生活垃圾焚烧尾渣-次轻混凝土冻融劣化特性及微观机制

尚明刚; 张云升; 何忠茂; 乔宏霞; 冯琼; 薛翠真; 张宇

doi:10.13801/j.cnki.fhclxb.20221226.005

生活垃圾焚烧尾渣-次轻混凝土冻融劣化特性及微观机制

doi: 10.13801/j.cnki.fhclxb.20221226.005

尚明刚^{1, 2,},
张云升^{1, 2, ,},
何忠茂^{1, 3},
乔宏霞^{1, 2},
冯琼^{1, 2},
薛翠真^{1, 2},
张宇^{1, 2}

1.
兰州理工大学　土木工程学院，兰州 730050
2.
甘肃省先进土木工程材料工程研究中心，兰州 730050
3.
宁波大学　科学技术学院，宁波 315211

基金项目: 国家自然科学基金(U21 A20150；52208249；51878153；52008196；52178216)；甘肃省青年科技基金(22 JR5 RA288)；甘肃省绿色智慧公路关键技术研究与示范(21 ZD3 GA002)；甘肃省高校自然科学创新基金(2022 CYZC-25)；重庆市科技局重点项目(cstc2021 jscx-jbgs0029)

详细信息

通讯作者:
张云升，博士，教授，博士生导师，研究方向为土木工程材料　E-mail：zhangyunsheng2011@163.com

中图分类号: TU528
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出版历程
- 收稿日期: 2022-10-19
- 修回日期: 2022-11-17
- 录用日期: 2022-12-01
- 网络出版日期: 2022-12-27
- 刊出日期: 2023-09-15

Freeze-thaw deterioration characteristics and micro-mechanism of solid waste incineration tailings and specified density concrete

SHANG Minggang^{1, 2
,},
ZHANG Yunsheng^{1, 2
, ,},
HE Zhongmao^{1, 3},
QIAO Hongxia^{1, 2},
FENG Qiong^{1, 2},
XUE Cuizhen^{1, 2},
ZHANG Yu^{1, 2}

1.
School of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, China
2.
Engineering Research Center of Advanced Civil Engineering Materials, Lanzhou 730050, China
3.
College of Science & Technology, Ningbo University, Ningbo 315211, China

Funds: National Natural Science Foundation of China (U21 A20150; 52208249; 51878153; 52008196; 52178216); Youth Science and Technology Foundation of Gansu Province (22 JR5 RA288); Research and Demonstration of Key Technologies of Green and Smart Highways in Gansu Province (21 ZD3 GA002); Natural Science Innovation Foundation of Gansu Higher Education Institutions (2022 CYZC-25); Key Projects of Chongqing Science and Technology Bureau (cstc2021 jscx-jbgs0029)

摘要

摘要: 针对混凝土在冻融环境中耐久性差及传统改善方法引起的成本问题，提出利用城市生活垃圾焚烧尾渣作为轻骨料，制备能够提高抗冻性降低成本的次轻混凝土。以水胶比0.3，尾渣轻骨料掺量为25wt%、50wt%和75wt%的次轻混凝土为研究对象，模拟严寒地区冻融环境。利用剥落量、质量损失、强度损失、动弹性模量损失等宏观指标探究次轻混凝土冻融劣化规律，从次轻混凝土吸水饱和度、孔结构特征、骨-浆界面等方面揭示了冻融劣化机制，最后建立基于损伤力学理论的次轻混凝土损伤劣化模型。结果表明：冻融循环侵蚀对普通混凝土造成的耐久性损伤程度比次轻混凝土更严重，普通混凝土表面产生了更多的砂浆剥落。尾渣轻骨料的掺入能够显著改善混凝土的抗冻性能。在冻融循环侵蚀条件下掺入25wt%、50wt%和75wt%尾渣轻骨料的次轻混凝土耐久性能分别比普通混凝土至少提高了15.2%、30.3%和33.3%。次轻混凝土的内养护作用加强、有益孔的数量增加和骨-浆界面强度增大等改善了孔隙结构和界面特征，提高了冻融侵蚀耐久性能。基于损伤力学建立的次轻混凝土劣化模型的拟合度为0.97以上，能够较好地研究次轻混凝土冻融变化规律和损伤程度。
- 城市生活垃圾焚烧尾渣 /
- 次轻混凝土 /
- 冻融损伤 /
- 孔结构 /
- 水饱和度 /
- 劣化模型
Abstract: In view of the poor durability of concrete in freezing-thawing environment and the cost problems caused by traditional improvement methods, municipal solid waste incineration tailing was used as lightweight aggregate to prepare specified density concrete which can improve the frost resistance and reduce the cost. Taking the light-weight concretes with water-binder ratio 0.3 and tailing lightweight aggregate content of 25wt%, 50wt% and 75wt% as the research objects, the freeze-thaw environment in severe cold regions was simulated. The freeze-thaw deterioration law of specified density concrete was explored by macro-indices such as spalling amount, mass loss, strength loss and dynamic elastic modulus loss, and the freeze-thaw degradation was revealed from the aspects of water absorption saturation, pore structure characteristics and bone-grain interface of specified density concrete. Finally, a damage degradation model for light concrete was developed using the damage mechanics theory. According to the findings, the durability damage of ordinary concrete caused by freeze-thaw cycle erosion is more serious than that of specified density concrete, and more mortar peeling occurs on the surface of ordinary concrete. The frost resistance of concrete can be considerably increased by the inclusion of tailing lightweight aggregate. Under the condition of freeze-thaw cyclic corrosion, the durabilities of the specified density concretes mixed with 25wt%, 50wt% and 75wt% tailing lightweight aggregate are improved by 15.2%, 30.3% and 33.3% higher than that of ordinary concrete, respectively. The porosity structure and interface characteristics of the specified density concrete are improved by strengthening the internal curing function, increasing the number of beneficial pores and increasing the strength of the bone-slurry interface, and the freeze-thaw erosion durability is improved. The freeze-thaw change rule and damage degree of specified density concrete may be studied more thoroughly thanks to the specified density concrete degradation model's fitting degree based on damage mechanics, which is above 0.97.
- municipal solid waste incineration tailings /
- specified density concrete /
- freeze-thaw damage /
- pore structure /
- water saturation /
- deterioration model

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图 1 骨料形貌

Figure 1. Morphologies of aggregates

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图 2 焚烧尾渣的化学元素

Figure 2. Chemical elements of incineration tailings

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图 3 次轻混凝土冻融循环试验

Figure 3. Freezing thawing cycle test of specified density concrete

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图 4 次轻混凝土冻融循环过程

Figure 4. Freeze-thaw cycle of specified density concrete

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图 5 Airvoid 210硬化混凝土气孔结构测试

Figure 5. Pore structure test of Airvoid 210 hardened concrete

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图 6 次轻混凝土表面积剥蚀量与冻融循环次数n的关系

Figure 6. Relationship between the surface area erosion amount of specified density concrete and freeze-thaw cycles n

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图 7 次轻混凝土质量损失与冻融循环次数的关系

Figure 7. Relationship between mass loss of specified density concrete and freeze-thaw cycles

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图 8 次轻混凝土劣化参数与冻融循环次数的关系

Figure 8. Relationship between deterioration parameters of specified density concrete and freeze-thaw cycles

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图 9 次轻混凝土含水饱和度和冻融循环次数的关系

Figure 9. Relationship between water saturation and freeze-thaw cycles of specified density concrete

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图 10 冻融过程中水分迁移过程^[21]

Figure 10. Water transfer process during freezing and thawing^[21]

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图 11 次轻混凝土孔径分布和冻融循环次数的关系

Figure 11. Relationship between pore size distribution and freeze-thaw cycles of specified density concrete

MIP—Mercury intrusion method

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图 12 次轻混凝土不同孔径范围的孔隙体积和冻融循环次数的关系

Figure 12. Relationship between pore volume and freeze-thaw cycles of specified density concrete in different pore sizes

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图 13 次轻混凝土微界面形貌

Figure 13. Micro interface morphologies of specified density concrete

AFt—Ettringite; CH—Sodium hydroxide; CSH—Calcium silicate hydrate

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图 14 次轻混凝土骨料与砂浆界面纳米硬度

Figure 14. Nanohardness of interface between aggregate and mortar of specified density concrete

ITZ—Interfacial transition zone; TLA—Tailings lightweight aggregate

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图 15 次轻混凝土损伤变量$ {D_{f(n)}} $与冻融次数n的关系

Figure 15. Relationship between damage variable of specified density concrete and freeze-thaw cycles n

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图 16 次轻混凝土损伤变量$ {D_{E(n)}} $与冻融次数n的关系

Figure 16. Relationship between damage variable of specified density concrete and freeze-thaw cycles n

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表 1 骨料物理性能

Table 1. Physical properties of tailings light aggregate

Type	Maximum particle size/mm	Apparent density /(kg·m⁻³)	Bulk density /(kg·m⁻³)	Cylinder compression strength /MPa	Water saturation	Water absorption/%
Type	Maximum particle size/mm	Apparent density /(kg·m⁻³)	Bulk density /(kg·m⁻³)	Cylinder compression strength /MPa	Water saturation	1 h	24 h	72 h
FA	2.5	2697	1632	—	—	1.02	1.21	1.25
CA	10	2636	1597	8.2	0.05	0.89	1.07	1.10
TLFA	2.5	1833	960	—	—	9.37	14.25	14.37
TLCA	10	1884	1062	4.3	0.27	7.76	9.83	10.12

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表 2 次轻混凝土配合比

Table 2. Mix proportion of specified density concrete (kg/m³)

Group	C	FA	TLFA	CA	TLCA	TP	RES	W	Apparent dry density
OC	467	711	—	1160	—	83	Appropriate amount	165	2366
LAC		—	711	—	1160				1963
SDC-25		533.25	177.75	870	290				2203
SDC-50		355.5	355.5	580	580				2109
SDC-75		177.75	533.25	290	870				2056
Notes: Adjust the dosage of water reducer to keep the slump as (120±20) mm; Mixing water does not include pre-absorbed water. C—Cement; TP—Tail powder; RES—Water reducer; W—Water; OC—Ordinary concrete; LAC—Lightweight aggregate concrete; SDC-25, SDC-50 and SDC-75—Specified density concrete mixed with 25wt%, 50wt% and 75wt% incineration tailings.

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表 3 次轻混凝土冻融过程气孔参数变化

Table 3. Variation of porosity parameters of specified density concrete during freezing and thawing

Group	Stomatal parameter	n=0	n=100	n=200	n=300
OC	G/%	1.42	1.82	2.37	—
	$ \overline L $/μm	218	249	420	—
	B	1.94	1.56	1.37	—
SDC-25	G/%	1.68	1.86	2.14	2.49
	$ \overline L $/μm	174	192	257	—
	B	2.24	1.95	1.72	1.54
SDC-50	G/%	1.77	2.04	2.31	2.64
	$ \overline L $/μm	152	160	191	294
	B	2.57	2.25	1.93	1.76
SDC-75	G/%	1.94	2.17	2.63	2.95
	$ \overline L $/μm	124	129	137	172
	B	2.75	2.57	2.24	1.72
LAC	G/%	2.37	2.47	2.71	3.34
	$ \overline L $/μm	95	98	104	122
	B	3.25	2.82	2.34	1.95
Notes: G—Air content; $ \overline L $—Stomatal spacing coefficient; B—Fractal dimension of the pore.

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表 4 次轻混凝土抗压强度损失衰减系数和相关系数

Table 4. Attenuation coefficient and correlation coefficient of compressive strength loss of specified density concrete

Number	a	b	λ	Correlation coefficient
OC	−3.931	0.019	−2.812×10⁻⁵	0.97
SDC-25	−4.134	0.019	−3.301×10⁻⁶	0.98
SDC-50	−3.331	0.008	−2.518×10⁻⁶	0.97
SDC-75	−3.592	0.009	−5.434×10⁻⁶	0.99
LAC	−3.989	0.011	−7.731×10⁻⁵	0.99
Notes: a, b—Influence coefficient of strength of specified density concrete; λ—Damage coefficient of specified density concrete.

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表 5 次轻混凝土动弹性模量损失衰减系数和相关系数

Table 5. Attenuation coefficient and correlation coefficient of dynamic elastic modulus loss of specified density concrete

Number	a	λ	Correlation coefficient
OC	−0.629	−0.003	0.99
SDC-25	−0.145	−0.006	0.98
SDC-50	−0.186	−0.005	0.98
SDC-75	−0.106	−0.006	0.99
LAC	−0.085	−0.006	0.99

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