低品位石灰石粉与粉煤灰复掺效应对C50海工混凝土抗Cl^-迁移的影响

分析了低品位石灰石粉和粉煤灰不同掺配比例的复合效应对C50海工混凝土抗氯离子迁移性能及强度的影响,试验结果表明:随着低品位石灰石粉掺量的增加,C50海工混凝土3 d、7 d、28 d抗压强度增长幅度均在10%以上;将低品位石灰石粉按胶凝材料总体质量的15%替代粉煤灰与其进行1∶1复掺时,C50海工混凝土的氯离子迁移系数与电通量值均为最低,分别降低了70.5%和67.4%,抗Cl^-迁移性能达到最佳;SEM结果表明,低品位石灰石与粉煤灰的复掺比例为1∶1时,低品位石灰石粉微集料效应与粉煤灰的火山灰的复合效应可以改变混凝土的空隙特征,提高了混凝土的密实性、强度及抗渗性能。

Composite Effect of Low Grade Limestone Powder and Fly Ash on the Resistance of C50 Marine Concrete to Chloride Ion Migration

The influence of different mixing ratios of low-grade limestone powder and fly ash on chloride migration resistance of C50 Marine engineering concrete is analyzed,the test results show that with the increase of the content of low-grade limestone powder,the 3 d,7 d and 28 d compressive strength of C50 Marine concrete shows an upward trend with an increase of more than 10%.When low-grade limestone powder replaces fly ash with 15%of the total mass of cementitious material and performs 1∶1 compounding,the chloride migration coefficient and electric flux value of C50 marine concrete are the lowest,respectively reducing by 70.5%and 67.4%,but with the best chloride migration resistance.By comparing SEM photos of concrete test block with different mixing ratios,when the mixing ratio of low-grade limestone and fly ash is 1∶1,its micro-aggregate effect and pozzolanic effect of fly ash are fully superimposed,the resulting composite effect increases the compactness,strength and improves impermeability of the concrete.