Ottawa Sand #20-30

Ottawa sand #20-30 is a naturally occurring, mechanically sorted, siliceous sand, mined from deposits near Ottawa, IL. It is commonly used as a standard sand in the United States and denoted by the numbers 20-30. The denotation refers to the passing and retaining sieve sizes. The specimens tested were purchased from AGSCO corporation. The material is classified as SP according to ASTM Unified Soil Classifications System (USCS). Particles of Ottawa Sand are rounded as shown in Fig. 4.7. Selected DIA images of Ottawa #20-30 are also presented in Fig. 4.8.

Grain size distributions of Ottawa #20-30 are presented using several size descriptors in Fig. 4.9. Fig. 4.10 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 Ottawa #20-30 is 856 µm. Typical particle size diameters in µm corresponding to several particle size descriptors are presented in Table 4.6. Comparison between EQPC sizes corresponding to various particle size diameters by weight/volume and number distributions are also presented in Table 4.7.

The density distribution for a number of commonly used shape descriptors is presented in Fig. 4.11 and summarized in Table 4.8. The distribution is clearly non gaussian and is thus fit with Johnson’s parameters. The fitting parameters are summarized in Table 4.9, and the goodness of fit is depicted in Fig. 4.12.

Fig. 4.7. Photo of Ottawa #20-30 sand with a 19 mm diameter US Penny for scale.

Fig. 4.8. Images of Ottawa #20-30 acquired using 2D DIA.

Table 4.6 Typical particle size diameters in µm corresponding to several particle size descriptors (by weight/volume distribution).

Ottawa #20-30	D1	D5	D10	D30	D50	D60	D90	D99
Feret-max	786	801	819	893	969	1012	1141	1692
EQPC	652	684	724	811	856	878	945	1129
Feret-min	548	636	657	709	762	790	912	948

Table 4.7 EQPC corresponding to various particle size diameters by weight/volume and number distributions

Ottawa #20-30	D1	D5	D10	D30	D50	D60	D90	D99
Volume	652	684	724	811	856	878	945	1129
Number	3	3	4	5	6	7	20	903

Table 4.8 Statistics of particle shape descriptors for Ottawa #20-30 by number and volume distributions.

Ottawa #20-30	AR	S	Cx	Rwadell
Number
Mean	0.78	0.77	0.96	0.78
Median	0.79	0.79	0.97	0.79
Standard Deviation	0.09	0.10	0.02	0.09
Volume
Mean	0.77	0.96	0.78	0.79
Median	0.79	0.97	0.79	0.80
Standard Deviation	0.10	0.02	0.08	0.09

Table 4.9 Johnson fitting parameters for Ottawa #20-30

Parameter	γ	δ	ξ	λ
AR	-0.72	1.34	0.43	0.58
S	-1.85	1.31	0.18	0.77
Cx	-3.08	1.07	0.69	0.30
Rwadell	2.10	2.50	0.93	0.15

Fig. 4.9. Particle size distributions of various size descriptors.

Fig. 4.10. Particle size by volume and number distributions.

Fig. 4.11. Particle shape density distributions (based on volume) for Ottawa #20-30.

Fig. 4.12. Johnson fitting of shape descriptors for Ottawa #20-30.