海洋环境下粉煤灰蒸养混凝土抗离子侵蚀研究

Research on Ion Erosion Resistance of Steam-Cured Fly Ash Concrete Under Marine Environment

摘要:

为探究不同粉煤灰掺量与养护制度对混凝土宏观力学性能、抗离子侵蚀及微观孔隙结构的影响规律,揭示粉煤灰掺量、养护制度与混凝土宏微观性能及抗离子侵蚀能力的内在关联,通过力学性能、电位滴定和孔结构测试,系统研究了不同粉煤灰掺量和养护制度下混凝土宏观、微观性能。结果表明,混凝土抗压强度随粉煤灰掺量的增加而降低;相同粉煤灰掺量下,蒸汽养护(蒸养)混凝土1 d抗压强度比标准养护(标养)混凝土提高了36.2%。随着粉煤灰掺量的增加,蒸养混凝土氯离子结合能力逐渐提升,硫酸根离子反应系数略有降低,当粉煤灰掺量为45%时,蒸养混凝土宏观、微观性能最佳。蒸养试件的孔径峰值高于标养试件,蒸养导致试件过渡孔和毛细孔占总空隙率的比例升高、凝胶孔的占比降低。

Abstract:

The influence laws of different fly ash dosage and curing regimes on the macroscopic mechanical properties, ion erosion resistance and microscopic pore structure of concrete are explored. The internal correlations among fly ash dosage, steam curing regime, macro-microscopic properties and ion erosion resistance of concrete are revealed. Through mechanical property tests, potentiometric titration and pore structure tests, the macroscopic and microscopic properties of concrete with different fly ash dosages and curing regimes are systematically investigated. The results show that the compressive strength of concrete decreases with the increase of fly ash dosage. At the same fly ash dosage, the 1 day compressive strength of steam-cured concrete is 36.2% higher than that of standard-cured concrete. With the increase of fly ash dosage, the chloride ion binding capacity of steam-cured concrete is gradually enhanced and the sulfate ion reaction coefficient decreases slightly. When the fly ash dosage reaches 45%, the steam-cured concrete exhibits the optimal macroscopic and microscopic properties. The pore size peak of steam-cured specimens is higher than that of standard-cured specimens and the steam curing increases the proportion of transition pores and capillary pores in the total porosity, while reducing the proportion of gel pores.