UHPC与混凝土基体间界面剪切强度的影响因素

薛善彬; 荆蜂杰; 王丹; 张鹏; 高小建

UHPC与混凝土基体间界面剪切强度的影响因素

薛善彬¹,
荆蜂杰¹,
王丹¹,
张鹏^{1, 2, ,},
高小建³

1.
青岛理工大学土木工程学院, 青岛 266525
2.
青岛理工大学山东蓝色经济区工程建设与安全协同创新中心, 青岛 266525
3.
哈尔滨工业大学土木工程学院, 哈尔滨 150001

基金项目: 国家自然科学基金(U2106220；52008222)；国家重点研发计划项目(2021YFB2600704)；山东省杰出青年基金(ZR2021JQ17)

详细信息

通讯作者:
张鹏，博士，教授，博士生导师，研究方向为混凝土耐久性　E-mail: peng.zhang@qut.edu.cn

中图分类号: TU528
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- 被引次数: 0
出版历程
- 收稿日期: 2024-01-09
- 修回日期: 2024-02-15
- 录用日期: 2024-03-08
- 网络出版日期: 2024-04-13

Factors influencing interfacial shear strength between UHPC and concrete substrate

1.
School of Civil Engineering, Qingdao University of Technology, Qingdao 266525, China
2.
Shandong Blue Economic Zone Engineering Construction and Safety Collaborative Innovation Center, Qingdao University of Technology, Qingdao 266525, China
3.
School of Civil Engineering, Harbin Institute of Technology, Harbin 150001, China

Funds: National Natural Science Foundation of China (U2106220; 52008222); National Key Research and Development Program Project (2021YFB2600704); Shandong Province Outstanding Youth Fund (ZR2021JQ17)

摘要

摘要: 超高性能混凝土(Ultra-high performance concrete, UHPC)具备优异的力学与抗渗性能，在混凝土结构补强加固工程中有着广阔的应用前景，如何提高UHPC与既有基体间的粘结性能成为土木工程领域普遍关心的重要课题。本文利用标准养护条件制备的试件开展试验研究，首先研究了UHPC水胶比与混凝土基体初始含水饱和度对二者间界面剪切强度的影响规律。此外，选取特定配合比的UHPC，研究了其与不同饱和度混凝土间界面剪切强度随龄期的演化规律。向UHPC中掺入预湿轻骨料以实现内养护，考虑UHPC中轻骨料取代率、混凝土基体含水饱和度的影响，研究了不同龄期养护后轻骨料UHPC与混凝土基体间界面剪切强度的演化规律。利用扫描电镜技术观测了UHPC与混凝土间界面的微结构。结果表明：(1)对于未掺轻骨料的UHPC：不论水胶比如何变化，其与饱水基体间的界面剪切强度最高，而与干燥基体间的界面剪切强度最低；其与干燥基体间的界面剪切强度随水胶比的升高而降低，与预湿基体间的界面剪切强度随水胶比的升高而先增长后降低。(2)水胶比为0.154的UHPC与不同饱和度基体间28 d时的界面剪切强度均较7 d时显著增长；90 d时，其仅与50%饱和度基体间的界面剪切强度进一步显著增长。(3)低轻骨料取代率能够提高UHPC与干燥基体间7 d时的界面剪切强度，而高轻骨料取代率能够显著提高UHPC与干燥基体间28 d和90 d时的界面剪切强度；28 d和90 d时，轻骨料UHPC与50%饱和度基体间的界面剪切强度显著高于干燥基体；7 d时，不同轻骨料取代率的UHPC与饱水基体间便可形成一定的界面剪切强度，且该强度在28 d和90 d时均进一步增长。
- UHPC /
- 基体饱和度 /
- 轻骨料 /
- 界面剪切强度 /
- 养护龄期
Abstract: Ultra-high performance concrete (UHPC) has excellent mechanical and impermeability properties, and has a broad application prospect in the concrete structure reinforcement project. How to improve the bonding performance between UHPC and existing substrate has become an important topic of general concern in the field of civil engineering. In this paper, experimental studies were carried out using specimens prepared under standard curing conditions, and the effects of the water-binder ratio (w/b) of UHPC and the initial water saturation of the concrete substrate on the interfacial shear strength between them were first investigated. In addition, the evolution law of interfacial shear strength with age between the selected UHPC with a specific mix proportion and concrete with different saturation was investigated. Pre-wetted lightweight aggregate was incorporated into UHPC to achieve internal curing, and the evolution law of the interfacial shear strength between lightweight aggregate UHPC and concrete substrate after curing with different ages was investigated by taking into account the effects of the replacement rate of lightweight aggregate in UHPC, and the water saturation of concrete substrate. The microstructure of the interface between UHPC and concrete was observed using scanning electron microscopy. The results show that (1) for UHPC without lightweight aggregates, the interfacial shear strength between it and water-saturated substrate is the highest while the interfacial shear strength between it and dry substrate is the lowest irrespective of the change of the w/b of UHPC. The interfacial shear strength between UHPC and dry substrate decreases with the increase of w/b, and that between UHPC and pre-wetted substrate increases first and then decreases with the increase of the w/b. (2) The interfacial shear strengths between UHPC with a w/b of 0.154 and different saturated substrate all increase significantly at 28d compared to that at 7d. At 90d, only the interfacial shear strengths between it and 50% saturated substrate further increase significantly. (3) A low lightweight aggregate replacement rate can increase the interfacial shear strength between UHPC and dry substrate at 7d, while a high lightweight aggregate replacement rate can significantly increase the interfacial shear strength between UHPC and dry substrate at 28d and 90d. The interfacial shear strength between lightweight aggregate UHPC and 50% saturated substrate is significantly higher than that between lightweight aggregate UHPC and dry substrate at 28d and 90d. At 7d, a certain interfacial shear strength can be formed between UHPC with different lightweight replacement rates and water-saturated substrate, and the strength further increases at both 28d and 90d.
- UHPC /
- substrate saturation /
- lightweight aggregate /
- interface shear strength /
- curing age

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图 1 UHPC-混凝土基体复合体制备流程

Figure 1. Preparation flow of UHPC-concrete substrate composite

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图 2 界面剪切强度测试

Figure 2. Interface shear strength test

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图 3 扫描电镜试验取样与测试

Figure 3. Sampling and testing of scanning electron microscope (SEM) test

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图 4 不同水胶比UHPC与不同饱和度混凝土间的界面剪切强度

Figure 4. Interfacial shear strength between UHPC with different w/b and concrete with different saturation

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图 5 不同龄期养护后UHPC与不同饱和度混凝土基体间的界面剪切强度

Figure 5. Interfacial shear strength between UHPC and concrete substrate with different saturation after curing at different ages

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图 6 不同轻骨料取代率UHPC与干燥混凝土基体间界面剪切强度

Figure 6. Interfacial shear strength between UHPC with different LWA replacement rates and dry concrete substrate

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图 7 内掺轻骨料UHPC与干燥混凝土基体的粘结过程

Figure 7. Bonding process between UHPC incorporating LWA and dry concrete substrate

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图 8 不同轻骨料取代率UHPC与部分饱水混凝土基体间界面剪切强度

Figure 8. Interfacial shear strength between UHPC with different LWA replacement rates and partially saturated concrete substrate

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图 9 不同轻骨料取代率UHPC与饱水混凝土基体间界面剪切强度

Figure 9. Interfacial shear strength between UHPC with different LWA replacement rates and water-saturated concrete substrate

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图 10 基于扫描电镜的UHPC与混凝土基体间界面微结构观测

Figure 10. Microstructural observation of the interface between UHPC and concrete substrate based on SEM

The nomenclature rule for the specimens is “the saturation of substrate - the replacement rate of LWA in UHPC”

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表 1 超高性能混凝土(UHPC)配合比(kg/m³)

Table 1. Mix proportion of ultra-high performance concrete (UHPC) (kg/m³)

Groups	Cement	Silica fume	Quartz sand	Water	SP	Steel fiber	LWA
UHPC-00	770	230	1000	154	42	156	0
UHPC-10	770	230	900	154	42	156	96
UHPC-20	770	230	800	154	42	156	192
UHPC-30	770	230	700	154	42	156	288
25-UHPC	770	230	1000	250	20	156	0
30-UHPC	770	230	1000	300	16	156	0
Notes: SP denotes superplasticizer. LWA represents lightweight aggregate. The UHPC group with a LWA replacement rate of 0%, 10%, 20% and 30% is designated as UHPC-00, UHPC-10, UHPC-20, UHPC-30. The UHPC group with a water-binder ratio (w/b) of 0.25 and 0.30 is designated as 25-UHPC and 30-UHPC, respectively.

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表 2 混凝土基体配合比(kg/m³)

Table 2. Mix proportion of concrete substrate (Unit: kg/m³)

Cement	Coarse aggregate	Fine aggregate	Water
375	1125	750	200

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表 3 各组变量汇总表

Table 3. Summary table of variables for each group

Groups	w/b	Saturation of the substrate	Replacement rate LWA	Curing age
UHPC-00	0.154	0%、50%、100%	0%	7 d、28 d、90 d
25-UHPC	0.25	0%、50%、100%	0%	28 d
30-UHPC	0.30	0%、50%、100%	0%	28 d
UHPC-10	0.154	0%、50%、100%	10%	7 d、28 d、90 d
UHPC-20	0.154	0%、50%、100%	20%	7 d、28 d、90 d
UHPC-30	0.154	0%、50%、100%	30%	7 d、28 d、90 d
Note: w/b refers to the water-binder ratio of UHPC.

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