want tell u guys u got a beautiful hard rock mine #1 thumps up .....and renantagum30 yes there so very strong cements but i know many way to turn it to dust ....i used a jackhammer on the stuff DIDNT WORK ,,,,,for all u other readers he is correct 100% about that cement (only) been around before 1928 because i know the hardest cement ive even seen was in the sub basement of building in NYC it was poured in 1928 that formula was used to build those twin building in malaysia ,,, but us miners we dont use jackhammers ....last time i seen a problem like this somebody used thermite and or shape charges
and there was no cage at the site and the work was a vertical above ground job (big job) works great on up to 4" thick steel to ......u know that black sand and XXXX make good thermite how u think the japanese did emergency welding jobs in the middle of no where (REMEMBER CAPTAIN KIRK AND AND THE SALTPETER OR TRAINS IN THE CIVIL WAR )