Guidance is provided on the use of methods to estimate the in-place strength of concrete in new and existing construction. The methods include: rebound number, penetration resistance, pullout, break-off, ultrasonic pulse velocity, maturity, and cast-in-place cylinders. The principle, inherent limitations, and repeatability of each method are reviewed. Procedures are presented for developing the relationship needed to estimate compressive strength from in-place results. Factors to consider in planning in-place tests are discussed, and statistical techniques to interpret test results are presented. The use of in-place tests for acceptance of concrete is introduced. The appendix provides information on the number of strength levels that should be used to develop the strength relationship and explains a regression analysis procedure that accounts for error in both dependent and independent variables. Keywords: coefficient of variation; compressive strength; construction; in-place tests; nondestructive tests; safety; sampling; statistical analysis.

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PDF Pages	PDF Title
1	CONTENTS
2	CHAPTER 1— INTRODUCTION 1.1— Scope 1.2—Need for in-place tests during construction
3	1.3—Influence of ACI 318 1.4—Recommendations in other ACI documents 1.5—Existing construction
4	1.6—Objective of report CHAPTER 2— REVIEW OF METHODS 2.1— Introduction 2.2—Rebound number (ASTM C 805)
5	2.3—Penetration resistance (ASTM C 803/C 803M)
6	2.4—Pullout test (ASTM C 900)
9	2.5—Break-off number (ASTM C 1150)
10	2.6—Ultrasonic pulse velocity (ASTM C 597)
11	2.7—Maturity method (ASTM C 1074)
13	2.8—Cast-in-place cylinders (ASTM C 873 2.9—Strength limitations 2.10—Combined methods
14	2.11—Summary CHAPTER 3— STATISTICAL CHARACTERISTICS OF TEST RESULTS 3.1—Need for statistical analysis
15	3.2—Repeatability of test results 3.2.1 Rebound number
16	3.2.2 Penetration resistance
17	3.2.3 Pullout test
19	3.2.4 Break-off test
20	3.2.5 Pulse velocity 3.2.6 Maturity method
21	3.2.7 Cast-in-place cylinder CHAPTER 4— DEVELOPMENT OF STRENGTH RELATIONSHIP 4.1—General 4.2—New construction 4.2.1 General 4.2.2 Number of strength levels 4.2.3 Number of replications
22	4.2.4 Regression analysis
23	4.2.5 Procedures for correlation testing 4.2.5.1 Rebound number
24	4.2.5.2 Penetration resistance 4.2.5.3 Pullout test 4.2.5.4 Break-off test 4.2.5.5 Ultrasonic pulse velocity
25	4.2.5.6 Maturity method 4.2.5.7 Cast-in-place cylinder 4.3—Existing construction 4.3.1 General 4.3.2 Developing strength relationship
26	CHAPTER 5— IMPLEMENTATION OF IN- PLACE TESTING 5.1— New construction 5.1.1 Preconstruction consensus 5.1.2 Number of test locations 5.1.3 Number of tests per location 5.1.4 Providing access to test locations
28	5.1.5 Distribution of tests
29	5.1.6 Critical dimensions 5.2—Existing construction 5.2.1 Pretesting meeting 5.2.2 Sampling plan 5.2.3 Number of tests
30	CHAPTER 6— INTERPRETATION AND REPORTING OF RESULTS 6.1—General 6.2—Statistical methods 6.2.1 Danish method (Bickley 1982b) 6.2.2 General tolerance factor method (Hindo andBergstrom 1985)
32	6.2.3 Rigorous method (Stone and Reeve 1986) 6.2.4 Alternative method (Carino 1993)
34	6.2.5 Summary 6.3—Reporting results
35	CHAPTER 7— IN-PLACE TESTS FOR ACCEPTANCE OF CONCRETE 7.1— General 7.2—Acceptance criteria 7.2.1 Molded cylinders 7.2.2 Cores 7.2.3 In-place tests
36	7.3—Early-age testing CHAPTER 8— REFERENCES 8.1— Referenced standards and reports
37	8.2—Cited references
40	APPENDIX A.1— Minimum number of strength levels
41	A.2—Regression analysis with X-error (Mandel 1984)
42	A.3—Standard deviation of estimated Y-value (Stone and Reeve 1986)
43	A.4—Example

Published By	Publication Date	Number of Pages
ACI	2003	44


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Standard Title	228.1R-03: In-Place Methods to Estimate Concrete Strength
Published Code	ACI
Publication Date	2003
Pages Count	44

ACI 228.1R 03:2003 Edition

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