FRP筋及纤维增强水泥基复合材料的性能研究

发布时间：2018-03-26 14:14

本文选题：纤维增强聚合物筋　切入点：纤维增强水泥基复合材料　出处：《武汉理工大学》2015年硕士论文

【摘要】：利用纤维增强聚合物(FRP)筋取代钢筋作为混凝土结构增强筋可以有效解决侵蚀环境下钢筋锈蚀问题,但由于FRP筋和混凝土均属于脆性材料,存在延性不足的问题,FRP筋混凝土结构常常呈脆性破坏。本文通过合理的纤维掺量制备得到一种具有高韧性的纤维增强水泥基复合材料(FRCC),并用FRCC代替普通混凝土作为基体,试图提高FRP筋混凝土结构的延性以及耐久性,为FRP筋-FRCC新型结构形式的推广应用做探索性研究。本文首先研究了纤维体积掺量以及纤维表面处理方式对FRCC力学性能和韧性的影响,确定了较优的配合比,然后研究了配筋FRCC梁的抗弯性能。其次,研究了FRP筋与水泥基体在不同环境下的粘结性能。最后,分析了海水环境对FRP筋与基体界面过渡区的影响。实验研究表明:(1)FRP筋可以显著提高FRCC梁的抗弯承载力和延性,其延性以及抗弯承载力均明显优于FRP筋混凝土梁,并且FRP筋-FRCC梁的弯曲破坏形式为塑性破坏,具有类似于钢筋混凝土梁的屈服平台特征,表现出良好的延性。(2)标准养护条件下,FRP筋和钢筋与普通混凝土的粘结强度大小相当,但FRP筋与普通混凝土的粘结破坏形式为混凝土劈裂破坏,相对滑移量较小,缺乏延性,呈现明显的脆性破坏。FRP筋与FRCC的粘结强度较普通混凝土大幅度提高,增长比例在60%~80%,并且FRP筋在FRCC中产生较大的滑移,FRP筋与FRCC的粘结破坏形式为FRP筋拔出且FRCC开裂,FRP筋与FRCC表现出较好的粘结延性。(3)海水环境下FRP筋与普通混凝土的粘结强度较标准养护条件下的粘结强度降低幅度达20%,破坏形式仍是明显的脆性劈裂破坏。海水环境下FRP筋与FRCC的粘结强度较标准养护条件下降低5%左右,破坏形式仍为FRP筋拔出且FRCC开裂。在海水环境下,FRP筋与FRCC的粘结性能无明显退化。(4)相比于海水浸泡环境,潮汐作用下FRP筋与FRCC的粘结强度出现小幅度下降,但仍然呈延性破坏,而FRP筋与普通混凝土在潮汐作用下的粘结强度较无潮汐环境降低15%左右。即使在潮汐环境下,FRP筋与FRCC的粘结强度也较标准养护条件下FRP筋与普通混凝土的粘结强度高出50%左右。因此,FRP筋与FRCC具有良好的粘结性能和耐久性能,使得FRP筋-FRCC结构在恶劣环境下具有良好的长期工作性能。(5)碱性环境会对BFRP筋、GFRP筋产生一定的侵蚀,导致其抗拉强度降低。海水腐蚀环境使得FRP筋与FRCC界面过渡区的显微硬度略微降低,宽度变大,并且在从SEM图中可以看出,海水环境下形成较多膨胀性产物AFt,导致裂纹,但总体来说FRP筋-FRCC结构的力学性能、耐久性能均明显优于FRP筋混凝土结构。FRP筋-FRCC新型结构形式在海洋工程、冬季撒除冰盐的道路与桥梁工程等领域将具有广阔的应用前景。
[Abstract]:Using fiber reinforced polymer (FRP) tendons to replace steel bars as reinforced bars of concrete structures can effectively solve the problem of corrosion of steel bars under corrosive environment. However, both FRP bars and concrete are brittle materials. In this paper, a kind of fiber reinforced cement matrix composite with high toughness is prepared by reasonable fiber content, and FRCC is used instead of ordinary concrete as matrix. This paper attempts to improve the ductility and durability of concrete structures with FRP bars. In this paper, the effects of fiber volume content and fiber surface treatment on the mechanical properties and toughness of FRP reinforced FRCC are studied, and the optimum blending ratio is determined. Then, the flexural properties of reinforced FRCC beams are studied. Secondly, the bonding properties of FRP tendons and cement matrix in different environments are studied. The influence of seawater environment on the transition zone between FRP bars and matrix is analyzed. The experimental results show that the flexural bearing capacity and ductility of FRCC beams can be significantly improved by using FRP tendons. The ductility and flexural bearing capacity of FRCC beams are obviously better than that of concrete beams reinforced with FRP bars. And the bending failure form of FRP beam-FRCC beam is plastic failure, which is similar to the yield platform characteristic of reinforced concrete beam, and shows good ductility. However, the bond failure between FRP tendons and ordinary concrete is in the form of concrete splitting failure, the relative slip is small, and the ductility is lacking. The bond strength between FRP tendons and FRCC is much higher than that of ordinary concrete. The ratio of increase is between 60% and 80%, and the form of bond failure of FRP tendons in FRCC is that FRP tendons are pulled out and FRCC cracks FRP tendons have good bond ductility with FRCC.) in seawater environment, FRP tendons and ordinary concrete show good adhesion and ductility. Compared with the standard curing condition, the bond strength of the joint strength is reduced by 20%, and the failure form is still obvious brittle splitting failure. The bond strength between FRP bars and FRCC in seawater environment is about 5% lower than that under the standard curing condition. Compared with seawater immersion, the bond strength of FRP tendons with FRCC decreased slightly, but it still showed ductile failure, compared with the seawater immersion environment, the bond strength between FRP bars and FRCC decreased slightly, but it was still ductile in seawater environment, and the bond strength between FRP tendons and FRCC was still ductile, compared with the seawater immersion environment, and the bond strength between FRP tendons and FRCC was decreased slightly, but it was still ductile in seawater environment. The bond strength between FRP bars and ordinary concrete under tidal conditions is about 15% lower than that of normal concrete under tidal conditions. Even in tidal environment, the bond strength between FRP tendons and ordinary concrete is stronger than that between FRP bars and ordinary concrete under standard curing conditions. The degree is about 50% higher. Therefore, FRP bar and FRCC have good bond performance and durability. The results show that the FRP tendon-FRCC structure has good long-term working performance under the harsh environment. (5) Alkaline environment will cause a certain erosion of the BFRP tendons. In seawater corrosion environment, the microhardness of the transition zone between FRP bars and FRCC is slightly reduced and the width is enlarged. It can be seen from the SEM diagram that more expansive products AFT are formed in seawater environment, which leads to cracks. But on the whole, the mechanical properties and durability of FRP reinforced FRCC structures are obviously superior to those of FRP reinforced concrete structures. FRP-FRCC new structural forms will have broad application prospects in ocean engineering, road and bridge engineering with desiccated salt in winter and so on.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.7;TB332

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