Issue No 1, April

Abstract

Refractories, materials used in steel works, are directly or indirectly, associated with a very wide range of environmental problems. When discussing the influence of refractories on the environment, one should consider: aspects related to the global environment, local environment, work environment and the generation of waste. Refractory wastes are historically disposed of as waste in industrial landfills. However, some of the refractory materials used have the potential to be recycled, contributing to environmental and economic sustainability. The addition of recycled aggregates in refractory concrete used to molded Impeller KR was evaluated for the development of refractory recycling technology after use. In general, the results of the dynamic slag test and industrial test indicated the potential of the use of recycled aggregates slide gate.

Abstract

The various methods presently available for the repair of brick masonry walls are reviewed. Particular attention is given to structural repair made necessary as the result of earthquake induced damage or retrofit measures to be applied to an existing masonry structure to increase seismic resistance. Among the techniques discussed are: crack injection with epoxy or resin, crack or void injection with a cement based grout, surface coating methods, base isolation, repointing or limited replacement of damaged elements and installation of steel reinforcing elements. Use of nondestructive evaluation methods to determine the initial damaged state and the condition of the repaired masonry wall will also be presented.

Abstract

A systematic approach to the study of durability of wall surface treatments has been set up by the authors since some years. The study, previously based on accelerated aging tests and subsequent measurement of surface deterioration of treated and untreated specimens, has now been extended to full-scale facades. Three small constructions designed by the authors with modular facades made of sandstone and/or soft-mud facing bricks have been built in open field. A continuous content of water in the subsoil can be provided so that the capillary rise of water into the masonry is assured; soluble salts can also be provided from the soil. Some of the facades have been treated with protective materials, some others will be treated after deterioration. Besides collection of data concerning the environment and the moisture and salt movements in the walls, the deterioration of the external surfaces, the influence of mortar joints on moisture distribution and of the position and exposure of the material on the deterioration are being taken into account. Comparison between the in-situ and laboratory results are being carried out in order to adjust the aging tests to the natural environment.

Abstract

Nowadays, many companies depend on good communication between their technologies and Wi-Fi signal, which are part of the X-waves frequencies. Communication may suffer interference due to wave propagation’s difficulty, mainly depending on the number of walls and where the building is located. Therefore, buildings should be adapted to avoid this interference in order to minimize signal losses. Interference in wave propagation depends not only on walls but also on their structure. The studies of building construction and wave propagation may be complementary since the structure and organization may negatively affect the signal strength. This work analyzes X-waves’ attenuation (from 8GHz up to 12 GHz) in ceramic walls to evaluate their effects on wave propagation. This work differs from Literature not only by the material used, considering that there are many jobs involving concrete blocks, but also by calculating the wave signal focusing on a loss function in the analyzed object, enabling anomalous behavior analysis. This propagation behavior allows evaluating the most valuable equipment in a house (wireless device, TV). Finally, ceramic blocks were studied because they have a low cost, they are lightweight, easy to handle, and have a high frequency of use. The tests were performed in an 80cm x 80cm wall. The x-waves were produced by two horn antennas (transmitter and receiver) located at 70 cm of the wall on opposite sides and directions. We found an enhancement of attenuation in the x-waves frequency band with a significant drop at 11GHz. The signal drop mainly occurs due to the material characteristics, a.k.a stop band. This drop is caused by the electromagnetic band structure produced by the difference between the dielectric constant of the ceramic blocks and their periodically repeated voids called Electromagnetic Band Gap structure.

Abstract

Non destructive test (NDT) methods applicable to masonry structures are defined, classified and reviewed in the context of the type of information required to suit different problems, which tests are appropriate to which application and when they should be used. Some of the more promising techniques are discussed at greater length in the light of current research at the Building Research Establishment.

Abstract

Nowadays, ball mills are widely used in cement plants to grind clinker and gypsum to produce cement. The research focuses on the mill speed as well as air classifier speed effect on the two compartment Cement ball mill performance in terms of Blaine, Sulphur trioxide contents, mill power, mill residue and mill residence time. Special importance was assigned to the study of the specific surface area and the surface area production rate, both during the variation with the mill speed and the air classifier speed. Within the content of this work, sampling campaigns were organized around a cement grinding circuit and varying cement ball mill speed as well as an air classifier speed at various dosage feed rate. The fact that such an examination has not been made previously by using industrial data rather than lab scale makes this work unique. The fineness is measured in terms of Blaine number. Mill speed and air classifier speed were the investigating parameters. It was deduced that depending on the speed of mill and air classifier, their effects on Blaine, SO3, mill power and mill performance were varied, ultimately all of them improved the performance of grinding and classification operations. The rapid expansion of ceramic wastes in China has raised great many interests in their sustainable uses in building materials The micro ceramic powder can be taken as a supplementary cementitious material to replace cement up to 40% for tuning the microstructure and mechanical properties of blend cement materials. The Blaine quality dictates strength, setting time and overall performance of cement. Optimum performance of ball mill could potentially refine Blaine fineness, thereby improving the cement quality. This study investigates the effects of separator speed and mill speed on Blaine fineness, mill residue, consumed power. Five speed levels used in closed cycle grinding mill are 200, 400, 600, 800 and 1000 rpm. The capacities were determined to obtain product Blaine surface areas in the limits between 2000 cm² / gram and Variations in clinker feed rate, mill speed and separator speed could proportionally impact the grain quality of Blaine. When the separator speed is increased from 850 to 900 rpm the Blaine is increased from 2800 to 3000 cm²/g and mill residue decrease from 15 to 10 microns. Therefore, optimum parametric combination could reduce power consumption while improving the cement quality. Knowledge of effects of parametric variations on the quality of end product could be helpful for controlling product quality. Furthermore, proper grinding of clinker produces fine Blaine at first place and reduces the need for recycling of coarse grains.