction.

According to the UN Environment Programme, the built environment and construction sectors make up 37% of total global emissions. Cement, in particular, is one of the highest-emitting materials, making up 8% of global emissions, the World Economic Forum reported.

Cement is the most commonly used material for soil solidification. Soil solidifiers are often used in construction, such as for building roadbeds or building foundations. The solidifiers are added to soil for better binding, compaction, water-resistance and strength.

But a team of scientists in Japan have found an alternative soil solidifier using Earth Silica, which is an alkaline stimulant sourced from recycled glass, and Siding Cut Powder (SCP), a waste product from construction. They published their findings in the journal Cleaner Engineering and Technology.

The resulting material was so effective that it surpassed the construction-grade threshold for soil compressive strength, 160 kilonewtons per square meter.

“This research represents a significant breakthrough in sustainable construction materials,” Shinya Inazumi, lead author of the study and a professor at the College of Engineering at Shibaura Institute of Technology (SIT), said in a statement. “By using two industrial waste products, we developed a soil solidifier that not only meets industry standards but also helps address the dual challenges of construction waste and carbon emissions.”

According to the study, there is a potentially vast supply of SCP from siding production. Siding panel manufacturing produces a powdered dust byproduct, of which 94.1% is wasted. This resource, combined with the reduced lifecycle costs from the durable, cement-free soil solidifier, could lead to major cost savings in construction, although the scientists noted more research is necessary on the full lifecycle and cost analysis of this material.

“By developing a geopolymer solidifier from readily available waste streams, we are not only offering a sustainable engineering solution but redefining how we value industrial byproducts in a resource-constrained world,” Inazumi said.

During the research, the scientists did detect some arsenic leaching from the recycled glass, but they were also able to address this concern and improve the environmental safety of the material. As Inazumi explained, the team added calcium hydroxide, which stabilized the calcium arsenate compounds in the soil solidifier.

“Sustainability cannot come at the expense of environmental safety,” Inazumi said.

The team has determined a wide variety of use cases for the material, including for stabilizing soil around bridges, roads and building foundations. According to Inazumi, this cement-free soil solidifier could be particularly useful on clay soils. 

The material could also be used for developing solid, durable soil blocks as an alternative to concrete or brick for buildings. Because the material works quickly and efficiently as a soil solidifier, it could also be deployed in emergency situations.

“By utilizing industrial byproducts such as SCP and ES, this approach not only reduces carbon emissions but also addresses waste management challenges in the construction industry,” the authors concluded. “The scalability and adaptability of these materials make them a promising solution for diverse geotechnical applications.”