Assessing the Influence of Asphalt Stabilization on the Deformation Resistance of Reinforced Earth Embankment Model

Abstract

Construction of roadway embankment with Gypseous soil exhibits hazard for the long term performance. The Gypseous soil is known to exhibit suitable strength after compaction; however, it loses the strength when subjected to environmental issues such as rain and the variation in the water table level. In the present investigation, an attempt has been made to implement Gypseous soil with 84.2 % of gypsum content which was obtained from Tikret region, (180 km north of Baghdad) in the preparation of an embankment model in the laboratory. The Gypseous soil was compacted to 95 % of its maximum pre-determined dry unit weight of (16.4 kN/m³ ) in six layers in a metal box with the dimensions of (50 x 50 x 30) cm and each layer is of 5 cm thickness to form a control embankment model, and subjected to vertical stress. Test was carried out using proving ring of 5 kN capacity. The vertical and lateral deformations of the embankment model were monitored until failure. The second embankment model was constructed using an aluminum reinforcing strips spread at five layers of the embankment height. The aluminum reinforcing strips was laid at equal spaces between each of them, which means that each layer was reinforced with four strips at a spacing of 10 cm center to center. The vertical and lateral deformations were also monitored until failure. In the third embankment model, the Gypseous soil was stabilized with M-30 cutback asphalt, then the embankment model was constructed using an aluminum reinforcing strips as in the second model. The fourth embankment model was constructed using the aluminum strips and a stabilized Gypseous soil with cationic emulsion. It was observed that the reinforced and the emulsion stabilized embankment models exhibits lower vertical deformation of (40 and 30) % as compared with the control embankment. On the other hand, the lateral deformation at the third embankment layer declines by (50, 39.2, and 35.7) % when the emulsion, cutback, and earth reinforcements were implemented respectively as compared with the control model. However, the lateral deformation at the fifth layer declines by (68.4, 55.5, and 68.4) % when the emulsion, cutback, and earth reinforcements were implemented respectively as compared with the control model. It was concluded that implementation of cutback and emulsion stabilization in addition to the earth reinforcement can better sustain vertical stresses applied on the embankment surface and present a sustainable solution for the roadway infrastructure.