Mostly, there are investigations about the shrinkage of the concrete. In that research, only the effect of the coarse aggregate on shrinkage is investigated; the fine aggregate is taken into account with the coarse aggregate. When the aggregate grain size increases or decreases, which results will be obtained and how this situation affecting the shrinkage should be determined. In this study, firstly, a widely literature research related to the effect of the aggregate grain size on the shrinkage were carried out. Then, with the help of the experimental studies, it is possible to determine the effect of the aggregate grain size on the shrinkage of the concrete and mortar whether if the aggregate grain size decreases or increases. These experimental researches are on the restrained and drying (free) shrinkage, moreover the compressive and tensile strength tests were carried out. When the effect of the aggregate grain size on the shrinkage, the shrinkage of the mortars with the 4mm maximum grain size is low if the amount of the aggregate is high. Compared to the mortars (especially maximum grain size is 9mm) the shrinkage value is lower. When the concrete with the 16mm maximum grain is produced according to the same ratios of the mortar, the shrinkage of the concrete is less than the shrinkage of the mortar. According to these results, the shrinkage decreases while the maximum grain size is bigger than 9 mm. Coarse aggregate restrains the development of the crack and supply as a micro-crack. The aggregate restrain the shrinkage if the strength of the concrete is high. The compressive and tensile strengths of the mortar and concrete are high at 28 days and decrease at 42 days because the microcracks reduce the strengths a little.

Although timber was used extensively as a structural material for traditional buildings in Turkey in the past, usage of structural timber decreased significantly over time and timber has been largely replaced by other materials. As timber is a natural, durable and sustainable material, it would be desirable to re-introduce timber structural elements to contemporary construction in a form that is appealing to industry. Timber-glass composite structural elements are potentially a good candidate for this purpose. To that end, a series of tests were conducted on load-bearing timber-glass composites in order to understand the long–term structural performance of the composite material under atmospheric conditions; to decrease the recurring cost of repair and maintenance; and to minimize the exhaustion of raw materials and energy. In this paper, the first part of this experimental work is presented, which focuses on the durability of timber-glass composite under the effects of accelerated aging, carried out on small-sized timber-glass composite specimens. Accelerated aging effects were observed under wetting-drying, freezing-thawing, UV effects, resistance to acids and high temperature. The mechanical strength of the timber-glass composite specimens before and after the effect of accelerated aging was measured by adhesion and shear strength tests and a comparative analysis of the results was carried out. The results of the experiments indicate that timber-glass composite is suitable to be used under protection from environmental conditions.

No abstract

Polycarbonate is a durable, strong, transparent new polymer material. It is used as building material or element because of its properties such as high strength, light transmittance, recycling, lightweight and vapor transmittance. Unlike most thermoplastics, polycarbonate undergo large plastic deformations cracking or breaking so it can be produced with different dimensions and shapes. Polycarbonate panels consist of different numbers of walls with different thickness. Generally, the properties of the polycarbonate panels are determined with all structures of the panels. However, the effect of the number of walls should be determined on the characteristic properties of the polycarbonate panels. Especially transparency and thermal transmittance should be effected by the number of walls. In this study, characteristic properties of the polycarbonate panels such as light transmittance, water vapor transmission, impact and bending strengths, should be tested with different numbers of walls or thickness. Finally, the characteristic properties of the polycarbonate panels are suitable when the number of walls and thickness are low. E50: 50 % impact energy (J) m: The constant weight of impact body (kg) g 'The gravity velocity (9,81 m/s 2 ) H50: The height of 50 % impact energy (m) H50 is calculated by below formula; Ha: The smallest height (m) ΔH: The change in the height (m) A: The damaged and non-damaged samples according to the heights N: The total number of damaged and non-damaged samples The standard deviation 1s calculated according to change in the heights by below formula; s: The standard deviation ΔE: The difference in energy A: The damaged and non-damaged samples according to the heights N: The total number of damaged and non-damaged samples B: The damaged and non-damaged samples according to the sguare of heights In Table 10. 50 % impact energy and the standard deviation is demonstrated. YATAĞAN / The Effect

Especially, the shrinkage has an essential role for the cement based materials. The shrinkage which is defined as volume change affects the strength and the characteristic properties of the materials and form the degradation mechanisms. Nowadays, according to some researches, the cracks of the restrained shrinkage has an important effect on the deformations of the materials. In laboratory researches, the crack width of the restrained shrinkage is measured by the electron microscope. On the other side, the amount of the shrinkage is measured for the drying shrinkage. The crack width of the drying shrinkage is not measured because it is no possible to measure the crack width accurately and the destructive methods are used to measure the development of the cracks of the drying shrinkage. In this study, the crack widths of the drying shrinkage are measured by the electron microscope used for the measurement of the crack widths of the restrained shrinkage. Therefore, the relationship between the amount of the drying shrinkage and the crack widths is determined. Also, the difference between the crack widths of the drying and restrained shrinkage is evaluated. Besides, there is a relationship between the drying shrinkage and restrained shrinkage. As a result of the microscopic observations of the crack widths of the drying and restrained shrinkage, if the dimensions of the ring samples and drying shrinkage samples are close each other and there are no different stresses, the drying shrinkage is just enough to determine the shrinkage behavior of the plain concrete. Especially, when the maximum aggregate grain size increases, the aggregate holds the cracks as the micro-cracks and supply the self-healing of the cement based materials because when the crack width is constant or develops less, the smaller widths become to close and forms self-healing of the cement based materials.