Rationale

The maximum loading rate for measuring the Modulus of Rupture for compliance with C1782 and Concentrated Center Load Capacity for compliance with C1944 are the same and are shown in A8.4.3.9 and A8.4.5, respectively. Users of the standard have reported that the current language of ‘a rate not exceeding 4lbf [18 N] per second for each 4 in. [100 mm] of width’ is confusing because it can be interpreted to indicate that the slab width be broken into 4 in. [100 mm] increments when determining the allowable maximum loading rate. For example, if a slab is 18 in. wide, it could be interpreted as being five ‘4 in.’ increments and would have a maximum loading rate of 20lbf per second. This ballot item proposes to modify the language to remove all ambiguity by changing it to ‘a rate not exceeding 1lbf [0.18 N] per second for each 1 in. [1 mm] of width’. In addition, this ballot item will renumber A8.4.5 as A8.4.4.4 because the requirement in the current A8.4.5 applies only to the measurement of concentrated center load capacity which is covered under A8.4.4, so this subsection should be a subsection of A8.4.4 and not a new A8.4.5. This corrects a mistake that was in the original ballot that introduced the concentrated center load capacity testing