Autogenous shrinkage is a consequence of self dessication in pores of hardened cement paste and is, at high performance concrete significantly greater than that of the ordinary concretes, mainly due to low water to cement ratio. In the graduation thesis we examined the main mechanisms that cause autogenous shrinkage. It can be reduced by internal curinginternal water reservoirs. As internal water reservoirs we used pre-soaked expanded clay Liapor. On specimens, in which we replaced 12 % of aggregate with pre-soaked expanded clay, we measured shrinkage and compressive strength. The results were compared with previously performed tests on high performance concrete without additives and on high performance concrete with addition of pre-soaked lightweight aggregate Lehnjak. We concluded that content of pre-soaked expanded clay has positive effect on shrinkage, but negative effect on the compressive strength.
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