Effects of Relative Humidity on Tensile Property Degradation of GFRP Rebars in Seawater and Sea Sand Concrete Environment

doi:10.16183/j.cnki.jsjtu.2022.034

Abstract

Abstract:

By establishing a quantitative analysis method of relative humidity, pore solution saturation, and corrosion reaction rate of concrete, the influence of environmental relative humidity on the mechanical properties of glass fiber reinforced polymer (GFRP) in seawater sea-sand concrete environment has been studied. Based on the pore size distribution of concrete and the surface tension formula of pore solution, the relationship between the relative humidity and pore solution saturation of seawater sea-sand concrete is established. It is assumed that the pore solution is uniformly smeared in concrete. Therefore, the concentration of corrosive ion OH^- can be obtained. The corrosion rate and strength retention rate of GFRP bars under the action of OH^- are evaluated using the etching model. The accuracy of the current method is verified by experimental results. Based on the climate statistics of some coastal cities in China, the influence of relative humidity on the strength retention rate of GFRP bars in seawater and sea sand concrete environment is predicted under the conditions of representative ambient temperature and water-cement ratio. The increase of relative humidity promotes the performance degradation of GFRP bars. According to relevant standards, the relations between relative humidity and service life of GFRP bars in seawater sea-sand concrete environment have been predicted.

Key words: composites, seawater and sea sand concrete, relative humidity, property degradation, service life

CLC Number:

TU528.59

WANG Wenhua, ZHAO Qi, ZHANG Daxu, ZHANG Peifu, CHEN Peng. Effects of Relative Humidity on Tensile Property Degradation of GFRP Rebars in Seawater and Sea Sand Concrete Environment[J]. Journal of Shanghai Jiao Tong University, 2023, 57(2): 148-160.

Figures/Tables 15

Fig.1

Tab.1

Fig.2

Fig.3

Fig.4

Tab.2

Values of solute parameters

溶质	g	$β M X (0)$	$β M X (1)$	$C φ M X$
NaCl	0.108 98	0.077 22	0.251 83	0.001 06
NaOH	0.536 82	0.170 67	-0.084 11	-0.003 42
KCl	0.057 12	0.046 61	0.223 41	-0.000 44
KOH	0.011 99	0.175 01	-0.016 34	-0.002 67

Tab.2

Fig.5

Fig.6

Fig.7

Tab.3

Tab.4

Fig.8

Fig.9

Fig.10

Fig.11

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w/c	φ₁	B₁/nm	φ₂	B₂/nm	φ₃	B₃/nm
0.4	0.431	0.99	0.424	5.02	0.134	32.76
0.5	0.350	1.01	0.469	5.00	0.168	32.05
0.6	0.289	1.02	0.500	5.09	0.196	32.39
0.7	0.243	1.03	0.519	5.26	0.220	33.20

时间/月	H_r=65%			H_r=85%			H_r=95%
时间/月	R_e	R_s	δ	R_e	R_s	δ	R_e	R_s	δ
1	92.5	94.4	2.1	92.0	91.5	0.5	81.2	88.0	8.4
2	90.0	89.0	1.1	84.1	83.4	0.8	71.2	77.3	8.6
3	88.1	84.6	3.9	82.0	76.3	7.0	62.7	66.7	6.4
4	86.7	78.6	9.3	76.9	68.3	11.1	58.3	57.2	1.8

城市名称	平均气温/℃	平均相对湿度/%
大连	12.15	60.00
青岛	13.90	68.35
上海	17.64	74.00
广州	22.30	81.00
海口	24.94	81.20
福州	19.30	76.00
北海	22.90	80.80