纳米SiO<sub>2</sub>复合碳化全再生骨料混凝土力学特性及强化机制

张美香; 丁亚红; 杨小林; 孙博

纳米SiO₂复合碳化全再生骨料混凝土力学特性及强化机制

张美香^{1, 2},
丁亚红^1, ,,
杨小林¹,
孙博^{1, 2}

1.
河南理工大学　土木工程学院, 焦作 454000
2.
新余学院建筑工程学院, 新余 338000

基金项目: 国家自然科学基金 (U1904188)

详细信息

通讯作者:
丁亚红，博士，教授，博士生导师，研究方向为建筑固废资源化利用、高性能混凝土等　E-mail: dingyahong@hpu.edu.cn

中图分类号: TU528.59
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- 文章访问数: 103
- HTML全文浏览量: 53
- 被引次数: 0
出版历程
- 收稿日期: 2024-04-19
- 修回日期: 2024-05-10
- 录用日期: 2024-05-17
- 网络出版日期: 2024-06-14

Mechanical properties and strengthening mechanism of fully recycled aggregate concrete prepared by nano-SiO₂ composite carbonated recycled aggregates

ZHANG Meixiang^{1, 2},
DING Yahong^{1
, ,},
YANG Xiaolin¹,
SUN Bo^{1, 2}

1.
School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454000, China
2.
School of Architectural Engineering, Xinyu University, Xinyu 338000, China

Funds: National Natural Science Foundation of China (U1904188)

摘要

摘要: 为探究碳化改性骨料对全再生骨料混凝土(FRAC)力学特性的影响规律，采用纳米SiO₂复合碳化改性再生骨料并制备FRAC，测试了其抗压性能、劈裂抗拉性能及抗折性能等宏观力学特性，采用纳米压痕测试了其微观力学性能，并结合SEM微观测试，揭示了碳化全再生骨料混凝土(CFRAC)多重界面强化机制。结果表明，NS复合碳化实现了再生粗骨料高效碳化改性，CFRAC力学特性均得到显著提高，其中抗压强度、劈裂抗拉强度及抗折强度最大提高幅度分别为33.12%、48.73%及24.53%；CFRAC各相平均弹性模量及显微硬度显著提高，最大提高幅度分别为171.05%、62.96%，其中旧砂浆及骨料-旧砂浆界面过渡区(ITZ₁)微观力学性能提高幅度最显著；通过“骨料墙效应”及“ITZ碳化强化效应”揭示了CFRAC强化机制。成果为再生骨料品质提升研究及FRAC推广应用提供理论支撑。
- 全再生骨料混凝土 /
- 纳米SiO₂ /
- 复合碳化 /
- 多尺度力学特性 /
- 强化机制
Abstract: To explore the influence of carbonated aggregate on the mechanical properties of fully recycled aggregate concrete (FRAC), FRAC using NS composite carbonated recycled aggregate was prepared in this paper. Macroscopic mechanical properties of FRAC including compressive strength, splitting tensile strength and flexural strength were tested, the microscopic mechanical properties of FRAC were tested by nano-indentation. Combined with SEM microscopic test, the multiple interface strengthening mechanism of carbonated fully recycled aggregate concrete (CFRAC) was revealed. The results show that NS composite carbonation can achieve efficient carbonation modification of recycled aggregate, and the mechanical properties of CFRAC are significantly improved. The maximum increase of compressive strength, splitting tensile strength and flexural strength are 33.12%, 48.73% and 24.53%, respectively. The average elastic modulus and micro-hardness of CFRAC are significantly improved, and the maximum increase are 171.05% and 62.96%, respectively. The micro-mechanical properties of old mortar and aggregate-old mortar interface transition zone (ITZ₁) are increased most significantly. The strengthening mechanism of CFRAC is revealed by ' aggregate wall effect ' and ' ITZ carbonation strengthening effect '. The results can provide theoretical support for the research on the quality improvement of recycled aggregate and application of FRAC.
- fully recycled aggregate concrete /
- nano-SiO₂ /
- composite carbonation /
- multi-scale mechanical properties /
- strengthening mechanism

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图 1 河砂及再生细骨料颗粒级配曲线

Figure 1. Particle size distribution curve for sand and recycled fine aggregate

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图 2 碳化前后再生粗骨料酚酞喷涂

Figure 2. Phenolphthalein spraying of recycled coarse aggregate before and after carbonation

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图 3 FRAC100与CFRAC100多重界面微观力学测试

Figure 3. Micromechanical test of multiple interfaces for FRAC100 and CFRAC100

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图 4 荷载-压痕深度典型曲线

Figure 4. Typical curve of load-indentation depth

P_max represents the maximum load of the indenter, h_f represents the indentation depth after unloading, h_c represents the contact depth, h_max represents the maximum indentation depth, S represents the initial slope of the load-indentation depth unloading curve

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图 5 FRAC宏观力学特性

Figure 5. Macroscopic mechanical properties of FRAC

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图 6 FRAC荷载-压痕深度曲线

Figure 6. Curve of load-indentation depth of FRAC

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图 7 FRAC各相弹性模量(GPa)

Figure 7. Each phase elastic modulus of FRAC (GPa)

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图 8 FRAC各相显微硬度(GPa)

Figure 8. Each phase microhardness of FRAC (GPa)

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图 9 FRAC ITZ微观形貌SEM图像

Figure 9. SEM images of ITZ for FRAC

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图 10 NS复合碳化FRAC强化机制模型

Figure 10. Strengthening mechanism model of NS composite carbonated FRAC

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表 1 碳化前后再生骨料物理特性

Table 1. Physical properties of recycled aggregate before and after carbonation

Aggregate type	Water absorption/%	Crush value/%	Apparent density/(kg·m⁻³)
Natural aggregate	0.6	8.1	2760
Sand	0.5	10.2	2591
Recycled fine aggregate	9.0	25.93	2453
Carbonated recycled fine aggregate	6.84(↓24%)	23.40(↓9.76%)	2512(↑2.41%)
Recycled coarse aggregate	4.71	16.2	2648
Carbonated recycled coarse aggregate	3.63(↓22.93%)	15.60(↓3.70%)	2694(↑1.74%)

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表 2 试验方案

Table 2. Test scheme

Series	Recycled coarse aggregate replacement percentage	Recycled fine aggregate replacement percentage	Carbonation	Number of test blocks ( blocks )
NA	0	0	—	3
RC	100%	0、30%、50%、70%、100%	No	15
RF	0、30%、50%、70%、100%	100%	No	15
CRC	100%	0、30%、50%、70%、100%	Yes	15
CRF	0、30%、50%、70%、100%	100%	Yes	15
Notes: NA represents concrete prepared by natural aggregates, RC represents fully recycled coarse aggregate concrete, RF represents fully recycled fine aggregate concrete, CRC represents carbonated fully recycled coarse aggregate concrete, CRF represents carbonated fully recycled fine aggregate concrete.

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表 3 全再生骨料混凝土(FRAC)配合比(kg/m³)

Table 3. Mix proportion of fully recycled aggregate concrete (FRAC) (kg/m³)

Series	Natural aggregate	Recycled coarse aggregate	Sand	Recycled fine aggregate	Water	Cement
NA	1220.36	0	703.38	0.00	167.31	371.80
RC0	0	579.96	1002.30	0.00	232.68	517.07
RC30	0	722.70	640.98	260.04	221.14	491.43
RC50	0	823.16	427.36	404.55	213.02	473.38
RC70	0	928.20	237.29	524.13	204.53	454.51
RC100	0	1095.05	0.00	652.91	191.04	424.54
RF0	1521.78	0.00	0	475.97	98.97	219.93
RF30	1065.41	445.05	0	475.97	130.81	290.68
RF50	761.94	742.93	0	482.18	149.82	332.92
RF70	403.47	918.13	0	554.58	167.30	371.77
Notes: In RC0, RC represents fully recycled coarse aggregate concrete, and 0 represents the replacement rate of recycled fine aggregate is 0%. In RF0, RF represents fully recycled fine aggregate concrete, and 0 represents the replacement rate of recycled coarse aggregate is 0%.

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