VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Development and mechanical performance analysis of high-temperature resistant concrete composite“ prepared by VILNIUS TECH, Linas Plioplys. The dissertation was prepared in 2020–2025. Scientific Consultant – Prof. Dr Viktor Gribniak.
The dissertation was defended at the public meeting of the Dissertation Defence Council of Materials Engineering in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 2 p.m. on 2 June 2025.
Refractory castables, or refractory aggregates and ultra-fine particles mixed with calcium aluminate cement and deflocculants, were created in the 1980s to protect industrial furnaces operating at high temperatures in metallurgy, chemistry, and the petrochemical industry. These materials demonstrate outstanding performance even over 1000 °C and can withstand compressive stresses, which emerge in typical applications due to high temperatures and mechanical loads. The extraordinary material performance has led to interest in using these materials for developing building protection systems against fires and explosions. Still, this application requires structural reinforcement to resist tensile stresses in the concrete caused by mechanical loads, making the bonding of reinforcement crucial. The different temperature expansion properties of the castables and reinforcement steel further complicate the bar interaction mechanisms with concrete. The dissertation conducts extensive tests to evaluate various combinations of refractory and reinforcing materials to develop a reinforced composite resilient to thermal and mechanical loads. These tests revealed the acceptable efficiency of conventional castables (CC), analysing the material cost and bond resistance balance. However, the typical CC strength of 50 MPa is insufficient to ensure the bonding performance of steel bars after treatment at 400 °C, and the plain bars lose their bond with the concrete, regardless of the concrete strength, due to the different thermal expansion properties of the materials. On the contrary, ribbed stainless Type 304 steel bars and the CC material, modified with 2.5% micro-silica (by weight of dry materials) to achieve a 100 MPa cold compressive strength (CCS), are promising candidates for developing the refractory composite. A finite element model has also been created to predict steel reinforcement’s bonding performance in refractory castables under a temperature impact of up to 1000 °C. The dissertation includes an introduction, three chapters, general conclusions, and a list of references. The First Chapter reviews the literature on testing methodologies and reinforcement behaviour in refractory composites under high temperatures, identifying gaps in existing research. The Second Chapter describes the experimental programme, detailing the testing setup, materials used, and data collected from materials characterisation, pull-out experiments, and bending beam tests. The Third Chapter analyses experimental results and develops a finite element model to simulate the bond behaviour of stainless-steel reinforcement in refractory concrete after high-temperature treatment. The author’s list of publications on the dissertation topic consists of three journal articles (indexed in the Web of Science database with an Impact Factor) and three conference presentations.
Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.
