Title:
Procedure for Determining P-Wave Speed in Concrete for Use in Impact-echo Testing Using a P-Wave Speed Measurement Technique
Author(s):
Jiunn-ming Lin, Mary Sansalone, and William B. Streett
Publication:
Materials Journal
Volume:
94
Issue:
6
Appears on pages(s):
531-539
Keywords:
concretes; cores; impact tests; performance; quality control;
structural members; tests;
DOI:
10.14359/337
Date:
11/1/1997
Abstract:
The dilatational or P-wave speed in concrete is needed in impact-echo testing if the dimensions of the structural elements or the location of flaws are to be determined. Previously the P-wave speed was determined from cores or from performing a test on a portion of the structure having known dimensions and no flaws. In cases where neither approach was possible, an estimate had to be made of the wave speed. This paper presents the details of a method for independently determining P-wave speeds in concretes by determining the time it takes the P-wave to travel between two points along the surface of a structure. This procedure is more accurate than procedures which involve the use of Rayleigh wave speed measurements, and thus it is a better technique for use in quality control situations and other testing situations where more accurate results are needed. In this paper the direct P-wave procedure is explained. Systematic errors involved in the measurement procedure are examined, and the accuracies that can be expected using the procedure in conjunction with the impact-echo test procedure are discussed. Improvements in data-acquisition equipment which take advantage of new hardware and software for increasing the accuracy of measurements are also described. The results of laboratory tests carried out on smooth and grooved surfaces are presented.