the substance that made him dead — "it was like Gately shot cement…"
it was like Gately shot cement instead of narcotics.
Context
The paradox of his drug of choice, reported by the men who used with him: off the narcotic, Gately was a great jolly stand-up guy; on it he went taciturn, interior, dead-like, and made whoever got high with him feel lonely. The thing he loved most turned him into the absence of himself — he shot cement — which is the disease's signature cruelty, the substance that promises comfort and delivers a man's own erasure to everyone around him.