超低温作用对超高韧性水泥基复合材料抗弯性能的影响

苏骏; 钱维民

doi:10.13801/j.cnki.fhclxb.20210823.001

超低温作用对超高韧性水泥基复合材料抗弯性能的影响

doi: 10.13801/j.cnki.fhclxb.20210823.001

苏骏^{1, 2,},
钱维民^1, ,

1.
湖北工业大学　土木建筑与环境学院，武汉 430068
2.
湖北工业大学　工程技术学院，武汉 430068

基金项目: 湖北省自然科学基金(2020CFB860)

详细信息

通讯作者:
钱维民，硕士，研究方向为纤维混凝土基本性能　E-mail：907415610@qq.com

中图分类号: TB332
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出版历程
- 收稿日期: 2021-06-25
- 修回日期: 2021-08-04
- 录用日期: 2021-08-12
- 网络出版日期: 2021-08-26
- 刊出日期: 2022-06-01

Effect of ultra-low temperature on flexural behavior of ultra-high toughness cementitious composites

SU Jun^{1, 2
,},
QIAN Weimin^{1
, ,}

1.
School of Civil Engineering and Environment, Hubei University of Technology, Wuhan 430068, China
2.
Hubei University of Technology Engineering and Technology College, Hubei University of Technology, Wuhan 430068, China

摘要

摘要: 超高韧性水泥基复合材料(UHTCC)作为一种具有良好力学性能和耐久性能的新型复合材料，弯曲韧性是评价其力学性能的重要指标。为探究UHTCC材料在超低温环境下的抗弯性能，设计了5组不同纤维体积掺量的UHTCC新材料，经过深冷处理后进行四点弯曲试验，对其进行等效强度分析，提出一种适用于超低温作用后的韧性评价方式，为UHTCC在超低温领域的广泛应用提供理论基础和技术支持。研究结果表明：超低温作用后UHTCC的弯拉强度显著提升，当温度降低至−160℃，UHTCC的弯拉强度最大可提升67.67%，但表现出明显的脆性；超低温环境下1.5vol%UHTCC的强度及韧性性能提升效果最佳，但超出最优掺量后，UHTCC的性能反而略微降低。
- 超高韧性水泥基复合材料 /
- 超低温 /
- 弯拉强度 /
- 抗弯韧性 /
- 纤维掺量
Abstract: As a new type of composite material with good mechanical properties and durability, the flexural toughness of ultra-high toughness cementitious composites (UHTCC) is an important indicator to evaluate its mechanical properties. To explore the bending performance of UHTCC materials under an ultra-low temperature environment, five groups of UHTCC materials with different fiber contents were designed. After cryogenic treatment, four-point bending tests were carried out, and the equivalent strength was analyzed. A toughness evaluation method suitable for ultra-low temperature was proposed, which provided the theoretical basis and technical support for the wide application of UHTCC in the field of ultra-low temperature. The results show that the flexural strength of UHTCC increases significantly after ultra-low temperatures. When the temperature decreases to −160℃, the flexural strength of UHTCC increases by 67.67%, but it shows obvious brittleness. In an ultra-low temperature environment, the strength and toughness of UHTCC with 1.5vol% volume fraction are the best, but the performance of UHTCC is slightly reduced after exceeding the optimal volume fraction.
- ultra-high toughness cementitious composites /
- ultra-low temperature /
- bending strength /
- toughness /
- fiber content

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图 1 试验设备及试件形态

Figure 1. Test equipment and specimen shape

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图 2 不同温度下超高韧性水泥复合材料(UHTCC)受弯荷载-挠度曲线

Figure 2. Bending load-deflection curves of ultra-high toughness cementitious composites (UHTCC) at different temperatures

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图 3 不同影响因素下的UHTCC弯曲韧性指数I₅

Figure 3. Bending toughness index I₅ of UHTCC under different influence factors

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图 4 不同PVA掺量UHTCC承载力变异与温度关系

Figure 4. Relationship between variation of bearing capacity and temperature of UHTCC with different PVA contents

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图 5 温度对UHTCC等效弯曲强度影响

Figure 5. Effect of temperature on equivalent bending strength of UHTCC

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图 6 能量吸收计算示意图

Figure 6. Schematic diagram of energy absorption calculation

P_max—Peak load

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图 7 不同掺量UHTCC韧性系数与温度关系

Figure 7. Relationship between toughness coefficient and temperature of UHTCC with different contents

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图 8 UHTCC孔隙水冰点与孔径关系

Figure 8. Relationship between pore water freezing point and pore size of UHTCC

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图 9 UHTCC纤维增强效应系数与温度关系

Figure 9. Relationship between fiber reinforcement coefficient of UHTCC and temperature

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表 1 聚乙烯醇(PVA)纤维性能指标

Table 1. Polyvinyl alcohol (PVA) fiber performance index

Name	Density/(g·cm⁻³)	Diameter/mm	Length/mm	Elastic modulus/MPa	Tensile strength/MPa	Elongation/%
REC15×12	1.3	0.04	12	120	526	6

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表 2 试件分组

Table 2. Specimen grouping

Group	PVA content/vol%	Temperature/℃	Fly ash/(kg·m⁻³)	Cement /(kg·m⁻³)	Sand/(kg·m⁻³)	Silica fume/(kg·m⁻³)
0vol%PVA/C30	0	20/0/−40/−80/−120/−160	533.3	120	133.3	13.3
0.5vol%PVA/C30	0.5	20/0/−40/−80/−120/−160	533.3	120	133.3	13.3
1.0vol%PVA/C30	1.0	20/0/−40/−80/−120/−160	533.3	120	133.3	13.3
1.5vol%PVA/C30	1.5	20/0/−40/−80/−120/−160	533.3	120	133.3	13.3
2.0vol%PVA/C30	2.0	20/0/−40/−80/−120/−160	533.3	120	133.3	13.3

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表 3 UHTCC试件平均弯拉强度试验值

Table 3. Test values of average flexural tensile strength of each group UHTCC specimens MPa

Group	20℃	0℃	−40℃	−80℃	−120℃	−160℃
0vol%PVA/C30	2.61	3.24	4.81	4.56	2.70	3.15
0.5vol%PVA/C30	3.46	2.81	3.75	3.81	2.95	4.85
1.0vol%PVA/C30	4.70	5.48	5.32	6.19	7.32	7.55
1.5vol%PVA/C30	5.30	6.09	6.32	7.13	7.88	8.88
2.0vol%PVA/C30	6.15	5.09	3.80	5.24	6.43	6.54

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表 4 UHTCC强度及韧性指标

Table 4. Strength and toughness index of UHTCC

Group	Temperature/℃	Initial crack load/kN	Initial crack deflection/ mm	Peak load/ kN	Equivalent bending strength/MPa	Equivalent bending strength I₅	Toughness coefficient C_i
Group	Temperature/℃	Initial crack load/kN	Initial crack deflection/ mm	Peak load/ kN	Equivalent bending strength/MPa	Equivalent bending strength I₅	i=1	i=2	i=3	i=4
0vol%PVA/C30	20	8.70	0.27	8.70	−	−	−	−	−
	0	10.80	0.54	10.80	−	−	−	−	−
	−40	16.02	0.76	16.02	−	−	−	−	−
	−80	15.21	0.86	15.21	−	−	−	−	−
	−120	9.01	0.64	9.01	−	−	−	−	−
	−160	10.49	0.65	10.49	−	−	−	−	−
0.5vol%PVA/C30	20	6.31	0.30	11.52	1.27	6.31	3.41	4.41	5.29	5.55
	0	4.53	0.14	9.35	0.86	6.31	0.48	0.56	0.65	0.68
	−40	7.95	0.24	12.49	1.28	4.57	0.42	0.55	0.64	0.68
	−80	8.96	0.19	12.70	1.47	4.91	0.33	0.46	0.53	0.57
	−120	5.09	0.37	9.82	0.97	6.30	1.50	1.77	2.04	2.16
	−160	9.92	0.34	16.17	2.46	4.47	1.45	1.73	1.91	2.05
1.0vol%PVA/C30	20	10.06	0.39	15.65	2.11	6.31	6.84	11.31	13.70	16.15
	0	9.57	0.44	18.28	1.58	5.55	3.30	3.86	4.00	4.12
	−40	10.75	0.33	17.72	2.31	6.75	1.11	1.71	2.08	2.45
	−80	11.86	0.44	20.64	2.38	6.46	1.50	2.14	2.38	2.55
	−120	11.36	0.43	24.40	2.11	6.58	4.36	5.17	5.40	5.55
	−160	11.29	0.33	25.17	1.82	6.01	3.20	3.28	3.36	3.43
1.5vol%PVA/C30	20	12.72	0.74	17.66	2.13	5.80	15.28	18.81	22.50	25.54
	0	12.66	0.58	20.30	1.59	3.97	4.11	4.32	4.53	4.76
	−40	12.74	0.61	21.05	1.68	4.37	2.13	2.26	2.42	2.51
	−80	15.06	0.56	23.78	2.14	4.41	1.95	2.32	2.52	2.71
	−120	18.24	0.64	26.28	2.62	3.88	4.82	6.19	7.04	7.79
	−160	15.01	0.64	29.61	2.15	4.92	6.17	6.30	6.51	6.77
2.0vol%PVA/C30	20	13.96	0.81	20.50	2.49	5.61	15.13	18.58	23.50	28.26
	0	10.87	0.74	16.97	1.97	5.07	3.64	4.80	5.67	6.72
	−40	9.09	0.58	12.68	1.51	4.46	0.92	1.30	1.52	1.73
	−80	13.11	0.64	17.48	1.79	3.65	1.23	1.60	1.83	2.04
	−120	9.17	0.63	21.43	1.82	7.28	5.70	6.27	6.96	7.21
	−160	10.78	0.37	21.80	2.09	7.08	2.55	2.93	3.34	3.61
Notes: Since the performance of UHTCC changes after the action of ultra-low temperature, its initial crack deflection increases, and its failure deflection decreases, resulting in that the toughness calculation method in the specification cannot well evaluate its toughness, and its toughness index I₅ can only be calculated, while I₁₀ and I₂₀ cannot be evaluated and analyzed because they cannot meet the deflection requirements.

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表 5 不同温度下各UHTCC试验组纤维增强效应系数

Table 5. Fiber reinforcement effect coefficients of each UHTCC test group at different temperatures

Group	Temperature/℃	Fiber reinforcement effect coefficient
0.5vol%PVA/C30	20	5.20
	0	0.67
	−40	0.68
	−80	0.56
	−120	2.05
	−160	1.94
1.0vol%PVA/C30	20	15.54
	0	4.07
	−40	2.57
	−80	2.43
	−120	5.35
	−160	3.16
1.5vol%PVA/C30	20	24.55
	0	5.21
	−40	2.69
	−80	2.56
	−120	7.71
	−160	6.47
2.0vol%PVA/C30	20	30.85
	0	7.24
	−40	1.85
	−80	2.18
	−120	7.23
	−160	3.67

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