Gatch refers to a limestone material generally used as a road base. It is another name for caliche, hardpan, kankur and duircrust. It is naturally occurring in arid and semi-arid regions of the world where there are high evaporation rates. It is generally found on the soil surface as opposed to the subsoil. The following is an overview of some of the properties of gatch and associated benefits and disadvantages in road construction.
Gatch is a well graded, clayey quartz sand with light cement-like properties. It offers advantages over sand because it is resistant to blowing and provides better traction for vehicles upon compaction. When found locally, it is an inexpensive option.
Gatch swells somewhat when wet, causing a loss in strength. It can be difficult to excavate in some areas. Moisture content varies from one sample to another, making the accurate determination of this important factor difficult.
The word gatch is mostly used in the deserts of the United Arab Emirates (UAE) and the Kingdom of Saudi Arabia (KSA), though similar materials (caliche-like limestone deposits) are found in Chile, Peru and southern parts of the U.S., such as Texas and New Mexico.