Code of Massachusetts Regulations
780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
Chapter 19 - Concrete
Section 1913 - SHOTCRETE
Subsection 1913.10 - Strength tests
Current through Register 1531, September 27, 2024
Strength tests for shotcrete shall be made by an approved agency on specimens that are representative of the work and which have been water soaked for at least 24 hours prior to testing. When the maximum-size aggregate is larger than 3/8 inch (9.5 mm), specimens shall consist of not less than three 3-inch-diameter (76 mm) cores or 3-inch (76 mm) cubes. When the maximum-size aggregate is 3/8 inch (9.5 mm) or smaller, specimens shall consist of not less than 2-inch-diameter (51 mm) cores or 2-inch (51 mm) cubes.
1913.10.1 Sampling. Specimens 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 one for each 50 cubic yards (38.2 m3) of shotcrete.
1913.10.2 Panel criteria. When 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.
1913.10.3 Acceptance criteria. The average compressive strength of three cores from the in-place work or a single test panel shall equal or exceed 0.85 f c with no single core less than 0.75 f c. The average compressive strength of three cubes taken from the in-place work or a single test panel shall equal or exceed f c with no individual cube less than 0.88 f c. To check accuracy, locations represented by erratic core or cube strengths shall be retested.
