Granite Construction Inc. said it agreed to acquire 30% of TIC Holdings Inc., an industrial construction company, for about $21 million. Granite, a heavy civil contractor, said it will acquire 10% of closely held Steamboat Springs, Colo.-based TIC this year and make an offer to TIC's shareholders for the additional 20% of the shares next spring after completion of TIC's 1996 audited financial statements. Granite, of Watsonville, said its long-term intent is to acquire a majority interest in TIC. The company said it plans to finance the deal through its existing credit lines. For the nine months ended Sept. 30, Granite Construction earned $24.6 million, or $1.36 a share, on revenue of $704.9 million. "Our investment in TIC gives us a strong foothold in the growing industrial process marketplace, provides a broader diversification of our core business and is expected to provide joint venture opportunities for our existing operations via a strategic alliance with TIC," said Granite President and CEO David H. Watts. TIC is one of the leading general heavy industrial contractors in the U.S. Granite shares lost 37.5 cents to close at $19.50 in Nasdaq trading.