Optimizing the mechanical behavior of clay using cement and PVC aggregates with the application of a mixture design method

Abstract

The present research work aims to use the mix design approach to develop some models that can predict the mechanical properties of clayey soil. For that, the proctor compaction test, direct shear test, and uniaxial compression test were performed on bentonite (B) and other mixtures incorporating different proportions of polyvinyl chloride (PVC) aggregates stabilized with cement (C). The experimental and modeling results indicated that a good correlation existed between the three factors (B, C, and PVC) and the values of the maximum dry density, cohesion, and compressive strength responses. It was also found that the majority of models gave relatively good correlation coefficients (R2 ≥ 0.90) for all the responses under study. The results obtained indicated that this bentonite had a compressive strength 180.24 kPa, with a cohesion 64.71 kPa, and a maximum dry density equal a 1.571 gr/cm3. In addition, the experimental and modeling findings showed that the mixture including C (55% ± 10%), PVC (35% ± 10%), and B (10% ± 10%) exhibited a quite high cohesion of 103 kPa (more than one and half times that of unreinforced samples), while the highest compressive strength of 445 kPa (two and half times more than that of unreinforced samples) was obtained for the mixture comprising of C (50% ± 10%), PVC (25% ± 10%) and B (25% ± 10%). In addition, it turned out that these results are very encouraging in terms of environmental protection because this technique allows recycling and valorizing huge quantities of PVC waste produced throughout the world. It has been revealed that PVC wastes can be utilized in the geotechnical field to improve the mechanical behavior for clay soils, and to assess the values of maximum dry density, cohesion, and compressive strength of mixtures not made in the laboratory using the derived statistical models.