单面盐冻条件下基于孔结构的玄武岩纤维混凝土抗压强度模型

Modeling of the Compressive Strength of Basalt Fiber Concrete Based on PoreStructure Under Single-side Freeze-Thaw Condition

通过单面冻融循环试验,研究不同玄武岩纤维掺量、冻融次数对混凝土抗冻性能和微观孔结构的影响;采用灰熵法分析微观孔结构参数对冻后混凝土抗压强度的影响规律;拟合得到不同冻融循环次数下玄武岩纤维贡献率公式;建立基于气孔比表面积、孔体积、玄武岩纤维贡献率的复合因素抗压强度模型。结果表明:不同纤维掺量下试件的抗压强度随冻融循环次数的增加逐渐减小,试件的含气量、气孔平均弦长和气孔间距系数随冻融次数的增加逐渐增大,试件的气孔比表面积随冻融次数的增加呈下降趋势。在本试验条件下纤维掺量为0.2%(体积分数)时混凝土抗冻性能最优。由灰熵分析可知,气孔比表面积和孔径小于100μm的孔体积与抗压强度的关联度较高。复合因素抗压强度模型与气孔比表面积、孔体积、玄武岩纤维贡献率之间回归效果显著,可预测单面冻融循环后玄武岩纤维混凝土抗压强度与孔结构的定量关系,评估寒冷地区玄武岩纤维混凝土的耐久性。

In this paper,the effects of different basalt fiber content and freeze-thaw times on the frost resistance and pore structure of concrete were stu-died through the single-side freeze-thaw cycle test.Grey entropy method was used to analyze the influence of pore structure parameters on the compressive strength of concrete after freeze-thaw cycles.The contribution rate formula of basalt fiber under different freeze-thaw cycles was obtained by fitting.The compressive strength model was established based on multiple factors such as pore specific surface area,pore volume and basalt fiber contribution rate.The results showed that the compressive strength of the different fiber contents specimens decreased with the increase of freeze-thaw cycles,the air content,average pore chord length and pore spacing coefficient of specimens increased with the increase of freeze-thaw cycles,and the specific surface area of pores decreased with the increase of freeze-thaw cycles.In this test,the frost resistance of concrete is optimal when the fiber content is 0.2vol%.According to the grey entropy analysis,the correlation degree of compressive strength with the pore specific surface area and pore diameter of less than 100μm is the highest.The regression effect of the compressive strength and the specific surface area of pores,pore volume and the contribution rate of basalt fiber is significant,which can predict the quantitative relationship between the compressive strength of basalt fiber concrete and the pore structure after the single-side freeze-thaw cycle test,and evaluate the durability of basalt fiber concrete in cold areas.