Quartz # ½

Quartz # ½ is formed by mechanical crushing of quartzite rock. Quartz Sands are denoted as # ½ by the distributor AGSCO, Inc, the number represents a size order. The material is classified as SP according to ASTM Unified Soil Classifications System (USCS). Particles of Quartz # ½ are angular as shown in Fig. 4.73. Selected DIA images of Quartz # ½ are also presented in Fig. 4.74. The resolution of DIA images is 4 µm/pixel, which contributes to the inability of the device to capture edge details precisely.

Grain size distributions of Quartz # ½ are presented using several size descriptors in Fig. 4.75. Fig. 4.76 also depicts variation between number and volume distribution. The size of number distribution is dominated by the finer particles while volume distribution is dominated by the larger particles. The grain size D50 of Quartz # ½ is 194 µm. Typical particle size diameters in µm corresponding to several particle size descriptors are presented in Table 4.50. Comparison between EQPC sizes corresponding to various particle size diameters by weight/volume and number distributions are also presented in Table 4.51. A large number of finer particles were generated during the crushing process, which resulted in a difference between number and volume distribution calculation.


Fig. 4.73. SEM (scanning electron microscope) image of Quartz # ½ sand.

Fig. 4.73. SEM (scanning electron microscope) image of Quartz # ½ sand.


Fig. 4.74. Images of Quartz # ½ acquired using 2D DIA.

Fig. 4.74. Images of Quartz # ½ acquired using 2D DIA.

The density distribution for a number of commonly used shape descriptors is presented in Fig. 4.77 and summarized in Table 4.52. Unlike coarser gradations of Quartz sand, Wadell Roundness could not be computed using DIA images due to the low resolution of the images (4 µm/pixel). The distribution is clearly non gaussian and is thus fit with Johnson’s parameters. The fitting parameters are summarized in Table 4.53, and the goodness of fit is depicted in Fig. 4.78.


Table 4.50 Typical particle size diameters in µm corresponding to several particle size descriptors (by weight/volume distribution).

Quartz #1/2 D1 D5 D10 D30 D50 D60 D90 D99
Feret-max 60 139 170 218 256 276 370 497
EQPC 43 103 129 168 194 210 280 350
Feret-min 41 90 112 147 174 187 249 318


Table 4.51 Typical EQPC corresponding to various particle size diameters by weight/volume and number distributions.

Quartz #1/2 D1 D5 D10 D30 D50 D60 D90 D99
Volume 43 103 129 168 194 210 280 350
Number 3 3 4 5 8 10 38 202


Table 4.52 Statistics of particle shape descriptors for Quartz # ½ by number and volume distributions.

Quartz #1/2 AR S Cx Rwadell
Number
Mean 0.67 0.79 0.91 …
Median 0.68 0.80 0.92 …
Standard Deviation 0.13 0.07 0.03 …
Volume
Mean 0.68 0.79 0.92 …
Median 0.68 0.81 0.93 …
Standard Deviation 0.13 0.07 0.03 …


Table 4.53 Johnson fitting parameters for Quartz # ½.

Quartz #1/2 γ δ ξ λ
AR -0.15 1.35 0.29 0.74
S -3.33 1.56 -0.11 1.03
Cx 2.16 1.62 0.96 0.02
Rwadell … … … …

Fig. 4.75. Particle size distributions using various size descriptors.

Fig. 4.75. Particle size distributions using various size descriptors.


Fig. 4.76. Particle size volume and number distributions.

Fig. 4.76. Particle size volume and number distributions.


Fig. 4.77. Particle shape density distributions (based on volume) for Quartz #1/2.

Fig. 4.77. Particle shape density distributions (based on volume) for Quartz #1/2.

Aspect Ratio - Fig. 4.78.1
Sphericity - Fig. 4.78.2
Convexity - Fig. 4.78.3

Fig. 4.78. Johnson fitting of shape descriptors for Quartz # ½.