Experimental Study on Early Mechanical Properties of Recycled Aggregate Concrete after NaHCO3 Carbonation
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摘要: 为提高再生骨料混凝土(Recycled Aggregate Concrete,RAC)的固碳效率和力学性能,采用碳酸氢钠(NaHCO3)溶液对RAC进行浸泡养护和加速碳化,进行了立方体、棱柱体抗压试验和四点抗折试验,研究了三种碳化环境(自然碳化、碳化箱碳化、NaHCO3溶液碳化)和碳化龄期(3~28 d)对RAC早期力学性能的影响。结果表明,相较于自然养护,NaHCO3溶液碳化环境最大可以提高RAC的8.4%的早期抗压强度和12.4%的抗折强度,但会提高脆性;在21 d之前,NaHCO3溶液碳化后的RAC的早期抗压强度和强度发展略低于碳化箱碳化环境,但在28d时显著提高;碳化龄期对RAC的抗折强度影响不大,但在相同龄期时,NaHCO3溶液碳化后的抗折强度最高。通过热重分析发现,NaHCO3溶液碳化后RAC的碳酸钙含量比碳化箱碳化后高10.3%,比自然碳化高16.5%。最后,提出了NaHCO3溶液碳化后RAC的早期力学性能指标计算方法和本构方程。Abstract: In order to improve the carbon fixation efficiency and mechanical properties of recycled aggregate concrete (RAC), sodium bicarbonate (NaHCO3) solution was used for soaking curing and accelerated carbonation of RAC. Cube and prism compression tests and four point bending tests were conducted to study the effects of three carbonation environments (natural carbonation, carbonation box carbonation, NaHCO3 solution carbonation) and carbonation age (3-28 d) on the early mechanical properties of RAC. The results showed that compared to the natural environment, the carbonation environment of NaHCO3 solution can increase the early compressive strength and flexural strength of RAC by up to 8.4% and 12.4%, respectively, but it can also increase brittleness. Before 21 days, the early compressive strength and strength development of RAC after carbonation of NaHCO3 solution were slightly lower than those in the carbonation environment of the carbonation box, but significantly improved at 28 days; The carbonation age has little effect on the flexural strength of RAC, but at the same age, the flexural strength of NaHCO3 solution after carbonation is the highest. Through thermogravimetric analysis, it was found that the calcium carbonate content in RAC after carbonation of NaHCO3 solution was 10.3% higher than that after carbonation in the carbonation box, and 16.5% higher than that of natural carbonation. Finally, a calculation method and constitutive equation for the early mechanical properties of RAC after carbonation of NaHCO3 solution were proposed.
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表 1 试件设计参数
Table 1. Design parameters of specimens
Specimen number Carbonation environment Environmental parameters Curing
age T/dRAC-3d Natural carbonation Natural
environment3 RAC-7d 7 RAC-14d 14 RAC-21d 21 RAC-28d 28 RAC-CB-3d Carbonation
boxCarbon dioxide
concentration of
20%, temperature of
20℃, humidity
of 70%3 RAC-CB-7d 7 RAC-CB-14d 14 RAC-CB-21d 21 RAC-CB-28d 28 RAC-L10-3d NaHCO3
solution10 g/L 3 RAC-L10-7d 7 RAC-L10-14d 14 RAC-L10-21d 21 RAC-L10-28d 28 表 2 再生混凝土(RAC)配合比(kg/m3)
Table 2. Mix ratio of recycled aggregate concrete (RAC) (kg/m3)
Cement Recycled coarse aggregate Machine-made sand Water Mineral powder Water reducing agent Limestone 340 1060 735 145 70 9.45 40 表 3 再生粗骨料和机制砂的基本性能
Table 3. Basic properties of recycled coarse aggregate and machine-made sand
Types of aggregates Density/
(kg∙m−3)Bulk density/
(kg∙m−3)Loose packing
porosity/%Mud
content/%Stone powder
content/%Clay
lump/%Total content of needle
shaped particles/%Crushing
indexRecycled coarse aggregate 2720 — 45 0.7 — 0.1 8 9 Machine-made sand 2710 1610 41 — 5.5 0.8 — — 表 4 力学性能指标
Table 4. Mechanical performance indicators
Specimen number fcu/ MPa fck/ MPa ft/ MPa μ Measurement
valueAverage Measurement
valueAverage Measurement
valueAverage Measurement
valueAverage RAC-3d 50.1 51.3 27.9 26.5 4.96 5.11 1.21 1.42 53.0 25.8 5.36 1.59 50.7 25.7 5.02 1.46 RAC-7d 62.4 60.7 31.6 32.2 4.41 5.05 1.56 1.45 58.8 33.4 5.50 1.46 60.9 31.6 5.26 1.33 RAC-14d 64.9 64.9 31.8 34.8 5.05 5.10 1.44 1.41 64.9 39.2 3.99 1.36 54.2 33.5 5.21 1.43 RAC-21d 64.9 67.9 36.2 37.5 5.10 5.21 1.38 1.34 70.9 35.7 5.34 1.34 37.8 40.7 5.18 1.31 RAC-28d 71.4 72.1 38.6 39.0 5.22 5.18 1.33 1.26 72.4 36.1 5.16 1.36 72.7 42.3 4.96 1.10 RAC-CB-3d 59.5 53.3 27.8 28.4 3.79 3.99 1.44 1.40 49.7 27.8 2.64 1.46 50.8 29.7 4.19 1.3 RAC-CB-7d 61.6 62.8 34.6 31.6 3.99 4.22 1.28 1.39 65.2 30.2 4.35 1.33 61.7 30.1 4.33 1.56 RAC-CB-14d 72.3 71.5 34.6 34.6 3.45 3.67 1.42 1.37 60.7 35.7 3.89 1.31 70.7 33.6 3.68 1.39 RAC-CB-21d 69.5 71.8 38.9 37.0 4.29 4.44 1.18 1.27 71.4 34.1 4.62 1.39 74.6 37.9 4.43 1.25 RAC-CB-28d 73.7 73.2 40.1 40.0 4.44 4.12 1.32 1.20 74.5 37.7 3.86 1.33 71.3 42.2 4.07 1.23 RAC-L10-3d 52.8 52.0 26.3 26.6 4.63 4.33 1.47 1.29 50.6 27.6 4.95 1.20 52.6 25.9 3.43 1.42 RAC-L10-7d 58.1 62.4 22.5 31.7 5.81 5.03 1.14 1.36 66.4 31.7 4.84 1.46 62.8 31.8 4.44 1.28 RAC-L10-14d 64.1 66.0 38.8 35.3 4.88 4.80 1.26 1.29 67.4 32.8 5.05 1.22 66.4 34.2 4.48 1.28 RAC-L10-21d 72.1 68.6 34.1 36.9 5.86 5.86 1.19 1.25 63.9 38.7 5.94 1.18 69.8 37.8 5.80 1.09 RAC-L10-28d 79.5 78.2 38.4 40.8 4.94 5.26 1.32 1.15 63.9 40.9 5.33 1.33 76.9 43.0 5.54 1.23 Notes: fcu, fck, and f represent the compressive strength of cubes, the compressive strength of prisms, and the flexural strength, respectively. μ is the ductility coefficient, which is calculated through the compressive stress-strain curve of a prism using the "equal energy" method[25]. The data in the table is taken as the average of the same operating conditions. -
[1] IPCC AR5. Climate change 2014: Synthesis report: Contribution of working groups I, II and III to the fifth assessment report of the intergovernmental panel on climate change[R]. Geneva: Intergovernmental Panel on Climate Change, 2014. [2] 中国建筑节能协会. 2021中国建筑能耗与碳排放研究报告: 省级建筑碳达峰形势评估[R]. 北京: 中国建筑节能协会, 2021.China Association for Building Energy Efficiency 2021 China Building Energy Consumption and Carbon Emissions Research Report: Evaluation of Provincial Building Carbon Peak Situation [R] Beijing: China Building Energy Efficiency Association, 2021(in Chinese) [3] DIXIT M K, FERNÁNDEZ-SOLÍS J L, LAVY S, ET al. Need for an embodied energy measurement protocol for buildings: A review paper[J]. Renewable and Sustainable Energy Reviews, 2012, 16(6): 3730-3743. doi: 10.1016/j.rser.2012.03.021 [4] TAVAKOLI M, SOROUSHIAN P. Strengths of recycled aggregate concrete made using field demolished concrete as aggregate[J]. Aci Materials Journal, 1996, 93(2): 182-190. [5] SILVA R V, NEVES R, DE BRITO J, et al. Carbonation behaviour of recycled aggregate concrete[J]. Cement and Concrete Composites, 2015, 62: 22-32. doi: 10.1016/j.cemconcomp.2015.04.017 [6] STEINOUR H H. Some effects of carbon dioxide on mortars and concrete discussion[J]. Journal of American Concrete Institute, 1959, 30: 905-907. [7] POSSAN E, FELIX F E, THOMAZ A W. CO2 uptake by carbonation of concrete during life cycle of building structures[J]. Journal of Building Pathology and Rehabilitation, 2016, 1(1): 7. doi: 10.1007/s41024-016-0010-9 [8] WEBER AP. Focus Group S-6: Using plants for carbon sequestration[M]. White Paper and Scientific Basis of the Strategic Research Agenda. 2021, 111. [9] MONKMAN S, MACDONALD M, HOOTON D R, et al. Properties and durability of concrete produced using CO2 as an accelerating admixture[J]. Cement and Concrete Composites, 2016, 74: 218-224. doi: 10.1016/j.cemconcomp.2016.10.007 [10] MONKMAN S, MACDONALD M. Carbon dioxide upcycling into industrially produced concrete blocks[J]. Construction and Building Materials, 2016, 124: 127-132. doi: 10.1016/j.conbuildmat.2016.07.046 [11] R. NIVEN, G. S, MONKMAN, D. FORGERON. Carbon dioxide treatment of concrete upstream from product mold[D]. Patent No. US8845940B2 (2014). [12] ZHOU L, WEINA M. Fundamental understanding of carbonation curing and durability of carbonation-cured cement-based composites: A review[J]. Journal of CO2 Utilization, 2021, 44: 101428. doi: 10.1016/j.jcou.2020.101428 [13] MOON E, CHOI C Y. Carbon dioxide fixation via accelerated carbonation of cement-based materials: Potential for construction materials applications[J]. Construction and Building Materials, 2019, 199: 676-687. doi: 10.1016/j.conbuildmat.2018.12.078 [14] LACKNER K S. A Guide to CO2 Sequestration[J]. Science, 2003, 300(5626): 1677-1679. doi: 10.1126/science.1079033 [15] MAROTO-VALER M M, FAUTH D J, KUCHTA M E, et al. Activation of magnesium rich minerals as carbonation feedstock materials for CO2 sequestration[J]. Fuel Processing Technology, 2005, 86(14-15): 1627-1645. doi: 10.1016/j.fuproc.2005.01.017 [16] BAO L, PINGPING H, JIANHUI L, et al. Microstructure of Portland cement paste subjected to different CO2 concentrations and further water curing[J]. Journal of CO2 Utilization, 2021, 53: 101714. doi: 10.1016/j.jcou.2021.101714 [17] LI Y, ZHANG S, WANG R, et al. Effects of carbonation treatment on the crushing characteristics of recycled coarse aggregates[J]. Construction and Building Materials, 2019, 201: 408-420. doi: 10.1016/j.conbuildmat.2018.12.158 [18] WU J, ZHANG Y, ZHU P, et al. Mechanical Properties and ITZ Microstructure of Recycled Aggregate Concrete Using Carbonated Recycled Coarse Aggregate[J]. Journal of Wuhan University of Technology-Mater. Sci. Ed., 2018, 33(3): 648-653. doi: 10.1007/s11595-018-1873-1 [19] ZHAN J B, XUAN X D, POON S C, et al. Effect of curing parameters on CO2 curing of concrete blocks containing recycled aggregates[J]. Cement and Concrete Composites, 2016, 71: 122-130. doi: 10.1016/j.cemconcomp.2016.05.002 [20] KASHEF HAGHIGHI S, SHAO Y, GHOSHAL S. Mathematical modeling of CO2 uptake by concrete during accelerated carbonation curing[J]. Cement and Concrete Research, 2015, 67: 1-10. doi: 10.1016/j.cemconres.2014.07.020 [21] HASELBACH L M, THOMLE J N. An alternative mechanism for accelerated carbon sequestration in concrete[J]. Sustainable Cities and Society, 2014, 12: 25-30. doi: 10.1016/j.scs.2014.01.001 [22] JANG J G, KIM H J, PARK S M, et al. The Influence of Sodium Hydrogen Carbonate On the Hydration of Cement[J]. Construction and Building Materials, 2015, 94: 746-749. doi: 10.1016/j.conbuildmat.2015.07.121 [23] GB/T 14685-2022. 建设用卵石、碎石[S]. 北京: 中国计划出版社, 2022.GB/T 14685-2022. Pebble and crushed stone for construction [S]. Beijing: China Planning Press, 2022(in Chinese) [24] CHEN Z , XU R, LIANG H. Residual mechanical properties and numerical analysis of recycled pebble aggregate concrete after high temperature exposure and cooled by fire hydrant[J]. Construction and Building Materials, 2022, 319: 126137. [25] ZHENLEI Z , JIANG D , MEILUN S . Quantitative Analysis of the Calcium Hydroxide Content of EVA-Modified Cement Paste Based on TG-DSC in a Dual Atmosphere[J]. Materials, 2022, 15(7): 2660. [26] WANG C , CHAZALLON C , BRAYMAND S , et al. Thermogravimetric analysis (TGA) for characterization of self-cementation of recycled concrete aggregates in pavement[J]. Thermochimica Acta, 2024, 733: 179680. [27] CEB - FIP. Model code for concrete structure: CEB - FIP International Recommendations[Z]. Paris, 1990. [28] JGJ/T15-2021, 早期推定混凝土强度试验方法标准[S]. 北京: 中国建筑工业出版社, 2008.JGJ/T15-2021, Standard for test method of early estimating compressive strength of concrete [S] Beijing: China Architecture&Building Press, 2008(in Chinese) [29] 朱伯芳. 大体积混凝土温度应力与温度控制[M]. 北京: 中国电力出版社, 1999.ZHU Bofang Temperature stress and temperature control of large volume concrete [M]. Beijing: China Electric Power Press, 1999(in Chinese) [30] GB 50010-2010. 钢筋混凝土结构设计规范[S]. 北京: 中国计划出版社, 2010.GB 50010-2010. Code for Design of Reinforced Concrete Structures [S]. Beijing: China Planning Press, 2010(in Chinese) [31] 肖建庄, 唐宇翔, 张凯建, 等. 再生粗骨料混凝土应力-应变关系[J]. 工程力学, 2024, 41(2): 43-55.XIAO Jianzhuang, TANG Yuxiang, ZHANG Kaijian, et al. Stress-strain relationship of recycled coarse aggregate concrete[J]. Engineering Mechanics, 2024, 41(2): 43-55(in Chinese)
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