Fungi-Biopolymer synergistic application in soil stabilisation

世界各地的建筑业使用水泥等高能和碳排放稳定剂来稳定用于开发土基础设施的有问题和脆弱的土壤。虽然水泥的加入改善了土壤的强度和耐久性，但它对地面造成了重大的环境影响，并降低了土壤可再利用的前景。为了限制碳排放和保护有限的自然资源，建筑业至关重要的是立即寻找合适的水泥和类似材料的替代品来稳定土壤。在最近的过去，土木工程中越来越多的人对使用生物岩土技术进行地面改造感兴趣。生物土工过程使用生物产生的过程或产品来稳定土壤。真菌和生物聚合物稳定剂等生物稳定化技术在土壤稳定化中具有取代水泥的巨大潜力，但在文献中尚未得到彻底的研究。在有机底物存在下，平菇等真菌菌种在土壤中形成菌丝网络，引起颗粒聚集，诱导土壤憎水。土壤中的有机底物是控制菌丝网络生长动力学的关键成分，影响菌丝网络的总生物量、穿透深度和生长速度。因此，真菌土壤稳定的效果直接取决于在将真菌接种到土壤中时使用的有机基质的类型。另一方面，像瓜尔豆胶和黄原胶这样的多糖生物聚合物与水混合在土壤中时，会形成一种被称为水凝胶的三维多孔结构，将土壤颗粒连接在一起，提高土壤的强度和耐久性。与水泥相比，只需要少量的生物聚合物来稳定大量的土壤，而且稳定的土壤有可能被重复利用。然而，当生物聚合物稳定的土壤暴露在较长的饱和期时，会导致水凝胶的部分或全部溶解，从而降低土壤强度。为了确保有效的生物聚合物土壤稳定，有必要确保水凝胶能够对水入侵具有弹性。考虑到生物聚合物可以作为菌丝网络生长的底物，而真菌可以诱导土壤憎水，确保水凝胶能够保持稳定，当这两种方法协同工作时，这两种生物稳定技术的需求就可以得到满足。考虑到真菌种类和生物聚合物的多样性，本研究建议对真菌和生物聚合物之间独特的协同作用进行优化设计。这项研究的结果将导致开发一套真菌-生物聚合物组合作为土壤稳定剂。此外，这些发现可以使现场工程师以水泥无法实现的不同方式修改地面，从而带来更新的土地改良机会。

Construction industries worldwide use high-energy and carbon-emitting stabilisers like cement to stabilise problematic and weak soils used in developing earthen infrastructure. Whilst the addition of cement though has improved soil strength and durability, it causes a significant environmental impact on the ground and reduces the prospects of soil reusability. To limit carbon emissions and conserve limited natural resources, it is pivotal for the construction industry to immediately seek suitable replacements for cement and similar materials for soil stabilisation. In the recent past, there is a growing interest in civil engineering to use bio-geotechnical processes for ground modification. Bio-geotechnical processes use biologically produced processes or products for soil stabilisation. Bio-stabilisation techniques like fungi and biopolymer stabilisations have huge potential to replace cement in soil stabilisation but have not been thoroughly investigated in the literature. Fungi species like Pleurotus ostreatus on inoculation to soil in presence of organic substrate form hyphal networks which cause particle aggregation and induce water repellency to the soil. The organic substrate in the soil is the crucial component which controls the growth kinetics of the hyphal network concerning its total biomass, penetration depth and growth rate. Thus, the efficacy of the fungi soil stabilisation is directly dependent on the type of organic substrate used during the inoculation of fungi into the soil. On the other hand, polysaccharide biopolymers like guar and xanthan gums when mixed in soil with water form three-dimensional porous structures called 'hydrogels' that interlink soil particles and improve soil strength and durability. Only small quantities of biopolymer are required to stabilise large quantities of soil in comparison to cement and further, the stabilised soil has potential to be re-used. However, biopolymer-stabilised soils when exposed to longer periods of saturation lead to the partial or full dissolution of hydrogels causing a reduction in soil strength. To ensure effective biopolymer soil stabilisation, it is necessary to ensure the hydrogels can be made resilient against water intrusion. The needs of the two bio-stabilisation techniques can be addressed when these methods are in synergy considering biopolymer can act as a substrate for hyphal network growth, while the fungi can induce water repellency to the soil ensuring hydrogels can remain stable against water intrusion. Considering the wide variety of fungi species and biopolymers available, the distinctive synergy between fungi and biopolymers is proposed to be optimally engineered in this study. The outcomes of the study will lead to the development of a suite of fungi-biopolymer combinations as soil stabilisers. Further, the findings can enable field engineers to modify ground in different ways which cement cannot perform leading to newer opportunities in ground improvement.