Schmidt Rebound hammer

Factors Influencing the Results
Type of cement
Concrete made of high alumina cement can give strengths up to 100% higher, whereas super sulphated cement concrete can give 50% lower strength compared to a calibration obtained on Portland cement cubes. It is necessary to recalibrate the hammer for different types of cement.

Type of aggregate

Gravel and most crushed rocks give similar correlations, but lightweight aggregates and aggregates with unusual properties require special calibration.

Surface and internal moisture condition of the concrete.

This method of testing is applied only on close textured concrete. Open texture concrete typical of masonry blocks, `honeycombed’ concrete, or no fines concrete cannot be tested using this method.

Trowelled and floated surfaces as in floors, are harder than moulded surfaces and in most cases will tend to overestimate the strength.

A wet surface will give rise to under-estimated of the strength of concrete calibrated under dry conditions. This influence can be considerable and in structural concrete it is about 10% lower on wet surfaces than on an equivalent dry surface.

Age of concrete
In a very old and dry concrete the surface will be harder than the interior, giving rebound values somewhat higher than normal. New concrete with moist surface generally has a relatively softer surface, resulting in lower than normal rebound.

OVER VIEW OF THE CONCRETE HAMMER

Non-destructive Testing Of Concrete via Rebound Hammer - Overview

INTRODUCTION
The standard method of determining strength of hardened concrete consists of testing concrete cubes in compression. The quality of entire concrete of a structure cannot be fully assessed by testing a few concrete cubes. The results obtained in testing cubes do not always reflect the actual strength of concrete in construction. In a whole day, concreting work cubes are cast in a few batches, the differences (unintentional and intentional) in the composition are not uncommon, their compaction and their hardening conditions always differ more or less from those of the structure. In addition, the number of test cubes is generally so small that they can only be considered as random tests. Sometimes, in case of failure of cubes, doubtful concrete, cracks, deterioration of concrete, etc. it becomes necessary to assess the quality and strength of concrete of the structure. As far back as early thirties, the necessity was felt to develop instruments by which in-situ strength of concrete may be obtained. Various non-destructive methods of testing concrete have been developed, which include, Firing method, Skramtayev’s method, Polakov’s method, Magnitostroy method, Fizdel ball hammer, Einbeck pendulum hammer, Ball indentation hammer, Rebound hammer, Pull out techniques, Windsor probe, Ultrasonic pulse velocity methods, Radioactive and nuclear methods, Magnetic and electrical methods. In all these methods of tests, due to simplicity, rebound hammer test based on surface hardness became most popular in the world for non-destructive testing of in-situ concrete.

ONLY ENGINEERS

TEST BETTER – BUILD STRONGER

FOR:

-CONSTRUCTION/BUILDING ENGINEERS

-CIVIL ENGINEERS

-STRUCTURAL/HIGHWAY ROAD ENGINEERS

-MECHANICAL ENGINEERS

FEATURES OF SCHMIDT CONCRETE HAMMER

Features of the HT-225 Concrete Rebound Test Hammer

1. The Concrete Rebound Test Hammer is used to test the Surface Hardness and Penetration Resistance of concrete.

2. It works by measuring the rebound of the spring-loaded hammer, when impacting against the surface of the concrete sample.

3. It is a non-destructive test which can help to estimate the compressive strength of concrete.

4. It is used to test the compressive strength of building structures, floors, bridges, dams, highway Roads and rocks, pavements, Slab, beam, Truss and Column etc

5. It is an easy-to-use instrument that provides a quick and on-the-spot test for obtaining an immediate indication of concrete strength in various parts of structures.

6. It is portable and Handy.

7. It is used in assessing the likely compressive strength of concrete with help of suitable co-relations between rebound index and compressive strength.

8. It is used in assessing the uniformity of concrete

9. It is used in assessing the quality of the concrete in relation to standard requirements

10. It is used in assessing the quality of one element of concrete in relation to another

11. It is most commonly used due to its simplicity and low cost.

Note: The Rebound Hammer method can be used with greater confidence for differentiating between the questionable and acceptable parts of a structure or for relative comparison between two different structures.

CONTACT US:

No. 18 Addis Ababa Crescent wuse zone

4, Abuja.

07036704465, 08096112962

concretereboundhammer@gmail.com

bestoever@yahoo.com