水泥基材料的自愈合及与BFRP筋复合结构的力学性能研究

发布时间：2018-10-11 12:32

【摘要】：混凝土开裂会导致一系列的耐久性问题,而常规裂缝修补方法费时费力却往往不能取得很好的效果。因此,具有裂缝限制能力的纤维增强水泥基复合材料及不锈高强FRP筋材可成为很好的钢筋混凝土替代材料,此外水泥基复合材料还具有一定的裂缝自愈合能力,两种材料优势互补,有望改善传统钢筋混凝土结构易开裂和锈蚀问题。为研究纤维增强水泥基复合材料的抗拉性能及自愈合能力,以及水泥基复合材料与BFRP筋复合结构的力学性能,本文进行了相关的试验研究。包括矿物掺合料对水泥基复合材料的拉伸性能的影响;以抗渗性、强度恢复、裂缝变化为评价标准的复合材料的自愈合性能;以及复合材料-BFRP筋复合梁的力学性能与裂缝自愈合对复合梁力学性能的影响。研究发现,矿渣能提升28 d龄期水泥基复合材料的结构致密性,材料抗渗性相应提升;掺加粉煤灰、偏高岭土、硅灰、矿渣的复合材料在纤维掺量为2%材料体积情况下,极限抗拉强度与极限应变能达到3.86 MPa与2.2%,受拉时多裂缝开展,能很好地限制材料的裂缝宽度;且在干湿循环养护条件下表现出上佳的裂缝自愈合能力,开裂材料干湿循环养护28 d后的强度能达到预裂加载时强度的117%;综合考虑自愈合效果及实际操作性,干湿循环是对复合材料自愈合最好的养护条件;初始裂缝宽度对裂缝自愈合起主导作用,小于50 μm的裂缝基本都能愈合,而大于150 μm的裂缝愈合效果不明显;采用复合材料替代70 mm混凝土梁受拉区并使用FRP筋代替普通碳素钢作为受拉主筋的混凝土梁受弯时,梁的抗弯承载力较仅采用BFRP筋提升10%左右,且梁的整体刚度提升明显,破坏时梁的挠度降低明显;复合梁预载并置于干湿循环养护条件下28 d后,梁整体刚度恢复明显且微裂缝愈合效果较好。
[Abstract]:Concrete cracking can lead to a series of durability problems, but the conventional crack repair method is time-consuming and laborious, but it can not achieve good results. Therefore, fiber reinforced cement matrix composites with crack limiting ability and stainless high strength FRP bars can be used as good substitute materials for reinforced concrete. In addition, cement matrix composites also have a certain ability of self-healing of cracks. Because the two materials complement each other, they are expected to improve the cracking and corrosion of traditional reinforced concrete structures. In order to study the tensile properties and self-healing ability of fiber reinforced cement matrix composites and the mechanical properties of composite structures of cement matrix composites and BFRP tendons, related experiments were carried out in this paper. The effects of mineral admixtures on the tensile properties of cement matrix composites and the self-healing properties of composites based on impermeability, strength recovery and crack change were evaluated. The mechanical properties of composite-BFRP composite beams and the effect of crack self-healing on the mechanical properties of composite beams are also discussed. It is found that slag can enhance the structure density and permeability resistance of cement-based composites at 28 days of age, and the composites with fly ash, metakaolin, silica fume and slag have 2% fiber volume. The ultimate tensile strength and ultimate strain can reach 3.86 MPa and 2.2, and the crack width of the material can be well limited by the development of multiple cracks during tension, and the excellent self-healing ability of crack is shown under the condition of dry-wet cycle curing, the tensile strength and the ultimate strain can reach 3.86 MPa and 2.2, respectively. The strength of cracking material after dry and wet cycle curing for 28 days can reach 1177.The dry and wet cycle is the best curing condition for composite material self-healing considering the effect of self-healing and practical operation. The initial crack width plays a leading role in fracture self-healing. Cracks less than 50 渭 m can basically heal, while those larger than 150 渭 m have no obvious healing effect. When the composite material is used to replace the tensile zone of 70 mm concrete beam and the normal carbon steel is replaced by the FRP bar, the flexural capacity of the beam is increased by about 10% compared with that of the BFRP bar, and the overall stiffness of the beam is obviously increased. The deflection of the composite beam decreases obviously when it is destroyed and the composite beam is preloaded and subjected to dry and wet cycle curing for 28 days the overall stiffness of the beam recovers obviously and the micro-crack healing effect is better.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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