Description
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.
Table of Contents
Chapter 1—Introduction
1.1—Scope
1.2—Need for in-place tests during construction
1.3—Influence of ACI 318
1.4—Recommendations in other ACI documents
1.5—Existing construction
1.6—Objective of report
Chapter 2—Review of methods
2.1—Introduction
2.2—Rebound number (ASTM C 805)
2.3—Penetration resistance (ASTM C 803/C 803M)
2.4—Pullout test (ASTM C 900)
2.5—Break-off number (ASTM C 1150)
2.6—Ultrasonic pulse velocity (ASTM C 597)
2.7—Maturity method (ASTM C 1074)
2.8—Cast-in-place cylinders (ASTM C 873)
2.9—Strength limitations
2.10—Combined methods
2.11—Summary
Chapter 3—Statistical characteristics of test results
3.1—Need for statistical analysis
3.2—Repeatability of test results
Chapter 4—Development of strength relationship
4.1—General
4.2—New construction
4.3—Existing construction
Chapter 5—Implementation of in-place testing
5.1—New construction
5.2—Existing construction
Chapter 6—Interpretation and reporting of results
6.1—General
6.2—Statistical methods
6.3—Reporting results
Chapter 7—In-place tests for acceptance of concrete
7.1—General
7.2—Acceptance criteria
7.3—Early-age testing
Chapter 8—References
8.1—Referenced standards and reports
8.2—Cited references
Appendix
A.1— Minimum number of strength levels
A.2—Regression analysis with X-error (Mandel 1984)
A.3—Standard deviation of estimated Y-value (Stone and Reeve 1986)
A.4—Example