This paper presents the testing of the durability of concrete where a part of cement was replaced with ground panel cathode ray tube glass (CRT) finer than 63 µm. The percentage of cement replaced with glass is 5%, 10%, 15%, 20%, and 35%, by mass. The highest percent share of mineral admixtures in CEM II (Portland-composiste cement) cement was chosen as the top limit of replacement of cement with glass. In terms of the concrete durability, the following tests are performed: freeze-thaw resistance, freeze-thaw resistance with de-icing salts-scaling, resistance to wear according to the Böhme test, sulfate attack resistance, and resistance to penetration of water under pressure. A compressive strength test is performed, and shrinkage of concrete is monitored. In order to determine the microstructure of concrete, SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) analyses were performed. The obtained research results indicate that the replacement of a part of cement with finely ground CRT glass up to 15% by mass has a positive effect on the compressive strength of concrete in terms of its increase without compromising the durability of concrete. The results obtained by experimental testing unequivocally show that concrete mixtures made with partial replacement (up to 15%) of cement with finely ground CRT glass have the same freeze-thaw resistance, resistance to freeze/thaw with de-icing salt, resistance to wear by abrasion, and resistance to sulfate attack as the reference concrete. In terms of environmental protection, the use of CRT glass as a component for making concrete is also very significant.
The topic of this paper is experimental and numerical analysis of the impact strength of unreinforced concrete slabs. Impact strength of concrete is significant in case of some accidental loads during exploitation. Impact strength can be determined experimentally, using Drop-weight test, Charpy test, Projectile impact test, Explosive test, etc. In this research, a numerical model for determining the impact strength of concrete slabs based on Finite element method (FEM) and high-end engineering software has been proposed. Modelling approach to this problem was applying the Explicit dynamics FEM analysis. Thereat, two different existing material models for concrete were enforced: Concrete damage plasticity model – CDP (implemented in ABAQUS/Explicit software), and the Riedel-Hiermaier-Thoma model – RHT (implemented in ANSYS Workbench software). Analysis parameters for both material models, necessary as input data, have been determined through a series of FEM analyses and validated by performed experiments, using drop-weight test. Results of the numerical analyses have been compared with the experimental ones, as well as mutually. Advantages and drawbacks of both material models are highlighted, as well as the reliability of the proposed numerical models. The proposed numerical FE models, confirmed by experiments, can be successfully used for determining impact strength of concrete slabs in further research.
The demand of the contemporary society for renewable energy sources lead to the increase of the bio-power plants. Accordingly, the amount of ash generated by burning the biomass is increased, and its disposal becomes a large environmental problem. The paper presents the research of potential use of biomass wood ash as a partial replacement for coal fly ash (10%, 20%, 30% and 40% of mass) in production of self-compacting concrete (SCC). The effects of biomass wood ash on the properties of SCC in fresh and hardened states have been examined, as well as on the properties of durability. Test results indicated that the biomass wood ash slightly reduces the flowability and passing ability of SCC, while its addition enhances the viscosity of SCC and significantly prevents segregation and bleeding. SCCs with the contents of biomass wood ash up to 20% have approximately same mechanical strength as the reference mixture. Biomass wood ash has no negative effect on the resistance of concrete to the action of water under pressure, but a decrease of freeze/thaw resistance with de-icing salt is detected as its contents increases. The addition of biomass wood ash into SCC increases the drying shrinkage in the initial period of drying (up to 14 days), and it is decreased in a later phase.
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