Quality control superintendent, Holnam Portland Plant, Florence, CO
Test Method for Evaluation of Cement Strength Uniformity from a Single Source (ASTM C 917) in the ASTM Annual Book of Standards, Volume 4.01, Cement, Lime, and Gypsum provides methods to evaluate the cement strength uniformity from a single source. Test data comparing 1976 through 1977 and 1991 show a general increase in strengths over that period of time. In 1976, 45% of the labs had annual average 7-day strengths less than 27.6 MPa (4000 psi), while in 1991 none of the plants had averages below that level. The data show the cement industry, overall, shipped a more consistent product in 1991 compared to 1976 through 1977. The percentage of plants with a standard deviation below 2.1 MPa (300 psi) at 7 days increased from 63 to 81% during that time period. A higher percentage of plants had the total coefficient of variation and corrected deviations below 6%. The testing error remained the same with the 1976 data and the 1991 data, but the testing error coefficient of variation improved.
Paper ID: CCA10141J