Study on Hygroscopic Swelling and Dehumidification Cracking Characteristics of Expansive Soil under Acid Rain and Cyclic Drying-Wetting

Table 3

The crack area ratio (M_f) of the sample after one-time cyclic drying-wetting.

pH value	Mf (%)
	Humidity
	22%	17–18%	12–14%	8–9%	4–6%
3	0.00	4.65	5.01	4.12	3.81
5	0.00	3.01	3.58	2.91	2.40
7	0.00	2.75	2.89	2.15	1.90