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- MakaleYalnız künye2014The effects of macro synthetic fiber reinforcement use on physical and mechanical properties of concrete
Bolat, Hakan; Şimşek, Osman; Çullu, Mustafa; Durmuş, Gökhan; Can, Ömer
Attempts to find a construction material having increased strength, ductility, toughness, and durability have led to interest in high performance fiber reinforced concrete. The use of such materials increases day by day. When the fibers are distributed in a homogeneous way and used in appropriate quantity inside the concrete, they reduce cracks, contribute to tensile strength, toughness, ductility and durability, and improve other mechanical properties. In this study, four types of concrete were produced: steel fiber (SFRC), polyester fiber (PYFRC), polypropylene fiber (PPFRC) reinforced concrete and a reference sample made of plain concrete (R1); these were then compared to one another. The ratio of fibers was used 4.25% of volume of concrete. The effects of the different types of fiber on hardened concrete were determined by conducting physical and mechanical experiments. Compressive strength, surface hardness, ultrasonic pulse velocity, carbonation, abrasion, capillarity and freeze-thaw resistance experiments were conducted on hardened concretes. SFRC had higher 12.4%, PYFRC 3.4% higher and PPFRC 4.3% lower compressive strength with respect to R1. PPFRC showed 8.04% higher compressive strength than R1 when it was determined by the surface hardness method. SFRC showed 5.4% higher compressive strength than R1 when we applied the ultrasonic pulse velocity method. In the abrasion experiment, the highest abrasion was found in SFRC with ∼0.5%, while the lowest was found in PPFRC at ∼0.18%. The highest and lowest amount of capillary water absorption was seen in R1 and PYFRC, respectively. In a carbonation experiment, SFRC was determined ∼130.8% higher than R1. It was concluded that the types of fiber used for reinforcement influenced the physical and mechanical properties of the concrete.
- MakaleYalnız künye2013The effects of antifreeze use on physical and mechanical properties of concrete produced in cold weather
Çullu, Mustafa; Arslan, Metin
This study examined the effects of antifreeze on the physical and mechanical properties of the concrete which are produced in cold weather. 30% Calcium Nitrate and 5% hydroxyethylaminemixture (HEA), Calcium Nitrate (KN) and Polyhydroxy Amine (PA) were used as additives in antifreeze. Prepared concrete samples were placed in a formwork and exposed to the frost at 0 °C, -5°C, -10°C, -15°C and -20°C for 2 days. Afterwards, concrete samples in the freezer were cured at the room temperature until the 28th day and permeable pore space volume, water absorption ratio, density, capillarity ratio, impermeability, compressive strength, static modulus of elasticity, Poisson's ratio and tensile strength values of the concrete samples were determined after the curing. In conclusion, 30% Calcium Nitrate and 5% hydroxyethylaminemixture (HEA) were found to be giving the best performance among the antifreeze types. The physical and mechanical properties of the concrete were negatively affected from all antifreeze types due to the temperature decrease of the exposed fresh concrete.