Expando came to the rescue in this small residential tunnelling project in North Sydney. The owner is in his early 70s and knows that in the future the 38 steps from his gate to his door are going to become a really big obstacle. The project involved tunnelling a horizontal shaft through sandstone to the rear of the garage under the front lawn and then under the existing lounge room, where a small elevator shaft was to connect the vertical shaft to the horizontal tunnel under the front lawn. The project was a hobby for the former mining engineer.
Due to the cost and time taken to excavate the first five metres of the tunnel, we were engaged to help. The challenge was to fill horizontal and vertical holes using the chemical solution Expando. We initially used a grout pump to fill the horizontal holes but the hire cost was too expensive for this residential job so we came up with an alternative method.
We filled long skinny bags with the chemical Expando and forced the bags into the horizontal holes using a PBC pipe and timber ream. The effect was the same as if we had poured it into the holes from the top.
Expando enabled tunnelling a horizontal shaft to proceed far enough under the house to start cutting in the vertical shaft. Holes were drilled up from the lower tunnel and as the rock was removed from the top it was simply dropped down the hole to be cleaned out through the garage. Success!
Expando is a non explosive demolition agent that cracks rocks and concrete without the need for blasting or heavy equipment like excavators, jackhammers or concrete saws.