Experimental Study on Silt Stabilization Using Alkali-activated Rice Husk Ash Geopolymer

doi:10.11988/ckyyb.20240522

Abstract

Abstract:

[Objective] To address the need for improving the mechanical properties and water stability of silt subgrade, this study takes silt stabilized with alkali-activated rice husk ash (RHA) geopolymer as study object and investigates its reinforcement mechanisms and engineering applicability, aiming to determine the optimal combination of activator concentration and RHA dosage.[Methods] NaOH solution and RHA were used synergistically to stabilize silt. Mix proportions were optimized through compaction tests, and macro-mechanical properties were evaluated via unconfined compressive strength tests and disintegration tests. X-ray diffraction (XRD) was used to analyze the composition of hydration products, and scanning electron microscopy (SEM) was employed to characterize the microstructural evolution, systematically revealing the “activation-cementation-strengthening” mechanism.[Results] The results showed that micron-sized RHA particles effectively filled the pores of the silt, while NaOH activated RHA to generate silicate gels, leading to a denser spatial network structure. Mechanical properties were significantly improved: at a NaOH concentration of 10% and an RHA dosage of 7.5%, the unconfined compressive strength reached 1.501 times that of the control group, and disintegration resistance was remarkably enhanced. The micro-macro performance indicated that the interfacial bonding strength of cementitious products is the main controlling factor for the improvements of compressive strength and disintegration resistance.[Conclusion] The alkali-activated RHA geopolymer achieves coordinated improvement of the mechanical properties and water stability of silt through the combined effects of physical filling and chemical cementation. The optimal mix proportion (10% NaOH+7.5% RHA) provides a low-carbon solution for silt subgrade reinforcement and promotes the resource utilization of solid waste (RHA), demonstrating notable engineering, economic, and environmental benefits.

Key words: silt, rice husk ash, alkali activation, soil stabilization, strength, disintegration

CLC Number:

TU472.5

XU Hong, WANG Xu, CHEN Wei, ZHANG Yue-lin, LI Bo-han. Experimental Study on Silt Stabilization Using Alkali-activated Rice Husk Ash Geopolymer[J]. Journal of Changjiang River Scientific Research Institute, 2025, 42(5): 192-199.

Figures/Tables 12

Fig.1 Particle size distribu-tion curve of soil

Table 1 Main chemical components and contents of RHA %

MgO	SiO₂	P₂O₅	SO₃	K₂O	CaO
0.7	89.16	1.49	0.38	4.87	1.45

Fig.2 Particle size distribution curve of RHA

Fig.3 Scanning electron microscope image of RHA

Table 2 Experimental schemes

序号	测试内容	掺量	养护龄期/d
1	UCS	0%RHA+0%NaOH	7
2		5%RHA+0%NaOH
3		7.5%RHA+0%NaOH
4		10%RHA+0%NaOH
5		5%RHA+5%NaOH
6		7.5%RHA+5%NaOH
7		10%RHA+5%NaOH
8		5%RHA+10%NaOH
9		7.5%RHA+10%NaOH
10		10%RHA+10%NaOH
11		5%RHA+15%NaOH
12		7.5%RHA+15%NaOH
13		10%RHA+15%NaOH

Fig.4 Disintegration test apparatus

Fig.5 Relationship curves between water content and dry density

Fig.6 Results of unconfined compressive strength tests

Fig.7 Disintegration curves

Fig.8 Scanning electron microscope images

Fig.9 Fractal dimension distribution of pore unit morphology in soil samples

Fig.10 XRD test results

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