CEMENT PASTE, MORTAR AND CONCRETE UNDER MONOTONIC, SUSTAINED AND CYCLIC LOADING By

The behavior of saturated specimens of cement paste and mortar under monotonic, sustained and cyclic loading, is compated to that of concrete at water-cement ratios of 0.5 and 0.7. Specimen age, at testing, ranges from 27 to 29 days. For monotonic loading, the behavior of each material is described in terms of peak stress, strain at peak stress, and initial modulus of elasticity. For sustained loading, the behavior is described in terms of creep strain as a function of stress- strength ratio and time under load. Mathematical relationships ate developed on the sustained load response to estimate the cumulative static creep for a cyclic test. Cyclic test results ate exatnined in terms of strain at 15 seconds, the difference between the strain at 15 seconds and the peak strain for a given cycle (cyclic strain), the estimated creep strain for a cyclic test (equivalent creep, based on sustained load test results), the difference between cyclic strain and equivalent creep (cyclic action strain), and the change in secant unloading modulus (a measute of material damage). The equivalent creep duting a cyclic test is used to distinguish between cyclic strai