Aug 2026· Frontiers of Physics· 0 citations· 38 references
Abstract
Coastal erosion severely threatens the stability of sandy shorelines, necessitating low-cost and sustainable bio-mediated treatment methods for shoreline protection. This study investigates an enzyme-induced carbonate precipitation (EICP) approach utilizing crude urease extracted from soybean hulls and concentrated seawater as an ionic source to enhance the erosion resistance of sand. The joint effects of urease activity, solution volume, treatment cycles, seawater concentration, and curing time were systematically evaluated through penetration strength, wind erosion, and hydraulic erosion tests, complemented by carbonate content measurements. Testing results indicate that the urease activity of the soybean hull extract scaled with the dosage, reaching a maximum of 2.27 mmol L
-1
·min
-1
. The seawater-based EICP treatment successfully formed a hardened surface crust, increasing the surface penetration strength to 0.841 MPa, while the critical wind velocity and critical flow velocity increased by up to 7.2 and 6.4 times, respectively, compared with untreated sand. Notably, multi-cycle spraying proved superior to a single application with the same total solution volume. While urease activity was the dominant factor governing carbonate production under relatively low-activity conditions, the number of treatment cycles exerted the strongest influence on hydraulic erosion resistance. Furthermore, power-law relationships were established between erosion-resistance indices and both carbonate content and penetration strength. Carbonate content showed consistently stronger correlations with erosion resistance than penetration strength, indicating that it provides a practical and reliable indicator for evaluating the erosion resistance of seawater-based EICP-treated sand. These findings demonstrate the feasibility of coupling agricultural by-product-derived urease with seawater-based EICP for cost-effective and sustainable stabilization of coastal sandy soils.
Soil reinforcement is a potential solution to mitigate wind‐induced sand erosion. Previously, microbiologically induced calcite precipitation (MICP) has been used to control sand erosion and enhance the strength of soil particles. However, it has limitations. The present study explores the effectiveness of an alternative biologically inspired method, enzyme‐induced carbonate precipitation (EICP), in enhancing the stability and strength of aeolian sand. The novelty of this study lies in the identification of an optimal dosage through a multiscale evaluation of EICP performance, specifically targeting high‐velocity erosion resistance (up to 30 m/s), surface strength uniformity, penetration depth, mechanical reinforcement and the explicit characterization of calcite thermal stability. Plant‐based Jack bean urease was used at varying concentrations with a 1‐M cementation solution. To mitigate wind‐induced sand erosion, surface treatment was performed using the spray method. The treated specimens were subjected to a wind tunnel test, a surface strength test, a calcite test, scanning electron microscopy (SEM) analysis and energy‐dispersive X‐ray spectroscopy (EDX) analysis. To evaluate the strength of soil particles, unconfined compressive strength (UCS) and split tensile strength (STS) samples were treated using the stopped and gravity flow methods and were tested for UCS, STS, ultrasonic pulse velocity (UPV) and calcite formation. Additionally, to assess the thermal behaviour of the formed calcite, thermogravimetric analysis (TGA) was performed. The study demonstrated that the EICP method effectively mitigates erosion up to a wind speed of 30 m/s and achieves optimal soil strength, with a maximum UCS value of 756 kPa and 5% calcite formation. However, practical implementation considerations, including extended treatment duration and long‐term durability under field conditions, require further investigation before large‐scale application.
Sand and dust storms (SDS) are severe geo-environmental hazards that threaten ecosystem stability and land productivity in arid regions. Enzyme-induced carbonate precipitation (EICP) is highly effective for SDS control and exhibits better ecological compatibility. Nevertheless, the specific interaction between engineering stabilization and vegetation restoration remains inadequately understood, which restricts further progress. This study evaluated an integrated EICP and vegetation treatment for rapid surface stabilization and early ecological restoration. The effects of soybean powder concentrations, reagent concentration, and mixed solution dosage on crust properties, water retention, soil chemistry, plant growth, and wind erosion resistance were systematically examined. Under clean airflow at 25 m/s, the untreated control exhibited a cumulative wind erosion ratio of 90.2%, whereas EICP treatment substantially reduced sand loss. The formed crust also reduced evaporation and maintained higher moisture contents during early seedling establishment. Vegetation decreased residual organic carbon and NH4+-N, indicating its contribution as a biological nitrogen sink. However, excessive treatment intensity increased crust resistance, conductivity, residual ammonium, and delayed seedling emergence. A treatment using 0.25 M reagent, 50 g/L soybean powder, and 3 L/m2 mixed solution provided the best overall balance among the tested conditions. These findings demonstrate the early stage of a complementary process in which EICP provides immediate protection while developing vegetation contributes nitrogen uptake, root reinforcement, and surface roughness.
Hengxing Wang, Xiaohao Sun, Linchang Miao et al.· Journal of Environmental Man...· 0 citations
The direct use of untreated seawater and sea sand for concrete production may adversely affect the mechanical properties and durability of concrete, thereby limiting their widespread application in civil construction. To address this issue, this study has investigated the performance evolution of seawater–sea sand concrete (SWSSC) under long-term exposure to a natural marine tidal environment. The effects of adding ultrafine metakaolin (UMK) and
nano
-
TiO
2
(NT) were also explored in their enhancement on the SWSSC performance. Seven mix designs, including control, binary (UMK), and ternary (UMK and NT) mixtures, were exposed to real-world tidal wetting–drying cycles for up to 360 days. Mechanical properties, including cubic and axial compressive strengths, elastic modulus, and flexural strength, were periodically evaluated. The results showed continuous strength development in all mixtures, with the ternary group exhibiting the most balanced and cost-effective improvement, where SWSSC-UMK-NT10 reached a 28-day compressive strength of 65.4 MPa. The synergistic action of the UMK and the NT also markedly enhanced the matrix compactness and cracking resistance. Scanning electron microscopy (SEM) revealed the refined pore structures and denser interfacial transition zones in the modified SWSSC. X-ray diffraction (XRD) confirmed a reduction in the harmful crystalline phases and an increase in the formation of dense hydration products. Furthermore, mercury intrusion porosimetry (MIP) demonstrated the reduced total porosity, along with a shift in the pore size distribution toward the finer gel pores, thereby restricting the fluid transport pathways. In conclusion, the combined addition of UMK and NT is an effective strategy to improve the microstructure and durability of SWSSC in marine environments.
Qing-Hai Luo, S. Fang, Shu-Zhan Lin· Journal of materials in civi...· 0 citations
Fly ash, generated in large quantities as a by-product of coal-fired power plants, presents both an environmental disposal challenge and a potential resource for sustainable geotechnical applications. Soil stabilisation using industrial by-products has gained increasing attention as a low-cost, environmentally friendly alternative to conventional binders such as cement and lime, which carry significant carbon emissions and cost implications. In Bangladesh, the Barapukuria Coal-Fired Thermal Power Plant alone generates approximately 52,000 metric tons of fly ash annually, the majority of which is disposed of in ash ponds, creating both land-use and environmental concerns. The main objective of this study is to investigate soil stabilization using fly ash, with a particular focus on assessing its influence on the shear strength of both cohesive (clay) and cohesionless (sand) soils. To comprehensively evaluate performance, fly ash (FA) was incorporated into the natural soil at proportions of 8.5%, 12%, and 15%. The effectiveness of these additions was examined through direct shear and unconfined compression tests. Notably, the approach included determining the baseline properties of both sand and clay samples, then systematically introducing fly ash and retesting to identify changes in mechanical behavior. The observed pattern in the results demonstrates a non-linear behaviour with the increase of fly ash content. At 12% fly ash content, the sandy soil and clayey soil exhibited improvements of 27% and 34%, respectively. Beyond this content, strength declined due to excess fines and reduced particle bonding efficiency. The observed improvements result from different mechanisms: improved particle interlocking and densification in sand, and pozzolanic cementation in clay. A quadratic regression model is proposed to predict the optimum fly ash dosage and corresponding strength gain. In summary, these results confirm that adding 12% fly ash is highly effective for maximizing mechanical benefit and provides a practical framework for the sustainable stabilization of subgrades, embankments, and other geotechnical applications.
MD. Moin Akon, Khan Md. Arman Shovon, Asif Alam Chowdhury et al.· Discover Soil· 0 citations
Prefabricated vertical drains are critical for accelerating pore-water pressure dissipation and consolidating water-saturated soft soils in coastal and riverine environments. Straw drainage boards, composed of agricultural straw and polylactic acid (PLA), offer an alternative to traditional plastic drains, mitigating potential water pollution and microplastic accumulation in sensitive aquatic ecosystems. However, their slow natural biodegradability can impact long-term hydraulic performance and post-construction settlement. This study investigates the enzymatic degradation characteristics of straw–PLA drainage boards to optimize their hydraulic behavior and degradation in simulated water-saturated soft soils. We explored the effects of various bio-enzymes, specifically cellulase and alkaline protease, on the structural integrity and hydraulic properties of the drainage boards. Our results demonstrate that both enzymes significantly alter the water flow capacity of the boards, indicating accelerated degradation. Furthermore, a synergistic effect was observed when cellulase and alkaline protease were applied concurrently, leading to more pronounced degradation. The findings suggest that enzyme-enhanced degradation offers a promising strategy to optimize the hydraulic performance of drainage boards, facilitating more effective pore-water pressure dissipation and rapid soil consolidation in offshore and coastal engineering projects.
Feng Liu, Jiancai Zhu, Yan Wang et al.· Water· 0 citations
Local scour of the seabed around the marine structures severely threatens the structure’s safety. Most previous studies utilized cement as a binder material to prevent scouring. However, the use of cement contributes to the carbon footprint and exhibits little resistance to harsh marine environment conditions. Therefore, this study develops an alkali-activated cementitious material (AACM) using dredged river sediments (DRS), fly ash (FA), and ground granulated blast-furnace slag (GGBS) to prevent scour around wind turbine foundations. An alkali-activated sediments-FA-GGBS (AASFG) slurry was prepared using a mixture of DRS (70%) and FA and GGBS (30% in
1
∶
1
), activated by sodium silicate solution and NaOH. Further, the AASFG slurry was amended with 0.1% polyacrylamide (PAM) to enhance its performance. The slurries were prepared at a modulus value of 1, 1.2, and 1.4 and 6%, 8%, and 10%
Na
2
O
content. The performance of AASFG and PAM amended AASFG (P-AASFG) slurry was tested for fluidity, setting time, turbidity (antidispersion test), washout resistance, and unconfined compressive strength (UCS) at 3- and 28-day curing periods, and then the optimal mix was determined. The AASFG slurry with 0.1% PAM shows a 1.7% to 12% decrease in fluidity and a 60% to 70% reduction in turbidity, enhancing the washout resistance (97.84%–99.66%) and producing UCS values between 1.87 and 7.48 MPa and an antiwashout strength ratio higher than 90%. The results revealed that the performance of both slurries depends on the modulus ratio and
Na
2
O
content. The sample M1.2N10 demonstrates optimum performance considering all parameters. Microstructural analysis revealed that the coexistence of ettringite, N─ A─ S─ H gel, C─ A─ S─ H gel, and C─ S─ H gel provides strength to the slurry. The characteristics of the P-AASFG slurry affirm its efficacy as a robust antiscouring material.
Deepak Patwa, Kai Yao, Zihan Sang et al.· Journal of materials in civi...· 0 citations
