Table 1. Exposure classes XA and limiting values for exposure classes for chemical attack from natural soil and groundwater.

	Chemical characteristic	XA1	XA2	XA3
Ground water	SO42- mg/l	≥ 200 and ≤ 600	≥600 and ≤3000	≥ 200 and ≤6000
Soil	SO42- mg/kg3 total	≥ 2000 and ≤ 3000*	>3000* and ≤12000	≥ 12000 and ≤ 24000

* the 3000 mg/kg limit shall be reduced to 2000 mg/kg where there is a risk of accumulation of sulphate ions in the concrete due to drying and wetting cycles or capillary suction