Section 9 states that when blending two SCMs, the amount of silica fume shall in the blend not vary more than +/- 2.5 percentage points and not more than +/- 5 percentage points for fly ash, natural pozzolans and slag cement with a 99% probability of compliance. In turn, to achieve this 99% probability of compliance, the standard deviation of the mass percentage of silica fume in the blend must be less than 1% and less than 1.9% for other SCMs. However, the appendix, which provides an example of the calculation to verify blend proportions, states that the amount of silica fume in the blend shall not vary more than +/- 1 percentage points instead of +/- 2.5%. This ballot action is aimed at correcting this discrepancy between section 9 of the standard and the example provided in the appendix.
Keywordsblend; fly ash; pozzolan; silica fume; slag cement; supplementary cementitious material;;
Draft Under Development