Kyushu shirasu volcanic-glass micro-powder as cement-replacement SCM

Problem solved

Silica fume is import-dependent and blast-furnace slag supply is shrinking as steelmaking shifts; a domestic natural pozzolan is needed that can replace part of cement without a new placement method.

Application contexts

• Precast concrete products needing early demould strength and later durability
• Slope-protection shotcrete / mortar in chloride, freeze-thaw or acidic soil
• Surface and deep soil mixing and grout
• Refractory castables seeking densification and a domestic silica source

Technical principle

SiO2-rich volcanic glass is milled to a controllable fineness. In alkaline pore solution it undergoes a pozzolanic reaction, consuming portlandite and forming additional C-S-H, which the company says supports early strength plus later densification. Official page states a design target of about 20–30% CO2 reduction by cement replacement and names example replacement bands of about 10–30% for ground improvement.

Typical use cases

• Partial cement replacement in factory-made precast
• Domestic substitute for silica fume in high-strength trial mixes
• SCM for slope shotcrete and soil-mixing grout