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9 Table 3. Derived statistical models for visco-elastic properties. Property Age Derived equations R 134 42.4 w/cm + 37.4 BT 21.6 (BC w/cm) Autogenous 7 days 0.96 20.1 (w/cm BT) 15.9 (BC BT) shrinkage 201 + 67.1 BT 40.6 w/cm 18.8 (BC w/cm) (strain) 56 days 0.93 + 17.8 (BC S/A) 308 71.1 w/cm + 35 BC + 48.4 (w/cm VMA) 28 days 0.78 Drying + 30.8 (VMA BT) shrinkage 554 58.1 w/cm + 48.4 BC + 37.4 S/A + 46.2 (w/cm (strain) 112 days VMA) + 41.9 (w/cm BT) 40.6 (BC VMA) 0.96 + 30.8 (VMA BT) 680 + 79.3 BT 37.5 w/cm + 30.6 (VMA BT) 28 days 0.75 Creep + 28.8 (w/cm BT) (strain) 1,036 + 73.6 BT + 38.8 BC + 40.7 (VMA BT) 112 days 0.89 + 34.9 (w/cm BT) 32.9 (BC S/A) Initial relative form pressure at 3.3 ft (1 m) in height cast age, most of which occurs in the first 28 days and can at 13.1 to 16.4 ft/h (4 to 5 m/h) varies between 0.80 and vary between 100 and 350 strain. 1.00 of hydrostatic pressure. The relative pressure Autogenous shrinkage is mostly affected by binder increases with the increase in binder content and w/cm type and paste volume. SCC made with Type III cement but decreases with the increase in S/A. and 20% Class F fly ash can develop higher autogenous Mechanical properties shrinkage and creep than that for concrete with Type Mechanical properties, including compressive strength, I/II cement. modulus of elasticity (MOE), and flexural strength, For a given w/cm, SCC made with high binder content increase with the decrease in w/cm. can exhibit high drying shrinkage that can range between Increase in binder content can lead to higher 56-day 500 and 1000 strain after 300 days. compressive strength but lower 18-hour MOE and 7-day SCC exhibits 5% to 30% higher drying shrinkage at flexural strength. 300 days than that of HPC made with similar w/cm (more The increase in S/A results in lower MOE at 18 hours detailed information on drying shrinkage can be found in (steam curing) and 56 days (moist curing), but leads to Attachment D). higher flexural strength. The increase in S/A can lead to higher long-term drying SCC made with Type III cement and 20% Class F fly ash shrinkage. can develop higher compressive strength and MOE at The binder type does not have significant effect on dry- 56 days but lower mechanical properties at 18 hours ing shrinkage but can significantly affect creep. SCC than those for concrete made with Type I/II cement made with Type III cement and 20% Class F fly ash mainly because of delayed setting resulting from greater exhibited higher creep compared with similar SCC HRWRA demand. proportioned with Type I/II cement, regardless of the Visco-elastic properties binder content, w/cm, S/A, and use of VMA. The increase in binder content increases drying shrink- The w/cm does not have considerable effect on creep because other parameters (binder content, binder type, age and creep. and S/A) have more predominant influence on creep. Theoretically, for a given binder content, drying shrink- SCC exhibited 10% to 20% higher creep after 300 days age increases with increase in w/cm; however, the derived than that for HPC made with similar w/cm (more detailed statistical models show an opposite trend because dry- information on creep can be found in Attachment D). ing shrinkage also includes autogenous shrinkage that decreases with the increase in w/cm. SCC mixtures made with Type I/II cement develop less 1.4 Validation of Code Provisions to creep and shrinkage than those prepared with Type III Estimate Mechanical Properties cement and 20% Class F fly ash. However, the latter con- Coefficients of prediction models in current codes and pro- crete has better workability and higher mechanical prop- cedures were modified to provide better prediction of mechan- erties than the former SCC. Therefore, use of Type III ical properties of SCC for precast, prestressed concrete bridge cement and 20% Class F fly ash will require reduction of elements. The following codes and models are recommended: binder content to ensure better overall performance. Concrete mixtures containing high binder content and ACI 209 and CEB-FIP codes with suggested changes to low w/cm can exhibit high values of autogenous shrink- coefficients for predicting compressive strength