再生细骨料UHTCC力学性能及作用机理

doi:10.12068/j.issn.1005-3026.2025.20240016

摘要/Abstract

摘要：

为探究再生细骨料（RFA）对超高韧性水泥基复合材料（UHTCC）工作性能和力学性能的影响规律，对RFA替代石英砂比率分别为0，25%，50%，75%和100%的UHTCC进行了流动性、抗压和单轴抗拉试验.结果表明：RFA替代率对UHTCC流动度影响不显著；UHTCC抗压强度和单轴抗拉强度均随RFA替代率的增加而降低，当RFA替代率达到50%后下降幅度增大，分别比全石英砂骨料时下降了13.9%~19.9%和11.3%~16.7%；直拉作用下UHTCC极限应变和裂缝数量随RFA替代率的增加而增加，当RFA替代率达到50%后，极限应变比全石英砂骨料时提升了27.2%~40.9%，试件逐渐呈现“饱和”细密多裂缝的破坏状态.微观结构分析表明，RFA替代率的增加有利于PVA纤维从UHTCC基体中拔出，纤维桥连裂缝作用增强.

关键词: 超高韧性水泥基复合材料, 再生细骨料, 工作性能, 力学性能, 替代率

Abstract:

To investigate the effect of recycled fine aggregate （RFA） on the workability and mechanical properties of ultra-high toughness cementitious composites （UHTCC）， flowability， compressive strength， and uniaxial tensile tests were conducted on UHTCC with RFA replacement ratios of 0， 25%， 50%， 75%， and 100% for silica sand. The results indicate that the RFA replacement ratio has little effect on the flowability of UHTCC. Both the compressive and uniaxial tensile strengths of UHTCC decrease with increasing RFA replacement ratios， with a more pronounced reduction observed after the RFA replacement ratio exceeds 50%， decreasing by 13.9%~19.9% and 11.3%~16.7%， respectively， compared to specimens with pure silica sand aggregate. Under direct tension， the ultimate strain and crack numbers in UHTCC increase with higher RFA replacement ratios. When the RFA replacement ratio reaches 50%， the ultimate strain increases by 27.2%~40.9% compared to specimens with pure silica sand aggregate， and the specimens gradually exhibit a “saturated” fine and dense multi-crack failure mode. Microstructural analysis indicates that increasing the RFA replacement ratio facilitates the pull-out of PVA fibers from the UHTCC matrix， enhancing the fiber bridging effect across cracks.

Key words: ultra-high toughness cementitious composite, recycled fine aggregate, workability, mechanical property, replacement ratio

中图分类号:

TU 528.572

陈猛, 刘富成, 张通, 吴迪. 再生细骨料UHTCC力学性能及作用机理[J]. 东北大学学报（自然科学版）, 2025, 46(9): 119-125.

Meng CHEN, Fu-cheng LIU, Tong ZHANG, Di WU. Mechanical Properties and Working Mechanism of UHTCC with Recycled Fine Aggregate[J]. Journal of Northeastern University(Natural Science), 2025, 46(9): 119-125.

图/表 14

图1 原材料粒径分布图

Fig.1 Particle size distribution of raw materials

图2 石英砂和RFA的微观形貌（a）—石英砂；（b）—RFA.

Fig.2 Microstructural images of silica sand and RFA

表1 PVA纤维物理性能

Table 1 Physical properties of PVA fibers

长度	直径	抗拉强度	弹性模量	密度
mm	μm	MPa	GPa	kg·m^-3
12	39	1 600	40	1 300

表2 UHTCC配合比 (kg/m3)

Table 2 Mix proportions of UHTCC

编号	水泥	粉煤灰	石英砂	RFA	水	减水剂	PVA纤维
S100R0	544	653	435	0	335	14	26
S75R25	544	653	326	109	335	14	26
S50R50	544	653	218	218	335	14	26
S25R75	544	653	109	326	335	14	26
S0R100	544	653	0	435	335	14	26

图3 单轴拉伸试验装置及试件尺寸示意图（a）—试验装置；（b）—试件尺寸.

Fig.3 Schematic diagram of uniaxial tensile test device and specimen dimensions

图4 UHTCC流动度随RFA替代率的变化

Fig.4 Variation of RFA replacement ratio on flowability of UHTCC

图5 UHTCC抗压强度随RFA替代率的变化

Fig.5 Variation of RFA replacement ratio on compressive strength of UHTCC

图6 UHTCC应力-应变曲线随RFA替代率的变化

Fig.6 Variation of RFA replacement ratios on stress-strain curves of UHTCC

图7 UHTCC裂缝处PVA纤维的微观形貌（a）—纤维桥连；（b）—纤维拔出或拔断.

Fig.7 Microscopic morphology of PVA fibers at UHTCC crack

图8 UHTCC裂缝分布随RFA替代率的变化（a）—S100R0；（b）—S75R25；（c）—S50R50；（d）—S25R75；（e）—S0R100.

Fig.8 Variation of RFA replacement ratio on crack distribution of UHTCC

图9 UHTCC抗拉强度随RFA替代率的变化

Fig.9 Variation of RFA replacement ratio on tensile strength of UHTCC

图10 UHTCC极限应变随RFA替代率的变化

Fig.10 Variation of RFA replacement ratio on ultimate strain of UHTCC

图11 RFA在UHTCC中的作用机理示意图（a）—0；（b）—50%；（c）—100%；（d）—RFA内部结构.

Fig.11 Schematic illustration of action mechanism of RFA in UHTCC

图12 断裂试件中PVA纤维的SEM图（a）—S100R0，纤维拔断；（b）—S100R0，拔断断面；（c）—S0R100，纤维拔出；（d）—S0R100，拔出断面.

Fig.12 SEM images of PVA fibers in fractured specimen

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