摘 要

水工混凝土在水下恶劣环境中使用，易遭受裂缝、溶蚀等危害，需经常修补。为了克服常用无机类修补材料存在的凝结速度慢、粘结强度较低的不足，常采用有机物改性修补材料，但是有机物改性修补材料又存在与混凝土相容性差，后期粘结强度难以保证的缺点。研究发现复配水泥基修补材料具有凝结时间短、强度损失小的优点，聚丙烯酰胺（PAM）是一种优良的絮凝剂，而醋酸乙烯-乙烯共聚物（EVA）则具有优良的粘结性和耐水性，若PAM和EVA对复配水泥基修补材料进行改性，则能提高水泥砂浆的水下抗分散性，显著增强其水下力学性能和粘结强度。

本文将硫铝酸盐和硅酸盐水泥进行复配得到二元复合水泥，并加入适当掺量的PAM、减水剂和EVA胶粉进行改性，制备出一种性能优良的混凝土快速修补砂浆。研究了PAM及减水剂对修补砂浆水下抗分散性和流动性的影响；EVA对修补砂浆水下抗折、抗压性能，水陆强度比，凝结时间等的影响，并对改性后修补砂浆进行了微观结构的分析。

研究结果表明：复配水泥的复配比为8：2时28d强度达到了59MPa，为纯硫铝酸盐水泥的92%，初凝时间为50min较纯硫铝酸盐缩短了45min,实现了快凝的目的；掺入适当配比的PAM和减水剂可提高修补砂浆的水下抗分散性及流动性，两者的最佳掺量为2%，此时砂浆流失率小，流动扩展度最大，达到174.3mm；EVA掺入形成聚合物膜，改善了修补砂浆的水下抗折、抗压强度和粘结强度，随着EVA掺量的增加，力学强度先增大后减小，当EVA掺量为8%时，水下抗折、抗压强度提高了1.3倍，粘结强度提高了1.5倍；EVA改善了修补砂浆的水下抗分散性，当掺量＞4%时水陆强度提高了10%以上。

关键词：修补砂浆；EVA；水下抗分散性；力学性能

Abstract

Hydraulic concrete are used in harsh environment like underwater and easy to suffer from cracks, corrosion and other hazards，they often need repairing. The organic modified materials is often used to the repair of underwater concrete in order to overcome the shortcomings of slow setting speed and low bond strength of common inorganic repair materials.But it has poor compatibility with concrete and it is hard to guarantee the consistency of the late bonding strength. The study found that the patching material based on compound cement has the advantages of shorter setting time and less strength loss. The polyacrylamide (PAM) is a kind of excellent flocculant and the vinyl acetate ethylene copolymer (EVA) has excellent adhesion and water resistance.If the repair material based on composite cement was modified by the PAM and EVA , its underwater antiwashout resistane can be improved and its mechanical properties and bond strength can be improved significantly too.

A rapid repair mortar with excellent performance was prepared in this work by composited sulphoaluminate cement with Portland cement composite cement and added proper amount of PAM, superplasticizer and EVA powder to modified. Effect of PAM and superplasticizer on the underwater antiwashout resistane and fluidity of mortar; effect of EVA on the flexural and com- pressive strength, the ratio of water, water and land intensity ratio and the setting time of repaired mortar;they were both studied in this work. Its Microstructure is also analyzed by SEM photos.

The results show that :when the compound cement mixed ratio is 8:2 ,28 day’s strength reached 59 MPa, which is 92% of pure sulphoaluminate cement.And its initial setting time is only 50min which is 45 minutes shorter than pure sulphoaluminate cement,realizing the aim of the quick coagulation; The mixing ratio of PAM and superpla-st icizer can improve the underwater antiwashout resistane and the fluidity of mortar, the best mixing amount is 2%,the mortar loss rate is small and the flow expansion is the largest, reaching 174.3mm; Polymer membranes formed by EVA improved the flexural strength, compressive strength and bond strength of the mortar; With the increase of EVA content, the mechanical strength increases first and then decreases, when the content of EVA was 8%, the flexural strength and compressive strength increased 1.3 times, and the bond strength increased 1.5 times; EVA improved the underwater antiwashout resistane of the mortar, and the water and land intensity ratio increased by more than 10% when the amount of the admixture was gt; 4%.

Key Word：repaired mortar ; EVA ; underwater antiwashout resistane ; mechanical property

目 录

摘 要 I

Abstract II

第1章 绪 论 1

1.1研究背景 1

1.2混凝土修补材料研究进展 2

1.2.1无机类修补材料 2

1.2.2 有机物改性修补材料 3

1.3 EVA改性水泥基修补材料研究进展 4

1.4复配水泥基修补材料的研究进展 5

1.5研究目的和意义 6

1.6研究内容 7

第2章 实验部分 8

2.1实验原料 8

2.2实验仪器 8

2.3实验过程 9

2.3.1修补砂浆的制备过程 9

2.3.2修补砂浆的成型方法 9

2.4测试与表征 9

2.4.1修补砂浆流动性试验 9

2.4.2修补砂浆的凝结时间的测定 9

2.4.3修补砂浆的力学性能试验 10

2.4.4修补砂浆的水下抗分散性测试 10

2.4.5修补砂浆的粘结强度测试 10

2.4.6修补砂浆的扫描电镜观察 10

第3章 结果与讨论 12

3.1 复配比对水泥基修补材料凝结时间、力学性能的影响 12

3.2 PAM、减水剂对修补砂浆水下抗分散、流动性的影响 14

3.3 EVA对修补砂浆水下力学性能的影响 16

3.4 EVA对修补砂浆水陆强度比的影响 18

3.5 EVA对修补砂浆水下粘结性能的影响 19

3.6 EVA对修补砂浆水下凝结时间的影响 20

3.7 微观形貌分析 21

第4章 结 论 22

参考文献 23

致 谢 25

第1章 绪 论

1.1研究背景

水泥混凝土是如今使用最广的建筑材料之一，它大量应用于建设工程中。在城市里，人们经常看到的造型各异的高楼大厦都是用混凝土材料建设而成，把世界各地串联起来的公路和铁路也是用混凝土材料铺设而成，横跨江河两岸的桥梁也是由混凝土材料搭建起来的。可以说水泥混凝土在人们的日常生活中有着无法取代的地位，且已逐渐成为人类生存和发展的基础，构建现代文明社会的“基石”^[1,2]。混凝土因其本身具有各方面优异性能在水工方面的应用发展迅速，大量的水库大坝、水电站、河海岸边的码头、输水工程中的渡槽、管涵、渠道也都是由混凝土材料构建而成。

近几十年来，国内外混凝土材料在使用过程中不断遭侵蚀破坏，影响了其使用寿命导致工程事故频发。这些事故发生的原因不是因为混凝土强度不足，而是因为其耐久性较差。在国外，许多国家正面对大量结构劣化的钢筋混凝土材料，随着投入使用的时间增长，还会有更多的混凝土材料受到损害，而已经破损的情况还会愈发严重。例如在中东以及阿拉伯地区，大量的混凝土结构因物理作用、化学和生物作用遭破坏^[3,4]。在美国，有一些仅仅使用了不到20年的混凝土建筑物出现了大面积破损；并且这种劣化的混凝土结构数量的正以极快的速率在增长^[5]。