The use of self-compacting concrete (SCC) has developed considerably in recent years, and much attention is paid to the study of their mechanical and rheological properties. The environment is a very important issue, and its preservation is a common responsibility, the wastes thrown by human beings compose a great danger on the environment, so it is necessary to encourage their elimination by recycling operation and their use as aggregates in the manufacture of self-compacting concrete. The study is based on the idea that the incorporation of rubber aggregates improves some behaviors of the SCC and enhances the use of waste, so the incorporation of aggregates in the composition of self-compacting concrete (SCC) has an interest that deserves to be studied. The objective of this work is to valorize the use of waste, especially used tires as rubber aggregates and also consists in studying the influence of the incorporation of these aggregates on the mechanical behavior of the self-compacting concrete. The dosages used in aggregates are of the order of 1 and 2% by weight of the concrete. This study will examine the role and influence of the rubber aggregate content on the characteristics of the SCC. The incorporation of these aggregates in the SCC is beneficial for the improvement of the ductility of the concrete material known for its brittleness in traction. The results of this work suggest that the pneumatic aggregates can be compared to other aggregates used as reinforcement in self-compacting concrete. They are completely suitable for use as reinforcement in self-compacting concrete.

The high temperature in the concrete destroys the hydrates of the cement paste. This destruction means the weakness of the materials caused by the deterioration of their mechanical properties. This work aims to study the behavior of high-performance fiber concrete sets at high temperatures; specifically, we used polypropylene fibers and studied their influence on deterioration behavior. This study includes high performance concrete and three types of fiber concrete, each containing a specific ratio of polypropylene fibers (0.12 %, 0.18 %, and 0.24 %). Consequently, cubic test specimens (15 cm x 15 cm x 15 cm) were subjected to the temperature of 250 °C, with a speed of 2 °C/min followed by a step of one hour at the target temperature then cooling to the ambient temperature. The results showed that fiber-reinforced concrete exhibited a better performance when exposed to the temperature studied. The mechanical properties were improved by up to 56% for compressive strength and 86% for tensile strength.