Title:
Statistical Methods for In-Place Strength Predictions by the Pullout Test
Author(s):
William C. Stone, Nicholas J. Carino, Charles P. Reeve
Publication:
Journal Proceedings
Volume:
83
Issue:
5
Appears on pages(s):
745-756
Keywords:
aggregates; compressive strength; concrete construction; lightweight aggregates; pullout ests; regression analysis; statistical analysis.
DOI:
10.14359/10668
Date:
9/1/1986
Abstract:
Pullout tests and comapnion cylinder tests were conducted to examine the variations in ultimate load with respect to concrete strength, and provide experimental data for the development of a new statistical procedure for predicting in-place compressive strengrth from the pullout test. The coeeficants of variation were found to be relatively constant with average values of 4 percent for cylinder tests and approximately 10 percent for pullout tests in concrete with hard coarse aggregates. Pullout test in lightweight concrete exhibited coefficants of variation of only 6 percent. Two test series were conducted with river gravel aggregate using apex angles of 54 and 70 deg. Both geometries produced coefficants of variation of 10 percent. A statistical procedure is developed for determining the correlation equation which accounts for: 1) the constant coefficants of variation in ultimate load, and 2) the X-variable (pullout load) error. Aprocedure is also developed to predict the in-place caracteristic strength to any desired confidence level. Amethod is presented to dtermine the appropriate number of in-place tests to be performed for a given concrete placement. A recommended minimum number of 8 to 12 pullout tests per 76 cubic meters (100 cubic yards) is proposed.