Interlock resistance is the resistance to shearing that arises from friction and interlocking between the grains in a granular material. Examples include crushed sand or aggregate.
Characteristics
Interlock resistance develops where grains touch and press against one another. Angular, rough grains interlock better than round, smooth grains and therefore give a higher interlock resistance. High interlock resistance means more internal stability and bearing capacity, because the grains cannot slide past each other as easily. Round river sand, with its smooth, rounded grains, has a lower interlock resistance. The property is thus closely tied to the grain shape and roughness of the material.
Applications
Because of their higher interlock resistance, foundation and road-base layers often use angular, crushed materials such as mixed aggregate and crushed sand instead of round river sand. This gives a sub-base under paving more stability and load capacity. When choosing sand or aggregate for a bearing layer, grain shape is therefore an important consideration: crushed material produces a firmer, less deformable layer.
Related terms
- grain stress
- aggregate
- crushed sand
- soil mechanics
- bearing capacity
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