Materiais alternativos para aterro em ECSR com geossintético

Abstract

This study aims to facilitate the use of Recycled Concrete Aggregate (RCA) and Recycled Asphalt Pavement (RAP) in lieu of natural aggregates as alternative backfill for Mechanically Stabilized Earth (MSE) walls. Although several studies on RCA and RAP have been conducted for use in roadway construction applications (FHWA 2004a; Anderson et al. 2009; Soleimanbeigi 2012; Soleimanbeigi et al. 2015), only a few studies have been conducted to evaluate RCA and RAP for specific use as MSE wall backfill. The selection of RCA, RAP and Geosynthetic reinforcements considered costs and environmental benefits. The use of RCA and RAP as backfill can reduce the costs associated with mining and transportation of natural aggregates, which can dominate the total cost of a MSE wall. In addition, the disposal of RCA and RAP into landfills is costly and can pose environmental risks to air and groundwater alike. The suitability of RCA and RAP as backfill for geosynthetically reinforced MSE walls is investigated in this study. Mechanical interaction between these recycled aggregates with four types of geosynthetic will be presented. The index and mechanical properties of RCA and RAP were measured. Interface shear resistance between geosynthetics and the recycled materials were measured using a pullout table and a large-scale direct shear machine. Two types of geotextiles (woven and non-woven) and two types of geogrids (uniaxial and biaxial) were used. The results conducted from laboratory tests in this study provide designers with the data to conduct preliminary design calculations to evaluate the efficacy of RCA and RAP in geotechnical construction. Recommended design parameters for RCA are: 48º for friction angle (Ф’), 0 kPa for cohesion (c’); 0.41, 0.30, 0.62 and 0.55 for efficiency factor (EФ), for woven and non-woven geotextile, and uniaxial and biaxial geogrid respectively; interaction coefficient (Ci) for geogrid 0.52 at normal stress < 20 kPa, and 0.29 at normal stress > 20 kPa and for geotextile 0.13 at normal stress < 20kPa and 0.24 at normal stress > 20 kPa. In the other hand, the parameters recommended for RAP are: 29.2 for Ф’, 0 kPa for c’; 0.77, 0.62, 1.15 and 1.41 for EФ, in woven and non-woven geotextile, uniaxial and biaxial geogrid respectively; Ci value of 0.16 for geogrid at normal stress < 20 kPa and 0.18 at normal stress > 20 kPa, and for geotextile the values are 0.21 at normal stress < 20 kPa and 0.22 at normal stress > 20 kPa. These design parameters are intended for preliminary design calculations. The final project should be conducted using measured properties for RCA, RAP and geosynthetics to be used. Field conditions should be simulated as closely as possible when conducting tests for final design.