Using recycled construction and demolition waste (RCDW) in geosynthetic reinforced soil (GRS) structures presents attractive environmental and economic aspects. However, bearing in mind installation damage can be responsible for significant changes in geosynthetic tensile-strain behavior, the damage caused by the RCDW must be assessed and quantified. This study aims to investigate the occurrence of mechanical damage during the installation of geogrids with RCDW backfill material using an in-field test facility. In order to understand the mechanisms related to the damage, the influences of the dropping height and compaction method were investigated. Statistical analysis using the Student's t-distribution was carried out to validate the occurrence of damage and calculate reduction factors for geogrids’ tensile strengths. Results revealed that dropping processes reduced the geogrid ultimate tensile strengths, but the compaction methods caused the highest reductions. The reduction factor values encourage the design of GRS structures with RCDW, an interesting option to satisfy the technical and economic aspects required for these structures in agreement with the environmental concerns.

Controlling and preventing soil erosion on slope surfaces is a pressing concern worldwide, and at the same time, there is a growing need to incorporate sustainability into our engineering works. This study evaluates the efficiency of bioengineering techniques in the development of vegetation in soil slopes located near a hydroelectric power plant in Brazil. For this purpose, twelve different bioengineering techniques were evaluated, in isolation and in combination, in the slopes (10 m high) of two experimental units (approximately 70 m long each) located next to the Paraíba do Sul riverbanks, in Brazil. High-resolution images of the slopes’ frontal view were taken in 15-day interval visits in all units for the first 90 days after implantation, followed by monthly visits up to 27 months after the works were finished. The images were treated and analyzed in a computer algorithm that, based on three-color bands (red–green–blue scale), helps to assess the temporal evolution of the vegetative cover index for each technique adopted. The results showed that most of the solutions showed a deficiency in vegetation establishment and were sensitive to climatological conditions, which induced changes in the vegetation phytosanitary aspects. Techniques which provided a satisfactory vegetative cover index throughout the investigated period are pointed out.

At the beginning of this century, due to well-established Brazilian recycling processes, geosynthetics’ manufacturers started to use recycled poly(ethylene) terephthalate (PET) yarns/filaments (from PET bottles) in geotextile production. Despite the fact that recycled products cannot act as reinforcement functions, geosynthetics are constantly under sustained tensile load and experiences evolutions of the axial strain (creep behaviour). Thus, this study aims to assess the influence of the structure of (needle-punched) non-woven geotextiles manufactured using recycled PET yarns on their creep behaviour. Two geotextiles with different fibre/filament production processes were investigated (short-staple fibres—GTXnwS—and continuous filaments—GTXnwC). Unconfined in-isolated conventional and accelerated (using the stepped isothermal method) creep tests were performed at 5%, 10%, 20%, 40% and 60% of geotextiles’ ultimate tensile strength. The geotextiles investigated provided similar creep behaviour to geotextiles manufactured with virgin PET material. The standard deviation of the axial strain tends to increase as the load level applied increase. The structure of the GTXnwS harms its tensile –strain behaviour, promoting axial deformation under sustained loads, at least 50% higher than GTXnwC for the same load level applied. The influence of the load level and geotextile structure in the initial axial strain is pointed out. Long-term predictions based on creep tests performed using the stepped isothermal method have proven to be conservative and they must be restricted for quality control of the investigated geotextiles.

Replacing natural aggregates in infrastructure with recycled construction and demolition waste (RCDW) works helps to meet the requirements established by sustainable development. This environmentally friendly proposal undoubtedly becomes better when it is carried out with geosynthetics, providing better technical performance and positive economic impacts. However, the chemical characteristics of RCDW may result in the degradation of the geosynthetics and, therefore, must be assessed and quantified. This study aims to assess the chemical degradation caused by RCDW for the mechanical properties of two types of polymeric geogrids (polyester and polyvinyl alcohol). The study evaluates the influence of the RCDW saturation condition in the chemical degradation and the possible synergism between the launching damage (drop height) and chemical degradation. Watertight tanks were constructed to maintain the geosynthetic reinforced layers in flooded, dry and open-to-environment conditions, simulating paved and unpaved roads. The occurrence of degradation was evaluated and quantified by reduction factors related to the properties of interest using statistical analysis. The results have shown a significant influence of chemical degradation on the geogrid characteristics (especially tensile strength and secant tensile stiffness), which increased when the specimens were subjected to prior launching process simulation. The reduction factor values reported herein encourage the combined use of these materials (geogrid and RCDW) and highlight the importance of assessing the chemical degradation for the design purposes of geosynthetic-reinforced roadways with alternative materials.