1. 2018 Revisions to NYCDOB Code
Presented by
Cas Bognacki, P.E., FACI

2. 1905.3.5 Field Changes to Concrete Proportions
Changes described in Sections and are permitted without requiring additional trial mixtures or field strength records.

3.
Do not require prior approval of the registered design professional of record.
1. Air-entraining dosage changes
2. Water reducing admixture changes

4. 1905.3.5.2 Changes that require prior approval from the registered design professional of record
1. Retarding and accelerating admixtures
2. Pigment
3. Fibers (Except Steel)
4. Corrosion inhibitor
5. Cementitious content can be increased a maximum of 12% ,with any change to w/cm ratio or % air.
6. Hydration control admixture (2018 Change)

5. 1905.3.5.2 (Source of Aggregates 2018 Change)
7. Source of aggregates can be changed if original source is no longer producing the required aggregates or quality of aggregates on longer meet ASTM – C 33 or NY DOT requirements.
7.1 New aggregate source is approved by the NYS DOT.
7.2 MOE is not specified.
7.3 The volume of fine and coarse aggregates the same and the nominal maximum size of the coarse aggregate is unchanged.
7.4 Light aggregates can not be substituted for dense nor dense for lightweight .
7.5 Registered design professional of record is informed of the reason for change.

6. 1905.3.5.2 (Cementitious Material 2018 Change)
8. Any changes to cementitious materials shall require an additional laboratory test trial batch. The mix with the new cementitious material shall maintain the same air and water/ cementitious ratio as the original mix ,and meet the strength requirements of ACI 301 Table b. Approval of the registered design professional of record and submission of either a three or seven day compressive strength test shall be required prior to the placement of concrete.

7. Mass Concrete
For areas of high strength mass concrete including but not limited to 8000 psi or greater and the least dimension being equal to or greater than 36 inches a thermal control plan complying with ACI 301 Section 8.1 and acceptable to the registered design professional of record shall be submitted by the contractor.

8. Mass Concrete
Install temperature devices that are capable of measuring the temperature of the concrete continuously and record temperature in time increments that do not exceed 30 minutes for a minimum period of seven days, per ACI 301 Section 8.1.

9. ACI 301 Section 8.1.3
(a) Maximum temperature in concrete after placement should not exceed 160° F.
(b) Maximum temperature difference between center and surface of concrete shall not exceed 35° F.

10. 1905.6.3.7 Mass Concrete (2018 Change – Added to Section)
In lieu of monitoring a concrete placement for core and outside face temperatures a computer simulated thermal study maybe submitted if approved by the registered design professional of record. The computer simulated thermal study shall be for the largest section placed for a specific concrete mix proportion and reflect the thermal properties of the specific cementitious materials and quantities in the concrete mix proportion. The thermal study shall cover the maximum temperature at which concrete maybe placed and the ambient temperature range anticipated for concrete placement.