Compressive and splitting tensile strength of autoclaved aerated concrete (AAC) containing perlite aggregate and polypropylene fiber subjected to high temperatures
This paper presents the results of an experimental study on the residual compressive and splitting tensile strength of autoclaved aerated concrete (AAC) containing perlite and polypropylene (PP) fiber subjected to high temperatures. Cylinder specimens were subjected to various temperature ranges of 100, 200, 400, 800, and 1,000°C. The mixtures were prepared with AAC cementitious materials containing perlite at 15%, 20%, and 30% sand replacement. The polypropylene fiber content of 0, 0.5%, 1%, 1.5%, and 2% by volume was also added to the mixture. The results showed that the unheated compressive and splitting tensile strength of AACs containing PP fiber were not significantly higher than those containing no PP fiber. Furthermore, the presence of PP fiber was not more effective for residual compressive strength than splitting tensile strength. The 30% perlite replacement of sand gave the highest strength. Based on the results, it can be concluded that addition of PP fiber did not significantly promote the residual strength of AAC specimens subjected to high temperatures.
Effect of High Temperature on the Mechanical Properties and Ultrasound Velocity of Cellular Gas Concrete
Exposure to high temperatures affects various properties of concrete and mortar, including their mechanical strength. Susceptibility to damage under high temperatures depends mostly on the properties of the matrix and the dispersed phase of the material. Because cellular gas concrete has very fine aggregate admixtures, evaluating its response to high temperatures requires testing the material as a whole, rather than considering the phases separately. In the case of fire damage, tests generally can be done on specimens taken from the affected areas. In addition, ultrasound velocity test is often used to evaluate the degree of damage indirectly. In this experimental research, the change of mechanical properties such as compressive strength and splitting tensile strength according to high temperature has been examined by ultrasound velocity. In these tests, the applied temperature changes from 100°C to 965°C and the results of these changes were determined. As a result, this paper tries to find out if there is a meaningful relationship between the mechanical properties of the material under high temperature and if testing the material with ultrasound velocity is an efficient and adequate option in order to examine and determine the damage occurs in the material after exposure to temperatures from 100°C to 965°C. In this context the relationship between each property such as compressive, flexural, splitting tensile strength and ultrasound velocity was determined. Under these observations it was tested that if there is meaningful correlation between these properties and ultrasound velocity.
New records of Grania (Clitellata, Enchytraeidae) in the Northeast Atlantic (from Tromsø to the Canary Islands), with descriptions of seven new species
Previous northeast Atlantic records of Grania have been mainly from Germany, southern Scandinavia, and the Atlantic shores of France, Spain and Ireland. They were referred to eight species, with one, G. atlantica, reported from the continental slope. We have examined various unpublished collections from sources spanning from the Canary Islands to the Norwegian Arctic. Apart from new information on morphology, taxonomy, and distribution of known species, we describe seven new taxa (G. canaria, G. fortunata, G. mauretanica, G. aquitana, G. vikinga, G. torosa, and G. papillinasus). The collection of G. papillinasus from 2630-2885 m represents a new depth record for Enchytraeidae. Twenty-five of the now 57 Grania species occur in the North Atlantic. The North Atlantic drift moderates sea temperatures along the northeast Atlantic coasts, probably facilitating the wide latitudinal range of some taxa, as well as actual dispersal within the region. A "chaetal index" (chaetal length : chaetal foot length) is proposed to differentiate L-shaped chaetae at the species level. Complex relationships within the "type 6 group" of Grania suggest that groupings established using certain combinations of penial, chaetal and spermathecal patterns may not be monophyletic. For a better phylogenetic resolution, additional morphological details of these and other characters are needed.