多因素协同强化煤矸石粗骨料混凝土断裂性能试验研究

李宝地; 崔正龙; 高明浩

多因素协同强化煤矸石粗骨料混凝土断裂性能试验研究

辽宁工程技术大学　土木工程学院, 阜新 123000

基金项目: 辽宁省教育厅基金 (LJ2019JL023)；辽宁工程技术大学学科创新团队资助项目(LNTU20TD-26)

详细信息

通讯作者:
崔正龙，博士，副教授，硕士生导师，研究方向为再生混凝土材料　E-mail: cui0815@126.com

中图分类号: TU528.79；TB332
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出版历程
- 收稿日期: 2024-08-20
- 修回日期: 2024-10-22
- 录用日期: 2024-10-27
- 网络出版日期: 2024-11-08

Experimental study on fracture performance of coal gangue coarse aggregate concrete reinforced by multi-factor synergy

School of Civil Engineering, Liaoning Technical University, Fuxin 123000, China

Funds: Liaoning Provincial Education Department Fund (LJ2019JL023); Liaoning Technical University Discipline Innovation Team Funding Project (LNTU20TD-26)

摘要

摘要: 煤矸石资源化利用符合我国绿色发展理念，但煤矸石骨料强度低、吸水率大等原因导致煤矸石混凝土的实际工程应用受到限制。为了研究不同骨料强化方法对煤矸石混凝土的损伤和断裂特性的影响，本文通过水泥浆包裹法(GC)、水玻璃浸泡法(SC)、水泥浆-碳化协同强化法(GT)和水泥浆-水玻璃协同强化法(GS)四种强化处理方法对煤矸石骨料进行强化处理。以碎石混凝土(NC)和无强化的煤矸石混凝土(MC)作为对照组，结合数字图像相关(DIC)技术，对强化后的煤矸石混凝土断裂性能进行了试验研究。结果表明：四种强化方式均可以延缓裂缝的产生与发展，提高煤矸石混凝土的抗断裂能力，其中协同强化效果最为明显，GS、GT组与MC组相比，试件的起裂韧度与失稳韧度分别提高了9.09%、13.64%和25.0%、36.21%；断裂能分别提高了12.63%、17.94%。GT组断裂性能提高幅度最大，与NC组相当。这为煤矸石混凝土的实际工程应用提供了理论依据。
- 煤矸石 /
- 混凝土 /
- 骨料强化 /
- 数字散斑 /
- 断裂性能
Abstract: The resource utilization of coal gangue is in line with the concept of green development in China, but the practical engineering application of coal gangue concrete is limited due to the low strength and high water absorption of coal gangue aggregate. In order to study the effects of different aggregate strengthening methods on the damage and fracture characteristics of coal gangue concrete, four strengthening treatment methods were used to strengthen coal gangue aggregates by four strengthening methods: cement slurry wrapping method (GC), water glass immersion method (SC), cement slurry-carbonization synergistic strengthening method (GT) and cement slurry-water glass synergistic strengthening method (GS). The fracture properties of the strengthened gangue concrete were studied by using crushed stone concrete (NC) and non-reinforced coal gangue concrete (MC) as the control group, combined with digital image correlation (DIC) technology. The results show that the four strengthening methods can delay the occurrence and development of cracks and improve the fracture resistance of gangue concrete, among which the synergistic strengthening effect is the most obvious, compared with the MC group, the cracking toughness of the specimen in the GS and GT groups are increased by 9.09% and 13.64%, and the instability toughness are increased by 25.0% and 36.21%. The fracture energies increase by 12.63% and 17.94%, respectively. The GT group has the largest improvement in fracture performance, which is comparable to that of the NC group. This provides a theoretical basis for the practical engineering application of coal gangue concrete.
- coal gangue /
- concrete /
- aggregate strengthening /
- digital speckle /
- fracture property

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图 1 三点弯曲断裂梁试件(单位：mm)

Figure 1. Three-point bending fracture beam specimen (Unit: mm)

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图 2 试验装置图

Figure 2. Diagram of the test setup

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图 3 部分混凝土试件断裂破坏截面图

Figure 3. Cross-sectional view of the fracture and destruction of some concrete specimens

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图 4 部分煤矸石混凝土切面微观扫描

Figure 4. Microscopic scanning of some gangue concrete sections

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图 5 碎石混凝土及强化前后煤矸石混凝土荷载-裂缝张开口位移(P-CMOD)、荷载-跨中挠度(P-δ)曲线

Figure 5. Load-opening displacement (P-CMOD)、load-mid-span deflection (P-δ) curves of crushed stone concrete and coal gangue concrete before and after strengthening

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图 6 骨料表面的亚微观显微图片

Figure 6. Submicroscopic microscopic image of aggregate surface

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图 7 混凝土的断裂韧度

Figure 7. Fracture toughness of concrete

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图 8 混凝土的断裂能

Figure 8. Fracture energy of concrete

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图 9 混凝土的应变变化

Figure 9. The strain variation of concrete

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图 10 DIC工作原理

Figure 10. Working principle of the DIC method

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图 11 DIC法与位移引伸计测得各组混凝土的P-CMOD曲线对比

Figure 11. Comparison of the P-CMOD curves of concrete measured by DIC method and displacement extensometer

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表 1 粗骨料的不同强化方式

Table 1 Methods of strengthening coarse aggregates

Species	Reinforcement methods	Specific practice
NC	Control group	Natural gravel
MC	Control group	Untreated coal gangue
GC	Cement slurry coating method	The cement slurry with a water-cement ratio of 0.35 is prepared to evenly wrap the coal gangue coarse aggregate, wherein the mass ratio of the coal gangue coarse aggregate to the cement slurry is 1:3, and it is moistened and cured for 28 days after hardening.
SC	Water glass immersion method	The coal gangue coarse aggregate was soaked in a water glass solution with a modulus of 3.0 and a concentration of 15% for 1 hour, and then dried naturally.
GS	Coating - water glass synergistic strengthening method	First, prepare a water glass solution with a modulus of 3.0 and a concentration of 15%, pour the cement slurry coal gangue aggregate cured to 28 days old into the configured water glass solution and soak it for 1 hour, and dry it naturally.
GT	Coating and carbonization synergistic strengthening method	The cement coarse aggregate cured to 28 days old is placed in a carbonization box for one week of carbonization curing, and the carbonization environment is temperature: (20±2)℃; Humidity: (70±5)%; CO2 concentration: (20±2)%.
Notes: NC is natural crushed stone concrete; MC is unreinforced coal gangue concrete; GC is coal gangue concrete reinforced by aggregate wrapped in grout; SC is coal gangue concrete strengthened by soaking the aggregate in water glass; GS is a coal gangue concrete with aggregate co-reinforced slurry-water glass; GT is a coal gangue concrete whose aggregate is coated with slurry and carbonization.

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表 2 天然粗骨料及强化前后煤矸石骨料的基本物理力学性能

Table 2 Basic physical and mechanical properties of natural coarse aggregate and coal gangue aggregate before and after reinforcement

Species	Apparent density/(kg·m⁻³)	Water absorption/%	Crushing index/%
NC	2713	1.1	6.7
MC	2523	10.6	17.3
GC	2554	10.2	13.3
SC	2561	8.6	15.4
GS	2581	7.8	12.7
GT	2594	8.1	12.3

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表 3 混凝土配合比及28 d立方体抗压强度

Table 3 Concrete fit ratio and 28 d cube compressive strength

Specimen number	Cement	Water	Sand	Crushed stone quality	Quality of coal gangue	Water reducing agent	Compressive strength /MPa
NC	312	175	863	1054	0	1.6	39.7
MC	312	175	829	0	1013	2.5	32.5
GC	312	175	834	0	1020	2.5	35.6
SC	312	175	836	0	1021	2.5	36.1
GS	312	175	839	0	1043	2.5	37.0
GT	312	175	842	0	1029	2.5	38.1

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表 4 双K断裂参数计算结果

Table 4 Calculation results of double K fracture parameters

Number	P_ini/kN	P_max/kN	${\text{CMO}}{{\text{D}}_{\text{c}}}$ /mm	$E$ /GPa	$K_{{\text{Ic}}}^{{\text{ini}}}$ /(MPa·m^1/2)	$K_{{\text{Ic}}}^{{\text{un}}}$ /(MPa·m^1/2)
NC	2.58	2.94	0.0798	32.4	0.80	1.95
MC	2.07	2.59	0.0538	22.4	0.66	1.16
GC	2.29	2.73	0.0584	25.2	0.71	1.33
SC	2.15	2.66	0.0556	24.7	0.68	1.27
GS	2.34	2.78	0.0591	28.7	0.72	1.45
GT	2.45	2.85	0.0608	31.7	0.75	1.58
Notes: P_ini and P_max are the initiation load and peak load; ${\text{CMO}}{{\text{D}}_{\text{c}}}$ is the critical opening displacement; E is the calculated modulus of elasticity for concrete; $K_{{\text{Ic}}}^{{\text{ini}}}$ and $K_{{\text{Ic}}}^{{\text{un}}}$ are initiation toughness and unstable toughness.

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表 5 混凝土断裂能计算

Table 5 Concrete fracture energy calculation

Number	${W_0}$ /J	${W_1}$ /J	${A_{{\text{lig}}}}$ /mm²	${G_{\text{F}}}$ /(N·m⁻¹)
NC	0.88	0.37	6000	208.3
MC	0.67	0.28	6000	158.3
GC	0.73	0.29	6000	170.0
SC	0.70	0.29	6000	165.0
GS	0.77	0.30	6000	178.3
GT	0.81	0.31	6000	186.7
Notes: ${W_0}$ is the work done by the external force of the concrete specimen; ${W_1}$ is the work done by the gravity of the concrete specimen itself; ${A_{{\text{lig}}}}$ is the area of the fracture zone of the concrete specimen; ${G_{\text{F}}}$ is the fracture energy of the concrete specimen

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参考文献(21)

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长摘要

目的
煤矸石资源化利用符合我国绿色发展理念，但煤矸石骨料强度低、吸水率大等原因导致煤矸石混凝土的实际工程应用受到限制。为了提高煤矸石在工程中的利用率，扩大其在工程中的应用范围，改善煤矸石混凝土脆性破坏的特征，降低工程中使用煤矸石混凝土带来的安全隐患，有必要对煤矸石进行强化，提高煤矸石粗骨料混凝土的断裂性能。
方法
本文通过水泥浆包裹法(GC)、水玻璃浸泡法(SC)、水泥浆-碳化协同强化法(GT)和水泥浆-水玻璃协同强化法(GS)四种强化处理方法对煤矸石骨料进行强化处理。以碎石混凝土(NC)和无强化的煤矸石混凝土(MC)作为对照组，结合数字散斑DIC技术对各种骨料的混凝土进行断裂试验研究，以探求骨料强化对煤矸石混凝土断裂性能的影响。用6种骨料制作515mm×100mm×100mm的三点弯曲试件，每组3个，试件浇筑时在中间部位用高40mm、厚度3.5mm的Ｔ型钢板预留出预制裂缝。试件标准养护28d后在预制裂缝左右各3cm范围内制作人工散斑场，加载设备采用位移加载的方式，加载速度为0.1mm/min。加载时采用数字散斑仪器、位移计、夹式引伸计对试件进行数据采集。对采集到的数据采用双断裂模型进行计算，得到混凝土各项断裂参数。最后通过DIC软件分析的模拟值与位移计、引伸计所测得的试验值进行对比，来验证DIC技术的准确性。
结果
强化后煤矸石骨料的吸水率、表观密度、压碎指标等较普通煤矸石骨料都有所提升，说明强化方法对煤矸石的基本物理力学性质有增强效果。试件破坏时，碎石混凝土呈现出砂浆剥离碎石粗骨料、碎石表面完整的现象；煤矸石混凝土呈现出骨料发生破碎的现象，这是由于煤矸石在开采、破碎的过程中出现的原始裂缝所致，而强化组试件中这一现象有明显改善。对包裹水泥浆的煤矸石骨料进行打磨处理，去除表面浆体，对骨料进行亚微观扫描，可以发现水泥浆填充了骨料的原始孔隙与裂缝。
结论
(1)水泥浆包裹、水玻璃浸泡、水泥浆-水玻璃协同强化和水泥浆-碳化协同强化对煤矸石混凝土的裂缝起裂和扩展均起到了一定的延缓作用，增强了混凝土的韧性。其中水泥浆-碳化协同强化组的起裂韧度及失稳韧度提高最大，分别提高了25.0%、36.21%，对混凝土断裂性能的改善更明显。(2)数字图像相关法(DIC)与位移引伸计所测得的曲线的吻合度较高，其误差大部分在5%以下，说明DIC法在煤矸石混凝土的断裂试验中有较高的准确性。(3)四种强化方式均提高了煤矸石混凝土的断裂能以及破坏时的极限应变，增强了煤矸石混凝土发生断裂时的耗能能力，改善了断裂性能。其中水泥浆-碳化协同强化的效果最为显著，断裂能提高了17.94%。

创新点

煤矸石资源化利用符合我国绿色发展理念，但煤矸石骨料强度低、吸水率大等原因导致煤矸石混凝土的实际工程应用受到限制。为了研究不同骨料强化方法对煤矸石混凝土的损伤和断裂特性的影响，本文通过水泥浆包裹法(GC)、水玻璃浸泡法(SC)、水泥浆-碳化协同强化法(GT)和水泥浆-水玻璃协同强化法(GS)四种强化处理方法对煤矸石骨料进行强化处理。以碎石混凝土(NC)和无强化的煤矸石混凝土(MC)作为对照组，结合数字图像相关(DIC)技术，对强化后的煤矸石混凝土断裂性能进行了试验研究。结果表明：四种强化方式均可以延缓裂缝的产生与发展，提高煤矸石混凝土的抗断裂能力，其中协同强化效果最为明显，GS、GT组与MC组相比，试件的起裂韧度与失稳韧度分别提高了9.09%、13.64%和25.0%、36.21%；断裂能分别提高了12.63%、17.94%。GT组断裂性能提高幅度最大，与NC组相当。这为煤矸石混凝土的实际工程应用提供了理论依据。
碎石混凝土及强化前后煤矸石混凝土P-CMOD、P-δ曲线
混凝土的应变变化

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多因素协同强化煤矸石粗骨料混凝土断裂性能试验研究

通讯作者: 崔正龙，博士，副教授，硕士生导师，研究方向为再生混凝土材料 E-mail: cui0815@126.com

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Experimental study on fracture performance of coal gangue coarse aggregate concrete reinforced by multi-factor synergy

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通讯作者:
崔正龙，博士，副教授，硕士生导师，研究方向为再生混凝土材料　E-mail: cui0815@126.com