PNIPAm水凝胶对水泥砂浆性能的影响

发布时间：2018-01-21 23:23

本文关键词： 道路工程水泥砂浆冻融循环水凝胶内养护抗裂性　出处：《中国公路学报》2017年04期 　论文类型：期刊论文

【摘要】：为了解决道路工程中水泥混凝土易出现的早期收缩开裂、抗冻性差等耐久性问题,采用温度敏感性水凝胶(PNIPAm)作为水泥砂浆的内养护剂,分别研究了不同吸水率、不同掺量PNIPAm对水泥砂浆的工作性能、力学特性以及韧性(折压比)的影响;采用平板法测试了水泥砂浆的早期抗裂性,根据冻融循环快冻法测试了水泥砂浆的抗冻性;利用扫描电子显微镜观察了PNIPAm改性水泥砂浆硬化体的微观结构,并采用压汞法定量测试了PNIPAm改性水泥砂浆的内部孔结构,最后分析了PNIPAm对水泥砂浆的改性机理。结果表明:PNIPAm改善了水泥砂浆的工作性能、抗折强度以及韧性,随着PNIPAm含量的升高,水泥砂浆的抗压强度略有下降;随着水泥水化的进行,水泥砂浆体系中的PNIPAm逐渐融合成薄膜网状结构,这种结构可以有效地分散水泥砂浆内部裂纹的尖端应力,降低水泥砂浆的开裂面积,延长水泥砂浆的开裂时间;PNIPAm释放的水分子对水泥砂浆起到了内养护的作用,使其无害孔含量提高,有害孔含量降低,PNIPAm的掺入有效提高了水泥砂浆的抗冻性能;综合PNIPAm对水泥砂浆强度、抗冻以及抗裂性能的影响,PNIPAm的掺量建议为水泥砂浆总质量的0.5%~0.75%。
[Abstract]:In order to solve the early shrinkage cracking prone to cement concrete road engineering problems, poor durability of frost resistance, using temperature sensitive hydrogel (PNIPAm) as curing agent in the cement mortar, were studied in different water absorption rate, different dosage of PNIPAm on performance of cement mortar, mechanical properties and toughness (fold compression ratio) the influence; the early cracking resistance of cement mortar were tested by plate method, according to the frozen fast freezing method of frost resistance of cement mortar test thaw; microstructure of PNIPAm modified cement mortar hardening was observed by scanning electron microscopy, and the mercury intrusion method quantitative internal pore structure of PNIPAm modified cement mortar test at last, analyzed the modification mechanism of PNIPAm cement mortar. The results show that PNIPAm improves the performance of cement mortar, flexural strength and toughness, with the increase of PNIPAm content, cement and sand The compressive strength of pulp decreased slightly; with the hydration of cement, cement mortar system PNIPAm gradually merged into the film network structure, this structure can effectively disperse the internal crack tip stress of cement mortar, reduce the cracking area of cement mortar, cement mortar cracking time; the release of water molecules in PNIPAm the curing effect on cement mortar to enhance harmless pore content, reduce the content of harmful holes, the incorporation of PNIPAm can effectively improve the frost resistance of cement mortar; on the strength of cement mortar PNIPAm, antifreeze and effect of anti cracking performance, the dosage of PNIPAm for cement mortar total quality 0.5%~0.75%.

【作者单位】：长安大学材料科学与工程学院;青海省交通科学研究院;
【基金】：国家自然科学基金项目(51308062) 青海省重大科技专项项目(2014-GX-A2A) 青海省自然科学基金项目(2017-ZJ-764) 中央高校基本科研业务费专项资金项目(310831163501,310831172201)
【分类号】：U414
【正文快照】： 0 引言水泥混凝土路面是道路工程中最常见的路面类型之一,但水泥混凝土材料的耐久性问题制约了该类型路面的发展。例如混凝土内部存在的温度梯度易导致混凝土发生不均匀变形而开裂;混凝土内部胶凝材料水化发生干燥收缩,收缩应力大于混凝土的抗拉强度导致混凝土产生裂缝[1]。

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