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Product Update – January 29, 2007
Frequently Asked Questions
GROUT SAMPLE BOX (GSB)
Description: The Grout Sample Box is a patented (Patent #5942192) product specifically designed for use in casting 3.125” X 3.125” X 6.250” prisms of masonry grout for verification of compressive strength. The GSB incorporates a unique corrugated insert that closely matches the absorption and “wicking” action of typical concrete masonry units, and is intended to replace or supplement the “pinwheel” method of forming test specimens currently described in ASTM C1019.
Advantages: The traditional “pinwheel” method of forming prism samples requires the use of at least twelve (12) concrete masonry units to produce three test specimens, a large flat area to accommodate the molding process, 3.5” X 3.5” X 1” spacers, filter paper, and materials to protect the samples in the field during the first twenty-four hours.
The GSB requires none of the above, yields specimens of consistent geometry, and provides an additional fourth specimen to be used as a reserve if needed.
C1019 now: The GSB is currently referenced in ASTM C1019, Note 6 as an alternate method for forming specimens. This alternate forming method is permitted with the approval of the architect or engineer for the project. Most specifiers, ready-mix producers, masonry contractors and testing laboratories prefer the GSB over the traditional pinwheel forming method because of its consistency, repeatability, and ease of use. Comparative tests have demonstrated no statistically significant differences between samples cast using the GSB and those cast using the traditional pinwheel method. Due to the wide differences between sampling/casting technicians, concrete masonry units and grout mixes, there is no precision statement in C1019 for the traditional pinwheel forming method. There is, however, general agreement that the more consistent forming method and specimen geometry provided by the GSB results in a much tighter “within test” variation than what is possible utilizing the pinwheel method.
Pending: Records indicate that, in the past four years, approximately 1,200,000 samples have been cast utilizing the GSB. This suggests the GSB is in general use and has become the preferred method for forming grout prism specimens. For this reason, language has been proposed and approved at C1019 Task Group level to move the reference to alternate forming methods out of Note 6 and into the body of C1019 in Section 6. The proposed change will require comparative tests between the traditional pinwheel forming method and the proposed alternate forming method, and the establishment of a correction factor (not to exceed 1.0). The proposed changes must still be voted upon by Subcommittee C12.02 and, upon approval by the subcommittee, by Main Committee C12.
Misinformation: “The Grout Sample Box does not comply with ASTM C1019”. Wrong. The GSB may be used with the approval of the architect or engineer for the project. Such approval is generally granted based upon the advantages as detailed above.
“The GSB will never be approved by ASTM”. True. ASTM does not approve products. ASTM does describe methods and materials to be used in the performance of approved test methods and procedures (ie.. concrete test cylinder molds).
Wording to incorporate the use alternate forming methods into C1019
has already been approved at task group level, and is pending
approval at subcommittee level.
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