Quality control of unshaped refractories is crucial throughout the entire process, from raw material intake to product delivery and construction. To assess their quality, a series of tests on their physical and chemical properties are required. The Chinese GB/T 4513 series of standards are equivalent to the ISO 1927 series of international standards, standardizing each stage of unshaped refractories production, from sampling and sample preparation to performance testing.
Key testing items include: sampling (according to GB/T 4513.2/ISO 1927-2), flowability (according to GB/T 4513.4/ISO 1927-4), sieve analysis (according to YB/T 5204), particle size distribution, moisture content, plasticity index (according to GB/T 4513.3/ISO 1927-3), air permeability, thermal shock resistance, thermal conductivity, sulfuric acid resistance (according to GB/T 4513.8/ISO 1927-8), carbonization mass loss, residual carbon content, and carbon recovery rate (according to GB/T 17732/ISO 10060), etc.
As an important type, the testing of the mechanical properties such as strength of refractory castables follows a series of domestic and international standards. Testing items include compressive strength, flexural strength, bulk density, apparent porosity, linear shrinkage rate, thermal shock stability, high-temperature flexural strength, abrasion resistance, corrosion resistance, and thermal conductivity, etc. Relevant testing standards include ASTM C133, ISO 8895, GB/T 3001 (flexural strength at room temperature), ASTM C583 (flexural strength at high temperature), ISO 12678-2, GB/T 2997 (bulk density and apparent porosity), GB/T 5988 (permanent linear change upon heating), ASTM C704 (abrasion resistance), and ISO 10060 (compressive strength at high temperature).
