首页|掺加纳米SiO2/GNPs/GO的冷再生沥青路面基层性能及作用机理

掺加纳米SiO2/GNPs/GO的冷再生沥青路面基层性能及作用机理

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为解决全深式冷再生基层单纯增加水泥出现的开裂、承载能力低、使用寿命短等问题,基于纳米材料具有的优良改性效果,采取优化级配、振动压实等基础措施进行调整的同时,将少量纳米材料掺入水泥稳定冷再生基层材料中以提升其路用性能.首先对粉体纳米材料(nano-SiO2、石墨烯纳米微片GNPs、亲水型的氧化石墨烯纳米片GO)进行分散预处理;其次在优化级配基础上,将纳米材料掺入再生混合料中,分别研究不同nano-SiO2、GNPs和GO掺量对水泥稳定冷再生混合料的力学影响规律,进而对改性后水泥稳定冷再生混合料的抗干缩性、抗温缩性和抗冻性能进行对比分析;最后应用工业CT三维扫描、SEM形貌表征等微观技术对改性前后水泥稳定冷再生混合料的孔隙结构和微观形貌进行深入分析,从细观到微观多尺度揭示纳米材料对水稳冷再生基层材料的作用机理.研究结果表明:改善混合料的级配组成,采用骨架密实结构等措施能增大混合料的密实度,显著提升其无侧限抗压强度,优化配合比后的水稳冷再生混合料7 d无侧限抗压强度超过3.5 MPa;掺加3%nano-SiO2材料,冻融后试件残留抗压强度增长33.8%,耐冻系数达到84.41%,GO掺量为0.1%时,冻融后试件的残留抗压强度达到峰值5.23 MPa,强度提高了 48.65%,耐冻系数达到86.02%,抗冻能力得到了显著提高;纳米颗粒能够增大水稳冷再生基层材料的干缩变形,对基层的抗裂性能产生不利影响,但影响程度会因不同纳米材料种类和发展阶段而表现出较大差异;纳米材料对水泥水化物的水化进程有促进增强作用,可细化混合料的孔隙结构;对集料-砂浆、旧沥青团块-砂浆等ITZ结构的界面密实度、黏结强度等有改善作用;GO纳米片层的掺入对水稳冷再生材料在细观上的孔隙结构会产生显著影响,使较大的毛细孔进一步细化,水泥浆体更加密实,进而对毛细微孔的连通发挥阻断作用;nano-SiO2能够填充小尺寸的微孔隙,GO与GNPs材料借助其自身薄片结构能够对较大空隙进行填充,在混合料内部受力时其交错分布的三维立体结构能有效发挥支撑拉结作用,凭借超高机械强度产生加筋阻裂的作用效果.
Investigating Performance and Mechanism of Sub-advanced Asphalt Pavement Full-depth Cold Recycled Base with Nano-SiO2/GNPs/GO
Basic measures such as optimizing the gradation and vibration compaction were adopted for solving the problems of cracking,low bearing capacity,and short service life of cement in a full-depth cold-recycled base based on the excellent modification functions of nano-materials.Simultaneously,a small amount of nano-materials was added to a cement-stabilized cold recycled base material to improve its road performance.First,powder nanomaterials(nano-SiO2,graphene nanosheets(GNPs),and hydrophilic graphene oxide nano-sheet GO)were dispersed and pretreated.Second,the gradation was optimized and the nano-materials were incorporated into the recycled mixture.The mechanical effects of the contents of nano-SiO2,GNPs,and GO on the cement-stabilized cold-recycled mixture were studied.The drying shrinkage resistance,temperature shrinkage resistance,and frost resistance of the modified cement-stabilized cold recycled mixtures were compared and analyzed.Finally,the pore structure and microstructure of the cement-stabilized cold recycled mixture before and after modification were analyzed by micro-techniques,such as industrial computed tomography(CT)three-dimensional scanning and scanning electron microscopy(SEM)morphology characterization,and the mechanism of the effects of nano materials on the water-stabilized cold recycled base material were revealed from the meso-scale to micro-scale.The results show that improving the gradation composition of the mixture and adopting a skeleton-dense structure,can increase the density of the mixture and significantly improve its unconfined compressive strength.The unconfined compressive strength of the water-stabilized cold recycled mixture after optimizing the mix ratio exceeds 3.5 MPa.By adding 3%nano-SiO2,the residual compressive strength of the specimen after freeze-thaw cycles increased by 33.8%,and the frost resistance coefficient reached 84.41%.When the content of GO is 0.1%,the residual compressive strength of the specimen after freeze-thaw cycles reached a peak of 5.23 MPa,the strength increased by 48.65%,the frost resistance coefficient reached 86.02%,and the frost resistance ability was significantly improved.Nanoparticles can increase the drying shrinkage deformation of the water-stabilized cold-recycled base material,which has an adverse effect on the crack resistance of the base.However,the degree of effect varies greatly owing to the different types of nanomaterials and development stages.Nanomaterials can promote the hydration of cement hydrates and refine the pore structures of mixtures.Nanomaterials can also improve the interface compactness and bonding strength of ITZ structures,such as aggregate-mortar and old asphalt agglomerate-mortar.The incorporation of GO nanosheets had a significant effect on the microscopic pore structure of the water-stabilized cold recycled material,which further refined the larger capillary pores and densified the cement paste,thereby blocking the connections between the capillary pores.Nano-SiO2 can fill small-sized micropores.GO and GNPs materials can fill large voids using their own sheet structures.The staggered three-dimensional structures of GO and GNPs can effectively play a supporting and pulling role when the mixture is subjected to an internal force,and the effects of reinforcement and crack resistance are produced by their ultrahigh mechanical strength.

pavement engineeringmechanism of actionexperimental studynanomaterialsfull-deep cold recycled mixturemicroscopic analysis

陈渊召、李振霞、冯纪兵、郭滕滕、闫浩博、王朝辉、房辰泽

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华北水利水电大学土木与交通学院,河南郑州 450045

河南省环境友好型高性能路面材料工程技术研究中心,河南郑州 450045

交通工程固废资源利用河南省交通运输行业技术创新中心(华北水利水电大学),河南郑州 450045

郑州商学院建筑工程学院,河南郑州 451200

长安大学公路学院,陕西西安 710064

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路面工程 作用机理 试验研究 纳米材料 全深式冷再生混合料 细微观分析

国家自然科学基金中原科技创新领军人才项目河南省高等学校科技创新团队支持计划

5237842924420051003124IRTSTHN011

2024

中国公路学报
中国公路学会

中国公路学报

CSTPCD北大核心
影响因子:1.607
ISSN:1001-7372
年,卷(期):2024.37(4)