The early age short-term creep of hardening cement paste: load-induced hydration effects

Short-term creep and shrinkage strains were monitored at early age on hydrated Portland cement pastes prepared with two different water-cement ratios (0.35 and 0.50). Creep experiments were conducted in an environmentally controlled chamber maintained at (96 +/- 2)% relative humidity. The three ages at loading investigated were 18, 24 and 30 h. The stress-strength ratio applied to the specimens at the age of loading, using a miniature loading system, was 0.30. Cement paste specimens were in the form of T-shaped columns with a minimum thickness value (for the web and flanges) of less than 1.2 mm. Load-induced hydration (not normally considered in creep prediction) of normal strength cement paste (w/c = 0.50) was found to occur at early times following the loading at 18 h. An analytical model was developed in order to predict the creep coefficient of normal and high strength cement pastes from early age data. The model accounts for load-induced hydration effects. (C) 2003 Elsevier Ltd. All rights reserved.