WAYNE, N.J. (AP) _ Chairman Samuel J. Heyman's buyout offer for GAF Corp., once a casualty of the stock market crash, ended 18 months after it was launched when shareholders accepted the $1.46 billion bid.

GAF told shareholders at a brief annual meeting Thursday that 94 percent of the shares for which votes were submitted approved the acquisition by a management group headed by Heyman.

The deal will likely be made final in two weeks when financing arrangements are completed, GAF said.

Stockholders will receive $46 in cash and an estimated $7 worth of subordinated debentures for each share. The transaction is backed by $885 million in bank loans led by Chase Manhattan Bank and $285 million in high- yield ''junk'' bonds underwritten by Drexel Burnham Lambert Inc. and Merrill Lynch Capital Markets.

Heyman and management group members are investing $100 million through the purchase of senior subordinated increasing rate notes.

A maker of specialty chemicals and building materials, GAF in 1988 earned $90.8 million, or $3.18 a share, before extraordinary credits, on revenues of $961.4 million.

As the announcement was made, the trial of GAF and Vice Chairman James T. Sherwin continued in federal court in Manhattan with the second day of the defense presentation.

The government accuses GAF, two subsidiaries and Sherwin with illegally trying to manipulate Union Carbide Corp. stock before GAF planned to sell Carbide shares in 1986.

''We are extremely gratified by the outcome of the shareholder vote,'' Heyman said in a statement. ''It clearly demonstrates the success of a process which was designed from the outset to realize for shareholders the highest current value for their ownership interest in the company.''

Heyman's first offer came in September 1987. It was valued at $2.3 billion, or $66.50 a share, and was withdrawn after the Oct. 19, 1987, crash, after which GAF shares traded at a low of $31.50.

The following December, stockholders were offered $48.50 a share and the bid was sweetened last year to its current $53 a share.

One analyst said the new ownership will have to do something to pay for the purchase.

''One thing is very clear: cash flow from the current operations cannot pay down the debt,'' said Charles J. Rose of Oppenheirmer & Co.

''It's hard for me to imagine any assets being sold,'' he said. ''Maybe there's a lot more of earnings potential to be realized.''

He also said Heyman may seek acquisitions.