Compressive constitutive model of polyvinyl alcohol fiber/cement composite material in frozen state
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摘要: 为了研究冻融循环后的聚乙烯醇纤维/水泥基复合材料在冻结状态下的抗压服役情况,设计了冻结聚乙烯醇纤维/水泥基复合材料抗压试验,先对试样进行0~300次的冻融循环,冻融循环试验后在−18℃的持续低温环境下对试样进行抗压试验,分析试样的抗压应力-应变关系及影响机制。在此基础上,结合等效应力原理和统计损伤理论,建立了冻结状态聚乙烯醇纤维/水泥基复合材料抗压本构模型,讨论了损伤变量随冻融循环次数的演化特征。结果表明:随着冻融循环次数的增加,冻结状态下聚乙烯醇纤维/水泥基复合材料的抗压峰值强度降低,峰值应变增加,极限破坏时脆性特征显著,高冻融循环次数下试样的弹性模量主要由试样中的孔隙冰来提供。建立的模型可以较好地预测实际经受冻融循环作用后的聚乙烯醇纤维/水泥基复合材料在冻结状态下的抗压应力-应变关系,冻融损伤变量和总损伤变量与冻融次数有显著相关性。
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关键词:
- 纤维增强水泥基复合材料 /
- 冻融循环 /
- 低温冻结 /
- 单轴压缩 /
- 本构模型
Abstract: In order to study the compressive service of polyvinyl alcohol fiber/cement composites under freezing condition after freeze-thaw cycle, the compressive test of polyvinyl alcohol fiber/cement composites under freezing condition was designed. Firstly, the samples were subjected to 0-300 freeze-thaw cycles, and then the samples were subjected to compressive test at −18℃ under continuous low temperature. The relationship between compressive stress and strain and its influence mechanism were analyzed. On this basis, combined with the principle of equiva-lent stress and statistical damage theory, the compressive constitutive model of polyvinyl alcohol fiber reinforced cement composites in frozen state was established, and the evolution characteristics of damage variable with the number of freeze-thaw cycles were discussed. The results show that: with the increase of freeze-thaw cycles, the peak compressive strength of polyvinyl alcohol fiber/cement composite decreases, the peak strain increases, and the brittleness is obvious at ultimate destruction. The elastic modulus of the sample under high freeze-thaw cycles is mainly provided by the pore ice in the sample. The established model can predict the compressive stress-strain relationship of polyvinyl alcohol fiber reinforced cement composites under freeze-thaw cycles. The freeze-thaw damage variate and total damage variate have significant correlation with freeze-thaw times. -
表 1 聚乙烯醇(PVA)纤维性能指标
Table 1. Performance index of polyvinyl alcohol fiber (PVA) fiber
Tensile strength
/MPaYoung's modulus
/GPaDiameter
/μmLength
/mmElongation
/%1600 40 40 12 6 表 2 PVA/水泥基复合材料(ECC)原材料配合比
Table 2. Mix proportion of raw materials of PVA/engineered cementitious composite (ECC)
Cement/
(kg·m−3)Fly ash/
(kg·m−3)Silica sand/
(kg·m−3)Water/
(kg·m−3)Superplasticizer/
(kg·m−3)mw/mb PVA fiber/
vol%252.64 1010.57 454.76 303.17 17.68 0.24 2.00 Notes: mw—Water consumption; mb—Cementitious material consumption; mw/mb—Water binder ratio. 表 3 PVA/ECC抗压理论模型相关参数
Table 3. Related parameters of PVA/ECC compression theoretical model
Freeze thaw cycles Parameter a Parameter b Related coefficient R2 0 0.58632 0.78675 0.85045 100 0.82549 0.98783 0.84895 200 0.63271 1.18297 0.87027 300 0.66074 1.52024 0.95792 -
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