Investigation of Different Superplasticizers Effect on Workability and Strength Parameters in Ultra High Performance Concretes

The use of ultra-high performance concretes (UHPC) in the modern construction industry is increasingly widespread. UHPCs are a type of concrete that provides advantages in solving many engineering problems. UHPCs have superior properties compared to conventional concretes in terms of workability, self-settling, as well as high strength and durability. However, although UHPCs have many advantages, achieving the desired workability is one of the biggest challenges of the production procedure, since they contain high amounts of powder materials. Therefore, the aim of this study is to determine the most suitable superplasticizer (SP) additive in terms of workability and strength by using different SP additives in UHPC mixtures. In this study, workability and strength parameters were tested on UHPC mixtures using 8 different SP additives. First of all, the spreading diameters of the obtained mixtures were measured. For each mixture, compressive strength, density, ultrasound velocity, Schmidt hammer rebound and Leeb hardness measurements were performed on 70x140 mm sized cylindrical samples taken on days 2, 7 and 28. Since SPs have a working principle at the interfaces of particles in the internal structure of concrete, different behaviors were observed on workability, even if a little. All the results obtained have been compared with the literature and it has been proven that they meet the UHPC specifications