Abstract
Autogenous shrinkage is typically regarded as a self-desiccation process, considered beneficial for concrete. because it occurs at the early ages of concrete hardening. This process usually leads to enclosing the microcracks that occur at this stage of hydration and leads to healing the concrete. However, if this type of shrinkage is out of control, it may lead to counterproductive results. The difficulty in implementing the autogenous shrinkage test resulted in a lack of data for this behaviour. Therefore, this research aims to study the possibility of enhancing the autogenous shrinkage behaviour of high-strength concrete by using fibres and internal curing technique. Four concrete mixes (reference mix,1% fibre mix, water absorption polymer balls WAPB mix, and Hybrid mix, which consists of fibres and WAPB) were tested through this work. A compressive strength test was conducted to determine the strength of the mixes. The enhancement in compressive strength was recorded for the hybrid mix and ranged between (8-15) % compared to the reference mix. The autogenous shrinkage was conducted at the early ages, from 1 hour to day 7, test results were supported by the SEM images. The results revealed that the Hybrid concrete mix shows the highest reduction in the autogenous shrinkage strain. This may open the horizon toward the use of fibres and internal curing in controlling the concrete shrinkage and reducing the formation of microcracks, which is reflected in the improvement of concrete durability.