The effect of the shape and size of HDPE plastic admixtures on to K125 concrete

This research uses admixture, namely HDPE plastic waste and aims to determine the effect of these admixture materials with different shape and size pieces on compressive strength and collapse as well as crack patterns on each concrete design, then to find the difference in the results of the compressive strength of each concrete made from material admixture as well as the shape and size of the pieces of plastic that are appropriately used as the material concrete admixture. This research used an experimental method, which compares the results of the compressive strength of normal concrete and concrete with the addition of plastic pieces of HDPE material, which are distinguished by shape and size. HDPE materials are cut into cubes with 1x1cm, rectangles measuring 0,5x2cm, and long sticks measuring 0.25 x 4 cm. The compassion of the percentage of material is added to the weight of cement which are equal to 5%. The results of compressive strength obtained respectively are, 136.915 kg/cm2 or 13.691 MPa for cube-shaped plastic pieces, 138.347 kg/cm2 or 13.835 MPa for concrete with rectangular plastic pieces which are the right shape and size to be used in concrete mix design, then 138,025 kg/cm2 or 13,803 MPa for concrete with long sticks pieces of plastic shaped, and the results of the concrete strength with admixture material are higher than the planned compressive strength and standard concrete. After that, the results of crack patterns for normal concrete were obtained, concrete with cube-shaped plastic pieces, concrete with rectangular plastic pieces, and long sticks plastic pieces of concrete, namely shear crack, crack voids and honeycomb, crack honeycomb, and crack concrete crazing and honeycomb. Whereas the collapse occurs between the coral joints with cement paste, and the plastic pieces are not damaged or broken. Therefore, the results of the study are found that differences in the shape and size of plastic pieces affect the value of slump, compressive strength, and collapse.