ASTM C20 Apparent Porosity, Water Absorption, Apparent Specific Gravity, and Bulk Density of Burned Refractory Brick and Shapes by Boiling Water

The following parameters of burned refractory brick are determined using ASTM C20 test method: apparent porosity, water absorption, apparent specific gravity, and bulk density. The SI units are to be taken as standard.

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$ASTM C20 Apparent Porosity, Water Absorption, Apparent Specific Gravity, and Bulk Density of Burned Refractory Brick and Shapes by Boiling Water$

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Overview
Scope, Applications, and Benefits
Test Process
Specifications
Instrumentation
Results and Deliverables

Overview

ASTM C20 is a standardized test method for determining the values of various important properties of burned refractory brick and shapes, including apparent porosity, water absorption, apparent specific gravity, and bulk density.

ASTM C20 test method is commonly employed for quality assurance, research and development, specification verification, and generating design data. It provides critical physical property data to identify the structure of refractory materials.

Scope, Applications, and Benefits

Scope

ASTM C20 is a standard for burned refractory brick and refractory products. The standard evaluates significant physical properties of fired refractory materials by employing a boiling-water saturation method to identify pore structures and density-related properties.

The standard measures:

– Apparent porosity
– Water absorption
– Apparent specific gravity
– Bulk density

Applications

Quality control of refractory manufacturing
Research and development of refractory materials
Performance evaluation of kiln and furnace linings
Steel, cement, glass, and petrochemical industries
Design calculations for refractory installations
Comparative material assessment

Benefits

Provides standardized physical property measurements
Ensures material consistency and reliability
Supports refractory selection and design
Evaluates pore structure and density characteristics
Assesses material durability in service environments
Improves quality assurance processes
Supplies critical data for engineering calculations

Test Process

Drying

Specimens are dried at 220–230 °F to constant weight.

Boiling & Soaking

Specimens are boiled in water for 2 hours, cooled while submerged, and soaked for at least 12 hours.

Suspended Weighing

Specimens are weighed while suspended in water using a copper wire loop.

Surface Weighing

Specimens are lightly blotted with a wet towel and weighed to obtain final measurements.

Technical Specifications

Parameter	Details
Applicable Materials	Burned refractory brick and shapes
Drying Temperature	220–230 °F
Boiling Duration	2 hours
Water Immersion After Boiling	Minimum 12 hours
Wire Specification	AWG 22 (0.643 mm) copper wire
Bulk Density Formula	B (g/cm³) = D / V

Instrumentation Used for Testing

Drying oven
Boiling water tank or container
Analytical balance (0.1 g precision)
Suspension apparatus
AWG 22 copper wire
Water immersion tank
Blotting towel

Results and Deliverables

Apparent porosity (%)
Water absorption (%)
Apparent specific gravity
Bulk density (g/cm³)
Test calculation sheets
Compliance reports

Frequently Asked Questions

The apparent porosity, water absorption, apparent specific gravity, and bulk density of fired refractory materials are determined by ASTM C20. These properties, in combination, provide information on the pore structure and density of the material, which are key factors in the resistance of the material to slag penetration, thermal shock, and high-temperature stability.

The boiling water process ensures that all interconnected open pores are fully saturated by displacing the air trapped in the pores. Boiling and subsequent submerged cooling result in consistent data, which makes it a reliable technique for comparing permeability and pore properties of refractory bricks.

Apparent porosity is a factor in both insulation properties and chemical resistance. The greater the porosity, the greater the resistance to thermal shock, but the lower the resistance to penetration by slag and molten material. The measured porosity is important in determining a balance between durability and thermal performance.

ASTM C20 typically requires five specimens to obtain representative averages. The test procedure includes drying, boiling, and cooling cycles, which normally take three to five working days in the laboratory.

The bulk density in the ASTM C20 test is calculated by dividing the dry weight of the specimen by its volume as determined by the buoyancy of the specimen in water.

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