Investigate the engineering properties of Rubbersoil and its application for fill slope

Rubbersoil™ is a newly developed environmental friendly construction material with excellent geo-technical properties. It is mainly composed of rubber chips derived from scrap rubber tires and bonded together by cementitious material. This innovative material can use as a fill material to stabilize sub-standard loss fill slopes in Hong Kong. Using Rubbersoil™ as fill material not only provides an alternative method for slope stabilization, but also gives an environmental friendly way to solve the scrap tires disposal problem. The objective of the study is to investigate the material properties of different kinds of Rubbersoil™ involved in the Rubbersoil™-fill slope by laboratory investigations. A full-scale field test was also carried out to look into the feasibility of Rubbersoil™-Fill Slope construction and its performance during one-year monitoring period. The results from unconfined compression test, direct shear test and consolidated drained test show the high shear strength of Rubbersoil™-LGM, while the permeability test shows its free drainage property. The soil water characteristic curve of Rubbersoil™-Primer and rainfall model test show one-way water drainage ability of Rubbersoil™-Primer that reduce the rainfall infiltration. The clogging test ensured the one way drainage ability of Rubbersoil™-Primer under long term condition. The unconfined compression strength of Rubbersoil™-Primer showed its properties for temporary cut slope protection. A series of direct shear tests were also carried to study the shear strength of various possible material interfaces in the Rubbersoil™-Fill Slope. The results showed that the adding a layer of Rubbersoil™-Primer can increase the shear strength between in-situ soil and Rubbersoil™. All the other potential interfaces have higher shear strength than common in-situ soil and therefore no weak plane is formed. Full-scale field test shows the feasibility of Rubbersoil™-Fill Slope construction. No special technique and equipment were required for the construction. Comparing with traditional loose fill slope upgrading method in Hong Kong, Rubbersoil™-Fill Slope can reduce the excavated and fill volume, in addition, it also increases the landscaping area. The field monitoring results showed the stability and good performance of the Rubbersoil™-Fill Slope during the entire monitoring period. The design charts for Rubbersoil™-Fill Slope show that it can effectively stability the slope un to a height of 9m with slope angle up to 50°