公路地下管网固废充填材料力学特性及耐久性研究

Research on Mechanical Properties and Durability of Solid Waste Backfill Materials for Highway Underground Pipe Networks

摘要

为推进工业固废在公路排水管道回填中的资源化利用，本文以粉煤灰（FA）和粒化高炉矿渣（GGBS）为基础材料，引入烟气脱硫石膏（DG）构建三元碱激发复合体系。设置GGBS∶（FA+DG）为70∶30、60∶40 和50∶50，DG 掺量为0%~12%，碱激发剂模数为1.0、1.2和1.4，共设计45组方案；采用无侧限抗压试验，并结合XRD和SEM分析DG对材料力学性能及微观结构的影响。结果表明：DG 掺入后材料强度呈先升后降趋势，最佳掺量约为6%；其中S60 组在6%DG、模数1.0 条件下1 d 抗压强度达到14.48 MPa，较基准组提高约23%。随着模数增大，材料抗压强度整体下降，S60-6%DG 组强度由14.48 MPa 降至1.50 MPa。掺6%DG 试样前3 d 强度增长最快，3 d 强度可达到14 d 最终强度的76.92%~79.70%。微观分析表明，适量DG可促进钙矾石和C-（A）-S-H凝胶生成，提高基体密实度；过量DG则会导致硫酸盐残留、凝胶相减少，不利于后期强度与结构稳定性。

Abstract

To promote the resource utilization of industrial solid wastes in highway drainage pipeline backfill, this study uses fly ash (FA) and ground granulated blast furnace slag (GGBS) as the base materials, and introduces flue gas desulfurization gypsum (DG) to construct a ternary alkali-activated composite system. The mass ratios of GGBS to (FA+DG) are set at 70∶ 30, 60∶40, and 50∶50, with DG content ranging from 0% to 12%, and the modulus of the alkali activator at 1.0, 1.2, and 1.4, resulting in a total of 45 mix proportions. Unconfined compressive strength tests are conducted, combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM), to investigate the effects of DG on the mechanical properties and microstructure of the material. The results show that the strength first increases and then decreases with the addition of DG, with the optimal dosage being approximately 6%. The S60 group achieves a 1 d compressive strength of 14.48 MPa at 6% DG and a modulus of 1.0, which is about 23% higher than that of the control group. As the activator modulus increases, the compressive strength decreases significantly, with the strength of the S60-6%DG specimen dropping from 14.48 MPa to 1.50 MPa. The specimens containing 6% DG exhibit the fastest strength development within the first 3 days, with the 3 d strength reaching 76.92%–79.70% of the 14 d strength. Microstructural analysis indicates that an appropriate amount of DG can promote the formation of ettringite and C-(A)-S-H gel, thereby improving matrix compactness, whereas excessive DG leads to sulfate residue and reduced gel phases, which is unfavorable to later strength and structural stability.

关键词

公路排水管道 / 固废回填材料 / 碱激发材料 / 烟气脱硫石膏 / 抗压强度 / 微观结构

Key words

Highway drainage pipelines / solid waste backfill materials / alkali-activated materials / FGD gypsum / compressive strength / microstructure

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基金资助

泰安市工业领域科技创新发展项目“市政道路路基填料地质聚合物固化研究”(2025GX076)

中建股份科技研发计划资助“山地城市洪涝灾害韧性提升关键技术与智慧运维系统研究”(CSCEC-2024-Z-31)