Rebound Hammer Test
(Schmidt Hammer Test)
Non-destructive assessment of surface hardness and estimated compressive strength of hardened concrete using a spring-driven hammer — the most widely used on-site concrete quality indicator.
What is the Rebound Hammer Test?
The Rebound Hammer Test (Schmidt Hammer Test) measures the surface hardness of hardened concrete by recording the rebound of a spring-driven plunger from the concrete surface. The rebound number (R-value) is correlated to an estimated concrete compressive strength using calibration curves specific to the cement type, aggregate type and surface condition.
Conducted as per IS 13311 Part 2 and ASTM C805, this test is extensively used for rapid quality control on site, comparative assessment of large concrete areas and identification of weak or suspect zones. Global Lab conducts rebound hammer testing with digital Schmidt hammers and provides grid-mapped strength contour reports.
Rebound Hammer Test — Site Images
How the Rebound Hammer Test is Conducted
-
1Surface PreparationConcrete surface is smoothed using a carborundum stone to remove loose material, paint or carbonation that would affect readings.
-
2Grid LayoutA testing grid is marked on the concrete surface with points spaced at 25mm intervals for a minimum of 16 readings per test area.
-
3Hammer ImpactThe Schmidt hammer plunger is pressed firmly against the concrete surface at 90° (or specified angle) and released.
-
4Rebound Number RecordingThe rebound value (R-number) is read from the scale and recorded. Minimum 16 readings are taken per test point.
-
5Strength Estimation & ReportingAverage R-value is converted to estimated compressive strength using calibration chart (IS 13311 / ASTM C805). Statistical analysis and NABL report issued within 24 hours.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| IS 13311 Part 2 | Methods of Non-Destructive Testing of Concrete — Rebound Hammer | Surface Hardness | Indian Standard |
| ASTM C805 | Standard Test Method for Rebound Number of Hardened Concrete | Rebound Test | ASTM |
| BS EN 12504-2 | Testing Concrete in Structures — Non-Destructive Testing — Rebound Number | NDT | British Standard |
| EN 13791 | Assessment of In-situ Compressive Strength in Structures | Strength Assessment | European Standard |