Strain‑Controlled Loading Consolidation Apparatus

Strain‑Controlled Loading Consolidation Apparatus

Model BTU-STC-1S

Description

This equipment is a strain‑controlled loading consolidation apparatus(constant rate of strain – CRS), model BTU-STC-1S, used to perform strain‑controlled loading consolidation tests (CRS) with real‑time pore pressure measurement. Main features:

• Specimen sizes: Φ61.8×H20 mm and Φ61.8×H40 mm
• Load frame: maximum axial force 10 kN, built‑in 4‑channel data logger
• Load cell: 0‑10 kN, accuracy ±0.1% FS
• Pore pressure sensor: 0‑3.2 MPa (accuracy not stated, assumed ±0.1% FS)
• Supplied with computer‑based data acquisition and control software

Test Standards (International)

• ASTM D4186(Constant rate of strain consolidation – CRS)
• ASTM D2435(One‑dimensional consolidation – CRS is a derived method)
• ASTM D4546(Load‑unload‑reload consolidation)
• ISO 17892‑5(Consolidation test)
• BS 1377‑6(Consolidation test)

The equipment can meet the requirements of these standards for loading, displacement measurement, pore pressure monitoring, etc.

Specification

> Note: The loading rate range, displacement stroke, etc., are not specified – refer to the product manual.

Detail

• Strain‑controlled loading (CRS)– Loads the specimen at a constant axial strain rate (e.g., 0.01 mm/min), continuously recording axial stress, strain, and pore pressure, thereby rapidly obtaining consolidation parameters (Cv, Cc, Pc, etc.).
• Two specimen heights– 20 mm (conventional) and 40 mm (longer drainage path).
• Real‑time pore pressure measurement– Monitors pore water pressure during consolidation, useful for calculating Cv and effective stress paths.
• Built‑in 4‑channel data logger– Simultaneously records axial load, displacement, pore pressure, etc.
• Maximum axial force 10 kN– Corresponds to a maximum axial stress of about 3.3 MPa (for Ø61.8 mm specimen), suitable for most soil consolidation tests.
• High‑precision load cell– ±0.1% FS, reliable data.
• Computer software– Fully automatic test control, real‑time display of stress‑strain and pore pressure‑strain curves, automatic calculation of consolidation parameters.

Application

• Rapid consolidation testing– CRS saves significant time compared to traditional step loading, suitable for batch testing.
• Low‑permeability soils– For clays and other low‑permeability soils, CRS efficiently provides consolidation coefficients.
• Effective stress analysis– Pore pressure measurement allows study of effective stress changes during loading.
• Soft soil subgrades– Evaluate consolidation characteristics for settlement prediction.
• Research and teaching– University soil mechanics laboratories, research institutions.

Advantages

• CRS rapid consolidation– Can save more than 80% of test time compared to step loading.
• Real‑time pore pressure measurement– Provides additional effective stress information, improving calculation accuracy.
• Two specimen heights– Flexibility for different research purposes.
• Built‑in data logger– Highly integrated, reduces external equipment.
• High‑precision sensors– 0.1% FS, meeting research requirements.
• Fully automatic software– Automatic control, acquisition, calculation, reducing human error.

What To Choose

Select this equipment or compare with other models based on testing requirements:

Process Flow

Example:CRS consolidation test (constant rate of strain)

• Specimen preparation
  • Cut undisturbed or remoulded specimen using a Φ61.8×20 mm or 40 mm ring.
  • Measure initial water content and density; saturate if required.

• Specimen installation
  • Place the specimen into the consolidation cell (with porous stones and filter paper), connect the pore pressure sensor.
  • Install the displacement sensor.
  • Position the cell in the load frame and connect the axial load cell.

• Set test parameters
  • In the software, select “CRS consolidation module”.
  • Set a constant strain rate (e.g., 0.01 mm/min).
  • Set maximum axial strain (e.g., 20%) or maximum axial force (10 kN).
  • Set data acquisition interval (e.g., 1 second).

• Start the test
  • Start the servo loading system to push the piston downward at a constant rate.
  • Software records axial force, axial displacement, pore pressure, and time in real time.
  • Plots stress‑strain curve and pore pressure‑strain curve.

• Stop condition
  • Automatically stops when the preset strain or maximum axial force is reached.

• Disassembly and cleaning
  • Unload, remove the specimen, weigh and dry to measure final water content.
  • Clean the consolidation cell and sensors.

• Data processing
  • Based on CRS theory, the software automatically calculates:
    • Coefficient of consolidation (Cv) from pore pressure and loading rate
    • Compression index (Cc), rebound index (Cs)
    • Pre‑consolidation pressure (Pc)
    • Coefficient of permeability (k) (indirectly)
  • Generates a test report.

Summary:

• BTU-STC-1Sis a strain‑controlled loading consolidation apparatus for CRS rapid consolidation tests, with a maximum axial force of 10 kN, pore pressure measurement, and suitable for rapid determination of consolidation parameters for fine‑grained soils.