The zeolite efficiency, an environmentally friendly agent, in crude oil (CO) adsorption has been well verified. However, this paper investigates the role of contact time in the lower-than-optimum percentage of zeolite. This study aims to evaluate the low-content zeolite’s capability to mitigate the negative consequences of CO pollution by addressing this insight in the CO-polluted silica sands. The G and φ (simple shear device), Cc parameter (consolidation test), and chemical study (Fourier-transform infrared spectroscopy, known as FTIR analysis) of coarse and fine-grain silica sands are examined and compared in the evaluation of contact time and zeolite condition of specimens. Low-content acidized zeolite and contact time significantly increased the dynamic strength of oil-polluted specimens. Results indicated that acidized zeolite (compared to natural zeolite), after a 4- month contact time, treated coarse and fine grain sands 14 % and 7 %, respectively (27 % and 20 % strength regain compared to oil-polluted specimens for O. S and B⋅S). This investigation reveals the efficiency of contact time in the pollution adsorption of low-content modified structure treatment agents.
