ASTM C99/C99M-25 PDF

Full title and description

ASTM C99/C99M-25 — Standard Test Method for Modulus of Rupture of Dimension Stone. This standard defines the specimen preparation, conditioning, test setup and calculation procedures used to determine the modulus of rupture (flexural strength) of dimension stone (all types except slate).

Abstract

This test method provides a repeatable laboratory procedure to determine and compare the modulus of rupture of dimension stone. It covers both inch‑pound and SI unit systems (to be used independently), specifies specimen geometry and orientation, conditioning (dry/wet), support and loading arrangements, and the method for reporting results and averages for rift‑parallel and rift‑perpendicular directions. The test is intended to show differences in flexural strength among stones and to assist in comparative evaluation.

General information

• Status: Active (current standard).
• Publication date: 2025 (designation C99/C99M-25; ASTM record last updated May 14, 2025).
• Publisher: ASTM International (American Society for Testing and Materials).
• ICS / categories: 91.100.15 — Mineral materials and products (dimension stone).
• Edition / version: C99/C99M-25 (2025 revision).
• Number of pages: 4.

Scope

The standard covers the determination of the modulus of rupture of all types of dimension stone except slate. It includes provisions that the inch‑pound and SI values are regarded separately as the standard and should not be combined. The method is intended for comparative evaluation of different stones and for reporting average values in both rift orientations.

Key topics and requirements

• Specimen geometry: sawed and ground specimens typically 4 in × 8 in × 2.25 in (nominal) for inch‑pound procedure (SI-equivalent specimens and dimensions treated independently).
• Rift orientation: specimens are marked and tested both parallel and perpendicular to the rift; separate averages reported for each orientation.
• Support and loading arrangement: specimens supported on two supports (common span ≈ 7 in for the 4×8 specimen) with a centered loading block; supports and loading block placement described to ensure repeatability.
• Conditioning: specimens may be tested dry or wet; typical drying procedure described (oven conditioning with periodic weight checks) when dry condition is required.
• Machine and loading rate: testing machine accuracy requirements and controlled loading until failure; typical procedural load rates are given in practice guidance (examples reported in test-lab summaries).
• Units and reporting: inch‑pound and SI units are separate standards; test results, individual specimen values and averages for orientations must be reported.

Typical use and users

Used by materials testing laboratories, dimension‑stone producers and fabricators, quality control/assurance groups, architects and specifiers, and research organizations to compare flexural strength (modulus of rupture) of granites, limestones, marbles, sandstones and other dimension stones (excluding slate). The results support material selection, quality acceptance and comparative performance evaluation.

Related standards

ASTM standards commonly used alongside C99/C99M include C97/C97M (Absorption and Bulk Specific Gravity of Dimension Stone), C170/C170M (Compressive Strength of Dimension Stone), C880/C880M (Flexural Strength of Dimension Stone) and ASTM terminology standards for dimension stone (e.g., C119/C119M). These standards together form the core ASTM suite for dimension stone evaluation.

Keywords

dimension stone, modulus of rupture, flexural strength, bending test, specimen conditioning, rift orientation, stone testing, ASTM C99, C99M.

FAQ

Q: What is this standard?

A: ASTM C99/C99M-25 is the ASTM test method that defines how to determine the modulus of rupture (flexural strength) of dimension stone (all types except slate).

Q: What does it cover?

A: It covers specimen dimensions and preparation, orientation relative to the stone rift, support and loading arrangements, conditioning (dry or wet), test machine requirements, loading to failure, and reporting of individual and average modulus of rupture values in either inch‑pound or SI units (each system used independently).

Q: Who typically uses it?

A: Materials testing laboratories, stone fabricators and quarries, architects, engineers, specifiers, and QA/QC personnel who need to assess or compare the flexural performance of dimension stone.

Q: Is it current or superseded?

A: It is current (active) as the C99/C99M-25 revision; ASTM records show the C99/C99M-25 version active and available from ASTM International (ASTM store record updated May 14, 2025).

Q: Is it part of a series?

A: Yes — C99/C99M is part of the ASTM suite of dimension‑stone standards (for example, C97/C97M for absorption and bulk specific gravity, C170/C170M for compressive strength, C880/C880M for flexural strength and related terminology standards). These standards are commonly used together for comprehensive stone evaluation.

Q: What are the key keywords?

A: Dimension stone, modulus of rupture, flexure, bending test, rift orientation, specimen conditioning, ASTM C99.