Family-owned manufacturer Mixer Systems Inc. of Pewaukee sold a majority stake to Milwaukee private equity firm Bel Air Growth Partners, which promoted a former Spancrete executive to president with plans to grow the business. Bel Air Growth Partners raised $10.8 million in capital from individual investors to acquire control of Mixer Systems, according to a filing with the U.S. Securities and Exchange Commission. The money includes rollover minority equity from the sellers of the business, said Bel Air Growth Partners managing director Steve Peterson. The company was founded in 1979 by William Boles, who died in 2014. After the transaction, Boles’ son David Boles and daughter Lesley Hill became minority owners of the company, Peterson said. Mixer Systems’ top executive Doug Duley will remain with the company as CEO before retiring, Peterson said. Former Spancrete executive Nick Passint, who joined Mixer Systems in February 2022, was promoted from general manager to president. The exact timing of the executive leadership transition remains to be determined. Duley and Passint also hold minority stakes in the company, Peterson said. Mixer Systems has 56 employees and an 86,000-square-foot facility in Pewaukee, Peterson said. The company’s largest customer base is precast concrete firms, which in the past included Waukesha-based Spancrete that was sold in 2020 to Wells Concrete , he said. Mixer Systems designs and manufactures concrete mixers, batch plants and accessories. Brand names include Turbin and Batchmaster. Peterson declined to disclose the company’s annual revenue. The investment was attractive because precast concrete is a growing market and Mixer Systems also is likely to benefit from both the reshoring trend for manufacturers and the federal infrastructure bill, Peterson said. Growth opportunities include boosting exports, he said. Passint said Wednesday he worked nearly 10 years at Spancrete before joining Mixer Systems. He said the company isn’t in need of any immediate investment but he’s excited about the future in the Bel Air Growth Partners portfolio. “It’s a good business with a solid product; we’ve got a solid team,” Passint said. “Now we’re continuing that with some fresh ideas, some new leadership and a strategic intent to grow. It’s going to be a really good opportunity for everyone here.” Bel Air Growth partners was founded in 2018 and takes a long-term approach to private equity investing, Peterson said. He previously was managing director of Brass Ring Capital of Milwaukee and Minneapolis.