228.1R-03
In-Place Methods to Estimate Concrete Strength
2003, 44 pp.
$69.50

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.

Contents:
Chapter 1—Introduction, p. 228.1R-2

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, p. 228.1R-4

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, p. 228.1R-14

3.1—Need for statistical analysis

3.2—Repeatability of test results

Chapter 4—Development of strength relationship, p. 228.1R-21

4.1—General

4.2—New construction

4.3—Existing construction

Chapter 5—Implementation of in-place testing,

p. 228.1R-26

5.1—New construction

5.2—Existing construction

Chapter 6—Interpretation and reporting of results, p. 228.1R-30

6.1—General

6.2—Statistical methods

6.3—Reporting results

Chapter 7—In-place tests for acceptance of concrete, 228.1R-35

7.1—General

7.2—Acceptance criteria

7.3—Early-age testing

Chapter 8—References, p. 228.1R-36

8.1—Referenced standards and reports

8.2—Cited references

Appendix, p. 228.1R-40

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