Behaviour of Square Footing Over Recycled Concrete Aggregate Resting on Loose Sand: Integrated Experimental and Numerical Analyses

This present study aimed to analyse the pressure-settlement behaviour of square footing (width = B) resting on recycled concrete aggregate layer overlaying on loose sand. A series of plate load tests were performed on two sizes of recycled concrete aggregate (5 and 10.6 mm) layer at relative densities of 30, 50, and 70%. The depth of the recycled concrete aggregate layer to the width of footing ratio was varied from 0.4 to 1.2 in an increment of 0.2. Apart from this large box direct shear test was performed to obtain the friction angle for both the sizes of recycled concrete aggregate at a relative density of 30, 50 and 70%. It was observed that when the recycled concrete aggregate layer was placed over loose sand, the bearing capacity of the soil was increased by 527.8% for 10.6 mm recycled concrete aggregate and 643.6% for 5 mm recycled concrete aggregate, and the corresponding reduction in the settlement was 0.65 and 0.61 (at relative density = 70% and depth of the recycled concrete aggregate layer to the width of footing ratio = 1.2), respectively. It has been noticed that at lower relative density, larger size aggregate performs better and at higher relative density, smaller size aggregate performs better. Further, the experimental results have been compared with the numerical model developed in ABAQUS 3D.