GB/T 38989-2020 in English
VALIDUniaxial compressive elastic modulus test method of materials stabilazed with inorganic binder (middle segment method)
- Issued on:2020-07-21
- Implemented on:2021-06-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$156.00
《GB/T 38989-2020无机结合料稳定类材料单轴压缩弹性模量试验方法（中间段法）》由TC458（全国混凝土标准化技术委员会）归口，主管部门为住房和城乡建设部。
Introduction
Technical background of the standard
This standard is formulated by the Ministry of Housing and Urban-Rural Development and managed by the National Technical Committee for Concrete Standardization. It mainly solves the standardization problem of measuring the elastic modulus of inorganic binder stabilized materials in road projects. Compared with the traditional method, the introduction of the middle section method effectively eliminates the measurement error caused by the end effect.
Core Terminology Analysis
| Terms | Definition | Technical Points |
|---|---|---|
| Middle Section Method | Test method for measuring the deformation of the middle section of the specimen | Fix the displacement sensor with a rigid ring, measuring interval 70mm±2mm |
| Uniaxial Compression Elastic Modulus | Compressive Stress Required for Unit Axial Deformation | Calculation Formula: E=(2Fγ)/(πd²×1.2ε0.3) |
| Eliminate end effect | Avoid friction on the end face of the specimen | Use polytetrafluoroethylene film + fine sand to treat the interface |
Key test requirements
Instrument configuration specifications
A hydraulic/electronic servo test system must be used, with a measuring range of 1.25-5 times the failure load, and a displacement sensor resolution of ≤1μm. Typical configuration includes:
- Loading plate: high-strength aluminum plate with spherical support
- Deformation measurement device: double rigid ring structure (spacing 70mm±2mm)
- Data acquisition system: 100-2000Hz sampling frequency
Test process control
- Wipe the surface dry after the specimen is immersed in water for 24 hours
- Pre-compression twice (15% unconfined compressive strength)
- Uniform loading at 1mm/min until failure
- Correct the starting point of the load-strain curve
Data quality control
| Material type | Standard deviation requirement | Outlier processing |
|---|---|---|
| Fine-grained soil/medium-grained soil | <10% | 3σ rule elimination, 2-3 outliers allowed |
| Coarse-grained soil | <15% |
When the coefficient of variation exceeds the standard, additional tests must be conducted at a 90% guarantee rate, and the new and old data must be merged and re-counted.
Project implementation suggestions
Key points for specimen preparation
- Dimension control: φ150mm×150mm (height tolerance ±2.5mm when drilling on site)
- Number of samples: ≥9 (considering the risk of outlier removal)
- Curging conditions: refer to T0845 regulations in JTGE51
Solutions to common problems
Curve oscillation correction:When oscillation occurs in the initial section of the load-strain curve, the true starting point should be determined by connecting the point (ε0.3,0.3Fγ) with the correction origin.
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