1905.3.5.2 Changes that require prior approval of the registered design professional of record for the structure.
BC § 1905.3.5.2
The following modifications to concrete proportions can be made only with prior acceptance by the registered design professional of record. Any added materials and the final mix proportions shall be indicated in a revised mix design submitted to the registered design professional of record prior to use: 1. Retarding and accelerating admixtures. Retarding and accelerating admixtures may be added to concrete mixtures or the dosage may be modified as needed to maintain practical set times.
2.Pigment. Pigment dosage may be adjusted to maintain uniform concrete color.
3.Fibers. Synthetic, glass or natural fibers may be added to the mix within the manufacturer recommended range. Any loss in workability shall be compensated with a water reducer. Exception: Steel fibers may not be added to a concrete mixture without the performance of a new mix design.
4.Corrosion inhibitor. Corrosion inhibiting admixtures may be added, provided the corresponding adjustment of mix water remains within the limits of the required water/cementitious material ratio. The added materials and the revised design mix shall be submitted for review by the registered design professional of record for the structure prior to use.
5.Cementitious content and water-cementitious material ratio (w/cm). The cementitious content may be increased by a maximum of 12 percent, or the w/cm ratio may be decreased while maintaining the same cementitious content, but the w/cm and air content shall not be increased. Aggregate quantities shall be adjusted, as required, to maintain the mix proportion and yield.
6.Hydration control. Admixture may be added for the purpose of delaying hydration and maintaining a workable mix.
7.Source of aggregate. Change to the source of aggregate may be approved by the registered design professional of record without providing additional test data only when the original aggregate source is no longer producing the required aggregates or the quality of the aggregates produced no longer meets the requirements of ASTM C 33 or the New York State Department of Transportation, provided: 7.1. The new aggregate source is approved by the New York State Department of Transportation; 7.2. A modulus of elasticity is not specified; 7.3. The volume of both the fine and coarse aggregates remains the same and the nominal maximum size of coarse aggregates is unchanged; 7.4. Lightweight aggregate shall not be substituted for dense, nor dense aggregate for lightweight, where lightweight aggregates are defined as having a specific gravity less than 2.5; and 7.5. The registered design professional of record is informed of the reason necessitating the change of aggregate.
8.Cementitious materials. Any change to cementitious materials shall require an additional laboratory testing trial batch. The new cementitious material shall maintain the same air and water cementitious ratio (w/cm) as the original mix and meet the strength requirements of ACI 301, Table 4.2.3.3 b. Approval of the registered design professional of record and submittal of data from either a three- or seven-day compressive strength test shall be required prior to the placement of concrete.
