矿物掺合料混合骨料混凝土冻融性能及微观试验研究

发布时间：2018-04-23 03:32

  本文选题：混合骨料混凝土 + 矿物掺合料　； 参考：《内蒙古工业大学》2013年硕士论文

【摘要】：浮石取代部分碎石骨料,可以使混合骨料混凝土获得良好的抗冻性能,而为了进一步改善混合骨料混凝土的抗冻性,可尝试在混凝土中掺入矿物掺合料取代部分水泥。这样,不仅能改善混凝土的抗冻性能,还减少了水泥用量,有效利用了工业废渣。 本文针对浮石替代率为30%的混合骨料混凝土,在单掺和复掺不同种类和掺量的矿物掺合料后,研究其抗冻性能,并分析改善混凝土抗冻性能的最佳矿物掺合料的组合。试验分别采用单掺30%粉煤灰、复掺20%粉煤灰和10%硅粉、复掺20%粉煤灰和10%矿粉、复掺20%粉煤灰和10%石粉替代水泥,研究矿物掺合料对混合骨料混凝土抗冻性能的影响。 试验方法是通过快速冻融法测试混凝土的宏观表现,再利用扫描电子显微镜(SEM)分析微观结构和水化产物,以宏观与微观相结合的手段全面分析矿物掺合料对混合骨料混凝土抗冻性能的影响。快冻法以质量损失率和相对动弹性模量损失率两项指标衡量混凝土的抗冻性,SEM分析以观察混凝土最薄弱环节—界面过渡区(ITZ)的微观结构为依据评价混凝土的抗冻性。 快冻法试验结果表明：掺入30%矿物掺合料的混凝土与未掺矿物掺合料的混凝土相比,抗冻性能有不同程度的降低。粉煤灰与硅粉复掺的混合骨料混凝土抗冻性能最高,且接近于未掺掺合料时的抗冻性,粉煤灰与矿粉复掺次之,单掺粉煤灰较低,粉煤灰与石粉复掺最低。 SEM试验结果表明：掺入30%矿物掺合料的混凝土界面结构与未掺矿物掺合料的混凝土相比均有不同程度的劣化,粉煤灰与石粉复掺劣化最严重,单掺粉煤灰次之,粉煤灰与矿粉复掺以及粉煤灰与硅粉复掺的界面稍有劣化,界面结构致密。此外,碎石-水泥石比浮石-水泥石界面结构劣化严重,说明浮石骨料可改善混凝土的界面过渡区。 复掺粉煤灰和硅粉的混合骨料混凝土具有良好的界面过渡区结构和抗冻性能,因此,研究成果可为寒冷地区混凝土材料的应用提供试验和理论依据。
[Abstract]:In order to further improve the frost resistance of mixed aggregate concrete, pumice stone can replace some crushed stone aggregate. In order to further improve the frost resistance of mixed aggregate concrete, mineral admixture can be used to replace some cement. In this way, not only the frost resistance of concrete can be improved, but also the amount of cement can be reduced, and industrial waste slag can be effectively utilized. In this paper, the antifreeze property of mixed aggregate concrete with 30% pumice substitution rate is studied after mixing with mineral admixtures of different kinds and amounts, and the best mineral admixture combination to improve the frost resistance of concrete is analyzed. 30% fly ash, 20% fly ash and 10% silica powder, 20% fly ash and 10% mineral powder, 20% fly ash and 10% stone powder were added to replace cement respectively. The effect of mineral admixture on the frost resistance of mixed aggregate concrete was studied. The test method is to test the macroscopic behavior of concrete by rapid freeze-thaw method, and then analyze the microstructure and hydration products by scanning electron microscope (SEM). The effect of mineral admixture on the frost resistance of mixed aggregate concrete was analyzed by means of macro and micro analysis. The frozen resistance of concrete was evaluated by using the two indexes of mass loss rate and relative dynamic elastic modulus loss rate. The freezing resistance of concrete was evaluated on the basis of observing the microstructure of the weakest link and interface transition zone (ITZ) of concrete. The results of rapid freezing test show that the frost resistance of concrete with 30% mineral admixture is lower than that of concrete without mineral admixture. The frost resistance of mixed aggregate concrete mixed with fly ash and silica fume is the highest, and it is close to the frost resistance of the concrete without adding fly ash and mineral powder. The mixture of fly ash and mineral powder is the second, only fly ash is lower, and fly ash and stone powder are the lowest. The results of SEM test show that the interfacial structure of concrete mixed with 30% mineral admixture has different degrees of deterioration compared with that of concrete without mineral admixture, the degradation of fly ash and stone powder is the most serious, and only fly ash is the second. The interface between fly ash and mineral powder and between fly ash and silica powder is slightly deteriorated and the interface structure is compact. In addition, the interface structure of pumice and cement stone is worse than that of pumice and cement stone, which indicates that pumice aggregate can improve the interfacial transition zone of concrete. The mixed aggregate concrete mixed with fly ash and silica fume has good interfacial transition zone structure and frost resistance. Therefore, the research results can provide experimental and theoretical basis for the application of concrete materials in cold regions.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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