Plastic waste is becoming a problem in various countries because of the difficulty of natural decomposition. One type is PET plastic(Polyethylene Terephthalate), which is often used as a bottle for soft drink packaging, and LDPE(Low Density Polyethylene), which is also widely used as a food or beverage packaging material. The use of these two types of plastic continuously, without good recycling, will have a negative impact on the environment. Building material waste is also becoming a serious environmental problem. This study aims to provide a solution to the problem of the above plastic waste and building material waste by making them into a mixture to be used as bricks. Research is carried out by mixing both materials, namely plastic heated at a temperature of 180-220oC and building material waste that had been crushed and sized to 30-40 mesh with homogeneous stirring. The ratios of PET and LDPE plastic to building material waste are 9 : 1, 8 : 2, 7 : 3, 6 : 4 and 5 : 5. After heating and printing, density, water absorption and compressive strength tests are carried out. Addition of PET and LDPE plastic can increase compressive strength, and reduce water absorption, porosity and density. A maximum compressive strength of 10.5 MPa is obtained at the ratio of 6 : 4.

Abstract
1. Introduction
    1.1 PET − Polyethylene Terephthalate
    1.2 LDPE — Low Polyethylene Density
2. Research Methodology
3. Results and Discussions
    3.1 Effect of mass ratio and type of PET andLDPE plastic
    3.2 Effect of mass ratio and water absorption onPET and LDPE plastic
    3.3 Effect of mass ratio and porosity on PET andLDPE plastic
    3.4 Effect of mass ratio and compressive on PETand LDPE plastic
4. Conclusions
References

• Syarifah Keumala Intan(Department of Civil Engineering, State Polytechnic of Lhokseumawe) Corresponding author
• Sandra Santosa(Department of Chemical Engineering, State Polytechnic of Malang)