Question

After eating some decent beef on weck at the Blackthorn, you stumble out onto Seneca Street and break your leg after falling into a deep pot hole. While waiting for your leg to heal, you decide to fill in the pot hole with some gravel so no one else gets hurt. You go to the garden store to buy gravel but no one has heard of the USCS system. That does not matter since they only have one type anyway. You buy a bag and run a sieve test on a 470g sample that produces the following data. Plot the grain size distribution curve, identify the coefficients of curvature and uniformity, and classify according to USCS. Explain why either a poorly graded gravel or a well graded gravel would be better for this application.

After eating some decent beef on weck at the Blackthorn, you stumble out onto Seneca Street and break your leg after falling into a deep pot hole. While waiting for your leg to heal, you decide to fill in the pot hole with some gravel so no one else gets hurt. You go to the garden store to buy gravel but no one has heard of the USCS system. That does not matter since they only have one type anyway. You buy a bag and run a sieve test on a 470g sample that produces the following data. Plot the grain size distribution curve, identify the coefficients of curvature and uniformity, and classify according to USCS. Explain why either a poorly graded gravel or a well graded gravel would be better for this application. Mass retained (g) 0 26 28 18 Sieve size (mm) 63 37.5 19 13.2 9.5 6.7 4.75 2.36 1.18 0.6 0.212 0.075 20 49 L 50 137 46 31 34 30

Answer 1

Solution:

Total Weight of sample = 470 g %age Finer Partical Size Distribution Sieve Size (mm) 63 37.5 Mass Retained (g) 0 19 28 %age Comm. mass %age retained Reatined 0.00 0.00 5.53 5.53 5.96 11.49 3.83 15.32 4.26 19.57 10.43 30.00 10.64 40.64 29.15 69.79 9.79 79.57 6.60 86.17 7.23 93.40 6.38 99.79 13.2 9.5 6.7 4.75 2.36 1.18 0.6 0.212 0.075 100 94.47 88.51 84.68 80.43 70.00 59.36 30.21 20.43 13.83 6.60 0.21 Percentage Finer (%) 50 137 46 31 0.01 0.1 1 10 100 34 30 Partical Size (mm) From PSD graph, D10 = 0.35 mm D30 = 2.5 mm D60 = 5mm

- Coefficient of Uni formi ty Coefficient of Curvature Cu = D6o 5 = 14.3 =230² = 2.5² 21:43 Dio 0.35 Dox Dio 5x0.352.73 Classificiration based on USCS ) > 50 Material is greater than sieve Noi 200 < > 50 1. .. material is smaller than Sieve No. 4 : 1 Hence soil.. is sand. 2) gt is fulfiling well Graded criteria @ Cosó .. Hence, soil is classified as ... O k ą <3 y well-graded Sandi