In many parts of the world, severe lost circulation and weak formations with low fracture gradients are common. These situations require the use of low-density cement systems that reduce the hydrostatic pressure of the fluid column during cement placement. Consequently, lightweight additives (also known as extenders) are used to reduce the weight of the slurry. Neat cement slurries, when prepared from API Class A, C, G, or H cements using the amount of water recommended in API Spec. There are several different types of materials that can be used as extenders.