There are other, non-API, terms used to classify cement. These include the following:
• Pozmix cement – This is formed by mixing Portland cement with pozzolan (ground volcanic ash) and 2% bentonite. This is a very lightweight but durable cement. Pozmix cement is less expensive than most other types of cement and due to its light weight is often used for shallow well casing cementation operations.
• Gypsum Cement – This type of cement is formed by mixing Portland cement with gypsum. These cements develop a high early strength and can be used for remedial work. They expand on setting and deteriorate in the presence of water and are therefore useful for sealing off lost circulation zones.
• Diesel oil cement – This is a mixture of one of the basic cement classes (A, B, G, H ), diesel oil or kerosene and a surfactant. These cements have unlimited setting times and will only set in the presence of water. Consequently they are often used to seal off water producing zones, where they absorb and set to form a dense hard cement.
Institute of Petroleum Engineering, Heriot-Watt University