The Rebound Hammer Test, also known as the Schmidt Hammer or Swiss Hammer Test, is a non-destructive testing method widely used in Bangladesh to assess the compressive strength and quality of hardened concrete in structures like buildings, bridges, and roads. Here’s a concise overview based on available information:

What is the Rebound Hammer Test?

  • Purpose: Measures the surface hardness of concrete to estimate its in-place compressive strength and assess structural stability.
  • Mechanism: A spring-loaded hammer is pressed against the concrete surface, releasing a mass that strikes the surface. The rebound distance (rebound number or R-value) is measured on a scale, indicating surface hardness, which correlates to compressive strength using calibration charts.
  • Applications: Used for quality control, structural integrity assessment, and determining if further in-depth testing is needed. It’s cost-effective, portable, and quick.

Types of Rebound Hammers in Bangladesh

  1. Type N:
  • Impact energy: 2.207 Nm (1.63 ft-lbf).
  • Suitable for concrete thicker than 100 mm (4 inches).
  • Measures compressive strength from 10-70 MPa (1,450-10,152 psi).
  1. Type L:
  • Lower impact energy: 0.735 Nm (0.54 ft-lbf).
  • Used for thinner concrete sections or lower strength ranges, providing repeatable values.

Common Models and Prices in Bangladesh

  • HT-225: A popular model with 2.207 Nm impact energy, used for compressive strength testing (100-600 kg/cm²). Price ranges from BDT 15,200 to BDT 350,000, depending on the supplier and features (e.g., digital vs. analog).
  • RH225-A: Fully automatic, digital model for non-corrosion detection and compressive strength (10-60 MPa). Price around BDT 20,000.
  • Proceq Original Schmidt OS8000: Advanced digital model with mobile app integration for real-time reporting. Pricing requires contacting suppliers like BD Trade International.
  • HT-225K Digital Rebound Hammer: Features Bluetooth, a 2.8-inch LCD, and a 3200mAh battery. Pricing available through suppliers like Mother’s Technology.

Suppliers and Services in Bangladesh

  • EMS Engineering: Offers testing services and equipment, emphasizing structural stability analysis.
  • RTC Dhaka: Imports and supplies HT-225 models, offering competitive pricing and free shipping for orders over USD 200.
  • Conchembd: Authorized Hilti product supplier, selling HT-225A models with online ordering and free delivery.
  • Urban Solutions: Provides rebound hammer testing alongside other construction services like waterproofing.
  • VERITAS Engineering & Consultant (VEC): Conducts tests with offices in Dhaka and Chittagong.
  • BDNDT.com: Supplies various models, including Proceq Schmidt hammers, with a focus on non-destructive testing equipment.
  • RVS Quality Certifications Pvt Ltd: Offers professional rebound hammer testing services, ensuring no structural damage.

Procedure and Standards

  • The hammer is pressed against the concrete until it trips, releasing the mass. The rebound number is recorded and compared to laboratory calibration charts (e.g., ASTM C805, EN 12504-2).
  • Standards followed include ASTM C805, GB/T9138-1988, JJG817-93, and JGJ/T23-2011.

Limitations

  • Provides an estimate, not precise strength values; results can vary due to surface conditions, moisture, or aggregate type.
  • Less accurate for thin or low-strength concrete unless using Type L hammers.
  • Often supplemented with other tests like Ultrasonic Pulse Velocity (UPV) or core sampling for precise results.

Availability and Market

  • Rebound hammers are widely available through local suppliers and importers in Dhaka, Chittagong, and online platforms like Bdstall and Daraz.
  • Digital models with features like Bluetooth and real-time data upload are gaining popularity for efficiency.

For specific pricing or to purchase, check with suppliers like RTC Dhaka (rtcdhaka.com), Conchembd (conchem.com.bd), or BDNDT (bdndt.com). For testing services, contact firms like EMS Engineering or VEC.

If you need details on a specific supplier, model, or testing service in a particular city, let me know!