Autogenous shrinkage of concrete with design strength 60-120 N/mm(2)

초록

It is well known that autogenous shrinkage of high strength concrete (HSC) with a low water-to-binder ratio (W/B) is a major contributor to premature shrinkage cracking, which reduces the durability, strength and aesthetics of concrete structures. For concrete containing silica fume and having a low W/B, it is essential to accurately predict the autogenous shrinkage behaviour. In order to investigate the autogenous shrinkage behaviour of HSC, very high strength concrete (VHSC) and ultra high strength concrete (UHSC), five different W/B (0.3, 0.25, 0.2, 0.16 and 0.12) were studied in this work. To estimate the influence of admixtures on UHSC with W/B less than 0.2, fly ash (FA) and granulated blast-furnace slag (BFS) were added (0, 10, 20% and 0, 15, 30% by weight of total binder respectively). The experimental results and published data relevant to autogenous shrinkage were predicted using five different models for various grades of concrete. The test results showed that the largest amount of autogenous shrinkage was observed at W/B = 0.16, and additions of both of FA and BFS reduced autogenous shrinkage. The Eurocode 2 model and the Jonasson and Hedlund model substantially underestimated autogenous shrinkage of UHSC below W/B = 0.2, whereas the JSCE model and Dilger and Wang model overestimated the results for HSC and VHSC.

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