Effect of freeze-thaw cycles on bond properties of FRP sheet-brick
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摘要: 研究了冻融循环对纤维增强树脂复合材料(FRP)加固砌块界面粘结性能的影响,分别采用碳纤维增强树脂复合材料(CFRP)片材和玻璃纤维增强树脂复合材料(GFRP)片材对烧结黏土砖和页岩砖进行了加固,通过试验研究了不同冻融次数条件下砖、砂浆、FRP片材和树脂各种材料性能的变化及FRP片材与砌体间的正拉粘结强度和单面剪切强度的变化规律。研究结果表明,冻融循环对黏土砖、页岩砖、砂浆块、CFRP片材、GFRP片材和粘贴环氧树脂的力学性能产生了显著的影响,均随着冻融次数的增加而明显降低;FRP片材与砖砌块界面间的正拉粘结强度和单面剪切强度随着冻融循环次数的增加而逐渐降低,经过30次冻融循环后FRP片材加固单砖的正拉粘结强度最大会降低45.49%,单面剪切强度最大可降低42.26%;FRP片材的种类对不同冻融次数条件下FRP片材-砌体的正拉粘结强度几乎没有影响,但对单面剪切强度有一定的影响。Abstract: The effect of freeze-thaw cycles on the interfacial bonding properties of fiber reinforced polymer (FRP) sheet reinforced blocks was studied. Two kinds of fiber sheets, carbon fiber reinforced polymer (CFRP) sheet and glass fiber reinforced polymer (GFRP) sheet, were used to strengthen clay brick and shale brick respectively. The tests of various material properties, pull-off bond and single-lap shear bond were carried out to study the effect of freeze-thaw times. The results show that the mechanical properties of clay brick, shale brick, mortar block, CFRP sheet, GFRP sheet and epoxy resin are seriously affected by freeze-thaw cycles, and all decrease significantly with the increase of freeze-thaw times. The pull-off bond strength and single-lap shear bond strength of FRP sheet and brick gradually decrease with the increase of freeze-thaw times. After 30 freeze-thaw cycles, the pull-off debonding force of FRP sheet and brick block is reduced by 45.49%, and the single-lap shear bond strength of FRP sheet and brick block is reduced by 42.26%. The type of FRP sheet has little effect on the pull-off bond strength under different freeze-thaw times, but has a certain effect on the single-lap shear bond strength.
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Key words:
- FRP sheet /
- brick /
- freeze-thaw cycle /
- bonding performance /
- durability
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图 19 FRP片材-砌块单面剪切强度的劣化曲线
Figure 19. Modeled degradation curves of single-lap shear debonding strength of FRP sheet-brick
${\sigma}_{(N)} $—Single-lap shear debonding strength of FRP sheet-brick after exposure to N times freeze-thaw cycle; ${\sigma}_{(0)} $—Single-lap shear debonding strength of FRP sheet-brick without freeze-thaw cycle
表 1 FRP片材-砌块正拉粘结强度试验结果
Table 1. Test results of pull-off strength of FRP sheet-brick and masory
Freeze-thaw time FRP type Block type Fpull/N Changing range/% Block type Fpull/N Changing range/% 0 CFRP sheet Clay brick 3300.09 – Clay masonry 2954.31 – 5 CFRP sheet Clay brick 2834.76 14.10 – – – 10 CFRP sheet Clay brick 2609.42 20.93 Clay masonry 2376.59 19.56 20 – – – – Clay masonry 2305.46 21.96 30 CFRP sheet Clay brick 2362.86 28.40 Clay masonry 2147.92 27.30 0 GFRP sheet Clay brick 3404.27 – – – – 5 GFRP sheet Clay brick 2867.27 15.77 – – – 10 GFRP sheet Clay brick 2569.79 24.51 – – – 30 GFRP sheet Clay brick 2535.82 25.51 – – – 0 CFRP sheet Shale brick 6111.55 – Shale masonry 5674.67 – 10 CFRP sheet Shale brick 6089.77 0.36 Shale masonry 5432.18 4.27 20 CFRP sheet Shale brick 5645.22 7.63 Shale masonry 5321.77 6.22 30 CFRP sheet Shale brick 4180.50 31.60 Shale masonry 4025.76 29.06 0 GFRP sheet Shale brick 6446.76 – – – – 10 GFRP sheet Shale brick 6269.08 2.76 – – – 20 GFRP sheet Shale brick 5093.38 20.99 – – – 30 GFRP sheet Shale brick 3513.97 45.49 – – – Note: Fpull—Pull-off strength of FRP sheet-brick and masonry. 表 2 FRP片材加固单砖和砖墙的单面剪切试验结果
Table 2. Test results of FRP sheet-brick and masonry in single-lap shear bond test
Freeze-thaw time FRP type Block type Fshear/N Changing range/% Block type Fshear/N Changing range/% 0 CFRP sheet Clay brick 9860.57 – Clay masonry 8239.11 – 5 CFRP sheet Clay brick 9145.31 7.25 – – – 10 CFRP sheet Clay brick 8510.16 13.70 Clay masonry 8010.50 2.77 20 – – – – Clay masonry 5280.50 35.91 30 CFRP sheet Clay brick 7722.36 21.68 Clay masonry 4757.33 42.26 0 GFRP sheet Clay brick 9268.90 – Clay masonry 9506.48 – 5 GFRP sheet Clay brick 8444.32 8.90 – – – 10 GFRP sheet Clay brick 7909.60 14.67 Clay masonry 8375.50 11.90 20 – – – – Clay masonry 7795.00 18.00 30 GFRP sheet Clay brick 6707.17 27.64 Clay masonry 6153.67 35.27 0 CFRP sheet Shale brick 11080.98 – Shale masonry 10984.59 – 10 CFRP sheet Shale brick 10483.91 5.39 Shale masonry 10112.00 7.94 20 CFRP sheet Shale brick 9032.16 18.49 Shale masonry 8675.50 21.02 30 CFRP sheet Shale brick 7013.81 36.70 Shale masonry 6707.33 38.94 0 GFRP sheet Shale brick 11358.93 – Shale masonry 9967.78 – 10 GFRP sheet Shale brick 10372.80 8.68 Shale masonry 9690.50 2.78 20 GFRP sheet Shale brick 9274.13 18.35 Shale masonry 8051.67 19.22 30 GFRP sheet Shale brick 8250.59 27.36 Shale masonry 7211.00 27.66 Note: Fshear—Single-lap shear strength of FRP sheet-brick and masonry. -
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