Products for cavity filling are used wherever large-volume voids and loose rock masses need to be filled and consolidated quickly and efficiently.

Voids are created either due to construction activities, such as tunneling or pipe jacking into fault zones, during extraction of raw materials in mining operations, or by pure accident, usually associated with water ingress, because of soil washout and soil redistribution. However, cavities may also already exist as in karstification or previous mining activities, in which case, for example, shafts, tunnels and other cavities can be easily backfilled, in a safe and economic way.

The stabilization and backfilling of cavities in coal mining also prevent methane accumulation and the associated risk of explosion. In potash mining, the void fillers are used to seal off ventilation structures. In the rehabilitation of near-surface mining, high-foaming products are used to construct closure dams even in hardly accessible areas.
Over the decades of experience with unwanted cavities underground, we have developed various products for void filling. All with the common quality of filling large voids relatively quickly with little product mass with little or no formwork at all required. The backfilling of cavities in coal mining also prevents methane accumulation and the associated explosion hazards. In potash mining, our void fillers are used to seal meteorological structures. In the rehabilitation of near-surface mining, high-foaming products are used to construct closure dams even in inaccessible areas.

In function of the situation, our high-foaming dual-component systems silicate and phenolic-based resin foams (WILLKAT^® FOAM and WILLFLEX^®) quickly restore safe operations. Filling the cavities usually prevents further fracturing of the rock strata. Drifting or mining can thus be resumed quickly.
In addition, WILLKAT^® FOAM and WILLFLEX^® 09 being flame retardant products, with relatively low reaction temperatures, can prevent spontaneous combustion and ignition of coal and coal dust. In contrast to polyurethane resins, these products have good mechanical workability (full- and road header, excavator, excavation hammer) and are therefore well suited for use in fault zones, since after backfilling and consolidation, excavation can be resumed in a gentle manner on the rock.