Study on mechanical properties and damage evolution of modified rubberized cement stabilized soil

Two modification approaches, namely vacuum heating and cement precoating, were applied to optimize the bulk hardening and surface treatment of rubber particles. The physicochemical characteristics of vacuum-heated modified rubber underwent comprehensive evaluation through rubber hardness testing, water contact angle assessments, and Fourier transform infrared spectroscopy. Unconfined compressive strength (UCS) tests combined with digital image correlation techniques were utilized to evaluate the strength improvement and damage evolution mechanism in modified rubber cement stabilized soil (RCS) specimens, while scanning electron microscopy was used to further characterize the microstructural failure mechanisms of modified RCS. The effectiveness of both methods was validated through significance analysis and nonlinear surface fitting of RCS strength data under varying modification parameters. Experimental results revealed that vacuum heating elevated rubber hardness by 34.6% and decreased water contact angle by 16.1° relative to untreated controls, significantly enhancing the UCS of RCS. The vacuum heating method could improve the cohesive properties and structural continuity of specimens, whereas cement precoated samples achieved strength gains without sacrificing material toughness. Both of the above two methods successfully facilitated rubber particle integration within the cement-stabilized soil matrix.