Incase of the vault is located inside the tunnel or in a hole burning with use of logs is messy instead I recommend to use a blow torch then put vinegar the heated area and you can easily break the brittle cement with use of chinsel. A small hole is enough to see inside and you can repeat the procedure if you want enlarge the hole so you can get the item inside.
You can use the dexpan if you have a electric or airtype drill so you can put the chemical inside your drill hole and dexpan can work, unless your type of dexpan application is in the surface of stone or cement only.
That small blowtorch is useless in actual portion of concrete demolishing....when we were amateur THr we always bring along a blowtorch, a gallon of vineger and chisel... hoping that it can demolish a portion of concrete.
When we tried it in a portion of concrete....it took us maybe 2 hours to chips a portion of concrete using blowtorch, splash vinegar and chisel......while a neighbor carpenter using only a chisel/hammer,
he was able to chiseled same amount of concrete at 15 minutes time !!!.....hahaha....
We realized that we were just a fool bringing along that blowtorch hoping that it would make our work faster. The carpenter is laughing at us, why we do that kind of chiseling using useless blowtorch. He told us, we make the work difficult and cumbersome, instead of simple work.
(Para pala kami mga gago nun dala ang suplete sa mga sites, wala palang silbe. mas mabilis pa ang panday magchisel na di gamit ang suplete...pinagtatawanan nga kami ng panday eh, napakasimple magsinsil...pero kaming mga THr pasuplete2 pa at pinapahirapan pa sarili.....nagmukha kami tuloy tanga)
