{"data":{"id":"us-nyc/n.y.c.-admin.-code-bc-1911","jurisdiction":"us-nyc","citation":"N.Y.C. Admin. Code § BC 1911","heading":"Section BC 1911: Shotcrete","body":"1911.1 General.\n\nShotcrete is mortar or concrete that is pneumatically projected at high velocity onto a surface. Except as specified in this section, shotcrete shall conform to the requirements of this chapter for plain or reinforced concrete.\n\n1911.1.1 Qualifications.\n\nNozzlemen shall be ACI certified.\n\n1911.2 Proportions and materials.\n\nShotcrete proportions shall be selected that allow suitable placement procedures using the delivery equipment selected and shall result in finished in-place hardened shotcrete meeting the strength requirements of this code. Prior to using shotcrete, the mix design for shotcrete shall be performed by the contractor and shall be approved by the registered design professional of record. The approved mix design shall be filed with the department based upon preconstruction tests performed in accordance with Section 1911.5.\n\n1911.3 Aggregate.\n\nCoarse aggregate, if used, shall not exceed 3/4 inch (19.1 mm).\n\n1911.4 Reinforcement.\n\nReinforcement used in shotcrete construction shall comply with the provisions of Sections 1911.4.1 through 1911.4.4.\n\n1911.4.1 Size.\n\nThe maximum size of reinforcement shall be No. 5 bars unless it is demonstrated by preconstruction tests that adequate encasement of larger bars will be achieved.\n\n1911.4.2 Clearance.\n\nWhen No. 5 or smaller bars are used, there shall be a minimum clearance between parallel reinforcement bars of 2 1/2 inches (64 mm). When bars larger than No. 5 are permitted, there shall be a minimum clearance between parallel bars equal to six diameters of the bars used. When two curtains of steel are provided, the curtain nearer the nozzle shall have a minimum spacing equal to 12 bar diameters and the remaining curtain shall have a minimum spacing of six bar diameters.\n\nException: Subject to the approval of the commissioner, required clearances shall be reduced where it is demonstrated by preconstruction tests that adequate encasement of the bars used in the design will be achieved.\n\n1911.4.3 Splices.\n\nLap splices of reinforcing bars shall utilize the noncontact lap splice method with a minimum clearance of 2 inches (51 mm) between bars. The use of contact lap splices necessary for support of the reinforcing is permitted when approved by the commissioner, based on satisfactory preconstruction tests that show that adequate encasement of the bars will be achieved, and provided that the splice is oriented so that a plane through the center of the spliced bars is perpendicular to the surface of the shotcrete.\n\n1911.4.4 Spirally tied columns.\n\nShotcrete shall not be applied to spirally tied columns.\n\n1911.5 Preconstruction tests.\n\nA test panel shall be shot by each nozzelman and then, cured, cored or sawn, examined and tested prior to commencement of the project. The sample panel shall be representative of the project and simulate job conditions as closely as possible. The panel thickness and reinforcing shall reproduce the thickest and most congested area specified in the structural design. It shall be shot for each proposed concrete mix, at the proposed angles. The equipment used in preconstruction testing shall be the same equipment used in the work requiring such testing, unless substitute equipment is approved by the commissioner. Cores taken from the test panel shall be used to demonstrate that the proposed mix design meets the requirements of the construction documents and this code. All sampling and testing of shotcrete shall be performed by a licensed concrete testing laboratory. Construction of the test panels shall be witnessed by the special inspection agency responsible for the shotcrete construction.\n\n1911.5.1 Sampling and testing.\n\nSix core samples shall be obtained from each preconstruction test panel:\n\n1. Three specimens with no reinforcing shall be sampled and prepared in accordance with ASTM C 42; and\n\n2. Three specimens with reinforcing steel.\n\n1911.5.2. Compressive strength testing.\n\nThe licensed concrete testing laboratory that sampled the preconstruction test panels shall test the core specimens with no reinforcing in accordance with ASTM C 39.\n\n1911.5.3 Evaluation of strength tests.\n\nThe shotcrete test panel strength shall be deemed acceptable if the mean compressive strength of the set of three cores shall equal or exceed f '\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\tc\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t with no individual core less than 0.75 f '\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\tc\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t.\n\n1911.5.4 Visual grading of cores.\n\nCore samples and/or test panels shall be cut with reinforcing steel and shall be visually evaluated by the registered design professional of record for the structural design, or a registered design professional acceptable to the registered design professional of record for the structural design. The nozzleman shall not proceed with work if cores and/or sections cut show the rebar not to be encapsulated with concrete to the satisfaction of the registered design professional of record for the structural design.\n\n1911.6 Rebound.\n\nAny rebound or accumulated loose aggregate shall be removed from the surfaces to be covered prior to placing the initial or any succeeding layers of shotcrete. Rebound shall not be used as aggregate.\n\n1911.7 Joints.\n\nExcept where permitted herein, unfinished work shall not be allowed to stand for more than 30 minutes unless edges are sloped to a thin edge. For structural elements that will be under compression and for construction joints shown on the approved construction documents, square joints are permitted. Before placing additional material adjacent to previously applied work, sloping and square edges shall be cleaned and wetted.\n\n1911.8 Damage.\n\nIn-place shotcrete that exhibits sags, sloughs, segregation, honeycombing, sand pockets or other obvious defects shall be removed and replaced. Shotcrete above sags and sloughs shall be removed and replaced while still plastic.\n\n1911.9 Curing.\n\nDuring the curing periods specified herein, shotcrete shall be maintained above 40°F (4°C) and in moist condition.\n\n1911.9.1 Initial curing.\n\nShotcrete shall be kept continuously moist for 24 hours after shotcreting is complete or shall be sealed with an approved curing compound.\n\n1911.9.2 Final curing.\n\nFinal curing shall continue for seven days after shotcreting, or for three days if high-early-strength cement is used, or until the specified strength is obtained. Final curing shall consist of the initial curing process or the shotcrete shall be covered with an approved moisture-retaining cover.\n\n1911.9.3 Natural curing.\n\nNatural curing shall not be used in lieu of that specified in this section unless the relative humidity remains at or above 85 percent, and is authorized by the registered design professional of record and approved by the commissioner.\n\n1911.10 Strength tests.\n\nStrength tests for shotcrete shall be made by an approved agency on specimens that are representative of the work, and that are sampled and prepared in accordance with ASTM C 42.\n\n1911.10.1 Sampling.\n\nSpecimens shall be taken from the in-place work or from test panels, and shall be taken at least once each shift, but not less than three cores for each 50 cubic yards (38.2 m\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t3\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t) of shotcrete. With the approval of the registered design professional of record, when in-place cores are not feasible due to rebar spacing, test panels shall be shot in the same position as the work represented. One panel shall be cast for each 50 cubic yards (38.2 m\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t3\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t) of concrete and 3 cores shall be taken per ASTM C 42.\n\n1911.10.2 Panel criteria.\n\nWhen the maximum-size aggregate is larger than 3/8 inch (9.5 mm), the test panels shall have minimum dimensions of 18 inches by 18 inches (457 mm by 457 mm). When the maximum-size aggregate is 3/8 inch (9.5 mm) or smaller, the test panels shall have minimum dimensions of 12 inches by 12 inches (305 mm by 305 mm). Panels shall be shot in the same position as the work, during the course of the work and by the nozzlemen doing the work. The conditions under which the panels are cured shall be the same as the work.\n\n1911.10.3 Acceptance criteria.\n\nThe average compressive strength of three cores from the in-place work tested in accordance with ASTM C 39 shall equal or exceed 0.85 f '\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\tc\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t with no single core less than 0.75 f '\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\tc\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t. The average compressive strength of three cubes taken from the in-place work or a single test panel shall equal or exceed f '\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\tc\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t with no individual cube less than 0.88 f '\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\tc\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t. To check accuracy, locations represented by erratic core or cube strengths shall be retested.","path":["New York City Administrative Code","Title 28","Chapter 7: New York City Building Code"],"source_url":"https://files.amlegal.com/pdffiles/NewYorkCity/Admin/XML.zip","current_through":"Local Law 2026/135 (enacted August 31, 2026)","vintage":"","retrieved_at":"2026-09-06T02:48:57Z","sha256":"ba1a27df1d041eba08a344e22cd2460d2424504a30e64b3690ac201c5bb80dc5","source_id":"us-nyc","stale":false,"prev":"us-nyc/n.y.c.-admin.-code-bc-1910","next":"us-nyc/n.y.c.-admin.-code-bc-1912"},"notice":"GroundRules: Original legal text. Not legal advice."}