ICSRR – E083 PERFORMANCE AND COST ANALYSIS OF TWO COMPONENT TBM PRIMARY GROUT Mani Arasan.Sa, Abinaya Ishwarya G Kb*

Two-component (A/B) grout systems are widely used in Tunnel Boring
Machine (TBM) tunnelling for annular gap backfilling. These systems
consist of a cementitious slurry (Component A) and an accelerator
(Component B, typically sodium silicate), which rapidly react to form a gel,
enabling quick setting and early strength development. The performance
and cost-effectiveness of such grouts depend on mix composition, including
cement, water, bentonite, supplementary cementitious materials like fly
ash, and accelerator dosage.
This study evaluates the relationship between grout performance
parameters—such as viscosity, gel time, bleeding, and compressive
strength—and overall project cost. The use of industrial by-products
reduces cost and environmental impact but may affect early strength and
setting characteristics. Therefore, optimization of mix design is essential to
achieve a balance between performance, cost, and sustainability. The study
highlights the importance of laboratory validation and techno-economic
analysis for selecting suitable grout compositions for TBM operations.
Keywords: TBM; Two-component grout; Sodium silicate; Fly ash; Cost
analysis; Tunnel grouting.