Flexural Behaviour of Carbon Textile-Reinforced Concrete with Prestress and Steel Fibres
Four-point bending tests were adopted to investigate the influences of the number of textile layers, volume content of steel fibres, and prestress on the flexural behaviour of carbon textile-reinforced concrete (TRC). The failure mode of the specimen changed from debonding failure to shear failure, accompanied by the matrix-textile interfacial debonding with an increasing number of textile layers. The interfacial bonding performance between the textile and matrix improved with the addition of steel fibres in the TRC specimens. The presence of prestress or steel fibres improved first-crack and ultimate stresses of the TRC specimen. In comparison with the first-crack stress, a more pronounced enhancement in the ultimate stress was achieved by the addition of steel fibres. However, the effect of prestress on the first-crack stress was found to be more significant than on the ultimate stress. The prestress combined with steel fibres further improved the flexural behaviour of the TRC specimens. The prestressed TRC specimens with 1% volume content of steel fibres effectively avoided debonding. Thus, the utilization of the textiles could be improved.
Uniaxial Tensile Behavior of Carbon Textile Reinforced Mortar
This paper investigates the effects of the reinforcement ratio, volume fraction of steel fibers, and prestressing on the uniaxial tensile behavior of carbon textile reinforced mortar (CTRM) through uniaxial tensile tests. The results show that the tensile strength of CTRM specimens increases with the reinforcement ratio, however the textile–matrix bond strength becomes weaker and debonding can occur. Short steel fibers are able to improve the mechanical properties of the entire CTRM composite and provide additional “shear resistant ability” to enhance the textile–matrix bond strength, resulting in finer cracks with smaller spacing and width. Investigations into the fracture surfaces using an optical microscope clarify these inferences. Increases in first-crack stress and tensile strength are also observed in prestressed TRM specimens. In this study, the combination of 1% steel fibers and prestressing at 15% of the ultimate tensile strength of two-layer textiles is found to be the optimum configuration, producing the highest first-crack stress and tensile strength and the most reasonable multi-cracking pattern.
Redescription of two ghost shrimps (Decapoda: Axiidea: Callianassidae) from the Middle Miocene of the Central Paratethys: systematics, intraspecific variation, and in situ preservation
A redescription of two Middle Miocene burrowing ghost shrimps of the Central Paratethys, Callianassa brocchii L renthey, 1897 and Callianassa pseudorakosensis L renthey in L renthey & Beurlen, 1929, is provided. Material forming the basis of this study comes from the Studienka Formation (lower 'Sarmatian', Serravallian) of the Slovak part of the Vienna Basin and exhibits preservation allowing reassignment of the studied taxa to the genera Neocallichirus Sakai, 1988 and Eucalliax Manning & Felder, 1991 respectively. The major cheliped of both species exhibits two distinct morphotypes interpreted herein as possible sexual dimorpism. Several specimens of both taxa are preserved within the tube structures and are interpreted as in situ preservation within the burrows. Type material of both studied taxa and additional collections from the roughly coeval strata of Hungary and Austria were also studied.