Question

A granular sample is proposed for highway base-course construction. Test results are Retained 0g Sieve 25 mm (1 in.) 19 mm (3/4 in.) 12.5 mm (1/2 in.) 9.5 mm (/8 in.) 4.75 mm (No. 4) Pan 3011 g 3895 g 4113 g 6349 g 11,943 g

Answer 1

• TO calculate the gradation we have to find the value of Cu & Cc .
• 1st prepare a chart that represent % passing through sieve.

• sieve size(mm)	weight retained(g)	weight passed(g)	%passing (%finess)
  4.75	0	482.4	100
  2.00	80.6	401.8	83.3
  1.18	122.0	279.8	58.0
  0.60	52.3	227.5	47.16
  0.425	35.1	192.4	39.88
  0.150	101.4	91	18.86
  0.075	83.7	7.3	1.51
  pan	7.3	-	-
  	total weight =482.4

• formula-

• $C^{u}=\frac{D_{60}}{D_{10}}$

• $C_{c}=\frac{D_{30}^{2}}{D_{60}\times D_{10}}$

• we have to caculate the value of D60,D10&D30  by linear interpolation from chart as following

Die = 0.0751 0.150 -0.075 78.86 -2.57*(18-86-10) + Dio = 0·113 mm mm 0.425 -0.150 Dizo = 0.150 + 39.88 -18.8T X / 39.88 - 30 39.88 - 18.9 m m 1.935 + Dyo = 0.279 mm Dgo = 1.187 20-11.00 x 183.3 - 60) + Doo = 1.935 anom there for Cu - Doo - 17.124; Ce=D302 (0.279) ? 1. DooxDio - 1.935x0.113 = 0.356 As per AASTHO classification for sand particles of cu>4 for gravel Taf both condition satisfied a cu>b for sand of & cc> [173 then it is well graded ] , then Here ce is not in between 1 to 5 hence it is [poorly graded]
grain size distribution curve

% finees vs. sieve size(mm) % finees HHH sieve size(mm)

FOR acceptance of material as per ASTM-

The amount of the fraction of material passing the No. 200 mesh sieve shall not exceed one-half the fraction passing the No. 40 mesh sieve.

ONE HALF OF FRACTION PASSING 40MESH SIEVE =39.88/2=19.9 WHICH IS GREATER THAN FRACTION PASSING THROUGH 200MESH SIEVE (1.51). HENCE IT CAN BE USED AS BASE COURSE ACCORDING TO ASTM.

BUT according to aastho claaassifiation-

1. For gradings C, D, and E, at least 50% by weight of the particles retained on the No. 4 sieve.
2. For gradings C-1, D-1, and E-1, at least 70% by weight of the particles retained on a No. 4 sieve.

but here 100% passing through sieve no-4 henceit is not suitable for base course material.