Results

• Conductivity
• Total Charge
• Current at early times

The results of the experiment are summarized in Table 4. The specimens are grouped by sample for direct comparison between specimens with different lengths from the same mixture. Although most of the specimens were more than two months of age at the time of testing, results of the total charge passed Q_T indicate that specimens from a range of qualities were tested. In fact, some of the tests had to be terminated due to excessive heating. Unfortunately, there were also some specimens that have no IS data due to computer software problems. However, the comparison among R_B, R₂₀, and R_o can be carried out for all but five specimens.

Table 4: Specimen bulk conductivity calculated from either the RCT ( σ_RCT ) or the IS measurement ( σ_IS ). The RCT resistance ( R _o ) was calculated from the initial RCT current ( I_o ) and the bulk resistance ( R _B ) was determined from impedance spectroscopy. The total charge ( Q_T ) passed during the RCT and the real component of the impedance at 20 kHz ( R₂₀ ) are also shown for comparison purposes. Reported uncertainties represent an estimated coverage of 95 %.

Specimen	Length (mm)	Age (day)	QT	Io (A)	Ro ( Ω )	RB ( Ω )	R20 ( Ω )	σRCT (µS / mm)	σIS (µS / mm)
A-1	50	66	[1]	0.5995	100.1 ± 0.1	98	98	63.6 ± 4.0	65.0 ± 4.3
A-2	100	66	10865 ± 2	0.2755	217.8 ± 0.5	215	213	58.5 ± 3.7	59.2 ± 3.8
B-1	50	73	[1]	0.9435	63.6 ± 0.1	[2]		100.1 ± 6.3
B-2	100	71	[1]	0.6238	96.2 ± 0.1	[2]		132.4 ± 8.4
C-1	50	64	[1]	0.3622	165.7 ± 0.3	[2]		38.4 ± 2.4
C-2	100	64	4389 ± 1	0.1592	377.0 ± 1.5	364	364	33.8 ± 2.1	35.0 ± 2.2
D-1	50	55	[1]	0.2935	204.5 ± 0.5	203	202	31.1 ± 2.0	31.4 ± 2.0
D-2	100	56	2818 ± 1	0.1103	544.1 ± 3.0	543	540	23.4 ± 1.5	23.4 ± 1.5
E-1	50	69	4564 ± 1	0.1358	441.8 ± 2.0	444	440	14.4 ± 0.9	14.3 ± 0.9
E-2	100	69	1455 ± 1	0.0580	1035 ± 11	1030	1014	12.3 ± 0.8	12.4 ± 0.8
F-1	50	48	6905 ± 1	0.1835	327.1 ± 1.1	336		19.5 ± 1.2	18.9 ± 1.2
F-2	100	49	2418 ± 1	0.0935	641.8 ± 4.2	638	631	19.8 ± 1.3	20.0 ± 1.3
G-1	50	76	4603 ± 1	0.1520	394.7 ± 1.6	379	373	16.1 ± 1.0	16.8 ± 1.1
G-2	100	76	1964 ± 1	0.0781	768.7 ± 5.9	759	738	16.6 ± 1.1	16.8 ± 1.1
H-1	50	75	1591 ± 1	0.0588	1020 ± 11	974	963	6.2 ± 0.4	6.5 ± 0.4
H-2	100	75	679 ± 1	0.0289	2074 ± 43	2050	1992	6.1 ± 0.4	6.2 ± 0.4
I-1	50	69	[1]	0.1980	303.1 ± 1.0	[2]		21.0 ± 1.3
I-2	100	69	3363 ± 1	0.1021	587.9 ± 3.5	[2]		21.7 ± 1.4
J-1	50	77	9128 ± 2	0.2514	238.6 ± 0.6	234	228	26.7 ± 1.7	27.2 ± 1.7
J-2	100	77	3625 ± 1	0.1384	433.5 ± 1.9	432	415	29.4 ± 1.9	29.5 ± 1.9
K-1	50	75	6944 ± 1	0.1848	324.6 ± 1.1	362	307	19.6 ± 1.2	17.6 ± 1.1
K-2	100	75	2271 ± 1	0.0807	743.6 ± 5.6	704	704	17.1 ± 1.1	18.1 ± 1.1
L-1	50	78	7662 ± 1	0.2376	252.5 ± 0.7	260	235	25.2 ± 1.6	24.5 ± 1.6
L-2	100	78	4021 ± 1	0.1492	402.1 ± 1.7	412	376	31.7 ± 2.0	30.9 ± 2.0
M-1	50	76	11067 ± 2	0.2921	205.4 ± 0.5	222	193	31.0 ± 2.0	28.7 ± 1.8
M-2	100	76	5373 ± 1	0.1804	332.6 ± 1.1	341	309	38.3 ± 2.4	37.3 ± 2.4

[1] Test terminated due to excessive heating. [2] No measurement.

The issue of measurement uncertainty is addressed in the Appendix. Uncertainties reported in Table 4 represent an estimate of two standard deviations ( 2σ ), or an estimated coverage of approximately 95 %. The uncertainties in the total charge passed Q_T were all less than 2 coulombs at ± 2σ, with most of the uncertainties less than 1 coulomb. The Appendix addresses the calculations of the reported uncertainties, and concentrates on the complicated issue of the uncertainty in Q_T .