Sand Stabilization Using Tofu Wastewater to Improve Pile Bearing Capacity Factor

Loose sand has limited capacity to support structural loads due to weak interparticle interlocking and its non-cohesive behavior. This study aimed to evaluate the effect of stabilization using tofu wastewater on the improvement of point resistance and bearing capacity factor of small-scale pile foundations in loose sand. The testing was conducted using a pile-driving test under two conditions: untreated sand with water as the control and treated sand with tofu wastewater. The results showed that the treatment with tofu wastewater increased the point resistance by up to 4.6 times, yielding a maximum bearing capacity factor of 951.56, compared to 228.92 in the control condition. Statistical analysis indicated a highly significant difference between the two treatments (p-value = 2.2 × 10⁻²⁰). The empirical correction to the theoretical Meyerhof value ranged from 3.8 to 5.4, indicating that using conventional bearing capacity factor values without adjustment may lead to inaccurate estimation of pile bearing capacity. These findings demonstrate that tofu wastewater effectively improves the mechanical behavior of loose sand by inducing calcium carbonate precipitation through enzymatic activity, and it has potential as an environmentally friendly and economical soil improvement method.