(10) US 2021/0032854 Al
(57) A precast building material contains: a substrate, a peripheral frame, a metal reinforcement unit, and a concrete layer. The substrate is in a parallelogram shape. The peripheral frame is mounted around the substrate so that an accommodation chamber is defined between the peripheral frame and the substrate. The peripheral frame includes multiple first connection rails having at least one first slot, multiple second connection rails having at least one second slot, multiple convex engagement portions, and multiple concave engagement portions. The respective first connection rail has multiple first locking orifices, and the respective second connection rail has multiple second orifices. locking The metal reinforcement unit is fixed in the accommodation chamber and includes multiple rebars. The concrete layer is filled with the accommodation chamber, and the concrete layer is connected with the peripheral frame and the metal reinforcement unit and is removable from the substrate.
(71) Yung-Chia Huang, Nantou City (TW)