The use of cement and concrete is becoming increasingly widespread all over the world. However, the high energy consumption required for the production of clinker and the greenhouse gas emissions generated during production negatively affect both the economy and the environment. In the studies conducted for many years, researchers have found that the substitution of various pozzolans with cement provides both technical advantages and environmental benefits. The use of pozzolans in cementitious composites provides advantages such as the improvement of the physical and mechanical properties of the material, the conservation of the environment and the economy in terms of the evaluation of industrial wastes. In recent years, studies on the use of nanoparticles in cementitious composites are positively. In this study, it was aimed to investigate the properties of fresh and hardened cement mortars using micro silica as pozzolan and nano silica as nanoparticle. For this purpose, four different cement pastes and mortars mixtures were prepared by substituting 0%, 1%, 2%, 3% nano SiO2 (silica) cement in mortar mixtures containing 5% micro silica. The effects of the nano silica on the micro silica-containing cement paste on the consistency and setting time were investigated. The mortar mixtures produced were subjected to flexural and compressive strength tests on days 7, 28 and 90th. SEM images of mortar mixtures were taken. As a result, it was found that 2% nano silica admixture of 5% micro silica containing cement admixture affects the flexural and compressive strength positively, whereas 2% nano silica admixture increased the flexural strength by 13% and compressive strength by 7%.
The purpose of this work is to determine the effect of the antifreeze additive on the behavior of the concrete under high temperature. For this purpose, two different types of C20 class concrete were produced with reference and antifreeze additive. Fresh concrete was poured into plate molds, after 14 days standard curing, core samples of Ø5x10 cm dimensions were taken from plaque concrete. On day 90, the core samples were exposed to temperatures of 20, 200, 400, 550 and 700 °C for 3 hours and they cooled by air and water spray. Experiments on water absorption, ultrasound transit speed and compressive strength were carried out on the core samples. Microstructures were analyzed by X-ray diffraction method in concrete specimens applied at temperatures of 20 and 700 °C. As a result, it has been determined that the concrete with antifreeze strain that is least affected by the temperature of 700 °C is cooled water.
In this study, fires occurred in Artvin city center between 2013-2017 were examined in the context of "building fires". The data required for the study were taken from the annual statistical sheets obtained from the Department of Fire Brigade of Artvin Municipality. Building fires were classified according to "types, burning site building materials and combustion". Losses and material damage were investigated in these events and the causes for start of fires were presented for both public and private buildings. As a result, during the last 5 years, a total of 161 fire incidents took place in the province center of Artvin, and it was determined that building fires accounted for 65% of the total fires. It was seen that 51% of the burning buildings were reinforced concrete and 27% were made of wood; fires in public buildings were 10.5% of all building fires; 10% of the public buildings that the firefighters intervened in all fire incidents were completely burned while 34% of private buildings were completely burned; the first place for the reasons in output of private building fires was the "electricity contact"; in the building fires, 1 person lost his/her life and the financial loss arising from building fires was 3.739.000 TL.
Bu çalışmada, Giresun'da meydana gelen yangın olaylarına ait istatistikler 2011-2016 periyodunda ele alınmış olup, yangınların yıllara göre dağılımı, yanan yerin inşa malzemesine göre cinsi, itfaiyenin yangına müdahale durumu ve yangın çıkış nedenleri araştırılmıştır. 2012 yılı örneklem alınarak yangınların aylara göre istatiksel dağılımı oluşturulmuştur. Ayrıca, tüm yangınlar içinde en büyük orana sahip olan ev yangınları irdelenmiştir. Sonuç olarak 2011-2016 yılları arasında Giresun ilinde toplam 842 adet yangın olayının meydana geldiği, yangın çıkış nedenlerinde ilk sırada elektrik kontağının, ikinci sırada ise baca tutuşmasının yer aldığı, yangınların % 43'ünün başlangıçta söndürüldüğü, 2012 yılının ilk 3 ayında baca yangınlarının fazla olduğu, ev yangınlarının çoğunun betonarme yapılarda meydana geldiği tespit edilmiştir. Son olarak, yangın olaylarının azaltılması ile ilgili önerilerde bulunulmuştur.
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