1904.2 Concrete Properties
Concrete mixtures shall conform to the most restrictive maximum water-cementitious materials ratios, maximum cementitious admixtures, minimum air-entrainment and minimum specified concrete compressive strength requirements of ACI 318 based on the exposure classes assigned in Section 1904.1.
|TYPE OR LOCATION OF CONCRETE CONSTRUCTION||MINIMUM SPECIFIED COMPRESSIVE STRENGTH (f 'c at 28 days, psi)|
|Negligible exposure||Moderate exposure||Severe exposure|
|Basement wallsc and foundations not exposed to the weather||2,500||2,500||2,500a|
|Basement slabs and interior slabs on grade, except garage floor slabs||2,500||2,500||2,500a|
|Basement wallsc, foundation walls, exterior walls and other vertical concrete surfaces exposed to the weather||2,500||3,000b||3,000b|
|Driveways, curbs, walks, patios, porches, carport slabs, steps and|
other flatwork exposed to the weather, and garage floor slabs
|2,500||3,000b, d||3,500b, d|
- Concrete in these locations that can be subjected to freezing and thawing during construction shall be of air-entrained concrete in accordance with Section 1904.2.
- Concrete shall be air entrained in accordance with ACI 318.
- Structural plain concrete basement walls are exempt from the requirements for exposure conditions of Section 1904.2.
- For garage floor slabs where a steel trowel finish is used, the total air content required by ACI 318 is permitted to be reduced to not less than 3 percent, provided the minimum specified compressive strength of the concrete is increased to 4,000 psi.
- Lines defining areas are approximate only. Local areas can be more or less severe than indicated by the region classification.
- A "severe" classification is where weather conditions encourage or require the use of deicing chemicals or where there is potential for a continuous presence of moisture during frequent cycles of freezing and thawing. A "moderate" classification is where weather conditions occasionally expose concrete in the presence of moisture to freezing and thawing, but where deicing chemicals are not generally used. A "negligible" classification is where weather conditions rarely expose concrete in the presence of moisture to freezing and thawing.
- Alaska and Hawaii are classified as severe and negligible, respectively.