GB/T 1927.5-2021

Test methods for physical and mechanical properties of small clear wood specimens—Part 5: Determination of density (English Version)

Standard No.: GB/T 1927.5-2021
Language: Chinese, Available in English version
Release Date: 2021
Published By: General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
Latest: GB/T 1927.5-2021
Replace: GB/T 1933-2009

Scope: This document describes the test method for determining the density of wood. This document is applicable to the determination of the density, air-dry density, absolute-dry density and basic density of small unblemished wood samples at the corresponding moisture content.

Introduction

Background of standard revision and technological evolution

GB/T1927.5-2021, as the fifth part of my country's standard system of test methods for physical and mechanical properties of wood, has achieved technical alignment with the international standard ISO130612:2014.

Added a new term definition system (3 chapters)
Improved the dimensional measurement accuracy to 0.01mm (5.1)
Improved the volume measurement specification by displacement method (9.2.2)
Optimized the accuracy of density calculation formula (6.3-9.3)

Core term definition

Term	Definition	Measurement conditions
Wood density	Wood mass per unit volume	Any moisture content state
Air-dry density	Mass-to-volume ratio at equilibrium moisture content (usually 12%)	Atmospheric equilibrium state
Absolute dry density	Absolute dry mass to absolute dry volume ratio	Dry at 103±2℃
Basic density	Absolute dry mass to green volume ratio	Moisture content ≥ fiber saturation point

Comparison of test methods

1. Dimension measurement method

Applicable to standard specimens (20×20×20mm). Use a 0.01mm accuracy measuring tool to measure the three-dimensional dimensions and calculate the density using the formula ρ=m/(a×b×l).

2. Drainage method

For irregular saturated samples, the drainage mass conversion volume is determined by the device in Figure 1. The key control points are:

The immersion depth of the metal needle remains consistent
The sample should avoid contact with the container wall
Reading accuracy0.01cm³

Evolution of key calculation formulas

Density type	2009 version formula	2021 version improvement
Air-dry density	ρ₁₂=ρ_w[1+0.01(1-K)(12-W)]	ρ₁₂=ρ_w(1+0.01(12-W))/(1+0.01(12-W)ρ_H₂O
Basic density	ρ_y=m₀/V_g	Specify V_max measurement requirements (moisture content ≥ fiber saturation point)

Implementation suggestions

Sample preparation: When the growth ring width is ＞4mm, it must contain ≥5 annual rings (6.1.2)
Moisture content control: Air-dried samples must be balanced according to GB/T1927.2-2021 (7.1.2)
Data Recording: It is recommended to use the standardized record form in Appendix A, including the sample size, tree species and other information required by 10.2
Equipment Verification: Regularly calibrate the balance (accuracy 0.001g) and measuring tools (accuracy 0.01mm)

GB/T 1927.5-2021 Referenced Document

GB/T 1927.2-2021 Test methods for physical and mechanical properties of small clear wood specimens—Part 2: Sampling methods and general requirements
GB/T 1927.4-2021 Test methods for physical and mechanical properties of small clear wood specimens—Part 4: Determination of moisture content
LY/T 1788-2008 Standard terminology relating to wood properties

GB/T 1927.5-2021 history

2021 GB/T 1927.5-2021 Test methods for physical and mechanical properties of small clear wood specimens—Part 5: Determination of density
2009 GB/T 1933-2009 Method for determination of the density of wood
1991 GB/T 1933-1991 Method for determination of the density of wood

GB/T 1927.5-2021 Test methods for physical and mechanical properties of small clear wood specimens—Part 5: Determination of density has been changed from GB/T 1933-2009 Method for determination of the density of wood.

GB/T 1927.5-2021 -All Parts