Building Forensics International provides Investigative services to determine concrete failure analysis. BFI has been provided Concrete Expert Witness service for more than 30 years. The following excerpt is from a report provided for a distressed concrete warehouse slab.

Image Description: Reflected light photomicrograph of lapped surface; green scale bar provides measure of the length of a bleed channel adjacent to quartzite particle (“Q”).

"The concrete was not air entrained.

Entrapped air voids made more than 3% of the concrete, by visual estimate; there was a noticeable increase in the entrapped voids present in this sample over other investigated cores (Figure 47). The voids ranged from nearly spherical in shape to oblong to elongated and irregular. Bleed channels up to 10 mm (⅜ in.) long and 3 mm (⅛ in) wide were observed. The abundance and size of the voids suggests that the water content of the concrete represented by the core was higher than observed in other samples. Most voids were free of secondary deposits and had a similar luster as the rest of the paste; in some cases coatings of portlandite-rich materials were observed that gave the void walls a porcelainous luster."