The effectiveness of the use of waste fly ash (FA) and cement (OPC) in the stabilization of subgrade soils and the reasons likely to influence the degree of stabilization were investigated. Incorporating waste fly ash (FA) and cement (OPC) as additives leads to significant environmental and economic contributions to soil stabilization. This study involves laboratory tests to obtain the Atterberg limit, free swell index (FSI), the unconfined compressive strength (UCS), the California bearing ratio (CBR), and the scanning electron microscope (SEM). The test results for the subgrade soil illustrate that the Atterberg limit, plasticity index, and free swell index are decreasing with the addition of different proportions of fly ash and cement, i.e., 0%, 5%, 10%, 15%, and 20% and 0%, 2%, 4%, 6%, and 8%, respectively. The CBR value of untreated soil is 2.91%, while the best CBR value of fly ash and cement mixture treated soil is 10.12% (20% FA+8% OPC), which increases 71.34% from the initial value. The UCS of untreated soil is 86.88 kPa and treated soil with fly ash and cement attains a maximum value of 167.75 kPa (20% FA+8% OPC), i.e., increases by 48.20% from the initial value. The tests result show that the stability of a subgrade soil can be improved by adding fly ash and cement. While effectiveness and usability of waste FA and cement are cost-effective and environmentally friendly alternatives to expansive soil for pavement and any other foundation work in the future.

中文翻译：

---

粉煤灰和水泥对稳定路基土工程特性影响的试验研究

研究了使用废弃粉煤灰 (FA) 和水泥 (OPC) 稳定路基土壤的有效性以及可能影响稳定程度的原因。将废弃粉煤灰 (FA) 和水泥 (OPC) 作为添加剂掺入会对土壤稳定产生重大的环境和经济贡献。这项研究涉及实验室测试，以获得阿特伯格极限、自由膨胀指数 (FSI)、无侧限抗压强度 (UCS)、加利福尼亚轴承比 (CBR) 和扫描电子显微镜 (SEM)。路基土的试验结果表明，随着粉煤灰和水泥的添加比例不同，即0%、5%、10%、15%和20，Atterberg极限、塑性指数和自由膨胀指数均呈下降趋势% 和 0%、2%、4%、6% 和 8%。未处理土壤的 CBR 值为 2。91%，而粉煤灰和水泥混合处理土壤的最佳CBR值为10.12%（20% FA+8% OPC），比初始值提高了71.34%。未处理土壤的UCS为86.88 kPa，粉煤灰和水泥处理的土壤达到最大值167.75 kPa（20% FA+8% OPC），即比初始值增加48.20%。试验结果表明，添加粉煤灰和水泥可以提高路基土的稳定性。虽然废弃 FA 和水泥的有效性和可用性是未来用于路面和任何其他基础工作的膨胀土的具有成本效益和环保的替代品。88 kPa 和粉煤灰和水泥处理的土壤达到最大值167.75 kPa（20% FA+8% OPC），即比初始值增加48.20%。试验结果表明，添加粉煤灰和水泥可以提高路基土的稳定性。虽然废弃 FA 和水泥的有效性和可用性是未来用于路面和任何其他基础工作的膨胀土的具有成本效益和环保的替代品。88 kPa 和粉煤灰和水泥处理的土壤达到最大值167.75 kPa（20% FA+8% OPC），即比初始值增加48.20%。试验结果表明，添加粉煤灰和水泥可以提高路基土的稳定性。虽然废弃 FA 和水泥的有效性和可用性是未来用于路面和任何其他基础工作的膨胀土的具有成本效益和环保的替代品。