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83More importantly, the performed direct shear test also yielded the angle of aggregate frictionto be 44 degrees (Figure 48). Friction angle and void ratio values obtained for prototypeaggregate pier material via direct shear test came out to be very consistent with theparameters of full size aggregate pier material and were deemed to be acceptable.Normal Displacement, mmNormal Displacement, mm0 1 2 3 4 5 62000 1 2 3 4 5 6200Normal Stress, kPaNormal Stress, kPa0 20 40 60 80 100 120 140 160250 0 20 40 60 80 100 120 140 160250Shear Stress. kPa150100500Shear Stress. kPa15010050050 psi100 psi100 psi50 psi150 psi150 psiShear Stress. kPa200200(a)(b)Figure 48: Direct shear (a) test results, failure envelope and (b) plotted friction anglefor crushed limestone aggregateShear Stress. kPa150 150100 100500500= 44 44 degreesDry Dry Density = 2,015 kg/m 3w% w% = = 2.6 2.6 %Scaled Aggregate Piers – Manufactured SandWhile the overall process of scaling AASHTO No. 57 aggregate was proven to be successful,the process resulted in a great amount of coarse material retained above #10 sieve to go towaste. Moreover, only limited amount full-scale AASHTO No. 57 limestone aggregate wasavailable and, therefore, additional sources of material had to be identified. The localavailability of manufactured sand material had solved the problem of aggregate deficiencyand the research was continued to carry on. Manufactured sand typically containsconsiderably lower amount of material greater than 2 mm in diameter. Thus, the issue ofexcessive generation of coarse aggregate waste product was resolved as well.The adopted process used to produce manufactured sands is typically through crushingaggregate to a finer level of gradation (