Table 1. Compressive Strength and Variability for RCC Spillways – QA Control Cylinders

1/ CW Continuous Weigh Plant; CV Continuous Volumetric Plant; BW Individual Batch Weigh Plant; P Pugmill Mixer; C Compulsory Mixer; D Drum Mixer
2/ * Standard deviation and coefficient of variation for the indicated design strength and test age.
3/ Cores tested two to three years after construction.

Structure Batchplant Type 1 C+P Content W/(C+P) Ratio Compressive strength (lb/in2) Standard deviation Coefficient of variation
Ib/yd3 28 day 90 day 1 year ib/in2 %
Cold Springs CW-P 292+0 0.52 5670* 7280 3/ 540 2/ 9.5 2
Ochoco CV-P 434+0 0.50 4930* 6230 1335* 27*
0.55 3936 3 733 19
0.45 6265 543 9
Pueblo BW-C 120+180 0.47 2230 4830* 430 9
Many farms BW-C 141+280 0.37 5480 6635* 7020 566* 8.5