2.2. pH titration test
The buffering capacity of the materials was determined by a pH titration test (CEN/TS, 2006). First, the initial pH of each sample was measured in a 1:100 sample/deionised water ratio. Next, consecutive volumes of 200 lL of 1 M HNO3 or 1 M NaOH were added,and the suspension was stirred. The resulting pH of the suspension was measured 20 min after each addition of the acid or base. The acid and base additions were repeated until the pH range of 2–12 was covered. This test also allowed for the determination of the acid neutralisation capacity (ANC) of the materials, which is defined as the quantity of acid or base (meq kg1) required to shift the initial pH of the material to a pH of 4. Therefore, for those materials with an initial pH higher than 4, the ANC permits prediction of its buffering capacity with respect to external acidic
stresses.
2.2. pH titration testThe buffering capacity of the materials was determined by a pH titration test (CEN/TS, 2006). First, the initial pH of each sample was measured in a 1:100 sample/deionised water ratio. Next, consecutive volumes of 200 lL of 1 M HNO3 or 1 M NaOH were added,and the suspension was stirred. The resulting pH of the suspension was measured 20 min after each addition of the acid or base. The acid and base additions were repeated until the pH range of 2–12 was covered. This test also allowed for the determination of the acid neutralisation capacity (ANC) of the materials, which is defined as the quantity of acid or base (meq kg1) required to shift the initial pH of the material to a pH of 4. Therefore, for those materials with an initial pH higher than 4, the ANC permits prediction of its buffering capacity with respect to external acidicstresses.
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