-
摘要: 为探究新型混凝土受硫酸盐侵蚀后的力学性能，采用质量分数为5%的硫酸盐溶液全浸泡加速侵蚀法，对11组聚丙烯纤维混凝土（PC）试块、11组聚丙烯纤维锂渣混凝土（PLiC）试块、8根PC大偏心受压柱和8根PLiC大偏心受压柱进行侵蚀试验，得到了不同侵蚀时间下混凝土的力学性能。基于分形理论分析了试块及构件破坏时表面裂缝分布的分形特征，详细讨论了试块及构件表面裂缝分形维数与其侵蚀时间、抗压强度、极限承载力之间的关系。研究表明，PC和PLiC立方体抗压强度随侵蚀天数先增加后降低，在120 d达到最大；试块及构件破坏时表面裂缝分布具有分形特征，试块表面裂缝分形维数随侵蚀天数的增加呈现先增加后减少再增加的规律，随试块抗压强度的提高而减少；PC及PLiC混凝土大偏心柱极限承载力随侵蚀天数的增加先增加后减少，锂渣的掺入可以提高聚丙烯纤维混凝土柱的抗硫酸盐侵蚀能力，构件破坏时表面裂缝分形维数随硫酸盐侵蚀天数呈现震荡上升的趋势；因此混凝土表面裂缝的分形特征可作为判定构件损伤程度的指标之一，可为今后对在役混凝土结构承载力和寿命预测提供参考。Abstract: Natural corrosion of concrete structure due to sulfate poses a serious threat to people's lives and property. Therefore, it is of great practical significance to study the phenomenon of sulfate corrosion on concrete. In order to explore the mechanical properties of a new type of concrete corroded by sulfate, a full immersion accelerated erosion method was used with 5% sulfate solution. Erosion tests were performed on 11 groups of polypropylene fiber reinforced concrete (PC) specimens, 11 groups of polypropylene fiber lithium slag concrete (PLiC) specimens, 8 PC columns with large eccentricity, and 8 PLiC large eccentric columns. The mechanical properties of concrete under different erosion times are obtained. Based on the fractal theory, the fractal characteristics of surface crack distribution of specimens and columns are analyzed. In addition, the relationship between the fractal dimension of surface crack and erosion time, compressive strength, and ultimate bearing capacity is discussed. Results show that the compressive strength of PC and PLiC initially increases and then decreases with increased erosion days, reaching a maximum of 120 days. The distribution of surface cracks is observed to be fractal when they are broken. With increased erosion days, fractal dimension of surface cracks initially increases, then decreases, and finally increases again. On the other hand, a decreasing trend of fractal dimension of surface cracks is observed with increased compressive strength. The ultimate bearing capacity of PC and PLiC columns with large eccentricity increases first and then decreases with erosion days. Addition of lithium slag is observed to improve the sulfate resistance of polypropylene fiber reinforced concrete columns. With broken members, fractal dimension of surface cracks presents a rising trend of shock with sulfate erosion days. Results signify that fractal characteristics of concrete surface cracks can be used as one of the indexes to determine the damage degree of members, which can provide reference for the prediction of bearing capacity and service life of concrete structures in the future.
-
Key words:
- sulfate attack /
- fractal theory /
- large eccentric column /
- polypropylene fiber /
- lithium slag
-
图 2 混凝土柱侵蚀及试验图。（a）已施加荷载的钢筋混凝土柱；（b）混凝土柱大偏心受压试验
Figure 2. Corrosion and test of reinforced concrete column: (a) loaded reinforced concrete column; (b) large eccentric compression test of reinforced concrete column
图 3 不同侵蚀时间下的聚丙烯纤维锂渣混凝土外观形貌。（a）0 d；（b）30 d；（c）60 d；（d）90 d；（e）120 d；（f）150 d
Figure 3. Appearance morphology of polypropylene fiber lithium slag concrete under different erosion times: (a) 0 d; (b) 30 d; (c) 60 d; (d) 90 d; (e) 120 d; (f) 150 d
图 4 PC混凝土柱和PLiC混凝土柱破坏形态
Figure 4. Failure modes of PC concrete column and PLiC concrete column
图 7 不同侵蚀时间下立方体抗压强度
Figure 7. Compressive strength of cube at different times of erosion
图 9 试块抗压强度与分形维数的关系
Figure 9. Relationship between the compressive strength of test block and fractal dimension
图 10 PLiC−30受压柱破坏裂缝图
Figure 10. Failure fracture diagram of PLiC−30 compression column
图 11 PLiC−30受压柱裂缝lnN(r)−ln(1/r)曲线
Figure 11. lnN(r)−ln(1/r) curve of PLiC−30 compression column crack
图 14 分形维数与极限承载力的关系
Figure 14. Relationship between fractal dimension and ultimate bearing capacity
表 1 锂渣粉末主要成分
Table 1. Main components of lithium slag powder
% Chemical composition SiO2 AI2O3 Fe2O3 SO3 CaO Li2O Mass fraction 54.30 1.80 1.40 8.30 7.90 0.70 
下载: 导出CSV
表 2 聚丙烯纤维参数
Table 2. Parameters of polypropylene fibers
Fiber type Length/mm Density/(g·cm−3) Tensile strength/MPa Diameter/μm Elasticity modulus/GPa Polyprorylene fiber 19 0.91 530 33 >3.5
下载: 导出CSV
表 3 混凝土配合比
Table 3. Mix proportions of concrete
Type of test
blockPolypropylene fiber/
(kg·m−3)Lithium slag/
%Cement/
(kg·m−3)Cobblestone/
(kg·m−3)Sand/
(kg·m−3)Water/
(kg·m−3)Water reducer/
(kg·m−3)PC 1.2 0 382 1161 682 172.8 1.92 PLiC 1.2 20 308 1161 682 172.8 1.92
下载: 导出CSV
表 4 不同侵蚀时间下试块抗压强度及裂缝分形维数
Table 4. Compressive strength and fracture fractal dimension of test block under different erosion times
Type of test block Cube compressive strength /MPa Fractal dimension R2 Type of test block Cube compressive strength /MPa Fractal dimension R2 PC−0 41.3 1.407 0.982 PC−sulfate−0 41.3 1.407 0.988 PC−30 42.7 1.425 0.991 PC−sulfate−30 42.0 1.415 0.987 PC−60 43.9 1.435 0.994 PC−sulfate−60 43.4 1.402 0.995 PC−90 46.6 1.451 0.991 PC−sulfate−90 45.0 1.396 0.994 PC−120 57.8 1.379 0.982 PC−sulfate−120 54.3 1.364 0.981 PC−150 54.3 1.375 0.993 PC−sulfate−150 51.6 1.438 0.989 PLiC−0 43.9 1.391 0.991 PLiC−sulfate−0 43.9 1.391 0.985 PLiC−30 44.7 1.401 0.989 PLiC−sulfate−30 44.0 1.402 0.993 PLiC−60 49.7 1.474 0.992 PLiC−sulfate−60 45.8 1.356 0.987 PLiC−90 52.3 1.441 0.987 PLiC−sulfate−90 49.5 1.365 0.986 PLiC−120 59.6 1.425 0.994 PLiC−sulfate−120 57.5 1.385 0.993 PLiC−150 55.3 1.483 0.992 PLiC−sulfate−150 55.8 1.435 0.991 Note：PC−sulfate−30 represents that polypropylene fiber concrete corroded in sodium sulfate solution for 30 days.
下载: 导出CSV
表 5 PC和PLiC大偏心受压柱承载力及破坏裂缝分形维数
Table 5. Bearing capacity of large eccentric compress reinforced concrete column and fractal dimension of failure crack
Type of test block Ultimate load/ kN Fractal dimension R2 Type of test block Ultimate load/ kN Fractal dimension R2 PC−0−0 175 1.261 0.997 PLiC−0−0 180 1.253 0.991 PC−30−0.1 180 1.224 0.991 PLiC−30−0.1 194 1.233 0.993 PC−60−0.1 188 1.142 0.995 PLiC−60−0.1 200 1.133 0.994 PC−90−0.1 192 1.342 0.993 PLiC−90−0.1 205 1.291 0.995 PC−120−0.1 200 1.212 0.994 PLiC−120−0.1 220 1.181 0.991 PC−150−0.1 185 1.265 0.997 PLiC−150−0.1 205 1.324 0.996 PC−90−0.2 198 1.228 0.996 PLiC−90−0.2 220 1.267 0.994 PC−90−0.35 175 1.279 0.994 PLiC−90−0.35 182 1.265 0.993 Note：PC−30−0.1 represents polypropylene fiber concrete with stress ratio of 0.1 and erosion days of 30 d.
下载: 导出CSV
-
参考文献
[1] Han Y D, Liu C, Wang Z B, et al. Uniaxial compressive behavior of ECC under sulfate erosion in drying-wetting cycles. J Build Mater, 2020, 23(4): 846 doi: 10.3969/j.issn.1007-9629.2020.04.016韩宇栋, 刘畅, 王振波, 等. 硫酸盐干湿循环下ECC的轴压力学行为. 建筑材料学报, 2020, 23(4):846 doi: 10.3969/j.issn.1007-9629.2020.04.016 [2] Zhang Z Y, Zhou J T, Zou Y, et al. Effect of sulfate attack on the shear performance of concrete. China Civil Eng J, 2020, 53(7): 64张中亚, 周建庭, 邹杨, 等. 硫酸盐侵蚀对混凝土抗剪性能的影响. 土木工程学报, 2020, 53(7):64 [3] Wee T H, Suryavanshi A K, Wong S F, et al. Sulfate resistance of concrete containing mineral admixtures. ACI Mater J, 2000, 97(5): 536 [4] Mangat P S, Khatib J M. Influence of fly-ash, silica fume, and slag on sulfate resistance of concrete. ACI Mater J, 1993, 92(5): 542 [5] Bai W F, Liu L A, Guan J F, et al. The constitutive model of concrete subjected to sulfate attack based on statistical damage theory. Eng Mech, 2019, 36(2): 66 doi: 10.6052/j.issn.1000-4750.2017.09.0734白卫峰, 刘霖艾, 管俊峰, 等. 基于统计损伤理论的硫酸盐侵蚀混凝土本构模型研究. 工程力学, 2019, 36(2):66 doi: 10.6052/j.issn.1000-4750.2017.09.0734 [6] Kou J L, Liu F F, Zhao D D, et al. Experimental study on resistance to sulfate attack of active powder concrete under normal temperature curing condition. J Nat Disast, 2020, 29(3): 76寇佳亮, 刘菲菲, 赵丹丹, 等. 常温养护条件下活性粉末混凝土抗硫酸盐侵蚀性能试验研究. 自然灾害学报, 2020, 29(3):76 [7] Shi L, Xie D, Wang X M, et al. Effect of liquid erosion inhibitor on water absorption and salt crystallization resistance of concrete. Materi Rev, 2020, 34(14): 14093 doi: 10.11896/cldb.19060175石亮, 谢德擎, 王学明, 等. 抗侵蚀抑制剂对混凝土吸水性能及抗盐结晶性能的影响. 材料导报, 2020, 34(14):14093 doi: 10.11896/cldb.19060175 [8] Li B X, Fang Q, Fang P, et al. Durability of high-volume mineral admixture concrete half immersed in sodium sulfate solution. J Harbin Eng Univ, 2020, 41(6): 892李北星, 方晴, 方鹏. 大掺量掺合料混凝土半浸泡于硫酸盐溶液中的耐久性. 哈尔滨工程大学学报, 2020, 41(6):892 [9] Lu J Z, Tian L Z, Liu Y, et al. Experimental study of the durability of concrete under coupling effect of axial compression and sulfate attack. J Basic Sci Eng, 2020, 28(2): 386逯静洲, 田立宗, 刘莹, 等. 轴压与硫酸盐实时耦合作用下混凝土耐久性试验研究. 应用基础与工程科学学报, 2020, 28(2):386 [10] Xiao Q H, Cao Z Y, Guan X, et al. Degradation law of recycled concrete under the coupling of freeze-thaw and sulfate erosion. Bull Chin Ceram Soc, 2020, 39(2): 352肖前慧, 曹志远, 关虓, 等. 冻融与硫酸盐侵蚀耦合作用下再生混凝土劣化规律. 硅酸盐通报, 2020, 39(2):352 [11] Li B L, Huo B B, You N Q, et al. Sulfate resistance of steel slag blended / GGBFS blended cement mortars under different curing conditions. J Southeast Univ Nat Sci, 2019, 49(6): 1144 doi: 10.3969/j.issn.1001-0505.2019.06.018李保亮, 霍彬彬, 尤南乔, 等. 不同养护条件下钢渣/矿渣复合水泥胶砂的耐硫酸盐侵蚀性能. 东南大学学报(自然科学版), 2019, 49(6):1144 doi: 10.3969/j.issn.1001-0505.2019.06.018 [12] Tuerkmen I, Gavgali M. Influence of mineral admixtures on the some properties and corrosion of steel embedded in sodium sulfate solution of concrete. Mater Lett, 2003, 57(21): 3222 doi: 10.1016/S0167-577X(03)00039-9 [13] Mandelbrot B B, Passoja D E, Paullay A J. Fractal character of fracture surfaces of metals. Nature, 1984, 308(5961): 721 doi: 10.1038/308721a0 [14] Armandei M, de Souza Sanchez Filho E. Correlation between fracture roughness and material strength parameters in SFRCs using 2D image analysis. Constr Build Mater, 2017, 140: 82 doi: 10.1016/j.conbuildmat.2017.02.103 [15] Yan A, Wu K R, Zhang D, et al. Influence of concrete composition on the characterization of fracture surface. Cem Concr Compos, 2003, 25(1): 153 doi: 10.1016/S0958-9465(02)00004-5 [16] Ince R Gör M, Alyamaç K E, et al. Multi-fractal scaling law for split strength of concrete cubes. Mag Concr Res, 2016, 68(3): 141 doi: 10.1680/macr.15.00070 [17] Konkol J, Prokopski G. Fracture toughness and fracture surfaces morphology of metakaolinite-modified concrete. Constr Build Mater, 2016, 123: 638 doi: 10.1016/j.conbuildmat.2016.07.025 [18] Cheng S, Jin N G, Tian Y, et al. New graphic method for quantitatively analyzing characteristic parameters of concrete cracks. J Zhejiang Univ Eng Sci, 2011, 45(6): 1062 doi: 10.3785/j.issn.1008-973X.2011.06.017成盛, 金南国, 田野, 等. 混凝土裂缝特征参数的图形化定量分析新方法. 浙江大学学报(工学版), 2011, 45(6):1062 doi: 10.3785/j.issn.1008-973X.2011.06.017 [19] Cao M S, Ren Q W. Damage detection of reinforced concrete structures based on fractal characteristic factor. China Civil Eng J, 2005, 38(12): 59 doi: 10.3321/j.issn:1000-131X.2005.12.010曹茂森, 任青文. 钢筋混凝土结构损伤检测的分形特征因子. 土木工程学报, 2005, 38(12):59 doi: 10.3321/j.issn:1000-131X.2005.12.010 [20] Jiao C J, Li X B, Cheng C M, et al. Dynamic damage constitutive relationship of high strength concrete based on fractal theory. Explos Shock Waves, 2018, 38(4): 925焦楚杰, 李习波, 程从密, 等. 基于分形理论的高强混凝土动态损伤本构关系. 爆炸与冲击, 2018, 38(4):925 [21] Chen W C, Shi H J, Chao Z Q. Developing nature of cracks in reinforced concrete beam bridge with fractal theory. J Chang'an Univ Nat Sci, 2003, 23(6): 44陈万春, 师晖军, 晁宗棋. 基于分形理论的钢筋混凝土梁式桥裂缝发育特征. 长安大学学报(自然科学版), 2003, 23(6):44 [22] Li Y Y, Rong X, Wang T C. Fractal characteristics of crack distribution of concrete beams with high strength stirrup. Eng Mech, 2009, 26(Suppl1): 72李艳艳, 戎贤, 王铁成. 高强箍筋混凝土梁裂缝分布的分形特征. 工程力学, 2009, 26(增刊1): 72 [23] Fan Y F, Zhou J, Feng X. Fractals in failure of corroded reinforced concrete members. Eng Mech, 2002, 19(5): 123 doi: 10.3969/j.issn.1000-4750.2002.05.023范颖芳, 周晶, 冯新. 受腐蚀钢筋混凝土构件破坏过程的分形行为. 工程力学, 2002, 19(5):123 doi: 10.3969/j.issn.1000-4750.2002.05.023 [24] Luan H Y, Fan Y F, Wang D W, et al. Study on the flexural behavior of the CFRP-reinforced concrete beam with fractal theory. Eng Mech, 2015, 32(4): 160栾海洋, 范颖芳, 王大为, 等. 基于分形理论的CFRP布增强混凝土梁抗弯性能研究. 工程力学, 2015, 32(4):160 [25] Ministry of Housing and Urban-Rural Development of the People’s Republic of China. GB50081—2019 Standard for Test Methods of Concrete Physical and Mechanical Properties. Beijing: China Architecture & Building Press, 2019中华人民共和国住房和城乡建设部. GB/T50081—2019混凝土物理力学性能试验方法标准. 北京: 中国建筑工业出版社, 2019 [26] Ministry of Housing and Urban-Rural Development of the People’s Republic of China. GB/T50152—2012 Standard for Test Method of Concrete Structures. Beijing: China Architecture & Building Press, 2012中华人民共和国住房和城乡建设部. GB/T50152—2012混凝土结构试验方法标准. 北京: 中国建筑工业出版社, 2012 [27] Mandelbrot B B. The Fractal Geometry of Nature. San Francisco: W. H. Freeman and Company, 1982 [28] Liu J H, Zhao L, Ji H G. Influence of initial damage on degradation and deterioration of concrete under sulfate attack. Chin J Eng, 2017, 39(8): 1278刘娟红, 赵力, 纪洪广. 初始损伤对混凝土硫酸盐腐蚀劣化性能的影响. 工程科学学报, 2017, 39(8):1278 [29] Wen Y, Xu H, Han D M. Study on the effect of lithium slag powders upon the sulfate corrosion resistance of cement material. Concrete, 2010(12): 90 doi: 10.3969/j.issn.1002-3550.2010.12.029温勇, 徐虎, 韩东明. 锂渣粉对水泥基材料抗硫酸盐侵蚀性能的影响. 混凝土, 2010(12):90 doi: 10.3969/j.issn.1002-3550.2010.12.029 -
点击查看大图
计量
- 文章访问数: 472
- HTML全文浏览量: 246
- PDF下载量: 15
- 被引次数: 0
