Combined effects of microsilica, steel fibre and artificial lightweight aggregate on the shrinkage and mechanical performance of high strength cementitious composite

Abstract

In this study, the effects of micro-steel fiber, pelletized fly ash lightweight aggregate and microsilica content on the fresh and hardened properties of high-performance cementitious composite (HPCC) were experimentally investigated. Micro-steel fibers having a length of 6 mm were used in the production of mixtures at the level of 0%, 1% and 2% by total volume. Besides, artificial lightweight aggregate produced by the pelletizing method was employed in the mixture production by 0% and 20% of total aggregate volume. 0% and 25% of the total binder content were designated as microsilica. Thus, a total of 12 different HPCC mixtures were obtained. The water-to-binder ratio of 0.2 was chosen in the design of all HPCC mixtures. A high-rate water-reducing chemical admixture is used to give a suitable flow for the fresh mixtures. The mechanical properties of HPCC mixtures are evaluated in terms of compressive and flexural strengths and elastic modulus. In addition to these, total water absorption and capillary water absorption tests were performed to evaluate the pore structure and permeability. The drying and autogenous shrinkage values were determined during the 60-day drying period. Thus, the effects of fiber content, microsilica addition, and artificial lightweight aggregate content were examined. The results of the experiment showed that the mechanical properties of HPCC and shrinkage behavior have been improved with the increase of steel fiber volume fraction. Furthermore, the negative effects of artificial lightweight aggregate can be eliminated by microsilica.