It is necessary to understand the water holding capacity of laterite soil

which is the basis of preventing cracking and instability of the soil subgrade. Firstly

soil water characteristic curves (SWCCs) of compacted samples with four different dry densities were investigated by using 15 bar pressure plate apparatus. Test results show that there has appeared a plateau stage in the soil water characteristic curve with the decreasing of dry density. What’s more

the length of the plateau stage is intimately related to the dry density of samples

the lower the dry density is

the longer the length of the plateau stage is. Then

combined with pore distribution curves of the four samples

reasons for their different water holding capacities are investigated from the viewpoint of microstructure. Finally

SWCC equations for soil of different compactnesses are established through data fitting.