Influence of cement matrix composition on early age shrinkage properties

University of Zagreb, Faculty of Civil Engineering, Department of Materials, Fra Andrije Kačića Miošića 26, Republic of Croatia

^* Corresponding author: kdidulica@grad.hr

Abstract

Early age shrinkage behaviour is an important factor in determining durability properties of cementitious composites. Shrinkage occurs in cement paste, but it can be tested in paste, mortar, and concrete. Differences in results obtained can be due to the mitigation influence of aggregates and other additions, like fibres. In order to better understand the early shrinkage properties on cementitious composites in use it is necessary to determine the influence of cement matrix composition. The use of mineral additives as a replacement for cement has been a practice for many years, which, in addition to improved mechanical properties of composites, also affects the reduction of waste and use of natural resources. Although similar to cement in composition, differences lead to variation in reactions during the hydration and thus to the shrinkage properties at early age. Delayed or accelerated reaction can be seen in temperature and humidity development and in values of shrinkage, autogenous as well as drying. Autogenous shrinkage was performed in accordance with modified HRN EN 12390-16 on prisms and ASTM C1698 on corrugated tube. Tests were performed on the cement paste of a reference mixture with w mixtures with different amounts of mineral additive as a cement replacement.