Effect of Alumina Additives on Mechanical and Fresh Properties of Self-Compacting Concrete: A Review

Self-compacting concrete (SCC) has been increasingly used in the construction sector due to its favorable characteristics in improving various durability and rheology aspects of concrete such as deformability and segregation resistance. Recently, the studies on the application of nano-alumina (NA) produced from factory wastes have been significantly considered to enhancing the performance, and mechanical strength, of SCC. Many experimental works show that NA can be used in SCC with appropriate proportion to enjoy the benefits of improved microstructure, fresh and hardened properties, durability, and resistance to elevated temperature. However, a limited detailed review is available to particularly study using NA to improve the performance of SCC, so far. Hence, the present study is conducted to fill the existing gap of knowledge. In this study, the effect of using NA in improving rheological, mechanical parameters, and elevated temperature resistance of SCC is reviewed. This research summarized the studies in this area, which have been different from the previous researches, and provided a discussion on limitations, practical implications, and suggestions for future studies.

Evaluation of gamma and electron radiations impact on vitamins for onion preservation

Food irradiation is a process in which food and other consumer products are exposed to gamma rays, X-rays or electron beams after extraction. This method is particularly important in order to reduce infectious agents and to extend the shelf life of the product. The target radiation is done with different devices, so self-sufficient radiation and panoramic radiation -including product and source overlap, planar and categorical radiation- is the major characteristics. Besides, a high performance liquid chromatography device (10% methanol, 70%-80% distilled water and 10% ethanol) is utilized to measure the chemical substance of pyridoxine (vitamin B3), thiamine (vitamin B6) and vitamin C of Vidalia or sweet onions. In our research, gamma-cell 220 and Rhodorton electron facilities were utilized to irradiate the onion crop. This project focuses on increasing the shelf life of agricultural products, especially onions, using energy of 1.25 MeV for both gamma irradiation and electron beam, and measuring the amount of vitamins B3, B6 and C, which are the nutrients of this product. The prepared onion samples were exposed under electron and gamma irradiations by two doses of 200 and 500 Gy at 25 °C. Then, a liquid chromatography device was utilized to measure the vitamins. The results showed that the onions were not damaged by 200 Gy doses and their nutritional properties were preserved, which means that not only can vitamins with this dose be retained without any spoilage for 30 days, but also eliminate pathogenic microorganisms. The process indicated that using 200 Gy radiations does not endanger the health of food and consumers.