ICC Soils (EC) Material Testing Practice Test 2026 – All-in-One Guide to Exam Success!

The characteristic that signifies tough soil is the ability to roll into a small string when manipulated. This property indicates that the soil has a suitable moisture content and sufficient cohesion to maintain its structure while being worked. When soil can be formed into a string, it demonstrates plasticity, which is often associated with a higher clay content. Tough soils generally have strong cohesive properties, making them less prone to breaking apart easily, thus contributing to their overall toughness.

In contrast, soils that can be squeezed easily or flake when dry lack this cohesive strength and plasticity. Soils that flake easily tend to be more brittle, indicating lower tensile strength and cohesion. Similarly, while retaining shape when dry can suggest some level of toughness, it does not directly imply the ability to form into a string, which is a clearer indication of a soil's toughness. Therefore, rolling into a small string is the most definitive sign of tough soil characteristics.