ABSTRACT
The genetic classification of rocks commonly used by geologists groups rocks in a way that can be of practical use as well as offering theoretical insight. The relationships of rock types in the classification often explains those between different rock types within one large rock mass and provides a model to be tested by exploration. Rocks can be crushed and graded to make aggregate, which can be added to a bonding material such as cement to form concrete, or bitumen to serve as a roadstone. Different civil engineering jobs require different grades of aggregate. Several rock types are grouped together according to their most important engineering properties and the group is given the name of a commonly known rock within it. The susceptibility of rock to future weathering, either as a rock mass or crushed to form aggregate also be considered in engineering projects. Full accounts of rock blasting methods are given by Langefors and K. Kihlstrom and K. McGregor.
