Abstract: Compound formworks were made from waste plastics (PE，PP) and carbide slag，and two molding methods，hotpressing and extrusion were compared. It showed that the extrusion molding was superior to hotpressing, dense and even-texture，better mechanical properties were obtained. The impact strength，the flexural strength，and the elasticity modules of the extrusion based formworks were 29. 8%，36. 6%，and 25. 9% higher than those based on hotpressing molding.

Key words: polymer particles, carbide slag, formwork, moulding process