Hydraulic characteristics and incubation methods for enhancing durability of Fungi- Mycelium treated silica sand using Rhizopus oligosporus and Rhizopus oryzae combination
Aswin Lim, Jonathan Yosuardi Sunaryo, Martin Wijaya, Alfrendo Satyanaga, Anastasia Prima Kristijarti
Abstract
Nowadays, the application of Fungi as a bio-mediated soil improvement technique is developing. The hydraulic properties of Rhizopus Fungi-Mycelium Treated Soil are unknown, and the treated sample tends to have low durability. This article presents experimental results of hydraulic conductivity and shear strength of Fungi-mycelium-treated silica sand. The fungi used in the experiments are a combination of Rhizopus oligosporus and Rhizopus oryzae, which is popular for making Tempeh, a local soybean cuisine from Indonesia. The samples are made by mixing the sand with Tempeh inoculum with various treatments and Tempe inoculum and rice flour dosages for enhancing the durability of the treated soil. The results showed that the saturated permeability of the treated soil could decrease about 10 times compared with the untreated soil. In addition, the Soil-Water Characteristic Curve of treated soil also developed. The effect of fungi appears to fill the void of soil and hence increases the Air Entry Value and residual suction of soil. The curing method outside the mold (O-method) with 10% Tempeh inoculum, and 5% Tempeh inoculum with 5% rice flour is proven can extend the durability of the treated sample, the undrained compressive strength is about 40 kPa at day 14. Scanning electron microscope was performed on the samples that lasted 4 months. The mycelium and hyphae are still clearly seen covering all sand particles with different percentages of Tempeh inoculum and rice flour. When the mycelium covered all sand particles and filled the pores, the water flow would partially be blocked. It might be attributed to the strong hydrophobicity of fungi that could prevent water from penetrating the soil.