海水环境下硅灰粉煤灰混凝土侵蚀—冻融特性试验研究

发布时间：2018-10-29 13:57

【摘要】：随着人类对海洋工程的不断开发与研究,海工混凝土逐渐发展起来。由于海工混凝土的应用环境十分恶劣,我国海洋工程的使用寿命普遍不足30年,混凝土的冻融和侵蚀也就渐渐成了大家的关注点。因此,如何保证海工混凝土结构具有良好的抗侵蚀性和抗冻性,便成了海洋工程安全性的关键所在。故研究硅灰粉煤灰混凝土的海水侵蚀与冻融性能,对提高海工混凝土的使用寿命具有重要实际意义。本文假设海水环境下的混凝土结构夏季主要受硫酸盐侵蚀作用,冬季主要受海水冻融作用。针对这种假设对单掺硅灰混凝土、单掺粉煤灰混凝土、复掺硅灰粉煤灰混凝土及普通混凝土进行了硫酸盐侵蚀与海水冻融单一作用及硅灰粉煤灰混凝土在两者先后作用下的劣化模型的研究。针对硫酸盐侵蚀试验、海水冻融试验及硫酸盐侵蚀-海水冻融先后交替试验采用相对动弹性模量、质量损失及相对抗压强度作为损伤评价指标,对混凝土的劣化规律进行了分析。作为应用基础研究,本论文的主要结论可为海洋工程中混凝土耐久性研究设计提供试验数据和理论参考。本文的研究内容主要概述为如下几方面:首先,对硅灰粉煤灰混凝土的强度发展规律进行了试验研究。结果表明,当硅灰掺量5%粉煤灰掺量30%时硅灰粉煤灰混凝土的抗压强度达到最高。其次,对复掺最佳掺量硅灰粉煤灰的混凝土(SFAC)、硅灰混凝土(SFC)、粉煤灰混凝土(FAC)、普通混凝土(PC)进行了硫酸盐侵蚀试验研究,以相对动弹性模量、质量损失、相对抗压强度作为损伤评价指标对四种混凝土在硫酸盐侵蚀试验后的变化规律进行了分析。结果表明,SFAC抗硫酸盐侵蚀性能最佳,且其质量与强度的变化趋势是先提高后下降,相对动弹性模量的变化趋势是不断下降。随后,对四种混凝土进行了海水冻融试验研究,以外观损伤、相对动弹性模量、质量损失及相对抗压强度作为损伤评价指标对冻融试验后的劣化规律进行了分析。结果表明,SFAC抗海水冻融性能同样是最佳的,并且随冻融循环次数的增加,其外观损伤越来越严重,质量、相对动弹性模量及强度不断下降。最后,先将相同作用时间下硫酸盐侵蚀与海水冻融分别作用于SFAC后其强度劣化程度进行了对比分析,发现海水冻融作用下的SFAC的强度劣化程度比硫酸盐侵蚀作用下的严重。然后对SFAC进行了硫酸盐侵蚀-海水冻融先后交替试验研究,分析了试件的外观损伤及质量损失、相对动弹性模量、相对抗压强度与交替循环次数之间的曲线关系。
[Abstract]:With the continuous development and research of marine engineering, marine concrete is gradually developed. Because the application environment of marine concrete is very bad and the service life of marine engineering in our country is less than 30 years, the freeze-thaw and erosion of concrete has gradually become the focus of attention. Therefore, how to ensure that marine concrete structure has good corrosion resistance and frost resistance becomes the key to the safety of marine engineering. Therefore, it is of great practical significance to study the seawater erosion and freeze-thaw performance of silica fume fly ash concrete in order to improve the service life of marine concrete. In this paper, it is assumed that the concrete structures under seawater environment are mainly affected by sulfate erosion in summer and freeze-thaw by sea water in winter. In view of this assumption, for concrete with single silica fume and fly ash, The single effect of sulfate erosion and sea water freezing and thawing and the deterioration model of silica fume fly ash concrete were studied in this paper. The relative dynamic elastic modulus, mass loss and relative compressive strength were used as the damage evaluation indexes for sulfate erosion test, seawater freeze-thaw test and sulphate-seawater freeze-thaw alternate test. The deterioration law of concrete is analyzed. As an applied basic research, the main conclusions of this paper can provide experimental data and theoretical reference for the research and design of concrete durability in marine engineering. The main contents of this paper are summarized as follows: firstly, the strength development law of silica fume fly ash concrete is studied experimentally. The results show that the compressive strength of silica fume fly ash concrete reaches the highest when the content of silica fume is 5% fly ash and the content of fly ash is 30%. Secondly, the sulphate erosion test of (SFAC), silica fume concrete, (SFC), fly ash concrete, (FAC), ordinary concrete (PC) with the best addition of silica fume fly ash is carried out, and the relative dynamic elastic modulus and mass loss are used. The relative compressive strength is used as the damage evaluation index to analyze the variation of four kinds of concrete after sulfate erosion test. The results show that the resistance of SFAC to sulfate erosion is the best, and the change trend of its quality and strength is first to increase and then to decrease, and the change trend of relative dynamic modulus of elasticity is decreasing. Then, four kinds of concrete were tested by sea water freeze-thaw test, and the damage, relative dynamic modulus of elasticity, mass loss and relative compressive strength were used as the damage evaluation indexes to analyze the deterioration law after freeze-thaw test. The results show that the anti-freezing and thawing performance of SFAC is also the best, and with the increase of freeze-thaw cycle times, the appearance damage becomes more and more serious, the mass, relative dynamic elastic modulus and strength decrease continuously. Finally, the strength deterioration degree of SFAC under the same action time was compared with that of seawater freeze-thaw. It was found that the strength deterioration of SFAC under seawater freezing and thawing was more serious than that under sulfate erosion. Then the SFAC was tested alternately by sulfate erosion and sea water freezing and thawing. The relationship between appearance damage and mass loss, relative dynamic elastic modulus, relative compressive strength and alternating cycle number was analyzed.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528;P75

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