This study presents the results of fall cone penetration tests conducted on clay and clay aluminum waste mixtures. The influence of aluminum waste (AW) gradations, which produced after cutting aluminum sections, on liquid limit and undrained shear strength of clay soil was checked throughout a series of tests. Three various particle gradations (4.75-0.075 mm, 0.6-0.075 mm, and 0.425-0.3 mm) of AW were added to low plasticity clay. The percentage of additive AW were 0%, 10%, 20%, 30%, 40% and 50%. The results of clay aluminum waste (CAW) mixtures explained that there is a linear relationship between cone penetration and water content. Liquid limit and undrained shear strength reached their minimum values at 10% of AW of both gradations (4.75-0.075 mm and 0.6-0.075mm) and at 30% of (0.425-0.3mm) AW gradation. By adding other percentages of AW, the amount of liquid limit and undrained shear strength were increased again. It was realized that the coarser the AW gradation the more the effect on liquid limit and undrained shear strength values. This may be due to the influence of larger particles of AW which made stronger connections between whole particles of AW and increased the resistance strength of the mixture against penetration. Also, a slight difference in both liquid limit and undrained shear strength values appeared when the gradation contains good amounts of same particle size.