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工程科学与技术:2021,53(4):101-109
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烧结法赤泥-沥青粉固化剂稳定粉土的路用性能研究
(山东省交通科学研究院 高速公路养护技术交通行业重点实验室,山东 济南 250102)
Study on Road Performance of Stabilized Silt with Sintering Red Mud-asphalt Powder Curing Agent
(Key Lab. of Expressway Maintenance Technol. Ministry of Transport, Shandong Transportation Research Inst., Ji’nan 250102, China)
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投稿时间:2020-07-18    修订日期:2020-11-10
中文摘要: 为解决黄河冲积平原地区粉土黏聚力低、水稳定性差等工程应用问题,以烧结法赤泥和基质沥青为主材制备粉土固化剂(RAC),对粉土进行综合稳定。按5%水泥优选掺量并附加0、2%、4%、6%、8% RAC成型稳定粉土试件,经过标准养护、浸水强度、循环加热、低温冻融、高温自愈等特定试验条件后,进行3、7和28 d龄期的抗压强度与单轴压缩弹性模量试验,对比分析不同掺量RAC稳定粉土综合路用性能的变化规律。采用扫描电镜(SEM)分别观察粉土、水泥稳定粉土和RAC稳定粉土的微观结构形貌和孔隙特征,进而探讨固化稳定机理。结合实体工程的应用实践对RAC稳定粉土的路用性能进行测试分析与验证。结果表明:与单掺水泥相比,RAC稳定粉土具有良好的力学性能和水稳定性,2%、4%、6%、8% RAC稳定粉土标准养护3 d,强度分别提高110%、146%、156%、161%,28 d龄期浸水强度损失率由大于50%降低至小于20%;5次循环加热水泥稳定粉土强度增幅不大,高于4%掺量的RAC稳定粉土强度增长超过140%;经低温冻融后,单掺水泥稳定粉土试件发生开裂损坏,而RAC稳定粉土试件完好无损,且强度损失率小于15%;高温自愈试验中,试件加载至90%极限荷载,循环加热5次后,2%、4%、6%、8%RAC稳定粉土强度变化率分别为-8.3%、-2.3%、8.0%、12.9%。SEM图像显示RAC稳定使粉土形成密实的胶结凝聚体和均匀分布的孔径小于1 μm的非连通微孔结构,有利于稳定粉土水稳定性和抗冻性的提高;高温条件下沥青组分发生湿润黏结包裹粉土颗粒及水化产物,同时加速扩散填充内部孔隙和微裂缝,实现了土体的损伤修复和结构补强。实体工程采用“4%RAC+5%水泥”对粉土稳定后用于道路基层,通车后,通过现场取芯、FWD弯沉等测试分析,道路整体承载能力和使用状况良好,未出现裂缝、坑槽、松散等损坏现象。
Abstract:In order to solve the engineering application problems such as low cohesion and poor water stability of silt in the alluvial plain of the Yellow River, the sintering red mud and matrix asphalt were utilized as the main materials to prepare red mud-asphalt powder curing agent (RAC) for comprehensively stabilizing the silt. Setting the optimum dosage of cement as 5% and adding 0, 2%, 4%, 6%, 8% RAC to form stable silt specimens, the compressive strength and uniaxial compressive elastic modulus tests were conducted at 3 d, 7 d, 28 d ages after standard curing, immersion softening, cyclic heating, low-temperature freeze-thaw and high-temperature self-healing methods. The change rules of comprehensive road performance of stabilized silt with different dosage of RAC were compared and analyzed. The scanning electron microscope (SEM) was used to observe the microstructure and pore characteristics of silt, cement stabilized silt and RAC stabilized silt, and then the mechanism of solidification and stabilization was discussed. Combined with the practical application of entity engineering, the road performance of RAC stabilized silt was tested and verified. The results showed that RAC stabilized silt had good mechanical properties and water stability compared to cement alone, the strength of 2%, 4%, 6%, and 8% RAC stabilized silt increased by 110%, 146%, 156%, and 161%, respectively after standard curing of 3 d, and the loss rate of immersion strength at 28 d age is reduced from more than 50% to less than 20%. The strength of cement stabilized silt increased slightly after 5 cycles of heating, but the strength of RAC stabilized silt increases by more than 140% when the dosage was higher than 4%. After the low-temperature freeze-thaw tests, the cement stabilized silt specimen cracked and damaged, the RAC stabilized silt specimen was intact, and the loss rate of strength was less than 15%. The specimen was loaded to 90% ultimate load and heated for 5 times, the strength change rates of 2%, 4%, 6%, and 8% RAC stabilized silt were –8.3%, –2.3%, 8.0%, and 12.9%, respectively. The SEM images showed that RAC stabilized silt had dense cemented aggregates and non-connected microporous structure with uniformly distributed pore diameter less than 1 μm, which were beneficial to improve the water stability and frost resistance of stabilized silt. The asphalt components wet-bonded and wrapped with silt particles and hydration products under high temperature conditions, which accelerated the diffusion to fill the internal pores and micro cracks and realized damage repair and structural reinforcement of stabilized soil. In the entity project, the road base was filled with “4% RAC+5% cement” stabilized silt. After opening to traffic, the overall bearing capacity and service condition of the road were in good condition through field coring and FWD deflection tests. There were no cracks, pits, loose and other damages.
文章编号:202000595     中图分类号:U414    文献标志码:
基金项目:山东省交通科技创新计划项目(2016B43);山东省重点研发计划项目(2019GSF109057)
作者简介:第一作者:孙兆云(1986-),男,高级工程师.研究方向:道路路基材料与固废利用.E-mail:andersontwo@163.com
引用文本:
孙兆云,韦金城,王林,李夏,吴文娟.烧结法赤泥-沥青粉固化剂稳定粉土的路用性能研究[J].工程科学与技术,2021,53(4):101-109.
SUN Zhaoyun,WEI Jincheng,WANG Lin,LI Xia,WU Wenjuan.Study on Road Performance of Stabilized Silt with Sintering Red Mud-asphalt Powder Curing Agent[J].Advanced Engineering Sciences,2021,53(4):101-109.