Use of Recycled Polyethylene Terephthalate Strips in Soil Improvement

Many studies have investigated polyethylene terephthalate (PET) and polypropylene fibers in soil improvement. However, there is a lack of research using inclusions of polymeric strips taken from recyclable materials, although strips from the reuse of waste have high potential for improving soil characteristics. This study evaluated the effects of the addition of PET strips from recycled bottles of different lengths and contents on sandy and clayey soil resistance. Unconfined compression and direct shear tests were performed in both soils at two different compaction degrees (CD): 95 and 100%. The results of unconfined compression tests showed that the highest strengths were obtained for sandy soil (L = 20 mm; 1.5%) and clayey soil (L = 30 mm; 1.5%). The selection of L = 20 mm; 1.5% was used to mold specimens for the direct shear tests. Analyzing the shear stress x displacement curves (τ x δH) obtained with CD = 100% (for both soils with and without strips), it is noted that the appearance of the obtained curves is quite similar when analyzing the highest applied stresses. An analysis of volumetric variation curves was important to show that the addition of the strips began to modify the behavior of the soil for the highest applied stress levels. The material starts to present more ductile behavior. The inclusion of PET strips was more effective in sandy soil, which presented an increase of 66.4% (CD = 100%) and 55.5% (CD = 95%) in the cohesive intercept.