Effects of salt content on leaching properties of synthetic bituminized wastes

Figures & data

Table 1. Characteristics of the Blown Bitumen AD Compound and 20/30.

	Blown Bitumen	Blown Bitumen
	AD Compound	20/30
Density at 25 °C	1–1.1	1–1.1
Softening point (°C)	80–90	>80
Penetration depth (0.1 mm)	35–45	20–30
Ductility (cm)	>3	>2

Table 2. Basic characteristics of the synthetic BWs.

	BWAD[11]	BW45	BW10,25,40,55,70
Bitumen	AD Compound	Blown Bitumen 20/30	Blown Bitumen 20/30
S/B ratio	45/55	45/55	10/90, 25/75, 40/60, 55/45, 70/30
Salt composition	Mixed salts^*	Mixed salts^*	100 wt.% NaNO3

^*Mixed salts: 60 wt.% NaNO₃, 24 wt.% NaNO₂, 7 wt.% other soluble salts, and 9 wt.% insoluble salts.

Figure 1. SEM images of the cross-sections of synthetic BWs. (a) BW_AD, (b) BW₄₅, (c) BW₁₀, and (d) BW₅₅.

Figure 2. SEM images of the cross-sections of synthetic BWs after the leaching test. (a) BW_AD, (b) BW₄₅, (c) BW₁₀, and (d) BW₅₅.

Figure 3. Relationship between the leaching fraction (C_t/C₀) and the square root of time of the soluble components for (a) BW_AD and (b) BW₄₅. □: Na⁺, ◯: NO₃⁻, and ♦: NO₂⁻.

Table 3. Diffusion coefficient of sodium, nitrate, and nitrite in the synthetic BWs at 25 °C.

	D (m^2/s)
Sample	Na^+	NO3^−	NO2^−
BWAD	1.3×10^−12	1.4×10^−12	1.5×10^−12
BW45	1.0×10^−12	1.1×10^−12	1.2×10^−12

Table 4. Diffusion coefficient of Na⁺ obtained in the aqueous leaching test of the bituminized wastes.

Sample	n	Bitumen	Leaching solution	Temperature (°C)	S/V ratio (mm^−1)	S/B ratio	Salt composition	D (m^2/s)
BW40	4	Shell blown 20/30	De-ionized water	25	0.37	40/60	100% NaNO3	(3.0 ± 2.2)×10^−13
Synthetic COGEMA-type BW [7]	1	Shell straight 60/80	De-ionized water	25	0.053	40/60	44% NaNO3, 50% BaSO4, 6% CsI	3×10^−13
Eurobitum BW [8]	1	Mexphalt R85/40	Clay water	23	0.025–0.030	40/60	75% NaNO3, 13% CaSO4, 12% insoluble salts	1.4×10^−13

Figure 4. Relationship between the diffusion coefficients of Na⁺ in the synthetic BWs and the volume fraction of the micropores.

Figure 5. Schematic images of the diffusion of a component in the BW (t: time, t₂ > t₁ > 0; X: distance from the center of the BW to interface between the BW and water in one direction, X₂ > X₁ > X₀; C_t: concentration of a component leached from the BW in time, C₂ > C₁ > 0; C₀: initial concentration of a component in the BW).

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