N.Y.C. Admin. Code § BC 1904: Section BC 1904: Durability Requirements

1904.1 General.

Concrete shall be designed and proportioned to comply with the durability, strength, exposure, and other requirements as specified in ACI 318 and Sections 1904.2 through 1904.5 of this chapter.

1904.2 Exposure categories and classes.

Concrete shall be assigned to exposure classes in accordance with ACI 318, Section 19.3.1, based on:

1. Exposure to freezing and thawing in a moist condition or exposure to deicing chemicals;

2. Exposure to sulfates in water or soil;

3. Exposure to water where the concrete is intended to have low permeability; and

4. Exposure to chlorides from deicing chemicals, salt, saltwater, brackish water, seawater or spray from these sources, where the concrete has steel reinforcement.

1904.3 Concrete properties.

Concrete mixtures shall conform to the most restrictive requirements of ACI 318, Section 19.3.2, based on the exposure classes assigned in Section 1904.2 of this chapter.

Exception: For occupancies and appurtenances thereto in Group R occupancies that are in buildings less than four stories above grade plane, normal-weight aggregate concrete is permitted to comply with the requirements of Table 1904.3 of this chapter in lieu of the requirements of ACI 318, Table 19.3.2.1.

Table 1904.3 Minimum Specified Compressive Strength (

f '

c

)

Location of Concrete Construction

Minimum Specified Compressive Strength (

f '

c

at 28 days, psi)

Basement walls, foundation walls, exterior walls and other vertical concrete surfaces, basement slabs, interior slabs on grade except for garage floor slabs, and foundations not exposed to the weather

3,000

a

Driveways, curbs, walks, patios, porches, carport slabs, steps and other flatwork exposed to the weather, and garage floor slabs

3,500

b

Structural concrete exposed to weather

4,500

For SI: 1 pound per square inch = 0.00689 MPa.

a. 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.

b. Concrete shall be air entrained in accordance with Section 1904.4.1.

1904.4 Freezing and thawing exposures.

Concrete that will be exposed to freezing and thawing, in the presence of moisture, with or without deicing chemicals being present, shall comply with ACI 318, Section 19.3.3, and Sections 1904.4.1 and 1904.4.2 of this code.

1904.4.1 Air entrainment.

Concrete exposed to freezing and thawing while moist shall be air entrained in accordance with ACI 318, Sections 19.3.3.1 and 19.3.3.3.

1904.4.2 Deicing chemicals.

For concrete exposed to freezing and thawing in the presence of moisture and deicing chemicals, the maximum weight of fly ash, other pozzolans, silica fume or slag that is included in the concrete shall not exceed the percentages of the total weight of cementitious materials permitted by Table 1904.4.2.

Table 1904.4.2 Requirements for Concrete Exposed to Deicing Chemicals

Cementitious Materials 

Maximum Percent of Total Cementitious Materials by Weight

a, b

Fly ash or other pozzolans conforming to ASTM C 618

25

d

Slag conforming to ASTM C 989

50

Silica fume conforming to ASTM C 1240

10

Total of fly ash or other pozzolans, slag and silica fume

50

c

Total of fly ash or other pozzolans and silica fume

35

c

a. The total cementitious material also includes ASTM C 150, ASTM C 595, ASTM C845 and ASTM C 1157 cement.

b. The maximum percentages shall include:

1. Fly ash or other pozzolans present in Type IP or I(PM) blended cement, ASTM C 595, or ASTM C 1157.

2. Slag used in the manufacture of an IS or I (SM) blended cement, ASTM C 595, or ASTM C 1157.

3. Silica fume, ASTM C 1240, present in a blended cement.

c. Fly ash or other pozzolans and silica fume shall constitute no more than 25 and 10 percent, respectively, of the total weight of the cementitious materials. The amount of fly ash or other pozzolans conforming to ASTM C 618 shall be permitted to be increased in accordance with footnote d, provided the maximum percentage of supplemental cementitious materials does not exceed the maximum values stated in Table 1904.4.2 when combining multiple types of supplemental cementitious materials.

d. Amount of fly ash or other pozzolans conforming to ASTM C 618 in a given concrete mixture can be increased to 35% provided that the concrete is not placed during cold weather as defined by ACI 306 or that the concrete is membrane cured and protected from freezing until the concrete has attained 3,500 psi.

1904.5 Alternative cementitious materials for sulfate exposure.

Combinations of cementitious materials for use in sulfate-resistant concrete that are alternative to those listed in ACI 318, Table 19.3.2.1, shall be permitted in accordance with ACI 318, Section 26.4.2.2.