Title: In Situ Pullout Strength of Concrete with Inserts Embedded by “Finger Placing”
Author(s): W.L. Vogt, V. Beizai, and R.L. Dilly
Publication: Symposium Paper
Appears on pages(s): 161-176
Keywords: compressive strength; concretes; embedment; inserts;
nondestructive tests; pullout tests; variability.
A review of available literature indicates that the "finger placing" technique of embedding pullout inserts in concrete after placement has not been used for determining an the in-situ concrete strength development durin construction. Early strength information may be a useful guide line for form removal, stressing or reshoring. This technique o embedding pullout inserts to determine the strength of hardene concrete was used during the construction of a box Culver requiring approximately 11,500 m3 of concrete. Thirty location on the structure were tested to determine the force required t extract embedded inserts at ages of two, four, and seven days higher pullout forces were required to extract insert as the concrete matured. Currently no criteria exist for eval uating the pullout test results; however, the data obtaine throughout this study appear to be normally distributed at earl The standard deviation and within test variation values ar higher than expected. Improvements in these parameters may b achieved by improvements in finger placing and testing techniques