Concrete is one of the construction materials commonly used on infrastructure. The rapid development of infrastructure needs to be supported with adequate materials and materials such as replacing gravel materials with High Density Polyethylene (HDPE) plastics. The selection of this type of plastic is because it has a harder and more resistant to fire damage. In this study, using HDPE plastic that has been used in the form of coarse aggregate size 1 cm - 2 cm with a variation of 0%, 2%, 4%, 6%, and 8% of gravel aggregate weight. This mixed aggregate is used to reduce plastic waste and make concrete weight lighter. A strong test of concrete press is performed at the age of 7 days and 28 days using a cube-shaped test object with a size of 15 cm x 15 cm x 15 cm and a total test object as much as 30 pieces. Before compressive testing is done, the concrete is heated first in the oven for ± 2 hours with a temperature of 120 ° C. This research aims to analyze the effect of the optimum temperature of HDPE plastic (120 °c) against strong press produced from concrete mixed plastics with a variation of 0%, 2%, 4%, 6%, and 8% of gross aggregate weight. Based on the results of this study obtained strong value of press highest at a mixture of 2% at 11.72 MPa at the age of concrete 7 days. A strong concrete compressive mixture of the variation of 4%, 6%, and 8% at the age of 7 days decreased by 28%, 36%, and 47% and at the age of 28 days decreased by 16%, 19%, and 25%. For concrete mixed weight variant 2%, 4%, 6%, and 8% decreased by 1.5%, 4%, 5.4%, and 6.8%.