Effects of hydration heat velocity on autogenous shrinkage of hiah-strenath concrete

摘要

The purpose of this study was to quantitatively investigate the effects of a micro encapsulated retarder (MER) on the hydration heat velocity (HHV) and autogenous shrinkage velocity (ASV) of high-strength concrete (HSC). A series of laboratory experiments was designed and conducted with the main variables being the amount of MER (0, 0-4 and 0-8% of total cement weight), specimen size (300 × 300 × 300 mm~3 and 100 × 100 × 400 mm~3) and two different curing conditions (semi-adiabatic and in air at 20℃). As a result, the MER was demonstrated to be effective for retarding the cement hydration process without reducing the compressive strength of the hardened concrete. Analysis of the results showed that the hydration temperature and the HHV of the HSC decreased as MER amount increased. Increasing the amount of MER also decreased the ASV and ultimate autogenous shrinkage for HSC. Finally, it was found that the HHV is strongly correlated with the ASV, and an approximate formula relating the two parameters is proposed. The findings in this study will be useful for optimum concrete design by controlling early-age shrinkage in HSC.