C40风积砂混凝土孔结构-强度模型研究

Pore Structure-strength Model of C40 Aeolian Sand Concrete

对C40风积砂混凝土进行宏观力学试验,结合扫描电镜(SEM)和核磁共振(NMR)技术,探讨风积砂混凝土孔隙结构与力学性能之间的内在关系,揭示其影响机理。利用回归分析,建立双因素下孔结构-强度模型。结果表明:随风积砂替代率的增加,风积砂混凝土微观结构先紧密后松散,孔隙率与无害孔占比先减后增大,抗压强度先增大后减小,替代率20%时抗压强度最高。适量的风积砂改善混凝土骨料级配,细化孔隙,使受荷面初始损伤减小,宏观性能增强。建立的以无害孔占比和无害孔隙率为因变量的孔结构-强度模型能较好地预测混凝土强度。

The macroscopic mechanical test of C40 aeolian sand concrete was carried out.Combined with scanning electron microscope(SEM)and nuclear magnetic resonance(NMR)technology,the internal relationship between pore structure and mechanical properties of aeolian sand concrete was discussed,and the influence mechanism was revealed.The regression analysis was used to establish the pore structure-strength model under two factors.The results show that with the increase of aeolian sand replacement rate,the microstructure of aeolian sand concrete is compact first and then loose,the porosity and harmless pore ratio decrease first and then increase,and the compressive strength increases first and then decreases.When the replacement rate is 20%,the strength is the highest.The appropriate amount of aeolian sand improves the aggregate gradation of concrete,refines the pores,reduces the initial damage of the loading surface,and enhances the macroscopic performance.The established pore structure-strength model with harmless pore ratio and harmless porosity as dependent variables can better predict the strength of concrete.