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Scope

1.1 The amount of water used in a castable has a significant influence on its performance. This practice covers the procedures for determining the consistency of a castable using the Ball-in-Hand Test.

1.2 This practice applies to regular weight castable refractories and insulating castable refractories which are described in Classification C 401. It also applies to such castables containing metal fibers.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (See 6.2.3 for a specific safety warning.)

Significance and Use

This practice is used primarily to determine if a freshly mixed refractory castable is of the proper consistency and therefore would most likely provide optimum performance. It can also be used to estimate the correct water addition rate of a castable when either the manufacturer’specified water content is not available or when unique circumstances have rendered that recommendation unusable.

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).

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.

The total wet mixing time of a castable influences the rheological and final properties and therefore should be monitored.

This practice can be performed in a laboratory or on a job site.

This practice is not intended to determine the proper consistency for gunning applications, although it may provide information of value for interpretation by a skilled operator.

Keywords

ball-in-hand; castable; consistency; mixing; refractory; water demand; wet-out

To find similar documents by ASTM Volume:

15.01 (Refractories, Activated Carbon; Advanced Ceramics)

To find similar documents by classification:

81.080 (Refractories Including ceramic refractories)

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