Title: Concrete Q & A: Requirements for Special Exposure Conditions

Author(s): Jon B. Ardahl and William Sherman

Publication: Concrete International

Volume: 32

Issue: 3

Appears on pages(s): 92

Keywords:

DOI:

Date: 3/1/2010

Abstract:
The Commentary for Section 4.0 of ACI 350-06, “Code Requirements for Environmental Engineering Concrete Structures,” contains this statement: “Specified compressive concrete strength fc' should correspond to maximum water-cementitious material ratios of 0.40 to 0.42 for concretes exposed to freezing and thawing, water, wastewater, and to corrosive gases or for preventing corrosion of reinforcement, as shown in Table 4.2.2 and Table 4.3.1.” 1 Table 4.2.2 of that document, however, shows that a maximum water-cementitious material ratio of 0.45 is permitted for “Concrete intended to have low permeability when exposed to water, wastewater, and corrosive gases.” As shown in Table 4.2.2, maximum water-cementitious material ratios for other exposure conditions do range from 0.40 to 0.42. Is concrete exposed to water, wastewater, and corrosive gases required to have a minimum specified strength of 4500 psi, rather than the 4000 psi listed in Table 4.2.2, or should the Commentary have read as follows? “Specified compressive concrete strength fc' should correspond to maximum water-cementitious material ratios of 0.40 to 0.42 0.45 for concretes exposed to freezing and thawing, water, wastewater, and corrosive gases or for preventing corrosion of reinforcement, as shown in Table 4.2.2 and Table 4.3.1.”