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Effects of sulphuric acid on mechanical and durability properties of ECC confined by FRP fabrics
Gulsan, Mehmet Eren,Mohammedameen, Alaa,Sahmaran, Mustafa,Nis, Anil,Alzeebaree, Radhwan,Cevik, Abdulkadir Techno-Press 2018 Advances in concrete construction Vol.6 No.2
In this study, the effects of sulphuric acid on the mechanical performance and the durability of Engineered Cementitious Composites (ECC) specimens were investigated. The carbon fiber reinforced polymer (CFRP) and basalt fiber reinforced polymer (BFRP) fabrics were used to evaluate the performances of the confined and unconfined ECC specimens under static and cyclic loading in the acidic environment. In addition, the use of CFRP and BFRP fabrics as a rehabilitation technique was also studied for the specimens exposed to the sulphuric acid environment. The polyvinyl alcohol (PVA) fiber with a fraction of 2% was used in the research. Two different PVA-ECC concretes were produced using low lime fly ash (LCFA) and high lime fly ash (HCFA) with the fly ash-to-OPC ratio of 1.2. Unwrapped PVA-ECC specimens were also produced as a reference concrete and all concrete specimens were continuously immersed in 5% sulphuric acid solution ($H_2SO_4$). The mechanical performance and the durability of specimens were evaluated by means of the visual inspection, weight change, static and cyclic loading, and failure mode. In addition, microscopic changes of the PVA-ECC specimens due to sulphuric acid attack were also assessed using scanning electron microscopy (SEM) to understand the macroscale behavior of the specimens. Results indicated that PVA-ECC specimens produced with low lime fly ash (LCFA) showed superior performance than the specimens produced with high lime fly ash (HCFA) in the acidic environment. In addition, confinement of ECC specimens with BFRP and CFRP fabrics significantly improved compressive strength, ductility, and durability of the specimens. PVA-ECC specimens wrapped with carbon FRP fabric showed better mechanical performance and durability properties than the specimens wrapped with basalt FRP fabric. Both FRP materials can be used as a rehabilitation material in the acidic environment.
Mechanical and durability properties of fly ash and slag based geopolymer concrete
Kurtoglu, Ahmet Emin,Alzeebaree, Radhwan,Aljumaili, Omar,Nis, Anil,Gulsan, Mehmet Eren,Humur, Ghassan,Cevik, Abdulkadir Techno-Press 2018 Advances in concrete construction Vol.6 No.4
In this paper, mechanical and short-term durability properties of fly ash and slag based geopolymer concretes (FAGPC-SGPC) were investigated. The alkaline solution was prepared with a mixture of sodium silicate solution ($Na_2SiO_3$) and sodium hydroxide solution (NaOH) for geopolymer concretes. Ordinary Portland Cement (OPC) concrete was also produced for comparison. Main objective of the study was to examine the usability of geopolymer concretes instead of the ordinary Portland cement concrete for structural use. In addition to this, this study was aimed to make a contribution to standardization process of the geopolymer concretes in the construction industry. For this purpose; SGPC, FAGPC and OPC specimens were exposed to sulfuric acid ($H_2SO_4$), magnesium sulfate ($MgSO_4$) and sea water (NaCl) solutions with concentrations of 5%, 5% and 3.5%, respectively. Visual inspection and weight change of the specimens were evaluated in terms of durability aspects. For the mechanical aspects; compression, splitting tensile and flexural strength tests were conducted before and after the chemical attacks to investigate the residual mechanical strengths of geopolymer concretes under chemical attacks. Results indicated that SGPC (100% slag) is stronger and durable than the FAGPC due to more stable and strong cross-linked alumina-silicate polymer structure. In addition, FAGPC specimens (100% fly ash) showed better durability resistance than the OPC specimens. However, FAGPC specimens (100% fly ash) demonstrated lower mechanical performance as compared to OPC specimens due to low reactivity of fly ash particles, low amount of calcium and more porous structure. Among the chemical environments, sulfuric acid ($H_2SO_4$) was most dangerous environment for all concrete types.
Noorazeela Zainol ABIDIN,Zulkefly Abdul KARIM,Mohd Shahidan SHAARI,Nisful LAILA 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.10
This study investigates the effects of FDI and other macroeconomic variables on Total Factor Productivity (TFP) in selected ASEAN+3 countries from 1981 till 2016. Total Factor Productivity (TFP) for each ASEAN+3 country was constructed using the Malmquist productivity index method. Then, a panel ARDL framework (dynamic heterogeneous panel), namely Pooled Mean Group (PMG), Mean Group (MG), and Dynamic Fixed Effect (DFE) are employed in examining the effects of FDI and other controlling variables on TFP. The new findings show that FDI has a significant and positive impact on TFP in the long run and the short run in ASEAN+3 countries. Besides, the results also reveal that in the long run, other variables such as the average number of years of schooling and the ratio of high-skilled to low-skilled labor also have a significant and positive effect on TFP. However, economic openness, government expenditure on R&D, and interaction between countries and FDI have a negative and significant impact on TFP. These findings implied that the recipient countries must ensure their political stability and offer various incentives to attract more investors. Furthermore, the influx of foreign investors, especially large ones and lower costs, should be encouraged by each country as FDI inflows can boost their TFP growth.
Muscular and collagenous cerebellar choristoma in a dog
Angel Ripplinger,Stella Maris Pereira de Melo,Dênis Antonio Ferrarin,Marcelo Luís Schwab,Mathias Reginatto Wrzesinski,Júlia da Silva Rauber,Mariana Martins Flores,Glaucia Denise Kommers,Alexandre Mazz 대한수의학회 2022 Journal of Veterinary Science Vol.23 No.2
This report aims to describe the first case of muscular and collagenous choristoma in a dog. A 10-yr-old female mixed-breed dog presented with lateral recumbence, vocalization, positional vertical nystagmus, divergent strabismus, anisocoria, and status epilepticus. The clinical condition evolved to stupor and ultimately, death. Necropsy revealed a white mass causing an irregular increase in the volume of the cerebellar vermis. In histological analysis, a well circumscribed, unencapsulated mass was observed in the cerebellum, consisting of fibers of striated skeletal muscle and collagen fibers, mostly mineralized. Based on the histopathological and histochemical findings, a diagnosis of muscular and collagenous cerebellar choristoma was made.