Title:
Concrete Surface Void Ratio: Perspective from the Testing Laboratory
Author(s):
Jacob L. Borgerson and Woodward L. Vogt
Publication:
Symposium Paper
Volume:
338
Issue:
Appears on pages(s):
36-44
Keywords:
aesthetics, bug holes, concrete, formed surfaces, surface void ratio, surface voids
DOI:
10.14359/51724725
Date:
3/1/2020
Abstract:
ACI 347.3R-13 provides guidance on the measurement and classification of surface voids (i.e., bug holes)
in as-cast formed concrete surfaces. This paper will provide perspective from a testing laboratory on the challenges
encountered when asked to perform surface void ratio measurements. Measurements were performed by field
technicians and an engineer using the method as described in ACI 347.3R-13, in addition to a modified approach.
Based on measurements performed on test areas of a cast-in-place shear wall for a high-rise condominium, it was
determined that the between-operator variation and the selected test area significantly impact the classification of the
surface. Because the test method does not specify methods for test area location selection or the number of test areas
to sample, test results can vary greatly. Specifically, two 24 in. x 24 in. (610 mm x 610 mm) areas that are within 12
in. (300 mm) of each other may possess the highest and lowest classification. Based on field test results, an alternative
method is proposed that provides better repeatability between operators and is more time efficient. In addition, based
on measuring several different test areas on the same concrete surface, the number of test areas needed to accurately
represent the void area of a surface was estimated.