3.1 This test method is used to determine if a freshly mixed refractory castable is of the proper consistency to provide optimum performance. There are times when the manufacturer’s specified water content and consistency will purposely not lead to the correct ball in hand but should be used to provide optimum performance. Contact the manufacturer when in doubt. This test method can also be used to estimate the correct water addition rate of a castable when either the manufacturer's specified water content is not available or when unique circumstances have rendered that recommendation unusable.
3.2 The correct water content is an important factor that must be controlled to obtain optimum castable performance. Excess water can reduce strength, increase volume shrinkage, and promote segregation of the castable ingredients. Insufficient water can produce “honeycombs” (air voids) in the castable because of the insufficient mobility during placement and in extreme cases can prevent the complete hydration of the cement (if used).
3.3 The Ball-in-Hand test is subjective and somewhat depends on the skill of the operator. However, it is a universally accessible method due to the simplicity of the equipment required, and it is readily used in the field.
3.4 The total wet mixing time of a castable influences the rheological and final properties and therefore should be monitored.
3.5 This test method can be performed in a laboratory or on a job site.
