M.Sc. Tezi Görüntüleme

Student: Ali Recai YILDIZ
Supervisor: Assis. Prof. Dr. Şirin KURBETÇİ
Department: İnşaat Mühendisliği
Institution: Graduate School of Natural and Applied Sciences
University: Karadeniz Technical University, Turkey
Title of the Thesis: Effect of Freeze-Thaw Cycling on the Performance of Self Compacting Concretes
Level: M.Sc.
Acceptance Date: 10/3/2006
Number of Pages: 110
Registration Number: i1678

      Self-consolidating concrete, under gravitational effects, takes the shape of the form in which it is poured, makes the construction of heavily congested structural elements and hard to reach areas easier without vibration. Thus, the variations in the mechanical properties of concrete can be eliminated and the production of high performance concrete can be made possible as well.

In the investigation, ten concrete mixes incorporating silica fume and fly ash along with their combinations were produced. Silica fume and fly ash was substituted by cement while the total binder in concrete mixes was being kept constant as 550 kg/m3. Five prisms measuring 10x10x40 cm from each mix were prepared. Three of the prisms were kept in standard curing condition and two of them were exposed in the atmosphere in the laboratory right after their production. One prism kept in standard curing condition for 28 days was tested for flexural and compressive strength. Then, one prism from each exposure was subjected to rapid freeze-thaw cycling. The rest prisms from each exposure were remained in associated conditions throughout experimentation. At the end of 300 rapid freezing-thawing cycles, the flexural and compressive strength, along with abrasion, sorptivity and capillary sorptivity properties of the concrete prisms were determined.

      Based on the results obtained after rapid freeze-thaw cycling, regardless of curing conditions, the strength loss of concretes containing mineral additives is lower than the strength loss of concretes without mineral additives. Concretes incorporating 6% silica fume and 24% fly ash were affected least from the detrimental effects of freeze-thaw cycling. Regardless of curing conditions, silica fume and fly ash substitution at low ratios seemed to decrease the extent of abrasion; however, the abrasion seems to increase slightly as the substitution ratio increases. Irrespective of curing conditions, fly ash replacement did not have a significant effect on sorptivity; whereas, it seemed to decrease in concretes with silica fume only as well as in concretes incorporating silica fume and fly ash combination as the substitution ratio increases. In all curing conditions, capillary sorptivity coefficient decreases as the mineral substitution ratio increases; however, the trend seems not to keep up to the same extent as with the substitution ratio.

      Keywords: Self-compacting concrete, Fly ash, Silica fume, Abrasion, Capillary sorptivity