Ph.D. Tezi Görüntüleme | |||||||||||||||||||||
|
|
||||||||||||||||||||
Summary: The performance of concretes and mortars produced using different mineral additives is investigated in this study. In this context, three series of concrete mixtures containing of 10%silica fume, 20% fly ash and 20% granulated blast furnace slag were produced. Mixtures without mineral additives were also produced for making comparisons. Totally 250 specimensof 15 cm cubes were prepared and they were kept in 2% sodium sulfate and magnesium sulfate solutions, seawater provided from Karadeniz and in the tap water, respectively. At certainintervals, concrete specimens exposed to sulfates were examined for surface hardness, ultrasound measurements and compressive strength. Meanwhile, the specimens wereperiodically monitored for surface deterioration. Within the context of experimental program, mortars without mineral additives, with silica fume, with fly ash and with granulated blastfurnace slag were produced and 4x4x16 cm prisms were prepared. The addition rate of mineral admixtures to mortar was 20% in all cases. The mortar prisms prepared were kept in 2%magnesium sulfate solution at room temperature, at 5oC and at 40oC throughout the testing program.Concretes with blast furnace slag cured in standard curing condition yielded the highest strength. This is followed by concretes with silica fume at early ages and concretes with fly ashat later ages. Concretes without mineral additives yielded the lowest strength throughout experimentation. The deterioration pattern of concretes subjected to magnesium sulfate was acombination of surface softening and cracking, while concretes subjected to sodium sulfate solution have indicated a similar deterioration pattern without surface softening. The mortarprisms immersed in magnesium sulfate solution at room temperature have indicated a deterioration pattern of disintegration. In addition to findings given above, some additionalfindings obtained from the study may be underlined that mineral admixtures have increased the performance of concrete subjected to sulfate solutions and the deterioration mechanismobserved in the mortar prisms has indicated a different pattern depending on the temperature. Key words: Fly ash, Granulated blast furnace slag, Silica fume, Sulfate attack, Seawater,Performance, Tobermorite, Ettrengite, Thaumasite. |