Masonry Magazine February 1980 Page. 26
2. Site Control Prisms:
a. Build prisms as required by Section 1.02.D.1 at the direction of the Architect/Engineer.
(1) Of site materials.
(2) Of brick units selected at random from units delivered to the project.
(3) At the project site.
(4) With same bonding, insofar as possible, as the structure.
(5) With site mortar.
(6) With same joint thickness as for the structure.
(7) With same workmanship.
3. Dimensions
a. Minimum height: 12 in. (305 mm).
b. Height-to-thickness ratio (h/t) range:
(1) Minimum: 2
(2) Maximum: 5
4. Mark each specimen for identification.
5. Store prisms:
a. Preconstruction prisms:
(1) In air at temperatures not less than 65° F. (18.3° C.).
b. Site control prisms:
(1) At site for not less than 24 hr.
(2) Thereafter, in air at temperatures not less than 65° F. (18.3° C.).
6. Test prisms:
a. Preconstruction prisms:
(1) Five after aging 7 days.
(2) Five after aging 28 days.
b. Site control prisms:
(1) After aging 7 days.
c. Cap each prism with suitable material to provide bearing surfaces on each end:
(1) Plane within 0.003 in. (0.076 mm).
(2) Approximately perpendicular to the axis of the prism.
7. Test in accordance with relevant provisions of ASTM
E 447- with the following provisions:
a. For h/t less than 5, reduce specimen compressive strength by correction factors as follows:
Ratio of height
to thickness (h/t) 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Correction factor(a) 0.73 0.80 0.86 0.91 0.95 0.98 1.00
(a) Interpolate to obtain intermediate values.
b. If the coefficient of variation of the sample tested exceeds 10%, obtain the compressive strength by multiplying the average compressive strength of the specimens by 1-1.5 (100-0.10) where v is the coefficient of variation of the sample tested.
B. Brick Tests:
1. Preconstruction Tests:
a. Test five brick for compressive strength to determine acceptability of units for compliance with specifications.