542,654 research outputs found
Lazarus Lami Lami
No full textLazarus Lami Lami, delegate from Goulburn Island and native Pastor, at the opening of the United Church, corner of Smith and Peel Streets. Lazarus Lami Lami is on end seat of official guests on platform.Cheater, F. and Cheater, K
Influence of hygrothermal ageing on the mechanical properties of CFRP-concrete joints and of their components
No full textExternally bonded (EB) fiber reinforced polymer (FRP) composites have been effectively employed to strengthen existing reinforced concrete (RC) structures. However, relatively limited information is available regarding the long-term behavior of FRP-concrete joints. In this paper, different experimental tests are employed to investigate the effect of hygrothermal ageing on the bond behavior of a carbon FRP composite applied to a concrete substrate and on the mechanical properties of the epoxy resin and FRP composite considered. The experimental campaign includes tensile tests of epoxy resin, carbon FRP (CFRP) coupon, pull-off tests of the CFRP bonded to the concrete substrate, and single-lap direct-shear tests of CFRP-concrete joints. Specimens were conditioned in warm water (38 ± 2 °C) for 500, 1000, and 1500 h to accelerate the possible degradation induced by a simulated high-moisture exposure environment. The parameters studied were the tensile properties of epoxy resin and CFRP coupons and the fracture energy of the CFRP-concrete interface, which was computed from the CFRP strain measured in the single-lap direct-shear tests using the digital image correlation (DIC) method. Results indicate that both the mechanical properties of the epoxy resin and the CFRP-concrete interface fracture energy were slightly affected by the exposure conditions
Durability of fabric-reinforced cementitious matrix (FRCM) composites: A review
No full textStrengthening and rehabilitation of masonry and concrete structures by means of externally bonded fabric-reinforced cementitious matrix (FRCM) (also referred to as textile reinforced mortar (TRM) composites was proposed as an alternative to the use of fiber-reinforced polymer (FRP) composites due to their good mechanical properties and compatibility with the substrate. However, quite limited studies are available in the literature regarding the long-term behavior of FRCM composites with respect to different environmental conditions. This paper presents a thorough review of the available researches on the long-term behavior of FRCM composites. Namely, (i) test set-ups employed to study the FRCM durability, (ii) conditioning environments adopted, and (iii) long-term performance of FRCM and its component materials (mortar and fiber textile) subjected to direct tensile and bond tests, are presented and discussed. Based on the available results, some open issues that need to be covered in future studies are pointed out
Experimental and numerical analysis of CFRP-concrete joint bond behavior after exposure to wet-dry cycles
No full textFiber-reinforced polymer (FRP) composites have been largely used for strengthening and retrofitting reinforced concrete members in the last few decades. However, limited information is available regarding their performance after prolonged exposure to different environmental conditions. In this paper, the effect of wet-dry cycles on the bond behavior of carbon FRP-concrete joints tested using a single-lap direct shear test set-up is investigated. Specimens were exposed to 50 wet-dry cycles, each comprised of 6 h of immersion in water at 25 °C followed by 18 h of drying at 50 °C. The digital image correlation technique was used to obtain the displacement field of the composite and determine the cohesive material law and fracture energy of the FRP-concrete interface. A finite element model was then used to reproduce the load response and reinforcement strain profile observed experimentally. The results show that wet-dry cycles affect the FRP-concrete bond properties and change the failure mode from a cohesive debonding within the concrete substrate to an adhesive debonding within the interface
Effect of wet-dry cycles on the bond behavior of fiber-reinforced inorganic-matrix systems bonded to masonry substrates
No full textIn recent years, inorganic-matrix reinforcement systems, such as fiber-reinforced cementi-tious matrix (FRCM), composite-reinforced mortars (CRM), and steel-reinforced grout (SRG), have been increasingly used to retrofit and strengthen existing masonry and concrete structures. Despite their good short-term properties, limited information is available on their long-term behavior. In this paper, the long-term bond behavior of some FRCM, CRM, and SRG systems bonded to masonry substrates is investigated. Namely, the results of single-lap direct shear tests of FRCM-, CRM-, and SRG-masonry joints subjected to wet-dry cycles are provided and discussed. First, FRCM composites comprising carbon, polyparaphenylene benzobisoxazole (PBO), and alkali-resistant (AR) glass tex-tiles embedded within cement-based matrices, are considered. Then, CRM and SRG systems made of an AR glass composite grid embedded with natural hydraulic lime (NHL) and of unidirectional steel cords embedded within the same lime matrix, respectively, are studied. For each type of composite, six specimens are exposed to 50 wet–dry cycles prior to testing. The results are compared with those of nominally equal unconditioned specimens previously tested by the authors. This comparison shows a shifting of the failure mode for some composites from debonding at the matrix–fiber interface to debonding at the matrix-substrate interface. Furthermore, the average peak stress of all systems decreases except for the carbon FRCM and the CRM, for which it remains unaltered or increases
Joshua Davis: Author of Spare Parts
No full textCitation: K-State First (2016). Joshua Davis: Author of Spare Parts [Flier]. Manhattan, Kansas: K-State First.Flyer advertising Joshua Davis's author talk at Kansas State University
Steven Johnson Author Talk Poster
No full textK-State Book NetworkA poster advertising an author talk by Steven Johnson at Kansas State University on September 3, 2014. Steven Johnson's book "The Ghost Map" was the 2014-2015 common book
Adhesively Bonded FRP Composites for Strengthening of RC Structures: Recent Advances
No full textBonding fiber reinforced polymer (FRP) composites to reinforced concrete (RC) structures has been accepted as a structurally-effective and cost-efficient strengthening and repair method. Research and development on this technique started in the Kliger et al.,.Eur J Wood Prod 74:319–330, 2016s and a great deal of effort has been made to study different behavioral aspects of FRP bonded concrete structures ever since, whose results have been reflected in several design codes and guidelines. Despite the extensive research, there is still knowledge gaps limiting the application of FRP materials in infrastructure. Long-term performance and uncertainty related to environmental durability and poor structural behavior at elevated temperature are among the most critical barriers. There are also issues related to debonding and how to increase the strengthening effect by means of using prestressed FRP laminates. This paper presents a review of the most recent works on FRP bonded RC structures related to abovementioned aspects conducted by different research groups in Sweden, Italy, and UAE
Experimental and Statistical Analysis of Repeated Impact Records of Hybrid Fiber-Reinforced High-Performance Concrete
No full textThe effect of fiber type and fiber hybridization on the repeated impact strength was investigated experimentally using six high-performance concrete mixtures reinforced with a 2.5% fiber volume fraction. The fiber types considered in this study included short steel fibers (SF) with 6 mm length, long SF with 15 mm length, and polypropylene (PP) fibers. The repeated impact test was conducted using a specially made automatic testing machine following the test setup recommendations of the ACI 544-2R test, where cracking (Ncr) and failure (Nf) impact numbers were recorded and the failure mode and crack pattern were observed. The results were statistically analyzed using the normality test and variations were discussed. The test results showed that specimens with pure long SF (S15) obtained the highest Ncr and Nf values, which were 20% and 327% higher than those of the mixture with pure short SF (S6) owing to the better bond between fibers and the cementitious matrix in S15. Replacing 0.5% of the mixture’s SF with PP decreased the cracking resistance by 7% to 15%, while its effect on Nf was dependent on the length of SF. In most cases, the Ncr and Nf records did not exhibit a significant departure from normal distribution, according to the Anderson-darling test
Study the effects of glutathione (GSH) on blood glucose level in diabetic male mice
No full textInvestigated effects of daily injections intra venially (IV) of glutathione (GSH) (11.37 mg/mice)forthe periods 10 and 20 days,for healthy mice and diabetic male micecompared them with control group and diabetic non treated male mice, blood sugar was testedfor fasting mice, induced diabetic, to study the glutathione daily injections e3.ffects on the blood sugar level, total glutathione assay in different body organs and finally study the expression level of the glutathione redox system enzymes glutathione reductase (GR) and glutathione peroxidase (GPx) in pancreas, spleen, testis, and epididymus by the Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). The experiment outcomes for the glutathione daily injection for the diabetic induced male mice high sugar level significantly decreased. Moreover, the oxidative stress in diabetic male mice leads to depletion of total glutathione level in body organs. Finally, Diabetes causes high oxidative stress in male mice which leads to increase expressions of antioxidants enzymes GR and GPx in pancreas, epididymus and testis
- …
