Damage analysis of meso-scale recycled aggregate thermal insulation concrete based on X-CT after high temperature
-
摘要: 火灾的发生往往会导致混凝土材料微细观结构的损伤劣化，体现在水化物分解、孔隙结构粗化、热开裂和水汽压力升高诱致开裂等，继而导致材料宏观力学性能及耐久性的下降。轻质高强、内部多孔、高热稳定的玻化微珠(GHB)的细观调控功能可实现混凝土耐高温性能的提升。为了研究受高温作用的再生保温混凝土(RATIC)内部细观结构及裂纹变化特征，本研究首先对高温作用后的RATIC开展了立方体抗压强度试验和CT扫描试验，之后利用基于改进的自适应阈值法和区域生长法的图像分割算法，建立了基于真实结构的RATIC细观模型，分析了不同GHB及再生骨料(RCA)掺量的RATIC试件随温度变化时其内部微裂纹的孕育、萌生、发展及贯通过程。并对RATIC破坏形态与CT结果进行了对比分析。研究结果表明：GHB对裂缝的延伸有显著阻断作用，为蒸汽压提供了释放通道，缓解了砂浆区域、孔隙边界处的开裂，减缓了热量的传播，提升了混凝土抗热致损伤性能。Abstract: The occurrence of fire often leads to the damage and deterioration of the micro-meso-structure of concrete materials, which is reflected in the decomposition of hydrates, the coarsening of pore structure, thermal cracking, and the cracking induced by the increase of water vapor pressure, which in turn lead to the decline of the macroscopic mechanical properties and durability of materials. The meso-regulatory function of the lightweight, high-strength, internally porous, and highly thermally stable glazed hollow beads (GHB) can improve the high-temperature resistance of concrete. In order to study the characteristics of the internal meso-scale structure and crack evolution of recycled aggregate thermal insulation concrete (RATIC) subjected to high temperature, the cube compressive strength test and CT test were firstly carried out on RATIC after high temperature. Then the RATIC meso-scale model was established based on the real structure by the improved image segmentation algorithm based on the adaptive threshold method and the regional growth method (IISA). The process of initiation, development and coalescence of internal microcracks in RATIC with different GHB and recycled coarse aggregate (RCA) contents with temperature change were studied. Furthermore, the failure patterns of RATIC under simulated conditions and CT re-sults were analyzed by contrast, which show that GHB can significantly block the extension of cracks, provide a release channel for vapor pressure, alleviate cracks in the mortar area and pore boundaries, slow down the spread of heat in the concrete. It has a positive effect on improving the heat-induced damage resistance of concrete.
-
图 3 不同温度下RATIC中截面CT扫描图像
Figure 3. CT scanning images of RATIC at different temperatures
图 4 蒸汽压作用机制
Figure 4. Mechanism of vapor pressure
σvp—Steam pressure stress; ft—Axial tension strength
图 5 不同温度下RATIC试件的残余抗压强度与GHB含量 (a) 和RCA取代率 (b) 的关系
Figure 5. Residual compressive strength of RATIC at elevated temperatures varying with GHB content (a) and RCA content (b)
图 6 不同温度下RATIC试件的相对残余抗压强度与GHB含量(a)和RCA取代率(b)的关系
Figure 6. Relative residual compressive strength of RATIC at elevated temperatures varying with GHB content (a) and RCA content (b)
图 7 灰度拉伸前后的RATIC CT图像灰度直方图
Figure 7. Gray histograms of RATIC CT images before and after gray expanding
图 8 改进的基于阈值法和区域生长法的图像分割方法算法实现图
Figure 8. Algorithm flow chart of the improved threshold segmentation method based on threshold method and region growing method
图 10 不同时间下受火阶段和自然冷却阶段的RATIC温度场分布
Figure 10. Temperature field distribution of RATIC in the fire stage and the natural cooling stage
图 11 不同受火时间下RATIC试件的温度应力分布(600℃)
Figure 11. Temperature stress distributions of RATIC specimens at different fire time (600℃)
图 12 不同受火温度下RATIC全截面达到受火温度和降温到室温所需的时间
Figure 12. Time required for the full section of RATIC to reach the fire temperature and cool down to room temperature at different temperatures
图 13 不同受火温度下RATIC的最大温度应力随时间的变化
Figure 13. Maximum temperature stresses of RATIC specimens change with time at different fire temperatures
表 1 骨料基本性能
Table 1. Properties of aggregates
Material Density/(g·cm−3) Percentage/% Bulk density Apparent density Water absorption at 24 h Water content Crushing index Loss of mass Sediment percentage Sand 1.48 2.67 3.70 0.80 — 5.8 2.57 NCA 1.45 2.65 2.40 1.13 9.1 4.7 0.62 RCA 1.16 2.48 5.35 1.56 14.6 8.9 0.58 Notes: NCA—Natural coarse aggregate; RCA—Recycled coarse aggregate. 
下载: 导出CSV
表 2 GHB基本性能
Table 2. Material properties of GHB
Material Bulk density/
(kg·m−3)Thermal conductivity/
(W·(m·K)−1)Cylindrical compress
strength/kPaPercentage/% Water absorption
at 24 hVolume floating
rateSurface vitrified
close cell contentGHB 130 0.03 23 207 90 89
下载: 导出CSV
表 3 再生保温混凝土(RATIC)配合比
Table 3. Mixture proportions of recycled aggregate thermal insulation concrete (RATIC)
Group Mix
detailRatio Cement content/
(kg·m−3)Water/
binderSand/
cementRecycled aggregate/
cementNatural aggregate/
cementWater reducer/
%Silica
fume/
%Glazed hollow
bead/concrete
mixture mass/%Group 1 R100-G0 0.52 1.07 2.40 0 1.18 7.44 0 484 R100-G70 0.52 1.07 2.40 0 1.18 7.44 4.89 484 R100-G100 0.52 1.07 2.40 0 1.18 7.44 6.84 484 Group 2 R0-G100 0.52 1.07 0 2.50 1.18 7.44 6.72 484 R50-G100 0.52 1.07 1.20 1.25 1.18 7.44 6.78 484 R100-G100 0.52 1.07 2.40 0 1.18 7.44 6.84 484 Notes: R—Recycled coarse aggregate; G—Glazed hollow beads; In Rx-Gy, x—Volume substitution rate; y—Volume content.
下载: 导出CSV
表 4 常温下(20℃) RATIC各细观组分的热工参数和力学参数
Table 4. Thermal parameters and mechanical parameters of meso-scale constituents of RATIC at room temperature (20℃)
Constitution ρ/(kg·m−3) k/(W·(m·K)−1) c/(J·(kg·K)−1) α/℃−1 fc/MPa ft/MPa Ec/MPa P NCA 2 600 3.100 798[29] 7.00×10−6 100.5 10.0 6.50×104 0.15 N-CPM 2 350 1.900[30] 813[28] 1.45×10−5 40.0[30] 4.0[30] 3.00×104 0.22 O-CPM 2 300 1.950 850 1.50×10−5 36.0 3.6 2.85×104 0.22 N-ITZ 2 300 2.100 906[30] 2.00×10−5 28.0 2.8 2.10×104 0.20 O-ITZ 2 280 2.000 860 1.95×10−5 25.0 2.5 2.00×104 0.20 GHB 140 0.032 1 050 3.00×10−5 — — 2.40×104 0.23 Notes: ρ—Density; k—Thermal conductivity; c—Specific heat; α—Coefficient of thermal expansion; fc —Compressive strength; ft —Tensile strength; Ec— Elasticity modulus; P—Poisson's ratio; N-CPM—New cement paste and mortar; O-CPM—Old cement paste and mortar;
N-ITZ—New interface transition zone; O-ITZ—Old interface transition zone.
下载: 导出CSV
-
[1] CHANG Y, WILKINSON S, POTANGAROA R, et al. Managing resources in disaster recovery projects[J]. Engineering, Construction and Architectural Management,2012,19(5):557-580. [2] CUI S, LIU P, SU J, et al. Experimental study on mechanical and microstructural properties of cement-based paste for shotcrete use in high-temperature geothermal environment[J]. Construction and Building Materials,2018,174:603-612. doi: 10.1016/j.conbuildmat.2018.04.106 [3] HAY R, DUNG N T, LESIMPLE A, et al. Mechanical and microstructural changes in reactive magnesium oxide cement-based concrete mixes subjected to high temperatures[J]. Cement and Concrete Composites,2021,118:103955. doi: 10.1016/j.cemconcomp.2021.103955 [4] KODUR V K R, DWAIKAT M B. Effect of fire induced restraint on fire resistance of reinforced concrete beams[J]. Journal of Structural Fire Engineering,2010,1(2):73-88. doi: 10.1260/2040-2317.1.2.73 [5] RYU E, KIM H, CHUN Y, et al. Effect of heated areas on thermal response and structural behavior of reinforced concrete walls exposed to fire[J]. Engineering Structures,2020,207:110165. doi: 10.1016/j.engstruct.2020.110165 [6] TU J, WANG Y, ZHOU M, et al. Heat transfer mechanism of glazed hollow bead insulation concrete[J]. Journal of Building Engineering,2021,40(2):102629. [7] WANG W, ZHAO L, LIU Y, et al. Mechanical properties and stress-strain relationship in axial compression for concrete with added glazed hollow beads and construction waste[J]. Construction and Building Materials,2014,71:425-434. doi: 10.1016/j.conbuildmat.2014.05.005 [8] ZHANG Y, MA G, WANG Z, et al. Shear behavior of reinforced glazed hollow bead insulation concrete beams[J]. Construction and Building Materials, 2018, 174: 81-95. [9] ZHANG Y, LI B B, LI Z, et al. Seismic performance of interior beam-column joints in reinforced glazed hollow bead insulation concrete frames[J]. Engineering Structures,2021,228:111494. doi: 10.1016/j.engstruct.2020.111494 [10] LI Y, ZHANG D. Effect of lateral restraint and inclusion of polypropylene and steel fibers on spalling behavior, pore pressure, and thermal stress in ultra-high-performance concrete (UHPC) at elevated temperature[J]. Construction and Building Materials,2021,271:121879. doi: 10.1016/j.conbuildmat.2020.121879 [11] FU Y, LI L. Study on mechanism of thermal spalling in concrete exposed to elevated temperatures[J]. Materials and Structures,2011,44(1):361-376. doi: 10.1617/s11527-010-9632-6 [12] 张科, 黄海东. 基于简化分析方法的混凝土高温爆裂数值模拟[J]. 防灾减灾工程学报, 2020, 40(2):268-278.ZHANG K, HUANG H D. Numerical simulation on high temperature cracking of concrete based on simplified analysis method[J]. Journal of Disaster Prevention and Mitigation Engineering,2020,40(2):268-278(in Chinese). [13] HENRY M, DARMA I S, SUGIYAMA T. Analysis of the effect of heating and re-curing on the microstructure of high-strength concrete using X-ray CT[J]. Construction and Building Materials,2014,67:37-46. doi: 10.1016/j.conbuildmat.2013.11.007 [14] 赵昕, 徐世烺, 李庆华. 高温后超高韧性水泥基复合材料冲击破碎分形特征分析[J]. 土木工程学报, 2019, 52(2):44-55.ZHAO X, XU S L, LI Q H. Fractal characteristics of fire-damaged ultra high toughness cementitious composite after impact loading[J]. China Civil Engineering Journal,2019,52(2):44-55(in Chinese). [15] 杜红秀, 樊亚男. 基于X-CT的C60高性能混凝土高温细观结构损伤研究[J]. 建筑材料学报, 2020, 23(1):210-215. doi: 10.3969/j.issn.1007-9629.2020.01.031DU H X, FAN Y N. Meso-structure damage of C60 high performance concrete at high temperature based on X-CT[J]. Journal of Building Materials,2020,23(1):210-215(in Chinese). doi: 10.3969/j.issn.1007-9629.2020.01.031 [16] XU S, SHEN L, WANG J, et al. High temperature mechanical performance and micro interfacial adhesive failure of textile reinforced concrete thin-plate[J]. Journal of Zhejiang University Science A,2014,15(1):31-38. doi: 10.1631/jzus.A1300150 [17] FARES H S, NOUMOWE A, COUSTURE A. High temperature behaviour of self-consolidating concrete: microstructure and physicochemical properties[J]. Cement and Concrete Research,2010,40:488-496. doi: 10.1016/j.cemconres.2009.10.006 [18] LIU X, YUAN Y, YE G, et al. Study on pore structure evolution of high performance concrete with elevated temperatures[J]. Journal of Tongji University: Natural Science,2008,36:1473-1478. [19] LIU Y X, HU J G, HOU S. SEM analysis of concrete heated on varied temperature[J]. Fire Safety Science, 2005, 15: 80-83. [20] KALIFA P, MENNETEAU F D, QUENARD D. Spalling and pore pressure in HPC at high temperatures[J]. Cement and Concrete Research,2000,30(12):1915-1927. doi: 10.1016/S0008-8846(00)00384-7 [21] BAŽANT Z P. Analysis of pore pressure, thermal stresses and fracture in rapidly heated concrete [A]. Proceedings of international workshop on fire performance of high-strength concrete (NIST Special Publication 919)[C]. Gaithersburg: NIST, 1997: 155-164. [22] 朋改非, 黄艳竹, 张九峰. 骨料缺陷对再生混凝土力学性能的影响[J]. 建筑材料学报, 2012, 15(1):80-84. doi: 10.3969/j.issn.1007-9629.2012.01.015PENG G F, HUANG Y Z, ZHANG J F. Influence of defects in recycled aggregate on mechanical properties of recycled aggregate concrete[J]. Journal of Building Materials,2012,15(1):80-84(in Chinese). doi: 10.3969/j.issn.1007-9629.2012.01.015 [23] LIU Y, JI H, ZHANG J, et al. Mechanical properties of thermal insulation concrete with recycled coarse aggregates after elevated temperature exposure[J]. Materials Testing,2016,58(7-8):669-677. doi: 10.3139/120.110902 [24] 刘利先, 吕龙, 刘铮, 等. 高温下及高温后混凝土的力学性能研究[J]. 建筑科学, 2005(3):16-20. doi: 10.3969/j.issn.1002-8528.2005.03.004LIU L X, LV L, LIU Z, et al. Investigation on mechanical behaviors of concrete at and after elevated temperature[J]. Building Science,2005(3):16-20(in Chinese). doi: 10.3969/j.issn.1002-8528.2005.03.004 [25] RASHAD A M, BAI Y, BASHEER P A M, et al. Chemical and mechanical stability of sodium sulfate activated slag after exposure to elevated temperature[J]. Cement of Concrete Research,2012,42(2):333-343. doi: 10.1016/j.cemconres.2011.10.007 [26] BASTAMI M, BAGHBADRANI M, ASLANI F. Performance of nano-Silica modified high strength concrete at elevated temperatures[J]. Construction and Building Materials,2014,68:402-408. doi: 10.1016/j.conbuildmat.2014.06.026 [27] VOSTEEN H D, SCHELLSCHMIDT R. Influence of temperature on thermal conductivity, thermal capacity and thermal diffusivity for different types of rock[J]. Physics and Chemistry of the Earth Parts A/B/C,2003,28(9-11):499-509. doi: 10.1016/S1474-7065(03)00069-X [28] C̆ERNÝ R, MADĔRA J, PODĔBRADSKA J, et al. The effect of compressive stress on thermal and hygric properties of Portland cement mortar in wide temperature and moisture ranges[J]. Cement & Concrete Research,2000,30(8):1267-1276. [29] JIN L, HAO H M, ZHANG R B, et al. Determination of the effect of elevated temperatures on dynamic compressive properties of heterogeneous concrete: A meso-scale numerical study[J]. Construction and Building Materials,2018,188:685-694. doi: 10.1016/j.conbuildmat.2018.08.090 [30] JIN L, ZHANG R B, DU X L. Characterisation of temperature- dependent heat conduction in heterogeneous concrete[J]. Magazine of Concrete Research,2017,70(7-8):325-339. [31] BANGI M R, HORIGUCHI T. Pore pressure development in hybrid fibre-reinforced high strength concrete at elevated temperatures[J]. Cement and Concrete Research,2011,41(11):1150-1156. doi: 10.1016/j.cemconres.2011.07.001 [32] SPRINGENSCHMID R. Prevention of thermal cracking in concrete at early ages[M]. Boca Raton: CRC Press, 1998. -
下载:
点击查看大图
计量
- 文章访问数: 1215
- HTML全文浏览量: 522
- PDF下载量: 86
- 被引次数: 0
