Nano-Bentonite and Bacillus Subtilis Treatments Innovatively Enhance Water Absorption and Strength in Rice Husk Ash-Based Geopolymer SIFCON

July 5, 2026

AIMS Press China

Overview

Recent AIMS Press research demonstrates that combined nano-bentonite and Bacillus subtilis treatments significantly improve water absorption behavior and mechanical performance in rice husk ash (RHA)-based geopolymer SIFCON. This innovative approach successfully reduces water absorption while enhancing compressive strength by precisely modifying the interfacial transition zone and densifying the matrix. This breakthrough opens new avenues for developing sustainable construction materials that balance durability and environmental performance.

In Depth

Key Findings

Groundbreaking research published by AIMS Press demonstrates that a combined treatment using nano-bentonite and Bacillus subtilis dramatically improves the performance of rice husk ash (RHA)-based geopolymer SIFCON (Slurry Infiltrated Fiber Concrete). The study successfully reduced water absorption by up to 25% while simultaneously increasing compressive strength by approximately 15%. This achievement was accomplished by modifying the interfacial transition zone (ITZ) and densifying the matrix of the geopolymer composite, opening new horizons in the field of sustainable, high-performance construction materials.

Technical / Clinical Details

The research team applied a unique combined treatment, incorporating nano-bentonite (typically 0.5-1.5 wt.%) and Bacillus subtilis (typically at concentrations of 10^6-10^7 CFU/mL), during the production of RHA-based geopolymer SIFCON. Nano-bentonite, with its high specific surface area and adsorption capacity, effectively fills the microstructure of the geopolymer matrix and improves its pore structure. Bacillus subtilis, on the other hand, facilitates the Microbial Induced Calcite Precipitation (MICP) process, generating calcium carbonate that fills micro-cracks and voids within the matrix, thereby strengthening the ITZ. This synergistic effect leads to effective blockage of water ingress pathways, significantly reducing water absorption. Concurrently, the densified matrix and reinforced ITZ enhance stress transfer efficiency, resulting in improved compressive strength. Electron microscopy observations confirmed a more uniform and dense microstructure in the treated samples, visually validating the improvement in the ITZ.

Background & Context

The construction industry consumes vast quantities of cement, whose production generates significant CO2 emissions, making the reduction of its environmental footprint an urgent imperative. Geopolymers, which utilize industrial waste such as fly ash and rice husk ash as raw materials, are gaining attention as sustainable binders to replace cement. However, despite their excellent compressive strength, geopolymer materials have room for improvement in water absorption and certain durability characteristics. Especially in high-performance fiber-reinforced concrete like SIFCON, the interfacial adhesion between the matrix and fibers significantly influences overall performance. This research offers an innovative solution to this challenge by combining nanomaterials with a biological approach, making a substantial contribution to the realization of eco-friendly and high-performance next-generation building materials.

Strategic Significance & Outlook

RHA-based geopolymer SIFCON, enhanced with nano-bentonite and Bacillus subtilis treatments, is expected to find applications in structural elements exposed to high humidity (e.g., bridges, marine structures, underground structures) and infrastructure projects requiring high durability. The utilization of recycled rice husk ash also contributes to waste reduction and the establishment of a resource-circulating society. Future research will focus on further evaluating long-term durability, freeze-thaw resistance, chemical resistance, and developing large-scale production technologies. This technology holds immense potential to play a crucial role in shaping the future of sustainable urban development and infrastructure. Furthermore, its economic viability is enhanced by utilizing industrial waste, making it an attractive option for large-scale adoption in the construction sector.

Source: https://www.aimspress.com/article/doi/10.3934/matersci.2026029?viewType=HTML

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