Use of Swiss Hammer for Estimating Compressive Strength of Hardened Concrete

A Simple and Portable Instrument for Use in Estimating the Compressive Strength of Hardened Concrete in Place Has Been Developed Recently by a Swiss Engineer. The Device, Popularly Known as the Swiss Hammer, Is Designed for Field Use and Is Not Intended as a Substitute for Control Testing. It Is Being Used in the Field to Gage Increases in Concrete Strength With Age and in Locating Low Strength Areas When Laboratory Tests of Control Concrete Cylinders or Other Conditions Indicate That Such Areas Might Exist. It Is Also Useful in Surveys of Old Structures. The Test Results Given in This Report Show That Factors Such as Surface Smoothness, Surface Moisture Condition, and Type of Coarse Aggregate Affect the Strength Values Obtained by the Use of the Device. /Author/