Chryso formulates backfill grout to replace bentonite

Sources: Chryso Group, Paris; CP staff

In a partnership with tunnel boring machine (TBM) lubricant specialist Condat SA of France, Chryso has developed a backfill grout solution, TBM SGS (Smart Grout System), exhibiting the potential as a substitute for bentonite. A clay that expands when hydrated, bentonite is commonly used in backfill mix designs but brings environmental impacts tied to transportation and site staging.  

Chryso TMB SGS 150 retarder and TBM SGS 400 stabilizer ensure grout stability over several days. Material stability and low viscosity allow for pumping grout over long distance and reduce the need for pipe flushing during machine stoppages. “We are bringing a high-performing environmentally-friendly backfill grout for tunnels and underground cities projects,” says Chryso Concrete Business Unit Deputy Director Marc Plançon. SGS performance attributes significantly reduce a tunneling construction site’s environmental footprint, he adds: The 400 stabilizer’s unique formulation allows complete substitution of bentonite, a nonrenewable raw material. 

“Furthermore, we offer a sustainable supply with SGS 400, which is based on renewable raw materials and [performs with] alternate cementitious materials such as GGBS slag for a reduced carbon dioxide footprint,” Plançon observes. “Our research plan is totally focused on providing sustainable solutions to our customers and lowering COemissions.”

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