Chemical Reaction Causes ‘Explosions’ on New Jersey Construction Site

Residents living near a Jersey City, New Jersey construction site were frightened as they watched “explosions” of smoke coming out of holes in the ground. 

In order to break up some rock in the subgrade, contractors used a chemical called Da-Mite, according to, which is a non-explosive rock splitting mortar.  Holes are drilled into the rock, the chemical is then poured into the holes, and the mortar then expands with a force of around 18,000psi, causing the rock to break apart, according to the manufacturer’s website.

City spokesperson Jennifer Morrill told that the chemical was not approved by the city’s Building Department.  Jersey City Fire Chief also told them that he believes the explosions happened because they reacted with the air temperature “in a way it wasn’t supposed to.”

The explosions of smoke continued for around two hours and McGill said that some windows were cracked by flying rock.

A representative from the general contractor explained to that the puffs of dust coming out of the holes is “completely normal” and does not agree that any windows were broken by the reaction.  The site was shut down earlier in the day due to haphazard jackhammering that “failed to protect neighboring property,” according to Morrill.

On Daigh Company, Inc.’s website, the maker of Da-Mite, they include a note at the bottom of their “how to use” page, which states:

“Let Drilled Holes Cool Off before placing Dā-mite® in them. Cover the area with a tarp or other device after loading with Dā-mite® to minimize effect of blowouts. Also cover in case of rain to keep product dry until after Dā-mite®'s chemical reaction is complete.”

Below is a video of one of the “explosions”, uploaded to Youtube by