PHYSICAL TESTS FOR INVESTIGATING PERFORMANCE OF CONCRETE

THREE CLASSES OF PHYSICAL TESTS THAT CAN BE MADE IN CONNECTION WITH AN INVESTIGATION OF FIELD CONCRETE ARE DISCUSSED: (1) NONDESTRUCTIVE TESTS, (2) STANDARD TESTS ON CORED OR CUT SECTIONS, AND (3) TESTS OF CONCRETE VISIBILITY OF 175 FEET. EACH OF THE REMAINING 25 PEDESTRAINS DISCUSSED IN THE FOLLOWING CATEGORIES: SONIC TESTING, IMPACT TESTING, LOCATING REINFORCING STEEL, AND DENSITY BY RADIOCATIVE METHODS. SONIC TECHNIQUES HAVE BEEN FOUND USEFUL FOR ACQUIRING THE FOLLOWING TYPES OF INFORMATION REGARDING THE CONDITION OF CONCRETE: (1) MEASURE OF UNIFORMITY WITHIN A STRUCTURE, PARTICULARITY WITH REGARD TO DEFINING THE EXTENT OF OBSERVED DETERIORATION (2) MEASURE OF CHANGES IN THE CONDITION OF CONCRETE WITH TIME BY REPETITION OF TESTS, (3) MEASURE OF GENERAL LEVEL OF QUALITY, AND (4) MEASURE OF DEPTH AND EXTENT OF CRACKS, BY TAKING INTO ACCOUNT THE FACT THAT SOUND WAVES PASS AROUND CRACKS OR VOIDS AND THEREFORE TRAVEL A LONGER PATH THAN IF THE DISCONTINUITY WERE NOT THERE. STANDARD TEST METHODS AND EQUIPMENT ARE DESCRIBED ON CORED OR CUT SECTIONS FOR THE FOLLOWING CONCRETE PROPERTIES: STRENGHT, ELASTICITY, AIR CONTENT, EFFECT OF ENVIRONMENT, ABSORPTION, PERMEABILITY, THERMAL EXPANSION, SHRINKAGE, AND UNIT WEIGHT. IN ADDITION TO VISUALLY EXAMINING AND TESTING THE CONCRETE IN A STRUCTURE, IT MAY BE DESIRABLE TO FABRICATE AND TEST MOLDED SPECIMENS IN CONNECTION WITH AN INVESTIGATION OF PERFORMANCE. THE COMPARISONS THAT ARE NECESSARY TO DEVELOP THE DESIRED INFORMATION USUALLY FALL INTO ONE OR A COMBINATION OF THE FOLLOWING CATEGORIES: (1) COMPARISON OF THE SAME OR SIMILAR CONSTITUENTS WITH OTHER CONSTITUENTS OF KNOWN PERFORMANCE, (2) COMPARISON OF VARIOUS PERCENTAGES OF THE SAME OR SIMILAR CONSTITUENTS, AND (3) INFLUENCE OF EXPOSURE BY SUBJECTING SIMILAR SPECIMENS TO A RANGE OF ENVIRONMENTAL CONDITIONS.