Nanozeolite-Modified Cement for Soft Clay Subgrade Stabilization

Soft clay soil is widely spread in the delta region of northern Egypt. However, in its natural state, it is difficult to use it as a subgrade due to its poor engineering properties such as strength and stiffness. Therefore, the current study aims to stabilize the soft clay soil with binders and agents such as Portland Cement (PC), El_Arish Modified Cement, and RoadCem (RC) nano-modifier. Different ratios of Portland cement, Portland cement with RoadCem, and El_Arish modified cement were tested to find the ideal stabilizer ratio. The optimum ratio was determined to be 16%PC (based on the dry weight of the soil) mixed with 0.6%RC (based on the weight of the cement). The laboratory tests included the index properties such as Atterberg limits, modified Proctor test, California Bearing Ratio, and consolidation test. Mechanical properties testing included unconfined compressive strength, resilient modulus, flexural tensile strength, indirect tensile strength, and durability tests after 7, 28, and 60 days of curing. The microstructure of the stabilized soil was also measured using Scanning Electron Microscopy and EDS was carried out on RC additive. According to the UCS results, the strength of the stabilized soft clay increased significantly, by 269% at 16% PC, but the addition of 16% PC+0.6% RC increased the strength by 329% after 7 days of curing. The M _R test results increased by 89.6% at 16% PC and by 103.4% at 16% PC+0.6% RC after 7 days of curing. The FTS demonstrated that 16% PC improved the strength of stabilized soft clay by 296.8%, while the addition of RC increased the strength by 365% after 7 days of curing. IDT test is increased by 312% and 350.5% for PC and PC+RC respectively. The results show a notable increase in the strength of the stabilized soft clay by using PC; however, the addition of RC increased the strength and stiffness significantly.