Influence of high temperature on flexural properties and micro structure of steel fiber-polyvinyl alcohol fiber-CaCO3 whisker multi-scale fibers/cement composite
-
摘要: 为促进钢纤维(SF)-聚乙烯醇(PVA)纤维-CaCO3晶须(CW)多尺度纤维/水泥复合材料的工程应用,考察其抗火耐高温性能,本文研究了SF-PVA-CW多尺度纤维/水泥复合材料高温后的弯曲性能及其微观结构。研究发现:随温度升高,SF-PVA-CW多尺度纤维/水泥复合材料弯曲强度总体下降,但在500℃以下时下降缓慢,CW掺量为3vol%的SF-PVA-CW多尺度纤维/水泥复合材料弯曲强度有所提高;800℃及以上时,SF-PVA-CW多尺度纤维/水泥复合材料的弯曲强度急剧下降。采用JSCE SF4规定的等效弯曲强度评价弯曲韧性。随温度升高,SF-PVA-CW多尺度纤维/水泥复合材料的等效弯曲强度逐渐降低,500℃以下时掺加CW显著增强了SF对裂缝的控制能力,其中小挠度阶段的作用效果优于大挠度阶段。800℃以上时,等效弯曲强度急剧下降,其中大挠度阶段下降更为显著。借助数码相机、光学显微镜和SEM进行多尺度观测,揭示了高温对SF-PVA-CW多尺度纤维/水泥复合材料弯曲性能影响的微观机制。Abstract: In order to promote the engineering application of steel fiber (SF)-polyvinyl alcohol (PVA) fiber-CaCO3 whisker (CW) multi-scale fibers/cement composite, and investigate its fire resistance and high temperature resistance, the flexural properties and microstructure of the SF-PVA-CW multi-scale fibers/cement composite after high temperature were studied. The results show that with the increase of temperature, the residual flexural strength of the SF-PVA-CW multi-scale fibers/cement composite decreases overall, but decreases slowly below 500℃ and the the SF-PVA-CW multi-scale fibers/cement composite with 3vol% CW still increase. The flexural strength decreases sharply at 800℃ and above. The equivalent flexural strength based on JSCE SF4 was used to evaluate the flexural toughness. With the increase of temperature, the equivalent flexural strength of the SF-PVA-CW multi-scale fibers/cement composite decreases gradually. At the temperature up to 500℃, the addition of CW significantly enhances the crack restricting of SF, and the effect of small deflection stage is better than that of large deflection stage. The equivalent flexural strength decreases sharply at 800℃ or above, especially at large deflection stage. With the help of digital camera, optical microscope and SEM, the micro mechanism of the influence of high temperature on the flexural properties of the SF-PVA-CW multi-scale fibers/cement composite was revealed.
-
Key words:
- whiskers /
- cement /
- fiber reinforced concrete /
- high temperature /
- flexural strength /
- flexural toughness /
- micro mechanism
-
表 1 原材料的基本性能
Table 1. Properties of raw materials
Raw material Density/
(g·cm−3)Size Mechanical property Origin Cement 3.20 Specific surface area 356 m2/kg — Dalian Onoda Cement Co. Ltd. Silica sand 2.65 Fineness modulus 1.9 Media
sandMoh’s hardness 7 Dalian SF 7.8 Length 13 mm; Diameter 200 μm Tensile strength ≥2 GPa; Elastic modulus 200–210 GPa Bekaert PVA 1.29 Length 6 mm; Diameter 31 μm Tensile strength 1.1 GPa; Elastic modulus 41 GPa Wanwei High-tech Material Co. Ltd., China CW 2.86 Length 20–30 μm; Diameter 0.5–2 μm Tensile strength 3–6 GPa; Elastic modulus 410–710 GPa Shanghai Fengzhu Co. Ltd. Notes: SF—Steel fiber; PVA—Polyvinyl alcohol fiber; CW—CaCO3 whisker. 表 2 钢纤维(SF)-聚乙烯醇(PVA)纤维-CaCO3晶须(CW)多尺度纤维/水泥复合材料的配比
Table 2. Proportions of steel fiber (SF)-polyvinyl alcohol (PVA) fiber-CaCO3 whisker (CW) multi-scale fibers/cement composite
Group Volume fraction/vol% Fiber dosage/(kg·m−3) SF PVA CW SF PVA CW PC 0 0 0 0 0 0 CW/C 0 0 1 0 0 28.6 SF-PVA/C 1.50 0.5 0 117 6.45 0 SF-PVA-CW/C1 1.50 0.5 1 117 6.45 28.6 SF-PVA-CW/C2 1.25 0.5 2 117 6.45 57.2 SF-PVA-CW/C3 1.25 0.5 3 117 6.45 85.8 -
[1] 张鹏, WITTMANN F, 赵铁军, 等. 高韧性PVA-SHCC多缝开裂后吸水特性研究[J]. 建筑材料学报, 2011, 14(3):324-328.ZHANG Peng, WITTMANN F, ZHAO Tiejun, et al. Water absorption of high toughness PVA-SHCC after multi-cracking[J]. Journal of Building Materials,2011,14(3):324-328(in Chinese). [2] ARORA A, YAO Y, MOBASHER B, et al. Fundamental insights into the compressive and flexural response of binder- and aggregate-optimized ultra-high performance concrete (UHPC)[J]. Cement and Concrete Composites,2019,98:1-13. doi: 10.1016/j.cemconcomp.2019.01.015 [3] ZHANG Y, JU J, ZHU H, et al. A novel multi-scale model for predicting the thermal damage of hybrid fiber-reinforced concrete[J]. International Journal of Damage Mechanics,2020,29(1):19-44. doi: 10.1177/1056789519831554 [4] YAO W, LI J, WU K. Mechanical properties of hybrid fiber-reinforced concrete at low fiber volume fraction[J]. Cement and Concrete Research,2003,33(1):27-30. doi: 10.1016/S0008-8846(02)00913-4 [5] 华渊, 连俊英, 周太全. 长径比对混杂纤维增强混凝土力学性能的影响[J]. 建筑材料学报, 2005, 8(1):71-76.HUA Yuan, LIAN Junying, ZHOU Taiquan. Relationship between the mechanical properties of hybrid fiber reinforced concrete and length diameter aspect ratio of hybrid fiber[J]. Journal of Building Materials,2005,8(1):71-76(in Chinese). [6] LI L, CAO M, XIE C, et al. Effects of CaCO3 whisker, hybrid fiber content and size on uniaxial compressive behavior of cementitious composites[J]. Structural Concrete,2019,20(1):506-518. doi: 10.1002/suco.201800185 [7] CAO M, XIE C, GUAN J. Fracture behavior of cement mortar reinforced by hybrid composite fiber consisting of CaCO3 whiskers and PVA-steel hybrid fibers[J]. Composites Part A: Applied Science and Manufacturing,2019,120:172-187. doi: 10.1016/j.compositesa.2019.03.002 [8] 张聪, 曹明莉. 多尺度纤维增强水泥基复合材料力学性能试验[J]. 复合材料学报, 2014, 31(3):661-668.ZHANG Cong, CAO Mingli. Mechancial property test of a multi-scale fiber reinforced cementitious composites[J]. Acta Materiae Compositae Sinica,2014,31(3):661-668(in Chinese). [9] 张聪, 余志辉, 韩世诚, 等. 混杂纤维增强应变硬化水泥基复合材料的压缩本构关系[J]. 复合材料学报, 2020, 37(5):1221-1226.ZHANG Cong, YU Zhihui, HAN Shicheng, et al. Compression constitutive relation of hybrid fiber reinforced strain hardening cementitious composites[J]. Acta Materiae Compositae Sinica,2020,37(5):1221-1226(in Chinese). [10] LI L, CAO M, YIN H. Comparative roles between aragonite and calcite calcium carbonate whiskers in the hydration and strength of cement paste[J]. Cement and Concrete Composites,2019,104:103350. doi: 10.1016/j.cemconcomp.2019.103350 [11] YANG Y, DENG Y. Mechanical properties of hybrid short fibers reinforced oil well cement by polyester fiber and calcium carbonate whisker[J]. Construction and Building Materials,2018,182:258-272. doi: 10.1016/j.conbuildmat.2018.06.110 [12] LI M, YANG Y, LIU M, et al. Hybrid effect of calcium carbonate whisker and carbon fiber on the mechanical properties and microstructure of oil well cement[J]. Construction and Building Materials,2015,93:995-1002. doi: 10.1016/j.conbuildmat.2015.05.056 [13] PAN J, CAI J, MA H, et al. Development of multiscale fiber-reinforced engineered cementitious composites with PVA fiber and CaCO3 whisker[J]. ASCE Journal of Materials in Civil Engineering,2018,30(6):40181066. [14] 张翼, 王冲, 张超, 等. 超高韧性水泥基材料的制备技术[J]. 土木建筑与环境工程, 2018, 40(1):83-89.ZHANG Yi, WANG Chong, ZHANG Chao, et al. Preparation technology of the ultra-high-toughness cementitious composite[J]. Journal of Civil, Architectural & Environmental Engineering,2018,40(1):83-89(in Chinese). [15] 张文华, 张仔祥, 刘鹏宇, 等. 多尺度纤维增强超高性能混凝土的轴心抗拉和抗压行为[J]. 硅酸盐学报, 2020, 48(8):1-13.ZHANG Wenhua, ZHANG Zixiang, LIU Pengyu, et al. Uniaxial tensile and compressive stress-strain behavior of multi-scale fiber-reinforced ultra-high performance concrete[J]. Journal of the Chinese Ceramic Society,2020,48(8):1-13(in Chinese). [16] YANG Y, ZHOU Q, DENG Y, et al. Reinforcement effects of multi-scale hybrid fiber on flexural and fracture behaviors of ultra-low-weight foamed cement-based composites[J]. Cement and Concrete Composites,2020,108:103509. doi: 10.1016/j.cemconcomp.2019.103509 [17] KHAN M, CAO M, ALI M. Effect of basalt fibers on mechanical properties of calcium carbonate whisker-steel fiber reinforced concrete[J]. Construction and Building Materials,2018,192:742-753. doi: 10.1016/j.conbuildmat.2018.10.159 [18] 陈明阳, 侯晓萌, 郑文忠, 等. 混凝土高温爆裂临界温度和防爆裂纤维掺量研究综述与分析[J]. 建筑结构学报, 2017, 38(1):161-170.CHEN Mingyang, HOU Xiaomeng, ZHENG Wenzhong, et al. Review and analysis on spalling critical temperature of concrete and fibers dosage to prevent spalling at elevated temperatures[J]. Journal of Building Structures,2017,38(1):161-170(in Chinese). [19] 郑文忠, 侯晓萌, 王英. 混凝土及预应力混凝土结构抗火研究现状与展望[J]. 哈尔滨工业大学学报, 2016, 48(12):1-18.ZHENG Wenzhong, HOU Xiaomeng, WANG Ying. Progress and prospect of fire resistance of reinforced concrete and prestressed concrete structures[J]. Journal of Harbin Institute of Technology,2016,48(12):1-18(in Chinese). [20] 邓明科, 成媛, 翁世强, 等. 高温后高延性混凝土的抗压性能及微观结构[J]. 复合材料学报, 2020, 37(4):985-996.DENG Mingke, CHENG Yuan, WENG Shiqiang, et al. Compressive properties and micro-structure analysis of high ductility concrete exposed to elevated temperature[J]. Acta Materiae Compositae Sinica,2020,37(4):985-996(in Chinese). [21] 高丹盈, 赵亮平, 陈刚. 高温中纤维纳米混凝土单轴受压应力-应变关系[J]. 土木工程学报, 2017, 50(9):46-58.GAO Danying, ZHAO Liangping, CHEN Gang. Compressive stress-strain relationship of fiber and nanosized material reinforced concrete in high temperature[J]. China Civil Engineering Journal,2017,50(9):46-58(in Chinese). [22] 高丹盈, 李晗. 高温后纤维纳米混凝土单轴受压应力-应变关系[J]. 土木工程学报, 2015, 48(10):10-20.GAO Danying, LI Han. Compressive stress-strain relationship of fiber & nanosized materials reinforced concrete after exposure to high temperature[J]. China Civil Engineering Journal,2015,48(10):10-20(in Chinese). [23] 元成方, 高丹盈. 聚丙烯纤维混凝土高温后的孔隙结构特征研究[J]. 华中科技大学学报(自然科学版), 2014, 42(4):122-126.YUAN Chengfang, GAO Danying. Performance of polypropylene-steel hybrid fiber reinforced concrete after being exposed to high temperature[J]. Journal of Huazhong University of Science and Technology (Natural Science Edition),2014,42(4):122-126(in Chinese). [24] 高丹盈, 李晗, 杨帆. 聚丙烯-钢纤维增强高强混凝土高温性能[J]. 复合材料学报, 2013, 30(1):187-193.GAO Danying, LI Han, YANG Fan. Performance of polypropylene-steel hybrid fiber reinforced concrete after being exposed to high temperature[J]. Acta Materiae Compositae Sinica,2013,30(1):187-193(in Chinese). [25] 高丹盈, 杨淑慧, 赵军. 高温后纤维矿渣微粉混凝土抗压强度[J]. 建筑材料学报, 2010, 13(6):711-715.GAO Danying, YANG Shuhui, ZHAO Jun. Compressive strength of fiber reinforced concrete with slag powder after high temperature[J]. Journal of Building Materials,2010,13(6):711-715(in Chinese). [26] CAO M, LI L, YIN H, et al. Microstructure and strength of calcium carbonate (CaCO3) whisker reinforced cement paste after exposed to high temperatures[J]. Fire Technology,2019,55(6):1983-2003. doi: 10.1007/s10694-019-00839-3 [27] 朋改非, 牛旭婧, 成铠. 超高性能混凝土的火灾高温性能研究综述[J]. 材料导报, 2017, 31(12):17-23.PENG Gaifei, NIU Xujing, CHENG Kai. Research on fire resistance of ultra-high performance concrete: A review[J]. Materials Reports,2017,31(12):17-23(in Chinese). [28] 朋改非, 杨娟, 石云兴. 超高性能混凝土高温后残余力学性能试验研究[J]. 土木工程学报, 2017, 50(4):73-79.PENG Gaifei, YANG Juan, SHI Yunxing. Experimental study on residual mechanical properties of ultra-high performance concrete exposed to high temperature[J]. China Civil Engineering Journal,2017,50(4):73-79(in Chinese). [29] 杨娟, 朋改非. 纤维对超高性能混凝土残余强度及高温爆裂性能的影响[J]. 复合材料学报, 2016, 33(12):2931-2940.YANG Juan, PENG Gaifei. Effect of fiber on residual strength and explosive spalling behavior of ultra-high-performance concrete exposed to high temperature[J]. Acta Materiae Compositae Sinica,2016,33(12):2931-2940(in Chinese). [30] LI Q, GAO X, XU S, et al. Microstructure and mechanical properties of high-toughness fiber-reinforced cementitious composites after exposure to elevated temperatures[J]. ASCE Journal of Materials in Civil Engineering,2016,28(11):401613211. [31] SANCHAYAN S, FOSTER S J. High temperature behaviour of hybrid steel-PVA fibre reinforced reactive powder concrete[J]. Materials and Structures,2016,49(3):769-782. doi: 10.1617/s11527-015-0537-2 [32] 王立闻, 庞宝君, 盖秉政, 等. 活性粉末混凝土高温后冲击压缩特性研究[J]. 工程力学, 2012, 29(9):245-251.WANG Liwen, PANG Baojun, GAI Bingzheng, et al. Investigation of dynamic compression properties of reactive powder concrete after exposure in high temperature[J]. Engineering Mechanics,2012,29(9):245-251(in Chinese). [33] 张聪, 夏超凡, 袁振, 等. 高温作用对混杂纤维增强高延性水泥基复合材料拉伸性能的影响[J]. 功能材料, 2020, 51(2):2007-2013.ZHANG Cong, XIA Chaofan, YUAN Zhen, et al. Effect of high temperature on the tensile properties of hybrid fiber reinforced high ductility cementitious composites[J]. Journal of Functional Materials,2020,51(2):2007-2013(in Chinese). [34] 李黎, 曹明莉. 混杂纤维增强水泥基复合材料弯曲韧性与纤维增强指数的定量关系[J]. 复合材料学报, 2018, 35(5):30-34.LI Li, CAO Mingli. Research progress on fiber hybrid effect in fiber reinforced cementitious composite[J]. Acta Materiae Compositae Sinica,2018,35(5):30-34(in Chinese). [35] 李黎, 曹明莉. 纤维增强水泥基复合材料的纤维混杂效应研究进展[J]. 应用基础与工程科学学报, 2018, 26(4):843-853.LI Li, CAO Mingli. Research progress on fiber hybrid effect in fiber reinforced cementitious composite[J]. Journal of Basic Science and Engineering,2018,26(4):843-853(in Chinese). [36] 曹明莉, 李黎, 李志文, 等. CaCO3晶须对钢-聚乙烯醇混杂纤维增强水泥基复合材料板弯曲性能的影响[J]. 复合材料学报, 2017, 34(11):2614-2623.CAO Mingli, LI Li, LI Zhiwen, et al. Influence of CaCO3 whisker on flexural behavior of steel-polyvinyl alcohol hybrid fiber reinforced cement matrix composite slabs[J]. Acta Materiae Compositae Sinica,2017,34(11):2614-2623(in Chinese). [37] Japan Society of Civil Engineers. Method of test for flexural strength and flexural toughness of steel fiber reinforced concrete: JSCE SF4[S]. Japan Society of Civil Engineers, 1984. [38] HUANG H, WANG R, GAO X. Improvement effect of fiber alignment on resistance to elevated temperature of ultra-high performance concrete[J]. Composites Part B: Engineering,2019,177:107454. doi: 10.1016/j.compositesb.2019.107454 [39] LI L, CAO M, MING X, et al. Microstructure of calcium carbonate whisker reinforced cement paste after elevated temperature exposure[J]. Construction and Building Materials,2019,227:116609. doi: 10.1016/j.conbuildmat.2019.07.335 [40] CAO M, ZHANG C, LI Y, et al. Using calcium carbonate whisker in hybrid fiber-reinforced cementitious composites[J]. ASCE Journal of Materials in Civil Engineering,2015,27(4):4014139. doi: 10.1061/(ASCE)MT.1943-5533.0001041 [41] CAO M, ZHANG C, LV H, et al. Characterization of mechanical behavior and mechanism of calcium carbonate whisker-reinforced cement mortar[J]. Construction and Building Materials,2014,66:89-97. doi: 10.1016/j.conbuildmat.2014.05.059 [42] 王建超, 项爱民, 刘小建. 聚乙烯醇的热氧老化与稳定性研究[J]. 中国塑料, 2008, 22(9):74-77.WANG Jianchao, XIANG Aimin, LIU Xiaojian. Research on thermal oxidative aging and stability of polyvinyl alcohol[J]. China Plastics,2008,22(9):74-77(in Chinese). [43] CAO M, MING X, YIN H, et al. Influence of high temperature on strength, ultrasonic velocity and mass loss of calcium carbonate whisker reinforced cement paste[J]. Composites Part B: Engineering,2019,163:438-446. doi: 10.1016/j.compositesb.2019.01.030 -