Assessment of some locally produced Egyptian ceramic wall tiles

Due to the fact that there are various types of wall tiles in the Egyptian market, of different qualities and prices, the aim of this research paper is to evaluate the properties and characteristics of tiles obtained from the local Egyptian market and attempt to identify the reasons for such differences. In other words, investigate the reasons why some tiles are more superior in quality than others. Test specimens were obtained from the local Egyptian market for fourteen factories. The mechanical properties (namely flexural strength) and physical properties (namely water absorption and apparent porosity) were measured, as they reflect the strength, the endurance during handling, as well as, the conditions to which the tiles are expected to be exposed to during use. The impact resistance and hardness were tested as well. Also, the phases (both major and minor) developed during the firing (maturing) step of manufacturing were identified. A correlation was made between the measured properties and the formed phases. The results showed that samples which yielded high physical and mechanical properties are those that constituted mainly the major phases, specifically, mullite and quartz, while those that contained impurities in the raw materials inevitably resulted in the development of minor phases, in addition to the major phases, had a negative effect on the measured properties. Consequently, it is feasible to obtain tiles that satisfy the requirements of ISO 13006 specification provided that the used raw materials are free (as much as possible) from impurities such as hematite, magnesium, and calcium

Properties of paving units incorporating slag cement

The aim of this study is to investigate the effect and possibility of using Portland slag cement in the production of interlocking paving units. Paving units consist of two layers. Four mixes were cast. The first mix was the control mix, in which Portland cement was used in the two layers. In the second mix, Portland slag cement was used in the upper layer, Portland cement was used in the backing layer. In the third mix, Portland cement was placed in the upper layer, while Portland slag cement was used in the backing layer. Finally, in the fourth mix, Portland cement was fully replaced by Portland slag cement in both layers. Tests were carried out in order to investigate the properties of the manufactured specimens at ages 28 and 180 days, respectively. Compressive strength and abrasion resistance were conducted according to the American Society for Testing and Materials (ASTM C 140 and ASTM C418). Water absorption, split tensile strength, abrasion resistance, as well as, skid resistance were performed according to both Egyptian Standard Specifications (ESS 4382) and European Standard (EN 1338). The Egyptian standard is identical with the European standard. The results indicate that it is feasible to use Portland slag cement in the manufacture of paving blocks as the conditions of the conducted tests were satisfied at age180 days except for the minimum splitting tensile strength test

صورة ورؤيا زاهد من سري لانكا / Portrait and Vision of A Sri Lankan Saint

[The translation covers the last chapter of Gananth Obeyeskere\u27s Medusa\u27a Hair, entitled Epilogue: The End and the Beginning. The research that went into this essay stemmed form an incident at Kataragama in 1973 whence Obeyesekere was awed by the view of an ecstatic woman worshipper at the shrine, with matted hair, which recalled medusa, and in turn Freud\u27s essay Medusa\u27s Head . In his epilogue, Obeyesekere goes on to recollect an incident which occured to him at Kataragama in 1979, six years after he had seen the fire-walking Medusa, when he saw what he believed to be a Sri Lankan Sinhala saint, a hair. Obeyesekere presents a biographical sketch of this man, Sada Sami: He was born in Galle in 1909 and his father died five years later. He was raised by his mother and his older brother. He left his home town for Tammuttegama after a violent encounter with his sister, and there he was hired as a shop assistant. Extensive reading made him quite religious and, consequently, he grew sick of his job, and commenced his own business twenty years later - an endeavor which he ultimately abandoned as well. In 1951 Sami acquired the gift of matted hair as a result of an anonymous person pouring water on his head in a dream and a subsequent fever that ailed him. Years later, he was instructed to conquer Mahasona (the strongest of demons), which he shrewdly did, and, as such, was no longer obliged to offer dola to the gods. His fame became wide spread (the working of the gods) and he went to Matara where he practiced rituals for healing the ill. His main objective, however, was to reach nirvana. In commenting on these experiences, Obeyesekere states that these dreams are recognized as dreams per se by Sada Sami, but indeed dreams, for Sami, are merely a reality which prevails in a different dimension. Sami has, as Obeyesekere contends, constructed images which correspond to his culture and its symbols. The author labels Sami\u27s dreams as myth dreams. He further hypothesizes that Sami\u27s case suggests that myths may have originated in the hypnomantic consciousness. He concludes that the myth conditions the dream as the dream conditions the myth. Obeyesekere then provides his readers which some interpretations of the symbols which appear in Sada Sami\u27s dreams, and their relation to his culture.

Performance evaluation of interlocking paving units in aggressive environments

This study evaluates the performance of interlocking paving when exposed to aggressive environments. Durability of paving units is an essential property as it determines its capability of withstanding the different conditions to which it is expected to be exposed to- Chemical, physical, and mechanical causes can result in lack of durability. Chemical cause can arise from attack by chlorides, physical cause may be due to exposure to high temperature variations, while mechanical causes are usually associated with abrasion. Experiments were carried out to determine product compressive strength, water absorption, and abrasion resistance according to both Egyptian Standard Specifications (ESS) and American Society for Testing and Materials (ASTM). An interlocking paving mix was chosen and exposed to various aggressive media for a duration of 2 months after being cured for 28 days. The aggressive environments were as follows: 1% HCl, 5% HCl solution (to simulate acid attack resistance), dry and wet cycles, as well as, air (room temperature) and dry cycles (to simulate different environmental conditions). The tested products were also X-rayed to investigate the mineralogical analysis. The following was concluded. The four aggressive media increased compressive strength when compared to the control mix. Also, they resulted in reducing water absorption percentages and met the criteria for water absorption concerning heavy duty according to ESS. Samples which were exposed to the four aggressive environments conditions did not satisfy both criteria of ESS and ASTM pertaining abrasion

Properties of paving units incorporating crushed ceramic

The aim of this study is to investigate the effects of using crushed ceramic in the production of interlocking paving units. Eight mixes were cast. The first mix was the control mix, in which natural aggregates were used in the upper and lower layers. In the second and third mixes, coarse crushed ceramic was used in the lower layer replacing 50% and 100% of crushed stone, respectively. In the fourth and fifth mixes, fine crushed ceramic was used in the lower layer replacing 50% and 100% of natural sand, respectively. In the sixth mix, coarse and fine crushed ceramic were used in the lower layer replacing 50% of crushed stone and 50% of natural sand, respectively. Finally, in the seventh and eighth mixes, fine crushed ceramic was used in the upper layer replacing 50% and 100% of natural sand, respectively while natural sand was used in the lower layer. Tests were carried out in order to investigate the properties of the manufactured specimens after 28 days of curing. Compressive strength and abrasion resistance were determined according to the American Society for Testing and Materials (ASTM C 140 and ASTM C418, respectively). Water absorption, split tensile strength, abrasion resistance, as well as, skid resistance were determined according to both Egyptian Standard Specifications (ESS 4382) and European Standard (EN 1338). The Egyptian standard is identical with the European standard. The results indicate that it is feasible to use fine crushed ceramic in the manufacture of paving blocks