Gravity retaining structures in gabion walls were built in the outdoor area of a shopping centre in the city of Manaus, State of Amazonas, Brazil. When the project was about half-way completed, horizontal displacements began to show excessive ‘bulging’, causing the stoppage of construction. Later studies revealed that the original geometric sections did not meet the requirements of internal, external and global geotechnical stability. Hence, it was necessary to study some alternatives to circumvent the problem. The fastest and most economical alternative proved to be increasing the cross-section of the walls, through the excavation of the backfill. The reconstruction of the walls and subsequent backfill compaction were performed step by step. The new cross-sections of the walls improved their theoretical and constructive stability, and this was proven by subsequent monitoring of horizontal and vertical displacements. It was found that the largest horizontal and vertical displacements of the gabion wall were about 20 mm and 11 mm, respectively.
There are high costs in paving services in the Brazilian Amazon region, mainly due to the lack of coarse aggregate-pebble or crushed stone-in addition to the elevated rainfall and the high geographic expanse of the region. The natural coarse aggregate often used in that region is extracted from the riverbeds a distance no less than 500 km from the major cities. In search of a technical, economic and environmental alternative to work around the problem, using an unconventional material that could replace the pebble or crushed stone, a study was carried out on natural clay, considered an abundant mineral resource, especially in the Amazon Basin. A manual mill was used for this purpose, consisting of four square metal nozzles of dimensions 12.7 mm, 9.5 mm, 4.8 mm and 2.0 mm, used for moulding the wet ribbon clay. After that, firing was carried out at temperatures of 780 °C, 850 °C, 950 °C, 1,050 °C to 1,150 °C. A comparative analysis between conventional hot mixed asphalt-using pebble as coarse aggregate-and that employing synthetic aggregate was made. In a general way, hot mixed asphalt using synthetic aggregate showed excellent results of physical and mechanical properties, in relation to the conventional mixture, mainly at higher temperature of aggregate calcination.
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