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

Table 4

The crack area ratio of the sample under four-time cyclic drying-wetting.

pH value	Mf (%)
	Humidity
	22%	19–21%	15–16%	10–11%	7–8%
3	0.00		6.54	6.72	6.33
5	0.00	4.41	5.85	6.01	5.58
7	0.00	2.29	5.38	5.01	4.67