The Moisture Variation effect on Soil Subgrade in Flexible Road Construction

The estimation of subgrade strength and the volume of traffic to be carried begins the design of the pavement layers to be laid over subgrade soil. The strength of the subgrade soil over which the various pavement layers will be laid has a significant impact on their design. CBR is the most common measure of subgrade strength (California Bearing Ratio). Weaker subgrades necessitate thicker pavement layers, whereas stronger subgrades benefit from thinner pavement layers. Precipitation, capillary action, floods, and abrupt rises or subtidal of the water table all affect the saturation level of the subgrade. The strength of the subgrade changes as the moisture level in the subgrade changes. It is therefore critical for an engineer to comprehend the precise nature of the relationship between subgrade strength and moisture variation. Understanding how the CBR strength of local soils is affected by water content will help to improve design and maintenance practices. The amount of saturation in the soil, i.e., the amount of water exposed to the soil, can affect the strength of the subgrade. As a result, an attempt was made in this study to vary the degree of soaking and thus the saturation level in various types of soils, as well as to investigate the engineering properties of soils, including CBR, at various saturation levels. The worst engineering properties are observed for coarse-grained soils after three days of soaking, and the same is observed for fine-grained soils after four days.