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稻壳灰改良膨胀土的临界掺量与性能演化机制

The Critical Dosage and Performance Evolution Mechanism of Expansive Soil Improved by Rice Husk Ash

岳霖烽

Environment and Resource / 2026,8(2): 160-169 / 2026-04-20 12 9

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• Information:

  西南石油大学地球科学与技术学院，成都

• Keywords:
  Improved expansive soil; Rice husk ash; Eco-friendly materials; Expansion performance; Mechanical properties
  改良膨胀土; 稻壳灰; 环保材料; 膨胀性能; 力学性质
• Abstract: In order to explore the mechanism and optimal dosage of rice husk ash to improve expansive soil, a systematic study on rice husk ash was carried out through the combination of indoor macroscopic test and microscopic characterization. The results show that there is a critical value of 25 % for rice husk ash content, which is divided into effective improvement area ( ≤ 25 % ) and performance attenuation area ( > 25 % ). In the effective improvement area, the results of the superposition of various mechanisms such as C-S-H gel formed by volcanic ash reaction, physical filling, ion exchange and mineral transformation lead to the gradual improvement of the improvement effect with the increase of dosage : the maximum decrease of free expansion rate is 79 %, the shear strength is continuously improved, and the anti-deformation performance is the best at the dosage of 25 %. The phenomenon of chemical cementation and physical filling is verified from the microscopic point of view. When the content is more than 25 %, the physical filling turns into a negative ‘skeleton replacement effect’ , and the excessive inert material dilutes the reaction system, so that the expansion index rebounds, the marginal benefit of strength growth plummets, and the comprehensive performance enters the attenuation zone. The study clarifies that 25 % is the best economic dosage, which provides a theoretical basis for the improvement of expansive soil engineering. 为探究稻壳灰改良膨胀土的作用机理与最优掺量，通过室内宏观试验与微观表征相结合，对稻壳灰进行系统的研究。结果表明：稻壳灰掺量存在25%的临界值，据此划分为有效改良区（≤25%）与性能衰减区（>25%）。在有效的改良区范围内，火山灰反应形成C-S-H凝胶、物理填充作用、离子交换作用以及矿物转变等多种作用机理相互叠加的结果导致其随着掺量增大改良效果逐渐提高：自由膨胀率下降幅度最大为79%，抗剪强度不断提高，在25%的掺量下抗变形性能最好，并从微观上验证了这种化学胶结和物理填充共同存在的现象。当掺量>25%后，物理填充转为负面的“骨架置换效应”，而且过量的惰性材料稀释了反应体系，使得膨胀指标回升、强度增长边际效益骤降，综合性能进入衰减区。研究明确了25%为最佳经济掺量，为膨胀土工程改良提供了理论依据。
• DOI: 10.35534/er.0802021 (registering DOI)
• Cite: 岳霖烽．稻壳灰改良膨胀土的临界掺量与性能演化机制［J］．环境与资源，2026，8（2）：160-169.