Modeling and Simulation of Electromutagenic Processes for Multiscale Modification of Concrete
Concrete contains numerous pores that allow degradation when chloride ions migrate through these paths and make contact with the steel reinforcement in a structure. Chlorides come mainly from the sea or de-icing salts. To keep the reinforcement from being exposed to chlorides, it is possible to electrokinetically force nanoparticles into the pores, blocking access. This procedure is called electrokinetic nanoparticle treatment. When the particles used are reactive in nature, the process becomes both structural and chemical in nature. We use the term electromutagenic processing to describe such extensive electrochemical remodeling. Filling the pores in a block of concrete with solid materials or nanoparticles tends to improve the strength significantly. In this paper, results obtained from modeling and simulation were aimed at multi-scale porosity reduction of concrete. Since nanoparticles and pores were modeled with spheres and cylinders having different sizes, the results were compared with traditional sphere packing problems in mathematics. There were significant differences observed related to the sizes of spheres and allowable boundary conditions. From traditional sphere packing analysis the highest porosity reduction anticipated was 74%. In contrast, the highest pore reduction obtained in this work was approximately 50%, which matched results from actual electrokinetic nanoparticle treatments. This work also compared the analytical and simulation methods used for several sizes of nanoparticles and pores.
Multi-sized Sphere Packing in Containers: Optimization Formula for Obtaining the Highest Density with Two Different Sized Spheres
This article provides a mathematical formula for determining the optimal sizes of two different sized spheres to maximize the packing density when randomized loose packing is employed in containers with various shapes. The formula was evaluated with numerous computer simulations involving over a million of spheres.
Application of Electrodeposition Technique for Concrete Rehabilitation
This paper presents an electrochemical technique as a means of rehabilitating deteriorated reinforced concrete structures. The aim of the electrodeposition in concrete rehabilitation method is to fill the cracks in concrete and coat the concrete surface by electrodeposits of chemical compounds. Investigations on concrete beam specimens were conducted. After causing specimens to crack under a specified load, they were immersed in a solution, then a constant current between the embedded steel in concrete and an electrode in the solution was applied for 8 weeks. The degree of crack closure and amount of surface coating from precipitation of electrodeposits were checked. Results indicate electrodeposits formed on the concrete surface are able to close concrete cracks and to coat the concrete surface. It was also noted that the presence of electrodeposits led to a substantial decrease of concrete permeability and some improvement of the mechanical properties of the cracked concrete. Therefore, it can be considered that the electrodeposition technique can be used as a rehabilitation method for cracked reinforced concrete structures.