Properties of gypsum particleboard with added mineral dolomite

Red pine (Pinus brutia) wood particles and dolomite mineral were used in varying proportions to form mineral-added gypsum particleboards. Mechanical, physical, and chemical properties of the boards were tested. The increasing  mineral content was found to improve the water absorption properties but the increased amount of  gypsum  in the mixture negatively affected the thickness swelling and water absorption properties. The usage of dolomite mineral in the board composition increased the internal bond properties and higher than the standard of 0,28 MPa. However, all types of boards had modulus of elastic, modulus of rupture and thermal conductivity results values below the standards.  Moreover, the thermal conductivity values decreased in all board types because of the reduction of the mineral dolomite. Thermal gravimetric analysis, Fourier transform infrared spectrometry tests were applied to examine the thermal and flame retardancy properties of inorganic materials, wood-gypsum composites, which are used at different rates for synergistic effect. The gypsum and dolomite amount affected the thermal variation, whereas the increment in the weight of the wood particles also increased the thermal degradation. It was determined that stresses at 850-980 cm-1 reveal Ca-O and Mg-O, reveal at 881cm-1 C-OH, weak vibration at 1619 cm-1 and a strong bond structure in the 1445-950-882 cm-1 bands. These bands express the characteristic presence of the CaO and MgO belonging to dolomite. The study demonstrated the feasibility of producing mineral-based gypsum board products using wood chips

Strengthening of infilled rc frames with carbon fiber composites

Çalışma kapsamında, birbirine bitişik, dolgu duvarlı çift taraflı sıva uygulamasının mümkün olmadığı betonarme yapılarda, tek yüz/çift yüz sıvanın etkisi ve çerçeveye olan katkısı, tek/çift taraflı karbon lifler ile güçlendirmenin yapıda nasıl bir performans göstereceği üzerinde çalışılmıştır. 6 adet, 1/3 ölçekli, tek açıklıklı, tek katlı numuneler üzerinde, bu tür sistemlerin yatay yük taşıma kapasiteleri, rijitlik ve enerji sönümleme gibi özelliklerini karşılaştırmak amacıyla deneysel ve analitik çalışmalar yapılmıştır. Numuneler; boş çerçeve, dolgu duvarlı / tek yüzü ve çift yüzü sıvalı çerçeve, dolgu duvarlı tek yüzü sıvalı tek yüzü/çift yüzü karbon lifli kompozitler ile güçlendirilmiş çerçeve olarak üretilmiş, her numune üzerinde yerdeğiştirme kontrollü yük artırımı yöntemi uygulanarak, numuneler deneye tabi tutulmuşlardır. Elde edilen sonuçlar kuramsal çözümlemeden elde edilen sonuçlar ile karşılaştırılmıştır. Deney sonuçlarına göre belirli işlem kriterlerine bağlı kalındığında söz konusu tek ve çift taraflı güçlendirme yönteminin her ikisinin de deney elemanlarının göçme davranışları, yatay yük taşıma gücü, enerji sönümleme miktarı ve rijitlik değerleri bakımından olumlu sonuçlar sağladığı ortaya konmuştur. Eşdeğer diyagonal basınç çubuğu kavramı kullanılarak dolgu duvarlar modellenmiş, analitik çalışma deneysel çalışmada elde edilen global davranışı yeterli bir yakınsaklıkla tahmin etmiştir. Anahtar Kelimeler: Karbon lifli kompozitler, dolgu duvarlı çerçeve, güçlendirme.The main contribution of this study is to analyze the effect of frames with single/double-sided plasters and its benefits on the frame in adjacent reinforced concrete structures with infilled walls where it is not possible to apply double-sided plasters as well as strengthening the walls with carbon fiber composites materials. Within the scope of work, 6 single-bay, one-story, 1/3 scaled reinforced concrete frames were designed which reflects the properties of reinforced concrete structures in practice and these specimens were tested to compare the lateral load capacity, rigidity and energy dissipation values of the specimens. Specimens were designed as bare frame, infilled frames with single/double side plastered and infilled frames of single side plastered, single side/double side strengthened with carbon fiber composites and tested under cyclic horizontal loads. Various researches have investigated the performance of reinforced concrete frames with infilled walls strengthened/unstrengthened with carbon fiber composites and applied single/double sided plastered and some principles were suggested for a successful application. The test results were compared with the numerical results obtained from the nonlinear static pushover analyses. For this purpose, the scope and purpose of the study, the concept of retrofitting, the effects of infilled walls to the behavior of rc frames and strengthening methods of infilled walls with carbon fiber composites were described in this study. It was highlighted that the strengthening method with carbon fiber composites would be used very frequently in the future. Also, the geometric properties of the specimens, the mechanical properties of materials used at producing the specimens and the procedure of the experimental study were explained. After the experimental results were described in detail, the analytical study was completed and the conclusions and recommendations based on the test results compared with the analytical studies. The test results proved that the both single and double sided strengthening method with carbon fiber composites applied on the infilled walls improved the lateral load capacity, rigidity and energy dissipation values of the specimens. The infilled walls were modeled by using equivalent diagonal strut concept and calibrated with the test results. The models generally predicted the global behavior of the specimens satisfactorily. The procedure of strengthening diagonally of the reinforced concrete frames with carbon fiber composites from one corner to other was suggested as a useful method and it was observed that the lateral load capacity of strengthened infilled frames is approximately two times bigger than the unstrengthened infilled frame with successful anchorage. More important, while the unstrengthened infilled frames shows bare frame behaviour after failure under cyclic horizontal loads, the strengthend frame dissipated more energy after failure of the specimen. CFRP anchors applied to the diagonal carbon fiber composites on the infilled walls provided to hold the CFRP on the infilled walls more efficiently. To increase the number of CFRP anchors from double sides on the infilled wall and at beam-column joints is recommended for efficient strengthening. Strengthened test specimens behaved more ductile and their maxiumum load carrying capacities were at higher values than unstrengthened specimens after failure of the specimen. Keywords: Carbon fiber, strengthening, infilled wall, equivalent strut, test