PSI - Issue 74

Maciej Gruszczyński et al. / Procedia Structural Integrity 74 (2025) 25 – 32 Maciej Gruszczyński / Structural Integrity Procedia 00 (2025) 000–000

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Table 1. Concentrations of nitrates and nitrites measured by ion chromatography in leaching solutions from samples (100 × 100 × 10 mm) of the reference mortar and the mortar with activated

carbon cement. Type of mortars

NO 2 - (mg/dm

3 )

NO

3 - (mg/dm

3 )

0.05 0.16

0.02 1.25

Reference

With 4% activated carbon

The results of the adsorption of nitrates and nitrites presented in Table 1 clearly show that the mortars with the addition of activated carbon have a significantly higher – compared to the reference mortar – nitrite adsorption capacity. The concentration of NO 3 – was in the case of this mortar by an order of magnitude higher than in the case of the reference mortar. Taking into account the relatively large thickness of the test samples (i.e. 10 mm) and taking into account that only the subsurface layer of the composite (up to 1 mm) is actively involved in the NO x adsorption process, it was decided to make another set of mortar samples with the same composition as in first stage but thinner. The thickness of the prepared samples was 2 mm but the cross – sectional area remained unchanged, i.e. 100 × 100 mm (Fig. 4).

(b)

(a)

Fig. 4. V iew of prepared samples with a thickness of 2 mm and 100 × 100 mm cross-section; (a) the reference mortar (1) and the mortar with 4% addition of activated carbon (2), (b) close- up of a sample with a visible crack .

The curing, carbonation and exposure of the mortar samples with a thickness of 2 mm were carried out in exactly the same way as for the samples with a thickness of 10 mm. But they were placed on a 1 mm thick stainless steel backing (Fig. 4) due to the delicacy and brittleness of such thin samples. The active area of these samples was 100 cm 2 . T herefore it was smaller than the area of 10 mm thick samples for which the active area was 240 cm 2 . The results of the nitrate and nitrite concentration measured by ion chromatography in leaching solutions from the reference mortar samples (100 × 100 × 2 mm) and from the mortar with activated carbon are shown in Table 2.

Table 2. Concentrations of nitrates and nitrites measured by ion chromatography in leaching solutions from samples (100 × 100 × 2 mm) of the reference mortar and the mortar with activated carbon cement. Type of mortars NO 2 - (mg/dm 3 ) NO 3 - (mg/dm 3 ) Reference 0.07 0.04 With 4% activated carbon 0.47 13.5

The results of the study of the concentration of nitrates and nitrites in the solutions leached from the samples – both 10 mm and 2 mm thick, confirm the hypothesis of high reactivity and the ability to adsorb NO x by the subsurface layer