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Ahmet Benli,Mehmet Karataş,M. Veysel Sastim 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.3
The aim of this study is to investigate the effect of the bond strength of self-compacting mortars (SCMS) produced from ground pumice powder (GPP) as a mineral additive. In this scope, six series of mortars including control mix were prepared that consist of 7%, 12%, 17%, 22% and 27% of ground pumice powder by weight of cement. A total of 54 specimens of 40×40×160 mm were produced and cured at the age of 3, 28 and 90-day for compressive and tensile strength tests and 18 specimens of 150×150×150 mm mortar were prepared and cured at 28 days for bond strength tests. Flexural tensile strength and compressive strength of 40×40×160 mm specimens were measured at the curing age of 7, 28 and 90-day. Mini V-funnel flow time and mini slump flow diameter tests were also conducted to obtain rheological properties. As a result of the study, it was observed that the SCMs containing 12% of GPP has the highest bond strength as compared to control and GPP mortars. Compressive strength slightly increased up to 12% of GPP.
Abir Soltani,Ahmet Beyareslan,Lütfiye Gençer,Soumaya Haouel Hamdi,Arbia Bousselmi,Moez Amri,Jouda Mediouni Ben Jemâa 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4
In recent years, as a consequence of climatic changes, the leafminer Liriomyza cicerina had emerged as a serious pest in chickpea crops causing considerable damage in Tunisia. Thus, the search of control methods is necessary. The aim of this research was to monitor and identify the naturally occurring parasitoids of the chickpea leafminer Liriomyza cicerina in insecticide-free chickpea-growing areas located in North-Western Tunisia. Chickpea leaves with mines were weekly sampled from Beja and Kef sites during 2016 and 2017 and kept to observe and count emerging leafminer and parasitoid adults in the laboratory. Results revealed that L. cicerina parasitoids complex species included three hymenopteran parasitoids namely Opius monilicornis (Fisher, 1962) (Braconidae); Diglyphus isaea (Walker, 1838) (Eulophidae) and Diaulinopsis arenaria (Erdös, 1951) (Eulophidae). These parasitoids were identified and recorded for the first time in Tunisia on L. cicerina with parasitism rate varied between 13% and 52.5%. The most common species was O. monilicornis. The correlation between infestation rate on chickpea plants and number of emerged three parasitoids was calculated revealing high significant and positive correlations. The diversity index (H′) was also calculated. The three parasitoids were found in two sites Beja and Kef; while the diversity differed during the developmental stage of chickpea crops.
Mehmet Karataş,Bilal Balun,Ahmet Benli 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.2
This paper presents the effect of aggregate type on high temperature resistance of self-compacting mortars (SCM) produced with normal and lightweight aggregates like expanded perlite and pumice. Silica fume (SF) and fly ash (FA) were used as mineral additives. Totally 13 different mixtures were designed according to the aggregate rates. Mini slump flow, mini V-funnel and viscometer tests were carried out on the fresh mortar. On the other hand, bulk density, porosity, water absorption and high temperature tests were made on the hardened SCM. After being heated to temperatures of 300, 600 and 900°C, respectively, the tensile strength in bending and compressive strength of mortars determined. As a result of the experiments, the increase in the use of lightweight aggregate increased total water absorption and porosity of mortars. It is observed that, the increment in the usage of lightweight aggregate decreased tensile strength in bending and compressive strengths of mortar specimens exposed to high temperatures but the usage of up to 10% expanded perlite in mortar increased the compressive strength of specimens exposed to 300ºC.
Fuat Koksal,Cem Bacanli,Ahmet Benli,Osman Gencel 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.82 No.1
The brittleness of concrete can be overcome by fiber reinforcement that controls the crack mechanisms of concrete. Corrosion-related durability issues can be prevented by synthetic fibers (SFs), while macro synthetic fibers have proven to be particularly effective to provide ductility and toughness after cracks. This experimental study has been performed to investigate the comparative flexural and mechanical behavior of four different macro-synthetic fiber-reinforced concretes (SFRCs). Two polyamide fibers (SF1 and SF2) with different aspect ratios and two different polypropylene fiber types (SF3 and SF4) were used in production of SFRCs. Four different SFRCs and reference concrete were compared for their influences on the toughness, compressive strength, elastic modulus, flexural strength, residual strength and splitting tensile strength. The outcomes of the study reveal that the flowability of reference mixture decreases after addition of SFs and the air voids of all SFRC mixtures increased with the addition of macro-synthetic fibers except SFRC2 mixture whose air content is the same as the reference mixture. The results also revealed that with the inclusion of SFs, 11.34% reduction in the cube compressive strength was noted for SFRC4 based on that of reference specimens and both reference concrete and SFRC exhibited nearly similar cylindrical compressive strength. Results illustrated that SFRC1 and SFRC4 mixtures consistently provide the highest and lowest flexural toughness values of 36.4 joule and 27.7 joule respectively. The toughness values of SFRC3 and SFRC4 are very near to each other.
Stress-strain behavior of geopolymer under uniaxial compression
Mehrzad Mohabbi Yadollahi,Ahmet Benli 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.4
The various types of structural materials that are available in the construction industry nowadays make it necessary to predict their stress-strain behavior. Geopolymer are alternatives for ordinary Portland cement concrete that are made from pozzolans activation. Due to relatively new material, many mechanical specifications of geopolymer are still not yet discovered. In this study, stress-strain behavior has been provided from experiments for unconfined geopolymers. Modulus of Elasticity and stress-strain behavior are critical requirements at analysis process and knowing complete stress-strain curve facilitates structural behavior assessment at nonlinear analysis for structures that have built with geopolymers. This study intends to investigate stress–strain behavior and modulus of elasticity from experimental data that belongs for geopolymers varying in fineness and mix design and curing method. For the sake of behavior determination, 54 types of geopolymer are used. Similar mix proportions are used for samples productions that have different fineness and curing approach. The results indicated that the compressive strength ranges between 7.7 MPa and 43.9 MPa at the age of 28 days curing.