Constitutive model of SAP-PVA fiber reinforced concrete under axial tensile damage at different temperatures
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摘要: 为研究不同温度下内养护聚乙烯醇纤维(PVA)增强混凝土试件的轴拉力学特性和损伤过程,进行了单轴抗压与拉伸试验,分析了其立方体抗压强度、高温质量损失率、拉伸应力-应变曲线等的变化规律;建立了考虑温度影响的单轴拉伸损伤本构模型,分析了损伤度的变化趋势,揭示了高温下内养护PVA纤维增强混凝土的损伤破坏机制。试验结果表明:立方体抗压强度随着PVA纤维掺量表现为先升高后降低的趋势,PVA纤维最优掺量为0.15%,高温下高吸水性树脂(SAP)颗粒释水收缩和PVA纤维的熔化是导致试件质量损失的主要原因;随着温度的升高,拉伸应力-应变曲线下降段逐渐趋向平缓,并出现了短暂的平台区;PVA纤维的掺入能较好的改善混凝土的韧性;建立的损伤本构模型适用于内养护PVA纤维增强混凝土,但仍具有一定的局限性,有待进一步改进。Abstract: In order to study the axial tensile mechanical properties and damage process of internally cured polyvinyl alcohol fiber (PVA) reinforced concrete specimens at different temperatures, uniaxial compressive and axial tensile tests were carried out to analyze the changing rules of its compressive strength, high temperature mass loss rate, stress-strain curve, etc.; a uniaxial tensile damage constitutive model considering the effect of temperature was established to analyze the trend of the degree of damage, which revealed the damage destruction mechanism of internally cured PVA fiber reinforced concrete at high temperatures. The test results show that: the compressive strength with the PVA fiber dosage shows a trend of increasing and then decreasing, the optimal dosage of PVA fiber is 0.15%, the water release shrinkage of super absorbent resin (SAP) particles and the melting of PVA fibers at high temperature are the main reasons for the loss of specimen quality; with the increase of temperature, the descending section of the stress-strain curve gradually tends to be flat, and there is a short-lived plateau area; The incorporation of PVA fibers can better improve the toughness of concrete; the established damage constitutive model is applicable to internally cured PVA fiber-reinforced concrete, but it still has some limitations and needs to be further improved.
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Key words:
- SAP /
- PVA fiber /
- mechanical properties /
- intrinsic model /
- damage mechanism
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表 1 内养护PVA纤维增强混凝土配合比(kg/m3)
Table 1. Mixture ratio of internal curing PVA fiber reinforced concrete (kg/m3)
Specimen number Water-
cement ratioInternal conservation
water contentCement Sand Water Coarse aggregate water
reducerSAP PVA C 0.323 0.0 480 640 155 1160 1.2 0.000 0.000 0.05%PVA/C 0.323 27.9 480 640 155 1160 1.2 1.116 0.645 0.10%PVA/C 0.323 27.9 480 640 155 1160 1.2 1.116 1.290 0.15%PVA/C 0.323 27.9 480 640 155 1160 1.2 1.116 1.935 0.20%PVA/C 0.323 27.9 480 640 155 1160 1.2 1.116 2.580 Notes: C—PVA fiber mix in specimen is 0%; SP-0.05%—PVA fiber mix 0.05%; SP-0.10%—PVA fiber mix in specimen 0.10%; SP-0.15%—PVA fiber mix in specimen 0.15%; SP-0.20%—PVA fiber mix in specimen 0.20%. 表 2 不同PVA纤维掺量混凝土试件的抗压强度值
Table 2. Compressive strength values of concrete specimens with different PVA fiber content
Specimen number Cube body compressive strength/MPa Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
valueC 41.71 42.65 42.99 44.54 43.43 43.06 0.05%PVA/C-25℃ 42.79 42.48 43.61 45.70 45.29 43.97 0.10%PVA/C-25℃ 45.60 46.52 49.48 47.55 43.56 46.54 0.15%PVA/C-25℃ 51.85 41.91 55.12 46.58 46.48 48.39 0.20%PVA/C-25℃ 47.19 40.36 46.47 51.32 42.99 45.67 表 3 不同PVA纤维掺量下混凝土试件高温质量损失率
Table 3. High-temperature mass loss rate of concrete specimens under different PVA fiber content
Specimen number Mass loss rate/% Sample 1 Sample 2 Sample 3 Average
valueC-200℃ 4.216 4.364 4.920 4.500 C-300℃ 5.829 5.988 5.419 5.745 C-400℃ 6.391 6.393 6.607 6.464 0.05%PVA/C-200℃ 4.802 5.431 4.931 5.055 0.05%PVA/C-300℃ 6.511 6.550 6.149 6.403 0.05%PVA/C-400℃ 6.724 6.341 6.744 6.603 0.10%PVA/C-200℃ 4.801 5.304 5.322 5.142 0.10%PVA/C-300℃ 6.697 6.464 6.978 6.713 0.10%PVA/C-400℃ 7.389 7.292 7.333 7.338 0.15%PVA/C-200℃ 4.767 5.379 4.761 4.969 0.15%PVA/C-300℃ 6.515 6.518 6.387 6.473 0.15%PVA/C-400℃ 7.139 8.003 7.128 7.423 0.20%PVA/C-200℃ 5.309 4.602 5.084 4.998 0.20%PVA/C-300℃ 6.489 6.344 6.688 6.507 0.20%PVA/C-400℃ 6.173 7.718 8.634 7.508 表 4 SAP-PVA纤维混凝土轴拉损伤本构模型拟合参数的平均值
Table 4. Average values of fitting parameters of the SAP-PVA fiber concrete axial tensile damage constitutive model
The specimen number a b c d R2 C-25℃ 0.420 0.041 0.621 1.500 0.999 C-200℃ 0.371 0.045 0.674 2.800 0.986 C-300℃ 0.712 0.145 0.560 3.180 0.993 C-400℃ 0.563 0.064 0.500 1.684 0.998 0.05%PVA/C-25℃ 0.472 0.040 0.568 2.234 0.968 0.05%PVA/C-200℃ 0.478 0.060 0.582 2.308 0.987 0.05%PVA/C-300℃ 0.427 0.044 0.617 2.853 0.980 0.05%PVA/C-400℃ 0.384 0.026 0.642 1.194 0.994 0.10%PVA/C-25℃ 0.454 0.050 0.597 2.082 0.987 0.10%PVA/C-200℃ 0.453 0.069 0.616 3.291 0.989 0.10%PVA/C-300℃ 0.382 0.047 0.665 1.714 0.993 0.10%PVA/C-400℃ 0.353 <10−3 0.647 0.994 0.991 0.15%PVA/C-25℃ 0.273 0.081 0.808 2.204 0.984 0.15%PVA/C-200℃ 0.568 0.100 0.532 2.984 0.991 0.15%PVA/C-300℃ 0.298 0.027 0.729 1.499 0.998 0.15%PVA/C-400℃ 0.549 0.110 0.561 2.065 0.996 0.20%PVA/C-25℃ 0.551 0.074 0.523 4.219 0.993 0.20%PVA/C-200℃ 0.482 0.075 0.593 3.050 0.987 0.20%PVA/C-300℃ 0.521 0.093 0.572 3.210 0.998 0.20%PVA/C-400℃ 0.196 <10−3 0.804 0.683 0.989 -
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