A Laboratory Investigation on a Mechanical Behavior of Sandy and Clayey Soils with Kraft Paper Fiber

Abstract

The literature has several studies on the addition of several agglomerating materials, waste, natural and artificial fibers, among others. Most of them aim to improve soil engineering properties. Certain studies combine this investigation with the environmental issue, that is, the issue of making the best use of a certain material that is discarded in nature and generates a significant environmental impact. Thus, this study aims to use paper fiber, from the cement bag, which is a construction waste, as reinforcement of a sandy soil and a clayey soil. Fiber-reinforced soil is considered an effective technique for soil improvement due to cost, adaptability, and reproducibility. Thus, the choice was to study the fiber of natural multifoliated kraft paper (NKP) as soil reinforcement, which was added randomly at the percentages of 5, 10, and 15% of dry soil mass. This study focused on soil resistance and its behavior with the addition of NKP fibers to a sandy soil (SC) and to a clayey soil (ML). Compaction, shear strength, and unconfined compression tests were performed in samples with the fiber contents mentioned. The results of the tests showed an improvement and an increase in the friction angle of the soils when 10% and 15% of fibers were added to the SC, and for ML, a significant increase in the friction angle was found in both optimum moisture and 28 days, with emphasis on 5% dosage and flooded for 15% dosage. Regarding the unconfined compression, an improvement was verified in the resistance at 10% for the CS, while for ML soil, the better dosage was 5% of fibers. One concludes that the use of NKP fibers can be considered a reinforcement material. The results indicated that the fibers made the soils ductile, able to maintain shear strength at high levels of strain.