... no seam,no bubble 3.lowcost original material HYW Precast concrete fence equipment 1.Introduction: 1) Adopt numerical parabolic controll and ... bubble,sand hole.4)Low cost raw materials,such as common jointing materials,sand,saw powder,nanameter coagulant .5)High efficiency ... :220-380V2)Workers:4 to 83)All the materials needed common jointing materials,sand,saw powder,nanameter coagulant.4)Working fund ...